bluuebunny/crossref_metadata_2025 huggingface dataset:
Circadian rhythms of lipogenic and hypoglycaemic responses to insulin in the golden hamster (Mesocricetus auratus)
Authors: Cincotta A. H. , Meier A. H.
Published: December 2008

Lipogenesis and blood glucose concentrations were determined at 4-hourly intervals in control and insulin-treated golden hamsters maintained on 14-h daily photoperiods (08·00–22·00 h). Lipogenesis was studied by measuring the incorporation of label into liver and fat pad lipids in animals killed 30 min after i.p. [3H]acetate injection and 2 h after insulin or saline (control) injections. Circadian rhythms of lipogenesis and plasma glucose concentration were present in both control and insulin-treated hamsters. In control animals most lipogenic activity occurred during the dark period and early during the daily photoperiod (14 h light: 10 h darkness). There were dramatic differences in the lipogenic (fat pad) and hypoglycaemic responses to insulin which varied as a function of the time of day at which insulin was injected. Insulin stimulated fivefold increases in lipid deposition (fat pad incorporation) when injected late during the dark period but had little or no effect 4–8 h after the onset of light. Daily injections for 8 days also produced variable cumulative effects on body fat stores as a function of the time of day. Insulin injected late during the dark period stimulated a 40% increase in abdominal fat weight over controls, whereas insulin injected at 4 and 12 h after the onset of light had no effect on abdominal fat weight. Insulin decreased plasma glucose concentrations markedly at 8 and 20–24 h after the onset of light but had no apparent hypoglycaemic activity (120 min after its injection) at 4 h after the onset of light. These response rhythms coupled with rhythms of insulin secretion provide a basis for temporal synergisms which could produce a spectrum of physiological conditions as a function of the phase relations between the rhythms.

J. Endocr. (1984) 103, 141–146
Androgen regulation of secretions in the sebaceous-like uropygial gland of the male Japanese quail
Authors: Abalain J. H. , Amet Y. , Daniel J. Y. , Floch H. H.
Published: December 2008

The uropygial gland of the male quail is a sebaceous-like, androgen-dependent structure. The waxes secreted by this gland consist of fatty acids esterified by alkane-2,3-diols. In adult male quail the relative concentrations of all fatty acids were not affected by castration and testosterone treatment; but in contrast, the relative concentration of dodecane diol was found to be correlated with the androgen levels. In castrated quail administration of testosterone induced an increase in the dodecane diol percentage which was blocked by protein-synthesis inhibitors. Furthermore, the effects of testosterone were found to be neutralized by the administration of cyproterone acetate. Consequently it may be stated that the relative concentration of dodecane diol is indeed a very good marker for androgenicity in the uropygial gland of the male quail. This experimental model seems well suited for evaluating the stimulators and inhibitors of the activity of the sebaceous gland.

J. Endocr. (1984) 103, 147–153
Alteration by thyrotrophin-releasing hormone of heterogeneous components associated with thyrotrophin biosynthesis in the rat anterior pituitary gland
Authors: Mori M. , Murakami M. , Iriuchijima T. , Ishihara H. , Kobayashi I. , Kobayashi S. , Wakabayashi K.
Published: December 2008

An influence of thyrotrophin-releasing hormone (TRH) on TSH heterogeneity in close association with de-novo biosynthesis was studied in rat anterior pituitary glands. Hemipituitary glands from adult male rats were incubated in Krebs–Henseleit–glucose media containing [3H]glucosamine and [14C]alanine for 3 and 6 h in the presence or absence of 10 ng TRH per ml. Fractions of TSH in the pituitary extracts were obtained using affinity chromatography coupled with an anti-rat TSH globulin. These TSH fractions were analysed by isoelectric focusing. The control pituitary glands were composed of four component peaks (isoelectric point (pI) 8·7, 7·8, 5·3 and 2·5) of [3H]glucosamine and [14C]alanine incorporated into TSH, and the amounts of radioactivity of these components were increased with the incubation time. Of these peaks, radioactive components of pI 8·7 and 7·8 coincided with the non-radioactive TSH components measured by radioimmunoassay. Addition of TRH increased incorporation of [14C]alanine into TSH in each of the components to a greater extent than that of [3H]glucosamine. In addition, new components with pI 7·2, 6·5 and 6·2, each component corresponding to each unlabelled TSH component, were demonstrated in the presence of TRH. Because addition of TRH did not change the amounts of [14C]alanine-labelled TSH in the media, the newly formed components were assumed to be connected with protein synthesis occurring in the anterior pituitary gland, which may be specific substances in response to TRH administration. These results indicate that TRH principally elicits an increase in protein synthesis in TSH at the anterior pituitary level, resulting in an alteration of TSH heterogeneity.

