bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth hormone stimulates granulation tissue formation and insulin-like growth factor-I gene expression in wound chambers in the rat
Authors: Steenfos H. H. , Jansson J.-O.
Published: December 2008

It has been reported that GH stimulates fibroblast growth and wound healing. In the present study we measured the effect of locally applied GH on insulin-like growth factor (IGF-I) mRNA concentrations and granulation tissue formation in wound cylinders, implanted s.c.

Four stainless-steel wiremesh cylinders were implanted s.c. in the back of male rats (280 g). Each cylinder was then injected every day with either 0·014 or 0·14 U human GH, or vehicle only. Ingrown granulation tissue and wound fluid was obtained on day 17 after implantation. The wet weight of granulation tissue was determined and concentrations of IGF-I mRNA in the tissue were measured by solution hybridization/RNAase protection assay. Similar assays were used to measure the levels of IGF-I receptor mRNA and GH receptor mRNA, while the IGF-I concentration in wound fluid and serum was determined by radioimmunoassay (RIA) after acid–ethanol extraction.

The concentrations of IGF-I mRNA in ingrown granulation tissue as well as the wet weight of this tissue were significantly higher in the GH-treated cylinders. There was no significant effect of GH on IGF-I receptor mRNA and GH receptor mRNA levels. Consistent with the results of previous studies, wound fluid IGF-I levels were lower than serum IGF-I levels, but no significant difference was found between the GH-treated cylinders and the control cylinders.

The results of the present study show that GH stimulates granulation tissue formation and increases the concentration of IGF-I mRNA in the ingrown granulation tissue.

Journal of Endocrinology (1992) 132, 293–298
Effect of fusidic acid on interleukin-1 (IL-1)- and IL-6-induced pancreatic β-cell functions in rats
Authors: Bendtzen K. , Diamant M. , Horn T. , Pedersen C. , Buschard K.
Published: December 2008

Fusidic acid and its sodium salt (fusidin) are antistaphylococcal drugs with a steroidal primary structure. Both compounds have been shown to prevent the lymphocyte co-stimulatory activities of the cytokines, interleukin (IL)-1 and IL-6, in a manner similar to that of cyclosporin A. As shown in this paper, fusidin also prevents the inhibitory effect of human recombinant IL-1β (rIL-1β) and the stimulatory effect of human rIL-6, on glucose-induced insulin production in vitro by normal rat pancreatic islets. The drug also inhibited rIL-1β-induced IL-6 production by the islets. Fusidin showed a dose-related effect at pharmacologically relevant concentrations from 3 to 30 μg/ml, and the drug was progressively less active when added 1, 4 and 24 h after rIL-1β. Electron microscopical studies showed that β cells cultured for 72 h with rIL-1β accumulated less lipid in the presence of fusidin, most probably reflecting the functionally protective effect of the drug. Other characteristic ultrastructural changes induced in β cells by rIL-1β were, however, not altered. It is suggested that fusidin may prove clinically effective as a modulator of IL-1- and IL-6-induced changes in β-cell functions.

Journal of Endocrinology (1992) 132, 345–352
Growth hormone control of tissue protein metabolism in dwarf mice: enhancement by a monoclonal antibody
Authors: Bates P. C. , Aston R. , Holder A. T.
Published: December 2008

Monoclonal antibody (MAb) to GH has been shown to increase the anabolic response induced by the hormone in individual tissues of dwarf mice. Dwarf mice were treated with GH at a low and a high dose (2·5 and 50 mU/day respectively), with and without complexing to an MAb. Treatment was for 7 and 14 days, at which times protein synthesis rates in skeletal muscle, liver and heart were determined from incorporation of labelled phenylalanine following injection of a flooding dose. The MAb potentiated the actions of GH and produced increases in the rates of protein synthesis in each of the tissues to a significantly greater extent than did GH alone.

The increase in protein synthesis rate induced by MAb appears to be mechanistically distinct from that observed by increasing the dose of GH. In skeletal muscle and liver there was a dose–response to the GH alone in terms of the RNA concentration, i.e. the capacity for protein synthesis, whereas in each tissue examined the MAb caused very little further response in the RNA concentration. The MAb-induced enhancement of protein synthesis rate was almost entirely due to an increase in the RNA activity, i.e. the efficiency of the synthesizing system.

Complexing GH to a particular MAb, or to antisera of restricted epitope specificity, has previously been shown to enhance the in-vivo effects of GH on whole body protein content; the mechanism for this enhancement has not been adequately determined. The present results suggest that the mechanism of MAb enhancement of GH activity is unlikely to be through prolonging GH action by increasing its serum half-life, but may be through effects on GH-receptor response, possibly through targeting of the GH to a particular receptor sub-type or through inhibition of internalization of the GH-receptor complex.

Journal of Endocrinology (1992) 132, 369–375
Involvement of physiological prolactin levels in growth and prolactin receptor content of prostate glands and testes in developing male rats
Authors: Pérez-Villamil B. , Bordiú E. , Puente-Cueva M.
Published: December 2008

