bluuebunny/crossref_metadata_2025 huggingface dataset:
Primiparous rhesus monkey mothers are more sensitive to the nursing-induced inhibition of LH and ovarian steroid secretion
Authors: Wilson M. E.
Published: December 2008

The duration of lactational infertility is prolonged significantly in adolescent, primiparous rhesus monkey (Macaca mulatta) mothers compared with adult, multiparous mothers. The present study examined the hypothesis that this parity/age difference in lactational infertility is due to a difference in the physiological responsiveness to nursing behaviour between adolescent and fully adult mothers and is not a consequence of differences in nursing behaviour, per se. At 22 weeks postpartum, mother–infant pairs were randomly assigned to one of four conditions: primiparous, nursing restricted (PR; n=9); primiparous, nursing unrestricted (PU; n= 11); multiparous, nursing restricted (MR; n= 12); and multiparous, nursing unrestricted (MU; n=8). Nursing was restricted for a 2-week period by mothers wearing a primate vest which prevented suckling behaviour but allowed infants to interact with their mothers. Nursing restriction resulted in a significant increase in serum oestradiol concentrations in both PR and MR mothers. Although nursing bout frequencies and durations were similar between PU and MU mothers, serum oestradiol also rose in MU mothers but remained suppressed in PU mothers. Once the nursing manipulation period ended and all mothers were allowed to nurse ad libitum, serum oestradiol concentrations continued to rise in all but the PU mothers. This brief interruption of nursing at 22 weeks postpartum advanced the subsequent timing of the first postpartum ovulation in MR and PR mothers relative to that of PU mothers. Again, despite similarities in nursing behaviour, the occurrence of first ovulation was also advanced in MU mothers compared with PU mothers.

Just prior to the first postpartum ovulation, females were randomly assigned to one of four treatment groups to determine the effects of nursing behaviour on the hormonal parameters of the luteal phase: primiparous, nursing restricted (PRL; n = 9); primiparous, nursing unrestricted (PUL; n = 11); multiparous, nursing restricted (MRL; n =10); and multiparous, nursing unrestricted (MUL; n=10). Nursing restriction significantly elevated serum progesterone concentrations in PRL females compared with other mothers. Serum concentrations of oestradiol were higher in PRL, MRL and MUL mothers relative to PUL females. Again, this difference in oestradiol between PUL and MUL mothers occurred despite similarities in nursing behaviour.

These data suggest that parity/age differences in the period of lactational infertility are not due to differences in nursing behaviour but rather to an increased sensitivity to the inhibitory aspects of the suckling stimulus in adolescent primiparous mothers. Furthermore, the lack of a difference in the reproductive parameters measured between nursing restricted and unrestricted multiparous mothers suggests that these females may become refractory to the inhibitory aspects of the suckling stimulus as lactation progresses.

Journal of Endocrinology (1992) 134, 493–503
Specific binding sites for 125I-labelled epidermal growth factor in the ovine corpus luteum and human placenta
Authors: Bramley T. A. , Menzies G. S.
Published: December 2008

Specific, high-affinity binding sites for radiolabelled mouse epidermal growth factor (mEGF) were demonstrated in homogenates and membranes of ovine corpora lutea. Subcellular fractionation on sucrose density gradients demonstrated that luteal EGF receptors were associated with fractions enriched in cell surface-membrane markers. Binding of 125I-labelled mEGF to ovine luteal EGF receptors was dependent on the pH, temperature and duration of incubation, and on the concentration of metal ions present in the incubation medium. Unlabelled mEGF and human EGF (urogastrone) competed for the binding of radiolabelled mEGF to ovine luteal homogenates at low doses (half-maximal inhibition of binding (IC50) at 2–3 nmol/l). Transforming growth factor-α also competed for mEGF-binding sites (IC50, 4–10 nmol/l), but a range of peptides, growth factors and protein hormones were ineffective at much higher concentrations. Concave Scatchard plots for 125I-labelled EGF binding and Hill coefficients of <1 for displacement radiolabelled EGF suggested negative co-operativity of binding sites, and dilution at equilibrium accelerated the rate of dissociation of 125I-labelled EGF from human placental (but not from ovine luteal) receptors.

Specific EGF-binding sites were also demonstrated in rat and rabbit placental homogenates, and in luteal homogenates of the pig. Luteal concentrations of EGF receptors appeared to be reduced significantly during early pregnancy in both the pig and sheep.

Journal of Endocrinology (1992) 135, 5–16
Epidermal growth factor concentrations in pig tissues and body fluids measured using a homologous radioimmunoassay
Authors: Vaughan T. J. , Littlewood C. J. , Pascall J. C. , Brown K. D.
Published: December 2008

A homologous radioimmunoassay for the measurement of epidermal growth factor (EGF) levels in pig tissues and body fluids has been developed using an antiserum to recombinant porcine EGF. The assay is highly specific, showing no cross-reactivity with a variety of other polypeptides including the structurally related protein, transforming growth factor-α. Furthermore, <1% cross-reactivity was observed with mouse EGF emphasizing the necessity for homologous assays for EGF measurement. Immunoreactive EGF was present in extracts of pig kidney and pancreas (3·44 ±0·43 and 0·76 ±0·13 (s.e.m.) pmol/g wet weight respectively), but was not detected in extracts of submaxillary gland or liver. Although immunoreactive EGF was not detectable in uterine, allantoic or ovarian follicular fluids, colostrum contained EGF at biologically active concentrations (0·84±0·15 nmol/l). Immunoreactive EGF was also present in pig urine, with similar concentrations in samples from male or female animals. In addition, pig urine inhibited the binding of 125I-labelled EGF to 3T3 fibroblasts and stimulated DNA synthesis in quiescent monolayers of these cells, indicating that the immunoreactive material in urine is biologically active. Quantitative comparisons of the data presented here with that published previously indicate considerable species variation in the EGF levels of various tissues and body fluids.