J. Endocr. (1984) 103, 165–171
Comparative rates of formation, in vivo, of 16-androstenes, testosterone and androstenedione in boar testis
Authors: Hurden E. L. , Gower D. B. , Harrison F. A.
Published: December 2008

Three mature Large White boars were anaesthetized and received [7(n)-3H]pregnenolone by continuous infusion into right and left spermatic arteries for up to 180 min. Spermatic venous blood flow was measured by separate timed collections of completely diverted outflow from each testis and blood not sampled was returned to the peripheral circulation.

The total radioactivity in plasma from each testis increased markedly during the first 60 min of infusion to reach a plateau from 80 to 180 min. Radiolabelling of 5α-androst-16-en-3-one, 5α-androst-16-en-3β-ol and -3α-ol showed similar patterns with ratios of mean radioactivity of 5:3:1 respectively between 80 and 180 min. In comparison, the amounts of tritiated 4,16-androstadien-3-one formed were very small. The radiolabelling of testosterone and 4-androstenedione occurred more rapidly than that of the 16-androstenes and reached maxima by 30 min. However the amounts were only one-fifth (testosterone) and one-tenth (4-androstenedione) those of the combined quantities of tritiated 16-androstenes.

Addition of human chorionic gonadotrophin (hCG) to the infusate to one testis in each animal (so that 5000 i.u. hCG were delivered in 15–20 min) produced no change in the outputs of radiolabelled steroids although radioimmunoassay of spermatic venous plasma in samples from the third experiment showed a transient increase in the concentration of 4-androstene-3,17-dione during the hCG infusion. It is suggested the lack of response to hCG could be produced by saturation and down regulation of binding sites by the very high local concentrations of hCG.

J. Endocr. (1984) 103, 179–186
Inverse changes in plasma prolactin and LH concentrations in female canaries after disruption and reinitiation of incubation
Authors: Goldsmith A. R. , Burke S. , Prosser J. M.
Published: December 2008

Prolactin and LH concentrations were measured in the plasma of female canaries sampled during the breeding cycle and after disruption and reinitiation of incubation behaviour. The late incubation period was characterized by low LH and high prolactin concentrations, and canaries separated from their nests at this stage showed an increase in LH and a decline in prolactin within 3 h. In one experiment mean (±s.e.m.) concentrations before and 24 h after nest deprivation were: prolactin 397 ± 86 and 18 ± 5 μg/l; LH 1·04±0·21 and 2·03±0·17 μg/l. Female canaries which abandoned their nests after the eggs had been removed also showed an increase in LH together with a fall in prolactin 24 h after egg removal. When nest-deprived canaries were allowed to resume incubation, plasma prolactin increased again within 5 h and after 2 days had reached levels normal for incubating birds (398± 46 μg/l). Concentrations of LH changed more gradually but had decreased 2 days after the resumption of incubation. Thus prolactin and LH show inverse changes after the disruption and reinitiation of incubation behaviour; it is not clear, however, if the change in one is dependent on the other or if both hormones are responding to the same external stimulus.