We have investigated the role of physiological prolactin levels in the development of prepubertal male rats. Prolactin GH and testosterone levels, as well as body, ventral prostate and testicular weight, have been analysed in both control and bromocriptine-treated rats between 21 and 60 days of life. Furthermore the role of prolactin in the regulation of its own receptors has also been studied during the same period. In control rats, prolactin levels showed a prepubertal peak of secretion at 25 days of age. At this time GH and testosterone levels were low and did not show any significant variation. After this age, prolactin levels increased more gradually; determinations of GH showed great variation with low levels in most of the rats and very high values in the other animals; testosterone levels remained low until day 35 after which they increased. Simultaneously with the serum prolactin peak on day 25, a decrease in prolactin-binding capacity of ventral prostate glands, was observed and a maximum rate of body, prostate and testicular weight gain was obtained. Furthermore, in rats with pharmacologically suppressed serum prolactin levels (lower than 1 μg/l), prolactin binding to prostate glands as well as the weight of body, ventral prostate and testes were lower than in control animals. When results were expressed in mg prostate or testes/g body weight, testes from 25-day-old treated rats weighed significantly less than controls. The later stages of development, from days 25 to 60, were characterized by an initial decline in serum prolactin levels at 29 days of age which was followed by a continuous increase until adult values were reached. During this period, prostatic prolactin receptors which were at their lowest value at 33 days of age showed a gradual rise parallel with the observed increase in plasma prolactin levels. When testicular tissue was analysed, no changes in prolactin-binding sites caused by sexual maturation were observed. The present results indicate that physiological prolactin secretion has a specific effect on the normal increase in the prostate, testes and body weight and clearly is also implicated in the regulation of its prostatic receptors at the earlier stages of development.

Journal of Endocrinology (1992) 132, 449–459
Thyrotrophin receptors in normal and neoplastic (primary and metastatic) canine thyroid tissue
Authors: Verschueren C. P. , Rutteman G. R. , Vos J. H. , Van Dijk J. E. , de Bruin T. W. A.
Published: December 2008

Thyrotrophin (TSH) is the conditional growth factor of thyroid epithelial cells. Abnormalities in TSH-receptor binding such as a low receptor number or low binding affinity may be a marker of thyroid carcinoma or metastases, or may exhibit a relationship with the functional variability of such tissues. The dog was used as a model to characterize TSH-receptor binding in normal thyroid tissues, naturally occurring thyroid neoplasms and distant metastases. In normal dog thyroid tissues, specific 125I-labelled TSH binding ranged from 2·7 to 15·5%, and low cross-reactivity with bovine LH (0·023%) was observed. One class of TSH-binding sites was found in eight normal thyroid tissues and 22 thyroid carcinomas; two normal thyroid tissues and one tumour exhibited two classes of binding sites. The concentration of binding sites was lower in the five carcinomas with reduced pertechnetate uptake (0·09 pmol/mg protein) than in the five thyroid neoplasms with increased uptake (0·19 pmol/mg) (P= 0·055). Compared with the original carcinoma tissues, TSH binding revealed a reduced binding affinity in eight out of eleven metastases. Two metastases showed a complete absence of TSH binding, suggesting that they were not dependent on TSH for growth. We conclude that one class of TSH-binding site is predominant in normal dog thyroid tissues and dog thyroid carcinomas. TSH could therefore contribute, at least in theory, to further growth of primary dog thyroid carcinomas. Secondly, assays measuring TSH binding may not be able to discriminate between malignant and benign dog thyroid tumours. TSH receptor number or affinity may be related to the functional variability of thyroid neoplasms. The absence of TSH binding in some metastases demonstrated that this characteristic can be acquired during the natural history of a differentiated thyroid carcinoma.

Journal of Endocrinology (1992) 132, 461–468
Modification of the amounts of G proteins and of the activity of adenylyl cyclase in human benign thyroid tumours
Authors: Delemer B. , Dib K. , Patey M. , Jacquemin C. , Corrèze C.
Published: December 2008

The possibility that a TSH post-receptor-binding defect is responsible for the pathogenesis of benign thyroid tumours was studied. Thus, we attempted to determine in hyperfunctioning (hot) nodules and non-functioning (cold) nodules whether the functional activity or the amount of G proteins were modified in comparison with surrounding normal tissues. The adenylyl cyclase response to agonists that bypass the TSH–receptor complex (forskolin, guanosine 5′- (β.γ-imido)triphosphate (Gpp(NH)p) or [A1F4]−) was studied on membranes from tumorous and adjacent normal thyroid tissues. We also examined the ability of G proteins to be ADP-ribosylated by cholera toxin (CT) or pertussis toxin (PT), and quantified G proteins by Western blot analysis with specific antisera directed against Gsα and Giα subunits.

Basal adenylyl cyclase activity was unchanged in hot tumours compared with normal tissue whereas the stimulation of adenylyl cyclase by Gpp(NH)p or [A1F4]− (which act directly on Gs) as well as by forskolin (which acts on the catalyst) was significantly (P<0·05) decreased in five of seven nodules studied. Two types of response were found in cold nodules, depending upon whether they were microfollicular or macrofollicular tumours. Basal as well as stimulated adenylyl cyclase activity was increased (0·02<P<0·05) in microfollicular tumours. In contrast, in macrofollicular tumours basal adenylyl cyclase was unchanged whereas stimulated adenylyl cyclase activity was decreased (0·02<P<0·05). The ability of Gs or Gi to be ADP-ribosylated by CT or PT respectively was maintained in tumorous tissue. Quantification of Gs revealed a 30% decrease (P<0·05) in the level of Gs in hot tumours and either an increase or a decrease in cold tumours compared with their respective normal tissue. Quantitative or qualitative changes in Gi protein were also observed, but there was no clear difference between the patients with hot and cold thyroid tumours. A decrease or an increase in adenylyl cyclase activity can therefore be explained by an alteration in the amounts of G proteins, at least in some benign thyroid tumours.