Journal of Endocrinology (1992) 135, 77–83
Atrial natriuretic peptide in eel plasma, heart and brain characterized by homologous radioimmunoassay
Authors: Takei Y. , Ando K. , Kawakami M.
Published: December 2008

A highly specific and sensitive radioimmunoassay has been developed for the measurement of eel atrial natriuretic peptide (ANP). The antiserum, raised against eel ANP-(1–27) did not cross-react with two other eel natriuretic peptides, i.e. eel ventricular natriuretic peptide and C-type natriuretic peptide (CNP), or with any mammalian ANPs, CNPs or brain natriuretic peptides so far identified. The minimal detectable amount was 0·39 fmol (0·90 pg)/tube with more than 99% confidence. Because of its high sensitivity, the radioimmunoassay makes it possible to measure eel ANP directly with only a few microlitres of plasma without extraction.

Using the radioimmunoassay we found high levels of ANP in the atrium (11 ± 2 pmol/mg wet tissue, n = 8), and much lower levels in the ventricle (56 ±8 fmol/mg, n=8) and the brain (22±1 fmol/mg, n = 8) of eels. Eel plasma contained a large amount of ANP (247 ± 66 fmol/ml, n= 8) compared with the levels reported in mammals, although atrial levels are similar between eels and mammals.

Gel-permeation chromography revealed that a major form of ANP stored in the eel atrium, ventricle and brain has a molecular mass of approximately 14 kDa but low molecular forms of about 3 kDa are predominant in eel plasma. A detailed analysis with reverse-phase high-performance liquid chromatography showed that a major molecular form circulating in eel plasma is ANP-(1–27). ANP-(1–27) was also detected in small amounts in the eel atrium, ventricle and brain.

Journal of Endocrinology (1992) 135, 325–331
Retention of normal ovarian function after hysterectomy
Authors: Metcalf M. G. , Braiden V. , Livesey J. H.
Published: December 2008

What are the long-term effects of hysterectomy on the ovaries of normal women? Ninety-three women aged 29–44 years (median, 38 years) who had undergone hysterectomy for benign reasons 0·3–9·1 years prior to investigation, contributed urine samples twice weekly for a period of 53–149 days (median 102 days) for pregnanediol analysis. The interval between successive pregnanediol peaks and their increment over baseline were measured.

The median peak interval was 27·3 days, and 93·3% of all intervals were of 21- to 35-days duration. Of the 337 peaks observed, 96·7% met the criteria previously used to define an ovulatory cycle. These are similar to the figures reported for menstruant women of comparable age. ANOVA showed no significant effect of age or time since hysterectomy on either the interval between peaks or peak increment (P > 0·10 in all cases). The evidence suggests that the ovaries of women who have no uterus behave like those of intact women.

Journal of Endocrinology (1992) 135, 597–602
IMMUNOHISTOCHEMICAL IDENTIFICATION OF ANDROGEN RECEPTORS IN GERM CELL NEOPLASIA
Authors: Rajpert-De Meyts E. , Skakkebæk N. E.
Published: December 2008

The highest prevalence of testicular cancer occurs in young men with high androgen activity. The presence and distribution of androgen receptors (ARs) was therefore investigated in germ cell neoplasia, using two specific monoclonal antibodies. Tissue samples from 18 patients with seminoma and/or carcinoma-in-situ (CIS) of the testis were examined. An indirect immunohistochemical method with a biotin-streptavidin-peroxidase or an alkaline phosphatase detection system was used. 45% of seminoma samples and 42% of CIS samples were AR-positive with antibody AN 1-15. The values obtained using antibody F 39.4.1 were 44 and 40% respectively. Some differences in specificity between the two antibodies were observed. Unusual granular staining of germ cells in normal testes, also present in malignant germ cells, was noted when antibody F 39.4.1 was used. The presence of AR protein immunoreactivity in neoplastic germ cells suggests that androgens may be involved in the pathogenesis of the disease.
Ontogeny and characterization of epidermal growth factor receptors on the fetal area of the sheep placenta
Authors: Lacroix M. C. , Kann G.
Published: December 2008

Studies of the binding of 125I-labelled epidermal growth factor (EGF) to the ovine placenta were carried out on days 50, 90–100 and 140 of pregnancy. Membrane fractions were purified from the fetal area of the cotyledon. Two classes of binding sites were found. Their dissociation constants (Kd) were not significantly different for the three stages of pregnancy considered (high-affinity Kd 54–70·2 pmol/l; low-affinity Kd 12·2 to 19 nmol/l). However, the number of high-affinity binding sites on days 90–100 was significantly (P < 0·01) greater (146 ± 19 fmol/mg protein) than on either day 50 or day 140 (respectively 74·2 ± 1·26 and 56·3 ± 5·6 fmol/mg protein). Affinity cross-linking studies followed by SDS-PAGE under reducing conditions demonstrated that the major part of the EGF was specifically cross-linked to a protein of molecular weight of 150 kDa and to lesser extent to 180 kDa and 130 kDa proteins. Membranes prepared from unfrozen tissues, in the presence of sodium iodoacetate to reduce endogenous enzymatic conversion of the 180 kDa form to the 150 and 130 kDa forms, still exhibited a major EGF-binding protein of 150 kDa. The occurrence of an increased number of EGF receptors at the period of rapid cotyledonary growth which coincides with the increase in placental hormonal secretions suggests that EGF has a role in the development of the ovine placenta.