J. Endocr. (1984) 103, 251–256
Mechanism of the regulation of the 1α,25-dihydroxyvitamin D3 receptor in the rat jejunum by glucocorticoids
Authors: Chan S. D. H. , Chiu D. K. H. , Atkins D.
Published: December 2008

The distribution of 1α,25-dihydroxyvitamin D3 (1,25-(OH)2D3) receptors in isolated jejunal villous and crypt cells was investigated in normal and adrenalectomized male rats, and also in animals treated with the synthetic glucocorticoid, dexamethasone, and/or the glucocorticoid antagonist, 11-deoxycortisol. Adrenalectomy caused an increase in 1,25-(OH)2D3 receptors whilst dexamethasone treatment led to a reduction in receptor number. 11-Deoxycortisol was able to reverse the 'down-regulation' effect caused by glucocorticoids. In all cases, the changes in receptor numbers were more pronounced in crypt cells. The data suggest that, in the small intestine, glucocorticoids may control the synthesis of 1,25-(OH)2D3 receptors via the mediation of a glucocorticoid receptor, and that the adrenal hormones mainly express their effect in crypt cells. It is proposed that this phenomenon may, in part, explain the reduction in calcium absorption which occurs in man after chronic glucocorticoid treatment.

J. Endocr. (1984) 103, 295–300
Effects of acute administration of 2-hydroxylated metabolites of oestrogens on LH and prolactin secretion in male and female prepubertal rats
Authors: Brar A. K. , Fink G.
Published: December 2008

The effects of catechol oestradiol and catechol oestrone on the release of LH and prolactin were investigated in immature male and female Wistar rats. In male rats both catechol oestradiol and catechol oestrone significantly increased the plasma concentration of LH, and catechol oestradiol but not catechol oestrone significantly increased the plasma concentration of prolactin and decreased the pituitary concentration of LH. The parent oestrogens, oestradiol-17β and oestrone, had no effect on plasma LH concentrations, but both increased significantly the plasma concentration of prolactin, and oestrone but not oestradiol-17β increased the pituitary concentration of LH. In immature female rats, catechol oestradiol inhibited the surge of LH and the increase in uterine weight induced by injecting pregnant mare serum gonadotrophin (PMSG). The injection of oestrone induced an increase in the plasma concentration of LH which was about nine times greater than that produced by oestradiol-17β. There were no significant differences in the effects of these steroids on plasma prolactin concentration. These results (i) confirm that in the immature male rat catechol oestrogens can stimulate LH release and show that catechol oestradiol can increase prolactin release, (ii) show that catechol oestradiol can inhibit the stimulatory effects of PMSG on LH release and uterine weight in the immature female rat, and (iii) demonstrate that oestrone can stimulate LH release in the immature female rat.

J. Endocr. (1984) 103, 317-325
Secretion of oxytocin and milk removal as affected by milking cows with and without manual stimulation
Authors: Mayer H. , Schams D. , Worstorff H. , Prokopp A.
Published: December 2008

Milking cows with a 1-min manual stimulation (treatment 1) and without any udder preparation (treatment 2) was compared by application of an improved, highly sensitive radioimmunoassay for oxytocin and recordings of milk-flow curves. Both treatments caused the release of oxytocin, but treatment 2 generally seemed to be less efficient. Milking characteristics supported the advantage of manual stimulation; milk yield and milk flow were significantly higher, while 'machine-on' time was shorter. This clearly indicates the importance of the right timing of release of oxytocin before commencement of milking. Substitution of stimulation by an i.v. injection of 0·5 i.u. oxytocin (treatment 3) resulted in milking parameters very similar to those of treatment 2. This implies that manual stimulation has other effects besides the secretion of oxytocin which are also responsible for optimal milk removal.

J. Endocr. (1984) 103, 355–361
Non-protein-bound oestradiol and progesterone in human peripheral plasma before labour and delivery
Authors: Anderson P. J. B. , Hancock K. W. , Oakey R. E.
Published: December 2008

Plasma samples were obtained at weekly intervals from the peripheral circulation of 12 women in the last 2–7 weeks of pregnancy. The concentrations of oestradiol and progesterone (isolated by chromatography) were measured by radioimmunoassay; the proportion of each hormone which was not bound to protein was measured by steady-state gel filtration. From these, the apparent concentration of the non-protein-bound form of each hormone was calculated.

The mean proportion of oestradiol not bound to protein varied from 0·84 to 2·71% in the different subjects, but within each subject variation was within experimental error. For progesterone, the mean proportion not bound to protein in the different subjects varied from 1·76 to 2·77%; within individuals the proportion remained essentially constant.