Journal of Endocrinology (1992) 132, 477–485
INTERLEUKIN-1 AND INTERLEUKIN-6 IN BREAST CYST FLUID: THEIR ROLE IN REGULATING AROMATASE ACTIVITY IN BREAST CANCER CELLS
Authors: Reed M.J. , Coldham N.G. , Patel S.R. , Ghilchik M.W. , James V.H.T.
Published: December 2008

Gross cystic breast disease is a common benign disease which may be associated with an increased risk for breast cancer. Breast cyst fluid (BCF) contains many steroids, peptide growth factors and proteins. We have now identified interleukin-1 (IL-1) and IL-6 in BCF by specific radioimmunoassays. Concentrations of IL-1 were similar in BCF with low or high Na+/K+ ratios (ratio <3 vs >3; 357 ± 72 pg/ml vs 308 ± 126 pg/ml). In contrast, IL-6 concentrations were significantly higher (P<0.01) in BCF with a Na+/K+ ratio >3 (2.75 ± 2.34 ng/ml) compared with BCF with a low electrolyte ratio (0.21 ± 0.09 ng/ ml). BCF (10%, v/v) stimulated aromatase activity when added to dexamethasone stimulated breast tumour-derived fibroblasts and there was a significant correlation between the stimulation of aromatase activity and BCF Na+/K+ ratio (r = 0.95, P<0.001). A significant correlation was also found between stimulation of aromatase activity and concentration of IL-6 in BCF (r = 0.80, P<0.01) but not IL-1 concentration (r = −0.39, not significant). Addition of IL-1 or IL-6 (50 ng/ml) to fibroblasts stimulated aromatase activity but was associated with a small (20%) decrease in cell growth. It is concluded that IL-6 may have an important role in regulating aromatase activity in breast cancer cells.
Possible mechanisms for reduction of circulating concentrations of progesterone by interferon-α in cows: effects on hyperthermia, luteal cells, metabolism of progesterone and secretion of LH
Authors: Barros C. M. , Betts J. G. , Thatcher W. W. , Hansen P. J.
Published: December 2008

Experiments were performed to determine the mechanism by which recombinant bovine interferon-αI1 (rbIFN-α) causes an acute reduction in plasma concentrations of progesterone. In experiment 1, administration of a prostaglandin synthesis inhibitor blocked rbIFN-α-induced hyperthermia but did not prevent the decline in plasma concentrations of progesterone. The decline in progesterone concentrations caused by rbIFN-α was, therefore, not a direct consequence of the associated hyperthermia or of pathways mediated through prostaglandin synthesis. It is also unlikely that rbIFN-α acts to increase the clearance of progesterone since injection of rbIFN-α did not decrease plasma concentrations of progesterone in ovariectomized cows given an intravaginal implant of progesterone (experiment 2). In experiment 3, rbIFN-α did not affect basal and LH-induced release of progesterone from cultured luteal slices, indicating that rbIFN-α is unlikely to affect luteal function directly. Injection of rbIFN-α did, however, cause a decrease in plasma concentrations of LH in ovariectomized cows (experiment 4) that coincided temporally with the decrease in progesterone concentrations seen in cows having a functional corpus luteum. The present results strongly suggest that rbIFN-α acts to reduce secretion of progesterone by interfering with pituitary support for luteal synthesis of progesterone. The finding that rbIFN-α can inhibit LH secretion implies that interferon-α molecules should be considered among the cytokines that can regulate hypothalamic or pituitary function.

Journal of Endocrinology (1992) 133, 175–182
The anabolic effect of 17β-oestradiol on the trabecular bone of adult rats is suppressed by indomethacin
Authors: Chow J. W. M. , Lean J. M. , Abe T. , Chambers T. J.
Published: December 2008

We have previously demonstrated that administration of oestrogen, at doses sufficient to raise serum concentrations to those seen in late pregnancy, increases trabecular bone formation in the metaphysis of adult rats. To determine whether prostaglandins (PGs), which have been shown to induce osteogenesis in vivo, play a role in the induction of bone formation by oestrogen, 13-week-old female rats were given daily doses of 4 mg 17β-oestradiol (OE2)/kg for 17 days, alone or with indomethacin (1 mg/kg). The rats were also given double fluorochrome labels and at the end of the experiment tibias were subjected to histomorphometric assessment. Treatment with OE2 suppressed longitudinal bone growth and increased uterine wet weight, as expected, and neither response was affected by indomethacin. Oestrogen also induced a threefold increase in trabecular bone formation in the proximal tibial metaphysis, which resulted in a substantial increase in trabecular bone volume. As previously observed, the increase in bone formation was predominantly due to an increase in osteoblast recruitment (as judged by an increase in the percentage of bone surface showing double fluorochrome labels), with only a minor increase in the activity of mature osteoblasts (as judged by the mineral apposition rate). Indomethacin abolished the increase in osteoblastic recruitment, but the activity of mature osteoblastic cells remained high. The bone formation rate and bone volume remained similar to controls. The results suggest that PG production may be necessary for the increased osteoblastic recruitment induced by oestrogen, but not to mediate the effects of oestrogen on the activity of mature osteoblasts.

Journal of Endocrinology (1992) 133, 189–195
Vasoactive intestinal peptide stimulation of aldosterone secretion by the rat adrenal cortex may be mediated by the local release of catecholamines
Authors: Hinson J. P. , Kapas S. , Orford C. D. , Vinson G. P.
Published: December 2008

The effects of vasoactive intestinal peptide (VIP) on adrenocortical function were investigated using several different preparations of adrenocortical tissue. VIP caused a significant increase in perfusion medium flow rate and in aldosterone and corticosterone secretion by the isolated perfused rat adrenal gland, with a threshold of 1 pmol in 200 μl, but did not affect basal steroid secretion by collagenase-dispersed adrenocortical cells at any concentration used, from 10 pmol/l to 10 μmol/l. The presence of VIP (100 nmol/l) had no significant effect on the response of zona glomerulosa cells to stimulation by ACTH at any concentration. In incubations of intact adrenal capsular tissue, VIP (10 μmol/l) caused a significant stimulation of aldosterone secretion, and also induced a significant release of adrenaline into the incubation medium. Addition of (−)alprenolol (100 nmol/l), a βadrenergic antagonist, to the incubation medium significantly attenuated the response of capsular tissue to VIP. It is concluded that the effects of VIP on aldosterone, which are only seen when the architecture of the zona glomerulosa is preserved, may be mediated by the local release of adrenaline.