Journal of Endocrinology (1993) 136, 43–50
Follicular development and ovarian hormone secretion following passive immunization of ewes against inhibin or oestradiol
Authors: Mann G. E. , Campbell B. K. , McNeilly A. S. , Baird D. T.
Published: December 2008

Immunization against inhibin or oestradiol causes an increase in the peripheral plasma concentration of FSH. In this study we have investigated the effect of this post-immunization rise in FSH concentration on follicular development by means of real-time ultrasonography, in ewes in which an ovary and its vascular pedicle had been autotransplanted to a site in the neck. Groups of ewes on day 10 of the luteal phase of the oestrous cycle were injected with a single 10 ml i.v. bolus of plasma from normal ewes (control; n = 4), antiserum to the 1–26 peptide fragment of the N-terminus of the α chain of porcine inhibin (n = 5) or antiserum to oestradiol-17β (n = 4). The plasma concentration of FSH was unaffected by treatment in the control group but showed a significant (P < 0·001) rise following treatment in both immunized groups (inhibin-immunized 175% over 19 h; oestradiol-immunized 138% over 22 h as a per cent of the original value). This rise in FSH concentration was accompanied by a significant (P < 0·001) rise in the total number of follicles > 2·0 mm per ovary in both immunized groups (inhibin-immunized 5·5±1·0 to 13·6± 1·4; oestradiol-immunized 4·6±0·5 to 11·5±1·0). In the oestradiol-immunized group, this rise was due to an increase (P < 0·001) in the number of small follicles (<3·5 mm) alone while, in the inhibin-immunized group, there was a rise in both the number of small follicles (P < 0·001) and the number of medium-sized follicles of 3·5–4·5 mm (1·3 ±0·5 to 3·2± 1·0, P <0·05). During the period from 12 to 20 h after immunization, when FSH concentrations were falling following the post-immunization rise, there was a significant (P <0·05) rise in the ovarian secretion rate of inhibin in the oestradiol-immunized group, and in the inhibin-immunized group the mean secretion rate of oestradiol was double that in the control group (2·7±0·5 vs 1·3 ±0·3 pmol/min, P <0·06). The temporal relationships suggest that the rise in FSH induced by passive immunization against oestradiol or inhibin stimulates the development of many antral follicles which contribute to the increased ovarian secretion of inhibin and oestradiol.

Journal of Endocrinology (1993) 136, 225–233
Transcription of prolactin gene in milk secretory cells of the rat mammary gland
Authors: Steinmetz R. W. , Grant A. L. , Malven P. V.
Published: December 2008

In-situ hybridization and Northern blot hybridization were used to identify mRNA for pituitary prolactin in mammary tissue obtained from female rats 1 day before expected parturition, 1 day after parturition and on day 7 of lactation. Prolactin cDNA was labelled with 32P for Northern analysis and with digoxigenin for in-situ hybridization. Total and poly(A)+ RNA from pituitary, mammary and control (fat and kidney) tissues were analysed by agarose gel electrophoresis with transfer to nitrocellulose and hybridization to a cDNA for rat prolactin. Although present in much smaller amounts than the 1·0 kb transcript in pituitary RNA homogenates, mammary RNA homogenates from all three stages contained mRNA of approximately 1·0 kb which hybridized with the prolactin probe. Similar analyses of fat and kidney failed to reveal any hybridization at the 1·0 kb size. When tissue sections were hybridized to the cDNA probe, specific hybridization was observed in the milk secretory cells of the mammary alveoli and the lactotroph cells of the anterior pituitary, but not in liver cells or in RNase-treated sections of mammary tissue. In summary, these results demonstrate that milk secretory cells of the rat mammary gland transcribe the gene for prolactin, and they raise the possibility that a primary target tissue for blood-borne prolactin may also synthesize prolactin.

Journal of Endocrinology (1993) 136, 271–276
Lack of long-term β-cell glucotoxicity in vitro in pancreatic islets isolated from two mouse strains (C57BL/6J; C57BL/KsJ) with different sensitivities of the β-cells to hyperglycaemia in vivo
Authors: Svensson C. , Sandler S. , Hellerström C.
Published: December 2008

Previous studies have shown that 4 weeks after syngeneic transplantation of a suboptimal number of islets into either C57BL/6J (BL/6J) or C57BL/KsJ (BL/KsJ) diabetic mice there is an impaired insulin secretion by the perfused grafts. After normalization of the blood glucose level with a second islet graft, the BL/6J strain showed restored insulin secretion whilst that of the BL/KsJ strain remained impaired. The aim of the present work was to study the effects of glucose on the in-vitro function of islet β-cells from these two mouse strains, with different sensitivities of their β-cells to glucose in vivo. Isolated pancreatic islets from each strain were kept for 1 week in tissue culture at 5·6, 11, 28 or 56 mmol glucose/l and were subsequently analysed with regard to insulin release, (pro)-insulin and total protein biosynthesis, insulin, DNA and insulin mRNA contents and glucose metabolism. Islets from both strains cultured at 28 or 56 mmol glucose/l showed an increased accumulation of insulin in the culture medium and an enhanced glucose-stimulated insulin release compared with corresponding control islets cultured at 11 mmol glucose/l. After culture at either 5·6 or 56 mmol/l, rates of (pro)insulin biosynthesis were decreased in BL/KsJ islets in short-term incubations at 17 mmol glucose/l, whereas islets cultured at 56 mmol glucose/l showed a marked increase at 1·7 mmol glucose/l. In BL/6J islets, the (pro)insulin biosynthesis rates were similar to those of the BL/KsJ islets with one exception, namely that no decrease was observed at 56 mmol glucose/l. Islets of both strains showed a decreased insulin content after culture with 56 mmol glucose/l. Insulin mRNA content was increased in islets cultured in 28 or 56 mmol glucose/l from both mouse strains. Glucose metabolism showed no differences in the rates of glucose oxidation, however, in islets cultured in 56 mmol glucose/l the utilization of glucose was increased in both BL/6J and BL/KsJ animals. There were no differences in DNA content in islets cultured at different glucose concentrations, suggesting no enhancement of cell death.