There was no consistent, recognizable trend as labour approached in (i) the concentration of oestradiol; (ii) the concentration of progesterone; (iii) the concentrations of non-protein-bound oestradiol or non-protein-bound progesterone; (iv) the ratio of the concentrations of progesterone and oestradiol; (v) the ratio of the concentrations of non-protein-bound progesterone and oestradiol. In nine out of 12 subjects, the ratio of the concentration of non-protein-bound progesterone to that of non-protein-bound oestradiol was greater than the corresponding ratio based on total hormone concentrations.

These results therefore provide no support for the hypothesis that human labour is preceded by alteration in the progesterone to oestradiol ratio which can be detected by measurement of these hormones in peripheral blood.

J. Endocr. (1985) 104, 7–15
Water and electrolyte contents, cell pH and membrane potentials of cultured turtle thyroid cells
Authors: Chow S. Y. , Yen-Chow Y. C. , Woodbury D. M.
Published: December 2008

Water and electrolyte contents, cell pH, membrane potential and 125I− uptake were determined in cultured follicular cells of turtle thyroid. The Na+, K+ and Cl− concentrations in the cultured thyroid cells were 59·2, 119·0 and 50·9 mmol/l cell water respectively. Treatment with TSH (10 mu./ml for 24 h) increased the K+ and Cl− and decreased the Na+ concentrations in cells. The water and protein contents of these cells were 81·6 and 8·7 g/100 g cells respectively. The cell pH was 6·91. With glass microelectrodes, the resting membrane potential of thyroid cells cultured in Medium 199 averaged 33·9 ± 0·63 mV which is slightly higher than 29·8 ± 1·6 mV as calculated from the data on the uptakes of [14C]methyltriphenylphosphonium and 3H2O by the cells. The potential varied linearly with the log of external K + concentration (between 15 and 120 mmol/l) with a slope of about 24 mV per tenfold change in K+ concentration. Both TSH and cyclic AMP depolarized the cell membrane. Calculations based on the values for the electrolyte concentrations in cells and in culture medium indicated that Na+, K+ and Cl− were not distributed according to their electrochemical gradients across the cell membrane. Na+ was actively transported out of the cells and K+ and Cl− into the cells. Follicular cells of turtle thyroid cultured in the medium without addition of TSH formed a monolayer. Their iodide-concentrating ability was low and they did not respond to TSH with an increase in iodide uptake. In contrast, cells cultured in medium containing TSH tended to aggregate and organize to form follicles. They had higher ability to concentrate iodide and respond to TSH.

J. Endocr. (1985) 104, 45–52
Permanent changes in the functional development of accessory sex organs and in fertility in male mice after neonatal exposure to cyproterone acetate
Authors: Jean-Faucher Ch. , Berger M. , De Turckheim M. , Veyssiere G. , Jean Cl.
Published: December 2008

Male mice were injected daily with cyproterone acetate for 10 consecutive days during one of the four following periods: 1–10 days, 11–20 days, 21–30 days or 31–40 days. At all stages studied cyproterone acetate caused a significant reduction in the relative weights of epididymis, vas deferens, preputial gland and seminal vesicle in males killed 24 h after the last injection; the androgen content (testosterone + dihydrotestosterone) of the accessory sex organs was also reduced but the differences were not always significant. Cyproterone acetate treatment from 1 to 10 days resulted in a definitive reduction in the relative weights of all accessory sex organs studied and when injected from 11 to 20 days in epididymis and vas deferens. When cyproterone acetate was injected after 20 days of age, the inhibition of sexual organ weights was reversible and at adulthood organs were normally developed. Cyproterone acetate treatment induced a high percentage of infertile males only when injected from 1 to 10 days. Spermatogenesis, androgen levels in plasma and accessory sex organs, and sexual behaviour were not affected in sterile males.

These results suggest that the functional development of accessory sex organs can be permanently affected by short-term neonatal exposure to endogenous androgens.