Journal of Endocrinology (1992) 133, 253–258
Daily rhythms in the hormone content of the neurohypophysial system and release of oxytocin and vasopressin in the male rat: effect of constant light
Authors: Windle R. J. , Forsling M. L. , Guzek J. W.
Published: December 2008

Patterns of neurohypophysial hormone secretion and changes in the hormone content of the hypothalamus and posterior pituitary lobe were monitored in the male rat for cycles of 24 h in association with changes in food and water intake and fluid excretion. Plasma oxytocin and vasopressin concentrations were seen to rise significantly over the hours of daylight, decreasing during the night. Parallel changes were seen in the immunoreactive material in the hypothalamus, whilst the content of the neurohypophysis was inversely related to plasma concentrations. The ratio of plasma oxytocin:vasopressin reached a significant peak at about 02.00 h which might be related to the feeding activity of the rats, food and water intake being largely confined to the night, as was fluid excretion. On exposure to constant light, despite initial disruption hormonal rhythms were still seen but showed a phase shift. The relationships between plasma and tissue levels were maintained. Patterns of food and water intake and urinary excretion were little affected by exposure to constant light, remaining largely confined to the former night phase. The hormonal rhythms appeared to be more closely related to the activity of the rats, which also showed a phase shift during constant light.

Journal of Endocrinology (1992) 133, 283–290
Phosphate transport by fibroblasts from patients with hypophosphataemic vitamin D-resistant rickets
Authors: Escoubet B. , Silve C. , Balsan S. , Amiel C.
Published: December 2008

It is accepted that renal phosphate wasting is the basis of hypophosphataemia in vitamin D-resistant hypophosphataemic rickets (VDRR). Abnormal renal adaptation to phosphate deprivation has also been reported in these patients. We studied sodium-dependent phosphate transport and its modulation by phosphate deprivation in skin fibroblasts cultured from healthy subjects and patients with VDRR. Control fibroblasts exhibited high-affinity sodium-dependent phosphate transport (77 ± 12 μmol/l) which resembled the ubiquitous transport of renal and non-renal cells. Phosphate deprivation (incubation in low phosphate medium) increased the maximal velocity (Vmax) of the transport by 2·7-fold after 24 h, with no change in the affinity. The increase in Vmax was dependent on gene transcription and protein synthesis. The sodium-dependent phosphate transport exhibited in fibroblasts from VDRR patients did not significantly differ from that of control subjects, except that the Vmax of the phosphate transport was higher in cells from patients with VDRR under normal and phosphate-deprivation conditions, although the difference was significant only after 24 h of phosphate deprivation (Vmax: 22·6 ± 2·4 pmol/mg protein per s in VDRR vs 16 ± 3·6 pmol/mg protein per s in controls, P < 0·05).

These data demonstrate that sodium-coupled phosphate transport in human skin fibroblasts has the properties of ubiquitous sodium-phosphate co-transport and show that this transport is not deficient in patients with VDRR. Indeed paradoxically the Vmax was 40% higher in VDRR than in control subjects after 24 h of phosphate deprivation. The transport must be either different from that of kidney cells responsible for the phosphate leak, or differently modulated. Therefore, skin fibroblasts cannot be used to determine the molecular defect responsible for the renal phosphate leak in VDRR patients.

Journal of Endocrinology (1992) 133, 301–309
Tri-iodothyronine stimulates rat osteoclastic bone resorption by an indirect effect
Authors: Allain T. J. , Chambers T. J. , Flanagan A. M. , McGregor A. M.
Published: December 2008

Tri-iodothyronine (T3) increases bone resorption in vivo and in vitro. In order to understand further the mechanisms by which this occurs we studied the effects of T3 at concentrations in the range of 1 pmol/l–1 μmol/l on bone resorption by osteoclasts isolated from neonatal rat long bones. Osteoclasts were disaggregated and incubated either with or without UMR 106 cells or with mixed bone cells. We found that there was no effect of T3 on bone resorption by osteoclasts incubated alone or co-cultured with UMR 106 cells. However, in culture with mixed bone cells there was a significant relationship between the concentration of T3 and bone resorption (r = 0·54, P= 0·01) The greatest effect was observed at a T3 concentration of 1 μmol/l at which a 1·8-fold increase in resorption was seen compared with control (P <0·005; paired t-test). We conclude that the ability of T3 to increase osteoclastic bone resorption is not due to a direct action of T3 on osteoclasts but is mediated by another cell present in bone. The observation that UMR 106 cells are unable to mediate this effect suggests that either the mediating cell is not osteoblastic or the phenotype of UMR 106 does not conform to the phenotype of osteoblastic cells that mediate the T3 responsiveness of bone.

Journal of Endocrinology (1992) 133, 327–331
Expression and translation of the growth hormone-receptor gene in the guinea-pig
Authors: Harvey S. , Fraser R. A.
Published: December 2008

The refractoriness of guinea-pigs to the growth-promoting actions of exogenous GH has been suggested to be due to a deficiency or defect in tissue GH receptors or in GH-receptor gene expression. GH-receptor mRNA was, however, demonstrated by Northern blot analysis and by the polymerase chain reaction in extracts of guinea-pig liver, adipose tissue, brain, hypothalamus and pituitary gland. High-affinity, low-capacity binding sites for radio-labelled ovine GH were also demonstrated on the plasma membranes of guinea-pig liver and were similar to those in rat liver. These results demonstrate that the unresponsiveness of guinea-pigs to exogenous GH is not due to the absence of GH receptors.