The present study indicates that, irrespective of genetic background, murine β-cells can adapt to very high glucose concentrations in vitro without any obvious signs of so-called glucotoxicity. Previously observed signs of glucotoxicity in vivo in BL/KsJ islets appear not to be related only to glucose but rather to an additional factor in the diabetic environment.

Journal of Endocrinology (1993) 136, 289–296
The effect of basic fibroblast growth factor on the growth and function of human thyrocytes
Authors: Taylor A. H. , Millatt L. J. , Whitley G. StJ. , Johnstone A. P. , Nussey S. S.
Published: December 2008

Basic fibroblast growth factor (bFGF) was quantitated in human primary thyrocyte cultures and thyroid cell lines produced by transfection with pSV3neo. Immunoreactive-bFGF (ir-bFGF) bound to heparin–Sepharose affinity columns eluted with 1·8–2·0 mol NaCl/l and had a molecular weight of approximately 17 000. Recombinant human bFGF in the presence of 5% serum increased the growth of transfected human thyrocytes but not the growth of primary human thyrocytes. Preincubation of cells with up to 100 μg bFGF/l potentiated TSH-stimulated cAMP release from the transfected cells but inhibited release from primary human thyroid cultures. bFGF may be an important modulator of thyroid cell function and growth.

Journal of Endocrinology (1993) 136, 339–344
Release of bioactive ACTH by perifused human placenta at early and late gestation
Authors: Waddell B. J. , Burton P. J.
Published: December 2008

This study assessed whether bioactive ACTH is released by the human placenta during perifusion in vitro at early and late gestation. Human placental villous fragments from early (8–12 weeks) and late (38–40 weeks) gestation were perifused at a constant rate for 6·5 h. To assess ACTH-like bioactivity released by this tissue, the perifusion effluent was redirected through adjacent chambers containing freshly dispersed adrenocortical cells obtained from adult rats. Baseline secretion of corticosterone by these adrenocortical cells averaged 95±26 (s.e.m.) fmol/min, and this increased at least fivefold (P <0·01, two-way ANOVA) in response to placental effluent at early and late gestation. The magnitude of this increase, expressed as a percentage of the maximal response to a subsequent stimulus with ACTH(1–24), was similar for placentas obtained at early (41 ± 12% of maximal response) and late (42 ± 17%) gestation. Immunoreactive (I)-ACTH was readily detectable in placental effluent from all preparations (5·5±2·3 fmol/min per g tissue), and there was no apparent difference with stage of gestation.

To determine whether all of the ACTH-like bioactivity released by the placenta was attributable to I-ACTH, a second series of placental/adrenal perifusions was conducted. In these, I-ACTH was selectively removed from placental effluent by immunoneutralization, and the residual bioactivity measured. Immunoneutralization involved preincubation of placental effluent with ACTH antiserum (1:100), and preincubation with normal rabbit serum (NRS) served as a control. Preincubation with ACTH antiserum, but not with NRS, resulted in a marked reduction in ACTH-like bioactivity present in placental effluent at both early (P <0·01, paired t-test) and late (P <0·05) gestation. This inhibition was significantly more effective (P <0·05, unpaired t-test) at early than at late gestation.

Overall, these data establish that the human placenta can release bioactive ACTH-like activity at both early and late gestation, and that much, but not all, of this bioactivity is directly attributable to I-ACTH. These findings clearly demonstrate a potential role for placental ACTH in directly influencing the maternal and/or fetal hypothalamic-pituitary-adrenal axes during human pregnancy.

Journal of Endocrinology (1993) 136, 345–353
Sex steroids affect glucocorticoid response to chronic inflammation and to interleukin-1
Authors: Da Silva J. A. P. , Peers S. H. , Perretti M. , Willoughby D. A.
Published: December 2008

The influence of gender and sex hormones upon both the hypothalamic-pituitary-adrenal (HPA) axis and the immune and inflammatory responses is well recognized, but it is not clear to what extent the two effects are interdependent. We have investigated this interaction using a chronic inflammation model. Corticosterone levels were measured in mature BALB/c male and female mice, which were intact, sham-operated or gonadectomized. No significant differences were found between groups in baseline corticosterone, but systemic inflammation (cotton-induced granulomas) resulted in stimulation of the HPA axis in a reproducible pattern. Corticosterone levels were higher in sham-operated females than in males, but gonadectomy had opposing effects in the two genders, resulting in reduced levels in females but significantly increased levels in males. A similar pattern emerged after stimulation by ether exposure or injection of interleukin-1β. In the chronic inflammatory model, replacement of ovariectomized females with physiological levels of progesterone restored a response similar to that of intact females. Physiological levels of 5α-dihydrotestosterone prevented the increase in corticosterone levels caused by castration in males and also resulted in reduced corticosterone levels in sham-operated females. Oestradiol treatment did not affect corticosterone levels. Release of interleukin-1 by peritoneal macrophages from intact and gonadectomized mice with chronic inflammation followed a similar pattern, females releasing more than males. These data suggest a complex inter-relationship between sex steroids, inflammatory stimuli and the HPA axis, such that females have a greater tendency than males to generate activating signals and in addition have a greater sensitivity to such factors.