J. Endocr. (1985) 104, 113–120
The role of fetal adrenal hormones in the switch from fetal to adult globin synthesis in the sheep
Authors: Wintour E. M. , Smith M. B. , Bell R. J. , McDougall J. G. , Cauchi M. N.
Published: December 2008

The switch from γ (fetal) to β (adult) globin production was studied by the analysis of globin synthesis in chronically cannulated ovine fetuses and newborn lambs. The γ/α globin synthesis ratio decreased from 0·98 ± 0·11 (s.d.) (n = 4 samples) at 100–120 days of gestation to 0·15± 0·07 (n = 4) in lambs of 150–156 days post-conception, and the β/α synthesis ratio increased from 0·04 ± 0·06 (n = 4) to 1·13 ± 0·21 (n = 4) over the same period. In bilaterally adrenalectomized fetuses, which survived in utero until 151–156 days, the γ/α and β/α synthesis ratios were 0·64 ± 0·14 (n = 3) and 0·25 ± 0·07 (n = 3) respectively in the 150- to 156-day period. Bilateral adrenalectomy did not affect the time of onset of β globin synthesis, but significantly decreased the rate. In one bilaterally adrenalectomized fetus the infusion of increasing concentrations of cortisol restored the rate of β globin synthesis to normal. Treatment of three intact fetuses with 100 μg cortisol/h for 3 weeks, from 100 to 121 days, did not affect the timing or rate of switch from γ to β globin synthesis. Thus fetal adrenal secretions, probably cortisol, affected the rate of change of γ to β globin synthesis but other factors must have been involved in the initiation of the switch.

J. Endocr. (1985) 104, 165–170
Lack of growth hormone-dependent somatomedins or growth retardation in hypophysectomized fetal lambs
Authors: Parkes M. J. , Hill D. J.
Published: December 2008

Fetal lambs were hypophysectomized and, after 8 days of recovery, given infusions of GH, prolactin, thyroxine and insulin with glucose. Hypophysectomy caused no consistent reduction in fetal plasma somatomedin-like activity. Fetal infusions of GH or prolactin caused no consistent change in plasma somatomedin-like activity. It was concluded that fetal somatomedin-like activity is not GH dependent. After hypophysectomy fetal lambs showed no reduction in body weight or length at term.

J. Endocr. (1985) 104, 193–199
Contrasting effects of prolactin on luteal and follicular steroidogenesis
Authors: Kalison B. , Warshaw M. L. , Gibori G.
Published: December 2008

To determine whether prolactin affects both luteal and follicular production of testosterone and oestradiol, pseudopregnant rats, either intact or hypophysectomized on day 8, were injected daily between days 8 and 9 with 1·5 i.u. human chorionic gonadotrophin (hCG), 250 μg prolactin or a combination of both. Control rats were given vehicle. On day 9, blood was obtained from the ovarian vein and corpora lutea and follicles were isolated and incubated in vitro for 2 h. Administration of hCG to intact rats increased ovarian secretion of testosterone and oestradiol dramatically, but did not affect progesterone secretion. Hypophysectomy on day 8 of pseudopregnancy was followed by a drop in ovarian steroid secretion. Prolactin treatment of hypophysectomized rats markedly enhanced progesterone production but had no stimulatory effect on either testosterone or oestradiol. In contrast, hCG dramatically enhanced ovarian secretion of both testosterone and oestradiol without affecting progesterone secretion. Prolactin administered together with hCG antagonized the stimulation of both testosterone and oestradiol secretion by hCG, yet increased progesterone production. When the specific effects of hCG and prolactin administration on follicles and corpora lutea were studied separately, it was found that hCG treatment in vivo greatly stimulated testosterone and oestradiol production by both tissues in vitro. Since hCG only marginally affected aromatase activity in the follicle, had no effect on aromatase activity in luteal cells and did not increase progesterone synthesis, it appears that hCG acts to increase the formation of androgen substrate for oestradiol biosynthesis. Prolactin, administered with or without hCG, inhibited both basal and hCG-stimulated testosterone and oestradiol synthesis by the follicle. In sharp contrast to its inhibitory effect on follicular production of steroids, prolactin appears to be essential for LH stimulation of testosterone and oestradiol by the corpus luteum. In the absence of prolactin, luteal cells gradually ceased to respond to LH and decreased their output of testosterone and oestradiol. Prolactin administration to hypophysectomized rats did not affect luteal cell production of either steroid. However, corpora lutea of rats treated with prolactin responded to the hCG challenge with an increase in testosterone and oestradiol synthesis.