Journal of Endocrinology (1992) 133, 357–362
The effects of hypo- and hyperthyroidism on fibre composition and mitochondrial enzyme activities in rat skeletal muscle
Authors: Lomax R. B. , Robertson W. R.
Published: December 2008

Hypo- and hyperthyroidism have been associated with changes in the activities of mitochondrial enzymes in homogenates of skeletal muscles, but it is unclear whether such changes were due to changes in single fibre enzyme activities or to previously documented changes in relative numbers of fibres. In this study the activities of the mitochondrial enzymes α-glycerol phosphate dehydrogenase (m-αGPDH) and succinate dehydrogenase (SDH) were measured in single fibres of the soleus and gastrocnemius muscles of the rat by cytochemical assays.

In the soleus muscles of hypothyroid animals there was a decrease in the mean percentage (± s.d.) of type II fibres from 8·0 ± 6·0 to 0·8 ± 1·9% (P < 0·05) and decreases in SDH activities in all fibre types (P < 0·005). In the gastrocnemius muscles of these animals there were no changes in fibre composition but type IIB fibres had reduced (P < 0·05) m-αGPDH activities. In the hyperthyroid animals, in which body weight had increased relative to the euthyroid animals, there were increases in the percentages of type IC and type II fibres in the soleus from 4·3 ± 1·7 to 13·1 – 9·0% (P < 0·05) and from 9·6 ± 7·2 to 33·4 ± 9·6% (P < 0·005) respectively and an increase in the percentage of type IIA fibres in the gastrocnemius from 92·9 ± 2·3 to 97·0 ± 2·9% (P < 0·05). However, there were no increases in single fibre mitochondrial enzyme activities. It is therefore suggested that the administration of moderate, growth-promoting doses of thyroid hormones to euthyroid animals can cause changes in muscle fibre composition without stimulating the activities of mitochondrial enzymes.

Journal of Endocrinology (1992) 133, 375–380
Enhancement of noradrenaline-induced inositol polyphosphate formation by glucocorticoids in rat vascular smooth muscle cells
Authors: Liu J. , Haigh R. M. , Jones C. T.
Published: December 2008

Glucocorticoids are known to regulate the contractility of vascular smooth muscle by increasing its response to noradrenaline. The molecular mechanisms for achieving this remain unclear. Recent results in our laboratory have demonstrated that glucocorticoids affect both α1-adrenoceptor number and coupling to G proteins. Whether this leads to an increase in second-messenger production has to be established. The present experiments, therefore, report the effects of dexamethasone on inositol polyphosphate production in vascular smooth muscle cells in culture. Noradrenaline induced the release of inositol polyphosphates from prelabelled [3H]inositol phosphoinositides in the membrane in a dose-dependent manner. The concentration of noradrenaline which caused half-maximal response was 1·26 μmol/l. Prazosin inhibited noradrenaline-induced inositol monophosphate formation to 10·26 ± 3·67% (mean ± s.e.m.; P < 0·01, n = 5) of control value whereas yohimbine reduced it to only 61·74 ± 11·82% (P < 0·05, n = 5), suggesting an action primarily through α1-adrenergic receptors. Dexamethasone (100 nmol/l, 48 h) enhanced noradrenaline-induced inositol monophosphate, bisphosphate and trisphosphate formation up to twofold (P < 0·001, n = 5). The enhancement of the response occurred despite the fact that dexamethasone reduced [3H]inositol prelabelling of membrane phosphoinositides by 49·5 ± 9·9% (P < 0·05, n = 3). The present results suggest that the potential action of glucocorticoids on vascular smooth muscle contractility is, at least in part, through controlling α1-adrenoceptor-mediated second-messenger production.

Journal of Endocrinology (1992) 133, 405–411
Prostaglandin F2α- and phorbol 12-myristate-13-acetate-stimulated progesterone production by cultured human luteal cells in the mid-luteal phase: prostaglandin F2α increases cytosolic Ca2+ and inositol phosphates
Authors: Endo T. , Watanabe H. , Yamamoto H. , Tanaka S. , Hashimoto M.
Published: December 2008

While prostaglandin F2α (PGF2α) has been thought to be a natural luteolysin in non-primates, a luteolytic effect in the human corpus luteum is less evident. We therefore investigated the action of PGF2α on monolayer cultures of human luteal cells obtained from mid-luteal phase corpora lutea.

PGF2α increased basal and human chorionic gonadotrophin (hCG)-stimulated progesterone production by human cultured luteal cells. A potent tumour-promoting phorbol ester, phorbol 12-myristate-13-acetate (PMA), also stimulated progesterone production by cultured human luteal cells.

Although human luteal cells were incubated for 24 h with PMA, hCG was still able to stimulate the production of progesterone by PMA-pretreated cells. However, PMA pretreatment blocked the ability of PGF2α to stimulate progesterone production. It is possible that the luteotrophic effect of PGF2α may be mediated, in part, by the activation of protein kinase C.

Addition of PGF2α to suspensions of human luteal cells preincubated with myo-[2-3H]inositol promoted an increase in labelled inositol phosphates. PGF2α also rapidly increased intracellular free Ca2+ in human luteal cells loaded with the fluorescent Ca2+ probe, fura-2.

We conclude that PGF2α and PMA stimulate progesterone production and that PGF2α increases the intracellular free calcium and inositol phosphates of human cultured luteal cells in the mid-luteal phase.