Journal of Endocrinology (1993) 136, 389–397
Effects of growth hormone and thyroxine on kidney insulin-like growth factor-I and renal growth in hypophysectomized rats
Authors: Marshall S. M. , Flyvbjerg A. , Jørgensen K. D. , Weeke J. , Ørskov H.
Published: December 2008

The effects of treatment for 11 days with human growth hormone (hGH; 140 μg/day), thyroxine (T4; 3 μg/day) and hGH + T4 on renal growth and content of insulin-like growth factor-I (IGF-I) in hypophysectomized rats have been compared with saline-treated hypophysectomized animals and intact control animals. Right kidney weight and kidney weight/body weight ratio remained low in the saline-treated group (313±9 vs 694±28 mg in controls on day 11, P<0·001 and 3·4±0·12 × 10−3 vs 4·2±0·10× 10−3, P< 0·005 respectively). In T4- and hGH-treated animals, kidney weight gain was similar (to 420 ± 14 and 450±22 mg on day 11 respectively, P>0·05), whilst the increase was greater in the group given hGH + T4 (to 572 ±34 mg, P< 0·001 compared with hGH- and T4-treated groups). The kidney weight/body weight ratio became normal in the T4- and hGH + T4-treated animals but remained low in the hGH-treated group. The renal content of IGF-I was low in the salinetreated animals throughout the study (92±10 ng/g on day 11 vs 219±8 ng/g in control animals, P< 0·001), but increased to a maximum of 88% above baseline on day 1 in the group given T4. In the hGH-and hGH + T4-treated groups, renal IGF-I concentration rose to a peak of 317% above baseline on days 2 to 4, then fell to the values seen in control animals on day 11 (hGH: 242±18 ng/g; hGH + T4: 320 ± 41 ng/g; controls: 219 ± 8 ng/g; P> 0·05 for all comparisons). Thus treatment with hGH or T4 results in similar kidney weight gain, despite a greater rise in the renal concentration of IGF-I in the hGH-treated animals. Treatment with both hGH + T4 leads to an increase in the renal concentration of IGF-I similar to that seen with hGH treatment alone, but a larger increase in kidney weight, suggesting that T4 does not stimulate renal growth via the IGF-I pathway and that growth promotion by hGH and T4 is additive.

Journal of Endocrinology (1993) 136, 399–406
The human chorionic gonadotrophin-induced inflammationlike response is enhanced in macrophage-depleted rat testes
Authors: Bergh A. , Damber J.-E. , van Rooijen N.
Published: December 2008

Liposome-entrapped dichloromethylene diphosphonate (Cl2MDP) was injected locally into the right testes of adult rats in order to deplete testicular macrophages. The number of testicular macrophages in the treated testes was reduced by at least 90% at 7 and 14 days after treatment. Unilaterally testicular macrophage-depleted animals were treated with 100 IU human chorionic gonadotrophin (hCG) subcutaneously and the inflammatory response was compared in the macrophage-depleted and intact contralateral testis. Four hours after hCG treatment, intratesticular testosterone was similarly increased in intact and macrophage-depleted testes. In macrophage-depleted testes there was a large increase in the number of leukocytes in testicular blood vessels and numerous leukocytes had migrated into the interstitial tissue. This response was greater than in the intact contralateral testis. It was concluded that testicular macrophages are probably not the origin of the inflammatory mediator secreted in the rat testis after hCG treatment. On the contrary, it appears that testicular macrophages may secrete factors inhibiting hCG-induced testicular inflammation.

Journal of Endocrinology (1993) 136, 415–420
Serum and urinary concentrations of sex hormones and genital swelling during the menstrual cycle of the gibbon
Authors: Nadler R. D. , Dahl J. F. , Collins D. C.
Published: December 2008

The relationship between sex hormone concentrations and female genital swelling during the menstrual cycle in the monogamous gibbon was comparable with that of polygamous female primates, such as the chimpanzee, which live in multimale groups and have larger swellings. The data, therefore, support the hypothesis proposed by C. R. Carpenter more than 50 years ago, that the gibbon's genital swelling, like that of other female primates, reflects basic physiological processes associated with progress of the menstrual cycle. Genital swelling increased during the follicular phase with increasing concentrations of oestradiol and oestrone glucuronide, reached maximal swelling in association with the mid-cycle peaks in the oestrogens and LH and began detumescence with the initial increases in progesterone during the luteal phase. The data also suggest that the menstrual cycle of the gibbon is shorter than previously reported, since cycles of 19–22 days exhibited hormone patterns that are consistent with ovulation. The genital swelling of the female gibbon is a useful marker for monitoring progress of the menstrual cycle and the presumptive time of ovulation.

Journal of Endocrinology (1993) 136, 447–455
The action of LH-releasing hormone and five analogues on oestradiol, oxytocin and vasopressin secretion by bovine granulosa cells in culture
Authors: Sirotkin A. V. , Nitray J. , Nikolajev S. V. , Burov S. V.
Published: December 2008

The release of oxytocin, arginine-8-vasopressin and oestradiol-17β by bovine granulosa cells in culture was analysed either with or without LH-releasing hormone (LHRH), its agonists (cyclo [Pro1dPhe6] LHRH and des 1–3, 10[dAla6] LHRH) or antagonists ([dPhe2dPhe6] LHRH, [dPhe2dPhe(NH2)6] LHRH or cyclo [Pro1dPhe2dPhe6] LHRH). All preparations used stimulated granulosa oxytocin and oestradiol secretion. Vasopressin release was significantly increased after all treatments with LHRH antagonists, but not after LHRH or its agonists.

Our observations demonstrated a direct influence of LHRH and its analogues on the secretion of oestrogen and nonapeptide hormones by bovine granulosa cells. A comparison of the effects of LHRH, its agonists and antagonists suggests that the action of these peptides at the hypophysial and ovarian level is relatively independent.