In summary, results of this investigation demonstrate that prolactin affects follicular and luteal production of testosterone and oestradiol in opposite ways. It acts on the follicle to inhibit both basal and LH-stimulated production of testosterone and oestradiol, yet it markedly enhances LH stimulation of testosterone and oestradiol synthesis by luteal cells.

J. Endocr. (1985) 104, 241–250
A solid-phase radioimmunoassay for human corticosteroid binding globulin
Authors: Robinson P. A. , Langley M. S. , Hammond G. L.
Published: December 2008

A radioimmunoassay (RIA) for human corticosteroid binding globulin (CBG) has been developed using 125I-labelled CBG and a monospecific solid-phase CBG-antiserum (CBG-Ab-cellulose). In an RIA of serum CBG concentrations, pure CBG standards (1–100 ng protein) or samples (1 : 200) were incubated (16 h at 20 °C) with 125I-labelled CBG and CBG-Ab-cellulose. After addition of 2 ml 0·9% NaCl, the tubes were centrifuged, supernatants were aspirated and the 125I-labelled CBG bound to the CBG-Ab-cellulose pellet was counted. The specificity of the RIA was confirmed by parallel displacement curves for serial dilutions of male, female and pregnancy sera, as well as pure CBG standards. The mean ± s.d. recovery (99±8%) of pure CBG (1·6–25·0 ng) added to a diluted serum sample verified the accuracy of the method, and a good correlation (r = 0·97; n = 43) existed between serum CBG cortisol binding capacity (nmol/l) measurements and CBG concentrations (mg protein/l) measured by RIA. Intra- and interassay precisions (C.V.) at low to high serum CBG concentrations were <5% and <9% respectively. The mean ± s.d. serum CBG concentrations (mg protein/l) measured by the RIA were: 21·8±4·6 in boys (n = 12), 20·0±4·2 in girls (n = 9), 20·7±2·7 in men (n = 6), 20·5±2·9 in women (n = 6) and 47·1 ±10·5 in pregnant women (n = 5). The sensitivity of the standard curve used in the routine RIA of serum CBG was 1·0 ng CBG/assay tube, but this could be increased to 0·2 ng/assay tube by reducing the amount of CBG-Ab-cellulose used. The RIA is suitable for both clinical and research purposes, and will aid the identification of abnormal forms of CBG and facilitate studies of the regulation of CBG production in vitro.

J. Endocr. (1985) 104, 259–267
Effect of a single injection of prolactin on the serum concentrations of thyroid hormones and corticosterone and liver monodeiodinase in the domestic fowl before and after hatching
Authors: Decuypere E. , Kühn E. R.
Published: December 2008

The influence of an intravenous injection of ovine prolactin on the liver monodeiodinase activity and serum concentrations of thyroid hormones and corticosterone was studied in Hisex embryos and chicks after hatching. An injection of 1 and 10 μg ovine prolactin into 18-day-old chick embryos increased serum concentrations of tri-iodothyronine (T3) five-and eightfold respectively after 2 h. At the same time serum concentrations of thyroxine (T4) and reverse T3 (rT3) were decreased in the chick embryo, but only with 10 μg prolactin. This was accompanied by a doubling of the liver monodeiodinase activity. Serum concentrations of corticosterone, however, were not influenced by the prolactin injections. In the 5-day-old chicken, serum concentrations of T3, rT3, T4 and liver T4-5′-monodeiodinase activity were not influenced by 1 or 10 μg prolactin. Serum concentrations of corticosterone after injection of 1 or 10 μg prolactin were doubled compared with controls. These results are compatible with a prolactin-induced shift from a T4-5-monodeiodination into a T4-5′-monodeiodination in the liver at the end of incubation. This effect, however, is not mediated through a prolactin-induced corticosterone release.