Journal of Endocrinology (1992) 133, 451–458
Localization of androgen receptors in human skin by immunohistochemistry: implications for the hormonal regulation of hair growth, sebaceous glands and sweat glands
Authors: Choudhry R. , Hodgins M. B. , Van der Kwast T. H. , Brinkmann A. O. , Boersma W. J. A.
Published: December 2008

A mouse monoclonal antibody against the N-terminal region of human androgen receptor (AR) was used to identify receptors by immunoperoxidase staining in frozen serial sections of skin from scalp, face, limb and genitalia of men and women aged 30–80 years. AR staining was restricted to cell nuclei.

In sebaceous glands, AR were identified in basal and differentiating sebocytes. The percentage of receptor-positive basal sebocyte nuclei in the temple/forehead region was greater in males (65%) than in females (29%).

AR staining was restricted to the cells of dermal papillae in anagen and telogen hair follicles. The percentage of dermal papillae containing AR was greater in males (58%) than in females (20%). The number of positively stained dermal papillae was lowest in female scalp skin. In 163 hair follicles sectioned, AR were absent from germinative matrix, outer root sheath (including the bulge region), inner root sheath, hair shaft and hair bulb, and from the capillaries present in some large dermal papillae.

AR were present in pilosebaceous duct keratinocytes, suggesting that androgens may influence pilosebaceous duct keratinization. AR were also identified in interfollicular epidermal keratinocytes and dermal fibroblasts although, in both cell types, intensity and frequency of staining were greatest in genital skin. AR were identified in luminal epithelial cells of apocrine glands in genital skin and in certain cells of the secretory coils of eccrine sweat glands in all body sites.

This study indicates that androgens regulate sebaceous gland and hair growth by acting upon two different types of target cells, the epithelial sebocytes of sebaceous glands and the mesenchymal cells of the hair follicle dermal papilla. AR staining in either cell type was not influenced by age in adults. The distribution of AR in human skin is consistent with the diverse effects of androgens on the structure and function of skin and its appendages.

Journal of Endocrinology (1992) 133, 467–475
OESTROGEN AND PROGESTOGEN SYNERGISTICALLY STIMULATE HUMAN AND RAT OSTEOBLAST PROLIFERATION
Authors: Slootweg M.C. , Ederveen A.G.H. , Schot L.P.C. , Schoonen W.G.E.J. , Kloosterboer H.J.
Published: December 2008

Oestrogens play an important role in bone metabolism; they preserve bone mass after the menopause. Their action in bone has recently been shown to be, partly, a direct one, as oestrogen receptors and their effects have been demonstrated in bone cells. The role of progestogens in bone metabolism is less clear. In this study it has been shown that 17β-oestradiol exerts only a small, although not significant, stimulatory action with regard to SaOS-2 human osteosarcoma cell proliferation. A pure progestogen (Org 2058) has no effect when added alone. In combination with 17β-oestradiol, however, it has a highly synergistic action on SaOS-2 cell proliferation. The same effect was observed in primary rat osteoblasts, showing that this synergism is a general phenomenon in osteoblastic cells. High numbers of oestrogen and progestogen receptors have been demonstrated in SaOS-2 cells, indicating that the effects of these steroids are mediated via the normal route of steroid receptors. These data provide a cellular basis for the clinically recognized positive effect of oestrogen/progestogen combinations on bone formation.
LONG TERM EFFECTS OF THYROID STIMULATING HORMONE AND INSULIN ON INTRACELLULAR pH IN FRTL-5 CELLS
Authors: Wood A.M. , Bidey S.P. , Soden J. , Robertson W.R.
Published: December 2008

We have studied the chronic effects of TSH (100μU/ml) and insulin (10μg/ml) on intracellular pH (pHi) in FRTL-5 cells using the pH sensitive probe 2′7-bis (2-carboxyethyl-5′-6′) carboxyfluorescein. FRTL-5 cells were cultured on Petri dishes either in the presence of 4H, ie. Coons F-12 containing cortisol (10nM), transferrin (0.5μg/ml), glycyl-histidyl lysine acetate (10ng/ml) and somatostatin (10μg/ml), or with 4H+insulin (5H), 4H+TSH, or 4H+TSH+insulin (6H). pHi was measured in small groups of cells by microspectrofluorimetry both in the presence and absence of bicarbonate ions after cells had been deprived of serum for at least a day. In
Effect of active immunization of heifers against inhibin on plasma FSH concentrations, ovarian follicular development and ovulation rate
Authors: Glencross R. G. , Bleach E. C. L. , McLeod B. J. , Beard A. J. , Knight P. G.
Published: December 2008

To study the effects of immunoneutralization of endogenous inhibin on gonadotrophin secretion and ovarian function, prepubertal heifers (n = 6) were actively immunized against a synthetic peptide replica of the N-terminal sequence of bovine inhibin α subunit bIα(1–29)Tyr30) coupled to ovalbumin. In contrast to ovalbumin-immunized controls (n=6), bIα(1–29)Tyr30-immunized heifers had detectable inhibin antibody titres (% binding to 125I-labelled bovine inhibin at 1:2000 dilution of plasma) of 17 ± 3% (s.e.m.) at puberty, rising to 31 ± 5% by the end of the study period 7 months later. Neither age (immunized: 295 ± 8 days; controls: 300 ± 5 days) nor body weight (immunized: 254 ± 13 kg; controls 251 ± 9 kg) at onset of puberty differed between groups. Although the difference did not reach statistical significance, mean plasma FSH concentrations recorded in inhibin-immunized heifers remained 35–40% higher than in controls throughout the 12-week period leading up to puberty (P = 0·14) and during nine successive oestrous cycles studied after puberty (P=0·10). Plasma LH concentrations did not differ between groups at any time during the study. Inhibin immunization had no effect on oestrous cycle length (immunized: 19·8±0·5 days; controls: 19·9±0·5 days). However, in comparison with controls, inhibinimmunized heifers had more medium sized (≥0·5 to <1 cm diameter) follicles during both the preovulatory (95%, P<0·001) and post-ovulatory (110%, P < 0·05 waves of follicular growth and more large (>1 cm diameter) follicles during the preovulatory wave (49%, P<0·05). In addition, the number of corpora lutea observed during the post-ovulatory phase of each cycle was significantly greater in the inhibin-immunized group (43%, P<0·01), as was the recorded incidence of cycles with multiple ovulations (19/56 in the inhibin-immunized group compared with 0/54 in controls; P<0·001). All six inhibinimmunized heifers had at least one cycle with multiple ovulation whereas none of the control heifers did so.