Journal of Endocrinology (1993) 136, 491–496
Interaction between insulin and thyroid hormone in rat pituitary tumour cells: insulin attenuates tri-iodothyronine-induced growth hormone mRNA levels
Authors: Prager D. , Weber M. M. , Gebremedhin S. , Melmed S.
Published: December 2008

Insulin has previously been shown to inhibit basal and stimulated rat GH (rGH) secretion as well as basal GH transcription in rat pituitary cells. The effect of physiological doses of insulin on tri-iodothyronine (T3)-stimulated GH mRNA levels in rat pituitary tumour cells was therefore examined. Insulin (7 nmol/l) suppressed T3-stimulated GH mRNA levels in GC and GH3 rat pituitary tumour cells by 58%. This inhibitory effect of insulin on T3-stimulated GH mRNA levels was already present after 24 h of treatment, and persisted for at least 48 h after insulin treatment was withdrawn. The effect of insulin on GH mRNA was selective, as rat prolactin mRNA was stimulated by insulin and T3 in the same cells. Treatment of cells with cycloheximide (10 μmol/l) did not alter the attenuation of GH mRNA levels by insulin, indicating that the insulin effect is independent of new protein synthesis. When de-novo mRNA synthesis was blocked with actinomycin D (4 μg/ml) for up to 7 h, an additional decrease in the relative amount of GH mRNA levels was observed after 24, 48 and 72 h of insulin treatment, indicating that an effect of insulin on GH mRNA stability is likely. The results show that physiological doses of insulin selectively attenuate the stimulatory effect of T3 on GH mRNA levels. This suppressive effect of insulin occurs independently of protein synthesis and is presumably mediated both at a transcriptional and post-transcriptional level.

Journal of Endocrinology (1993) 137, 107–114
Influence of growth hormone deficiency on growth and body composition in rats: site-specific effects upon adipose tissue development
Authors: Flint D. J. , Gardner M. J.
Published: December 2008

Neonatal female rats were treated for 3 weeks (short term) or 8 weeks (long term) with antiserum to rat GH (anti-rGH) with or without replacement therapy with recombinant bovine GH (bGH). Body weight gain and tail length were significantly suppressed within the first 3 weeks and were even more markedly suppressed when treatment was continued for 8 weeks. When treatment was stopped in short-termtreated animals the rate of body weight gain recovered, although without evidence of catch-up growth. These effects were all normalized by concurrent treatment with bGH. Long-term anti-rGH treatment caused a profound reduction (80%) in the number of differentiated adipocytes in two internal fat depots, whilst the subcutaneous depot was only moderately affected (20%). In contrast, after recovery from short-term treatment with anti-rGH, the internal depots were only marginally decreased in both weight and adipocyte numbers, whereas the subcutaneous depot was actually doubled in size compared with controls, due entirely to an increase in the number of differentiated adipocytes. These data clearly demonstrate for the first time that GH is required for the differentiation of adipocytes in vivo. In addition, the results demonstrate distinct effects at different anatomical sites and suggest that GH may be one factor responsible for the differences described in numerous metabolic parameters and hormonal sensitivities of adipose tissue derived from different locations within the body.

Journal of Endocrinology (1993) 137, 203–211
Effects of recombinant human activin A on growth hormone secretion by human somatotrophinomas in vitro
Authors: Daniels M. , Harris P. E. , James R. A. , Turner S. J. , Dewar J. H. , Kendall-Taylor P.
Published: December 2008

Activin A is a homodimer of inhibin βA subunits, and was first isolated from gonadal fluids on the basis of its ability to stimulate FSH secretion by rat pituitary cells in vitro. The βA subunits of activin and their mRNAs have been found in many cell types, in several species and at different stages of development, suggesting that activin A has a wide range of diverse biological roles. Apart from the modulation of gonadotroph function, in-vitro studies have demonstrated inhibitory effects of activin A on GH synthesis, GH secretion and possibly somatotroph proliferation. We have therefore investigated the potential role of activin A in the pathophysiological regulation of GH secretion by human somatotrophinoma cells using in-vitro techniques.

Cell cultures were established by enzyme dispersion of adenoma tissue obtained from six patients with acromegaly, and treated for 72 h with 0·01–10 nmol recombinant human activin A/1 followed by a 2-h stimulation test with 10 nmol GH-releasing factor (GRF)/l. Medium was collected at 24, 48 and 72 h, as well as after GRF treatment, and GH concentrations were measured by immunoradiometric assay. Basal GH secretion from the cells of two tumours was significantly stimulated 12–63% above control values during treatment with 0·01–10 nmol activin A/1, whereas the peptide had no effect on GH release from cells of the remainder of the tumours. GRF significantly stimulated GH release from the cells of two different adenomas, and pretreatment with 0·01–1 nmol activin A/1 partially but significantly blocked GRF-stimulated GH release from the cells of one of these.

These data demonstrate that activin A stimulates basal GH secretion from the cells of some, but not all, human somatotrophinomas in vitro. Pretreatment with the peptide may also partially block GRF-stimulated GH release from GRF-responsive somatotrophinoma cells. The importance of these actions in the pathophysiological regulation of human somatotrophinomas remains to be determined.

Journal of Endocrinology (1993) 137, 329–334
Anabolic effects of insulin-like growth factor-I (IGF-I) and an IGF-I variant in normal female rats
Authors: Tomas F. M. , Knowles S. E. , Chandler C. S. , Francis G. L. , Owens P. C. , Ballard F. J.
Published: December 2008

Administration of IGF-I over a 14-day period to growing female rats via s.c. implanted osmotic pumps led to an increased body weight gain, an improved N retention and a greater food conversion efficiency. The effects were dose-dependent, with the highest daily dose tested, 278 μg/day, producing 18–26% increases in these measurements. LR3IGF-I, a variant of human IGF-I that contains an amino terminal extension peptide as well as glutamate-3 replaced by arginine and exhibits very weak binding to IGF-binding proteins, was substantially more potent than the natural growth factor, in that 44 μg/day of this peptide produced similar effects to the high IGF-I dose. Organ weight and carcass composition measurements showed that the two IGF peptides generally maintained body proportions at those existing when the experiment began. Muscle protein synthesis and myofibrillar protein breakdown were both slightly increased by IGF treatment, so that the observed improvement in N retention could not be explained through protein accretion rates calculated from these measures. Infusion of human GH at a dose of 213 μg/day did not stimulate body growth. This investigation establishes that IGF peptides stimulate the growth of normal growing animals, with IGF-I variants that bind less well to IGF-binding proteins being more active than IGF-I.