These results support the conclusion that immunoneutralization of endogenous inhibin using a synthetic peptide-based vaccine can enhance ovarian follicular development and ovulation rate in heifers. Whether this ovarian response is dependent upon the expected increase in secretion of FSH remains to be established.

Journal of Endocrinology (1992) 134, 11–18
The supraoptic nucleus in the pig hypothalamus: postnatal development and the effect of gonadal steroids
Authors: Van Eerdenburg F. J. C. M. , Lugard-Kok C. M. J. E. , Swaab D. F.
Published: December 2008

Postnatal development of the supraoptic nucleus (SON) in the pig hypothalamus was studied morphometrically. The volume of the SON increased from 6·2±0·45 (s.e.m.) mm3 at 7 weeks postnatally to 18·5 ± 1·35 mm3 at 2·5 years of age. A sex difference was found at the development point when the SON volume increased, with earlier SON enlargement in males. This sex difference was 30% at 30 weeks and 50% at 1 year of age. At 2·5 years of age no difference in volume was apparent between the sexes. The number of SON neurones was similar for all age groups concerned (43 500 ± 1475), except for the 2·5year-old females where 40% more were found (55 500 ± 3285). No significant difference was found in neurone number between gonadectomized and sham-operated animals, but the operation caused a 30% reduction in the number of neurones and SON volume. Testosterone supplementation following gonadectomy, during the first 4 weeks postnatally, resulted in sexual dimorphism, the males having more SON neurones than the females. The volume showed only a trend in the same direction. Testosterone supplementation at other ages did not result in any difference when compared with controls.

The results of this study show that the postnatal development of the SON of the pig is sexually dimorphic, and that it continues after puberty in females. In contrast to the vasopressin- and oxytocincontaining nucleus, the development of the SON was not influenced by gonadectomy and only slightly by gonadal steroids.

Journal of Endocrinology (1992) 134, 19–25
Concanavalin-A-bound and -unbound prolactin in normal and hyperprolactinaemic rats
Authors: Champier J. , Claustrat B. , Harthe C. , Chevallier P. , Trouillas J.
Published: December 2008

Concanavalin-A (Con-A)-bound and -unbound forms of prolactin were studied in female Wistar–Furth rats, both normal and with hyperprolactinaemia induced by treatment with oestrogen or a prolactinoma graft. In normal rats, Con-A-bound prolactin was the major circulating form (more than 50%) and a minor pituitary component (less than 10%), essentially as 25 kDa prolactin. In oestrogen-treated rats, plasma prolactin levels were 100-fold higher and pituitary weight was fivefold higher than in the controls, but total pituitary prolactin content was unmodified. Under oestrogen, Con-A-bound prolactin represented about one-third of the total hormone levels in the plasma and less than 10% in the pituitary. In the pituitary, bound prolactin was found essentially as 25 kDa and unbound prolactin as 22, 30 and 40–45 kDa. A similar increase in plasma prolactin levels was induced 6 months after the graft of a prolactinoma. Pituitary weights and total pituitary prolactin contents were slightly decreased. Plasma and pituitary Con-A-bound prolactin levels were similar to those observed in oestrogen-treated rats. On the other hand, unbound prolactin was only present as a 22 kDa monomer. In the tumour, Con-A-bound prolactin (essentially as 25 kDa prolactin) represented one-third of the total hormone level and unbound prolactin was composed of the 22 and 45 kDa forms, this latter form being partially transformed into 22 kDa by heating.

As Con-A-bound prolactin was previously characterized as glycosylated prolactin, these data suggest that glycosylated prolactin is present in the plasma of the normal rat as a major circulating form, unglycosylated 40–45 kDa is only present when the rate of the prolactin synthesis is high (in the pituitary of oestrogen-treated rats and in the tumour of grafted rats); this result supporting the hypothesis of a precursor product relationship between dimeric and monomeric prolactin. The manners in which prolactin is synthetized are not comparable in normal and tumour cells, percentages of glycosylated prolactin being different in normal pituitary and prolactinoma.

Journal of Endocrinology (1992) 134, 27–32
Short-term changes in the 3,5,3′-tri-iodothyronine nuclear receptor-binding capacity of porcine skeletal muscle following food intake
Authors: Morovat A. , Dauncey M. J.
Published: December 2008

The time-course of changes in the nuclear 3,5,3′-tri-iodothyronine (T3) receptor-binding capacity (Bmax) of longissimus dorsi muscle has been investigated in cold-acclimated young pigs after a single large meal. Measurement of Bmax values 4, 8, 12 and 24 h after feeding indicated a decline in receptor numbers after food intake with the lowest values occurring at 8 h. The receptor numbers then increased significantly, with the values at 12 h being more than 50% higher than those obtained at 8 h. The Bmax values reached their highest level 24 h after feeding. No significant changes in the dissociation constant were observed. Possible reasons for the changes in T3 receptor numbers are discussed and it is suggested that the increase in T3 receptor numbers 12–24 h after feeding may play a role in enhancing the thermogenic capacity of the tissues in response to food.