Journal of Endocrinology (1993) 137, 413–421
Effects of chronic corticotrophin treatment on aldosterone metabolism in the rat
Authors: Abayasekara D. R. E. , Onyezili N. I. , Whitehouse B. J. , Laird S. M. , Vinson G. P.
Published: December 2008

Chronic treatment with high doses of ACTH leads to marked reduction in aldosterone biosynthesis and secretion both in vivo and in vitro. In contrast, it has been reported that peripheral plasma aldosterone levels may be elevated following prolonged ACTH treatment. The present study attempts to determine the reason(s) for this apparently paradoxical finding. ACTH treatment (40 μg/100 g body weight) of male Sprague–Dawley rats for 7 days caused a decrease of more than 90% in aldosterone secretion into the adrenal vein in vivo and aldosterone production by intact adrenal capsules incubated in vitro. In contrast, peripheral plasma aldosterone levels appeared to be increased when measured by radioimmunoassay using two different polyclonal antibodies (antibody 1 (AB1) raised against aldosterone-3-carboxymethyloxime–bovine serum albumin (BSA) and antibody 2 (AB2) raised against aldosterone-21-hemisuccinate–BSA). However, when a highly specific monoclonal antibody (raised against aldosterone-3-carboxymethyloxime–BSA and showing low cross-reactivity to aldosterone metabolites) was used, peripheral plasma aldosterone levels appeared to be reduced in ACTH-treated rats. Following chromatographic fractionation of peripheral plasma, significantly more material with aldosterone-like immunoreactivity, but which was less polar than authentic aldosterone in chromatographic mobility, was detected in the fractions using antibodies AB1 and AB2. The absence of this material from fractions of adrenal vein plasma leads us to infer that this material is generated in the peripheral circulation, probably as a result of hepatic metabolism. In addition, the overall metabolic clearance rate (MCR) of [3H] aldosterone was found to be significantly decreased following prolonged ACTH treatment. We conclude that the seemingly discrepant findings with regard to the effects of chronic ACTH treatment on peripheral plasma aldosterone levels and the secretion of aldosterone in vivo can be reconciled by (1) the changes in the overall MCR of aldosterone and (2) the generation of increased quantities of aldosterone metabolites such as 5α-dihydroaldosterone and 3α,5β-tetrahydroaldosterone which show significant cross-reactivity with some aldosterone antibodies.

Journal of Endocrinology (1993) 137, 445–455
Expression of components of the insulin-like growth factor system in pig mammary glands and serum during pregnancy and pseudopregnancy: effects of oestrogen
Authors: Lee C. Y. , Bazer F. W. , Simmen F. A.
Published: December 2008

To gain insight into the involvement and interactions of the insulin-like growth factors (IGFs) and oestrogen in mammary growth and differentiation, the temporal expression of mammary mRNAs encoding components of the IGF system in pregnant and pseudopregnant pigs was examined. Pseudopregnant pigs received 5 mg oestradiol valerate or vehicle daily from day 45 after oestrus and underwent mammary biopsy on days 60, 90 or 112. In mammary tissue of pregnant pigs, steady-state levels of the mRNAs encoding IGF-I, IGF-II and type-I IGF receptor as well as the levels of the membrane-associated type-II IGF receptor were higher during the early phase of mammogenesis (≤day 45) than during the subsequent stages of mammary development. Mammary IGF-I, IGF-II and type-I receptor mRNAs were expressed at their lowest levels around day 90 of pregnancy (20–40% of those for day 30 of pregnancy) coincident with the onset of β-casein mRNA accumulation. Mammary IGF-binding protein-2 (IGFBP-2) mRNA levels increased twofold during the latter half of pregnancy, whereas the amount of IGFBP-3 mRNA declined after day 30 to undetectable levels by midpregnancy. Pseudopregnant pigs had reduced levels of these mRNAs (except for IGF-II) relative to their pregnant counterparts and this was associated with premature differentiation of mammary tissue as reflected by an earlier onset of β-casein mRNA accumulation in the former. The administration of oestradiol valerate decreased the levels of IGF-I and type-I IGF receptor mRNAs by day 60 of pseudopregnancy, but the reverse was evident by day 112. Oestradiol administration increased β-casein mRNA levels in pseudopregnant pigs, but had no effect on mammary IGFBP-2 and IGFBP-3 mRNA levels. Mammary IGF content was greater in late pregnancy (≥day 90) and pseudopregnancy than at early pregnancy. Serum IGF-I and IGF-II levels declined steadily during pregnancy and this was similar to, but not correlated with, mammary IGF mRNA levels, whereas in pseudopregnant pigs, serum IGF concentrations did not change temporally or in response to oestradiol. Serum IGFBP-2 levels were unaltered during pregnancy or pseudopregnancy, but serum IGFBP-3 levels declined after day 60 of pregnancy. In pseudopregnant pigs, serum IGFBP-3 levels did not change temporally, but declined after oestradiol treatment. Results indicate that mammary IGF-I and type-I IGF receptor systems are down-regulated during pregnancy-associated differentiation of this tissue and in response to oestrogen. Locally produced (autocrine and paracrine) IGFs are likely to mediate mammogenesis, whereas oestrogen stimulates mammary differentiation and lactogenesis in the pig. However, the high mammary IGF content and the reciprocal expression of mammary IGFBP-2 and IGFBP-3 mRNAs during late pregnancy suggests the involvement of IGFs in lactogenesis as well.