Journal of Endocrinology (1992) 134, 67–72
Discordant secretion of relaxin by individual porcine large luteal cells: quantitative analysis by a reverse haemolytic plaque assay
Authors: Taylor M. J. , Clark C. L.
Published: December 2008

Individual large luteal cells (LLC) derived from pregnant swine differ conspicuously in their ability to secrete the peptide hormone relaxin under basal and stimulated conditions – the phenomenon of functional heterogeneity. The purpose of this study was to quantitate knowledge of this phenomenon through use of a reverse haemolytic plaque assay, a technique that utilizes antibody-directed, complement-mediated erythrocyte lysis to detect hormone secretion by single LLCs in culture.

Measurement of individual plaque areas (an index of the amount of relaxin secreted) demonstrated an approximate 100-fold range in the amount of relaxin secreted by a single cell under basal conditions. This range was doubled by exposure to the phorbol ester, 4β-phorbol 12β-myristate 13α-acetate (PMA; 50 nmol/l). Under basal conditions, 50 and 80% of the total amount of relaxin was secreted by approximately 10 and 30% of all LLCs respectively. The size of these fractions was not influenced by the time of incubation (1–8 h), or by the presence of either of two non-specific stimulatory relaxin secretagogues, PMA (50 nmol/l) or arachidonic acid (1 μmol/l). The unimodal frequency distribution of plaque areas (under basal or stimulated conditions) suggests that relaxin-secreting LLCs comprise a discrete functional population of secretory cells, at least under these experimental conditions.

We conclude that a remarkably small fraction of LLCs secretes the majority of relaxin, and that the size of this fraction was not influenced by time or secretagogues.

Journal of Endocrinology (1992) 134, 77–83
Hormone-induced resistance of rat Leydig cells to the cytotoxic effects of ethane-1,2-dimethane sulphonate
Authors: Teerds K. J. , de Rooij D. G. , Wensing C. J. G. , Rommerts F. F. G.
Published: December 2008

Several studies have shown that the cytotoxic agent ethane-1,2-dimethane sulphonate (EDS) specifically destroys Leydig cells in the adult rat testis. It has also been reported that when rats are pretreated with human chorionic gonadotrophin (hCG), administration of EDS does not result in the complete destruction of the Leydig cell population. It has been suggested that hCG pretreatment 'protects' Leydig cells against the cytotoxic action of EDS. In the present study the underlying principles for this resistance to the cytotoxic effects of EDS have been investigated. Within 48 h of the start of daily hCG treatment the number of nuclear profiles of Leydig cells (henceforth called relative number of Leydig cells) had increased from 1014 ± 40 to 1368 ± 30 cells per 1000 Sertoli cell nuclei. Previous experiments have indicated that these newly formed Leydig cells probably develop from differentiating Leydig cell precursors. When EDS is administered concomitantly with the third injection of hCG (2 days after the start of hCG treatment), the relative number of Leydig cells surviving EDS treatment was 388 ± 52 per 1000 Sertoli cells. Hence, there is a similarity between the increase in the relative number of Leydig cells after 2 days of hCG treatment and the relative number of EDS-resistant Leydig cells. The Leydig cells that survived EDS administration showed characteristics which also occur in developing Leydig cells in the immature testis. It is concluded that, in rats pretreated with hCG for 2 days before EDS administration, new Leydig cells with some immature characteristics are formed. One of these characteristics is that these cells are insensitive to EDS.

Journal of Endocrinology (1992) 134, 85–90
3β-Hydroxysteroid dehydrogenase inhibitor reduces ovarian steroid production but increases ovulation rate in the ewe: interactions with gonadotrophins and inhibin
Authors: Webb R. , Baxter G. , McBride D. , McNeilly A. S.
Published: December 2008

Two experiments were carried out during the breeding season in ewes, first to investigate the effects of oral administration of a 3β-hydroxysteroid dehydrogenase (3β-HSD) inhibitor (epostane) on the number of corpora lutea, and secondly to investigate the mechanism through which epostane acts.

In the first experiment Dorset Horn ewes were treated orally with 25, 50, 100 or 200 mg epostane twice daily between days 10 and 15 of the oestrous cycle. All doses of epostane resulted in an increase in the number of corpora lutea per ewe, although the response was curvilinear, with the 25 mg dose showing the largest response and the 200 mg group the smallest response. Although there was no difference between groups in the number of ewes showing oestrus, the higher doses of epostane had a detrimental effect on fertility.

In the second experiment Welsh Mountain ewes were treated twice daily with 25 mg epostane from day 10 of the oestrous cycle and the ovaries were removed for analysis during either the luteal or the follicular phases. Treatment significantly increased the number of follicles >6 mm in diameter, but significantly reduced in-vitro follicular oestradiol and testosterone production. Despite a marked increase in peripheral inhibin concentrations there was no effect on in-vitro inhibin production. Epostane treatment also caused a significant reduction in peripheral FSH concentrations and an increase in mean LH concentration. The latter was due to an increase in LH pulse frequency during the luteal phase and LH pulse amplitude during the follicular phase.

These results confirm that treatment of ewes with epostane orally has a significant effect on follicular steroidogenesis and causes a significant increase in the number of corpora lutea per ewe. This effect on ovulation rate is not via an increase in peripheral FSH concentration, but may be caused by a reduction in follicular steroid activity either directly on the ovary or via an alteration in the pattern of LH secretion.

Journal of Endocrinology (1992) 134, 115–125