Journal of Endocrinology (1993) 137, 473–483
Relaxin alters the plasma osmolality-arginine vasopressin relationship in the rat
Authors: Weisinger R. S. , Burns P. , Eddie L. W. , Wintour E. M.
Published: December 2008

During pregnancy, in women and the rat, there is a resetting of the plasma osmolality–arginine vasopressin relationship (Posmol/PAVP) such that a decrease in Posmol is maintained without suppression of PAVP. This occurs at a time when relaxin is detectable in plasma. The hypothesis tested here was that relaxin could alter the Posmol/PAVP in the non-pregnant rat. One group of ovariectomized rats (n = 15) was treated for 7 days with intravenous synthetic human relaxin (10 μg/h) in 10 pi 0·9% (w/v) NaCl. Controls were two groups of rats either with no treatment (n = 15) or treated with vehicle alone (n = 15). One-third of each group received hypertonic saline (0·4 mol NaCl/l, 2 ml/100 g body weight i.p.) on day 7, and one-third were deprived of water for the final 24 h. All rats were killed by decapitation and blood was collected rapidly (<40 s) for hormone and osmolality assays. The Posmol in all relaxin-treated rats was significantly (P < 0·001) lower than that in both control groups, but the PAVP was unchanged. The log PAVP/Posmol regression line was significantly shifted in elevation (P <0·001) but not in slope. Thus treatment of ovariectomized rats with relaxin caused changes in fluid balance which mimic those occurring in normal pregnancy.

Journal of Endocrinology (1993) 137, 505–510
Modulation of the prostaglandin responses of conscious rabbits to the pyrogen polyinosinic: polycytidylic acid by corticotrophin-releasing factor-41
Authors: Milton N. G. N. , Hillhouse E. W. , Milton A. S.
Published: December 2008

The pyrogenic interferon inducer polyinosinic: polycytidylic acid (Poly I: C) was shown to stimulate rises in both prostaglandin E2 (PGE2) and prostaglandin F2α (PGF2α) in conscious rabbits in vivo. Poly I:C (2·5 μg/kg) stimulated a fivefold rise in circulating immunoreactive (ir) PGE2, with a lag phase of 60 min, which was sustained during the subsequent 4-h period of observation. Poly I:C also stimulated a 2·5-fold rise in circulating irPGF2α with a lag phase of 90 min, which was followed by a return to basal levels after 5 h. The rises in circulating irPGE2 and irPGF2α stimulated by Poly I:C were prevented by pretreatment with the non-steroidal anti-inflammatory drug ketoprofen. Both the irPGE2 and irPGF2α responses to Poly I:C (2·5 μg/kg, i.v.) were antagonized by the corticotrophin-releasing factor-41 (CRF-41) receptor antagonist (α-helical CRF (9–41), 25 μg/kg, i.v.) administered 5 min prior to the pyrogen. Peripheral immunoneutralization using an anti-CRF-41 monoclonal antibody (KCHMB001, 2·5 mg/kg, i.v.) administered 5 min prior to the pyrogen, also inhibited both the PGE2 and PGF2α responses to Poly I:C (2·5 μg/kg, i.v.). However, control mouse IgG also inhibited the PGE2 response. In conclusion, these results suggest a modulatory role for endogenous peripheral CRF-41 in the circulating prostaglandin responses to the pyrogen Poly I: C and this effect may be responsible for the antipyretic actions of peripherally administered CRF-41 antagonists and antibodies.

Journal of Endocrinology (1993) 138, 7–11
[125I]Iodomelatonin-binding sites in the bursa of Fabricius of birds: binding characteristics, subcellular distribution, diurnal variations and age studies
Authors: Liu Z. M. , Pang S. F.
Published: December 2008

The melatonin-binding sites in membrane preparations of the bursa of Fabricius of birds were studied using [125I]iodomelatonin as a radioligand. The binding sites were stable, saturable, reversible and of high affinity. Scatchard analysis of specific binding revealed equilibrium binding constants (Kd) of (means±s.e.m.) 43·1 ±5·9 73·3±7·6 and 35·3±4·8 pmol/l respectively at the mid-point of the light period (mid-light) in chickens, pigeons and quail, with a total number of binding sites (Bmax) of 1·23 ±0·15, 1·33±0·18 and 0·94 ±0·07 fmol/mg protein. The diurnal variation in [125I]iodomelatonin binding showed that the Bmax was 45, 115 and 70% higher at mid-light than at mid-dark in the bursae of chickens, pigeons and quail respectively. The Kd value determined from kinetic analysis was 49·0 ±6·4 pmol/l at mid-light in the chicken bursa. The [125I]iodomelatonin-binding sites of chicken bursal membranes had the following order of pharmacological affinities: 2-iodomelatonin > melatonin > 6-chloromelatonin > 6-hydroxymelatonin > N-acetylserotonin > 5-hydroxytryptamine, tryptamine, 5-methoxytryptophol, 1-acetylindole-3-carboxaldehyde, 3-acetylindole, l-tryptophan, 5-hydroxyindole3-acetic acid, 5-hydroxytryptophan suggesting that the [125I]iodomelatonin-binding sites were highly specific for melatonin. The subcellular distribution of binding sites in the chicken bursa was in the following descending order: nuclear > mitochondrial > microsomal > cytosolic fraction. There was an agerelated decrease in [125I]iodomelatonin-binding in chicken bursal membranes, with higher densities in the neonate. Our studies of [125I]iodomelatonin-binding sites in the bird bursa indicate that this primary lymphoid tissue is a target organ for melatonin, and that melatonin has a direct effect on the immune system.

Journal of Endocrinology (1993) 138, 51–57