J. Endocr. (1985) 104, 363–366
The Second International Reference Preparation of Thyroid-Stimulating Hormone, Human, for Immunoassay: calibration by bioassay and immunoassay in an international collaborative study
Authors: Gaines Das R. E. , Bristow A. F.
Published: December 2008

Four batches of ampouled materials in ampoules coded 80/558, 81/502, 81/565 and 81/615 were evaluated by 22 laboratories in nine countries in an international collaborative study for their suitability to serve as a replacement for the First International Reference Preparation (IRP) of TSH, Human, for Immunoassay. The ampouled preparations were calibrated by immunoassay and bioassay. The preparation coded 80/558 had satisfactory stability and contained acceptably low levels of contamination with FSH and LH. Estimates of the immunoreactive TSH content of a set of specimens of serum in terms of 80/558 showed agreement in ranking order and no increase in variability compared with estimates made by assay against the First IRP. On the basis of these results, with the agreement of the participants in the study, and with the authorization of the Expert Committee on Biological Standardization of the World Health Organization, the preparation coded 80/558 was established in 1983 as the Second International Reference Preparation of TSH, Human, for Immunoassay, with a defined potency of 37 mi.u./ampoule. Preparations coded 81/502, 81/565 and 81/615 were found suitable to serve as working standards.

J. Endocr. (1985) 104, 367–379
Control of zona glomerulosa function in the isolated perfused rat adrenal gland in situ
Authors: Hinson J. P. , Vinson G. P. , Whitehouse B. J. , Price G.
Published: December 2008

The extent to which results obtained using in-vitro techniques can be taken to reflect in-vivo physiological responses in the study of adrenocortical function has not been subjected to systematic study. Some evidence suggests that in-vitro preparative methods may affect the secreted steroid profile. For this reason it seemed desirable to study adrenal function using an isolated perfused whole gland technique, and this study reports results obtained with known aldosterone stimulants.

Angiotensin II, ACTH and potassium ions all stimulated aldosterone secretion in a dose-dependent manner. The stimulation thresholds of these substances were compatible with their normal circulating concentrations. For angiotensin II stimulation this preparation was two orders of magnitude more sensitive than any in-vitro preparation. Most importantly, the specific glomerulosa effectors, angiotensin II and potassium, selectively stimulated aldosterone output, and had no consistent effect on corticosterone secretion at any dose used. On the other hand, ACTH stimulated both corticosterone and aldosterone output at all effective concentrations.

The actions of α-MSH were also studied using this preparation. Low doses of α-MSH selectively stimulated aldosterone secretion, while higher doses were needed to stimulate corticosterone. The onset of response to all stimulants was invariably seen within the first 10 min after administration of stimulants. Maximal aldosterone output was achieved within the first 10 min whereas corticosterone secretion usually peaked 10–20 min later. The amount of aldosterone produced by this preparation was much higher than the amount produced by dispersed cell preparations, and closely approximated to the levels of aldosterone obtained in adrenal vein blood.

The data indicate that the isolated circulation perfused gland system is a sensitive preparation which approximates to the physiological condition. In particular, aldosterone is the prominent glomerulosa product, and corticosterone is, in this system, a more specific marker for inner zone function.

J. Endocr. (1985) 104, 387–395
Administration of synthetic human pancreatic growth hormone-releasing factor for five days sustains raised serum concentrations of growth hormone in steers
Authors: Moseley W. M. , Krabill L. F. , Friedman A. R. , Olsen R. F.
Published: December 2008

Serum GH concentrations in steers were examined during extended treatment with synthetic GH-releasing factor(1–44)NH2 (GRF). The results indicate that GRF given as frequent microinjections stimulate and sustain raised serum GH concentrations for at least 5 days in steers. The GH secretory pattern remained episodic and was characterized by a significant increase in the amplitude of the GH pulses without a change in the number of GH pulses per day.

In the first of two experiments, young Holstein steers received 0, 0·05, 0·5 or 5·0 mg GRF during a 24-h period as microinjections every 3·75 min. The 5·0 mg GRF/24 h dose significantly increased baseline GH, amplitude of GH pulses and area under the GH curve compared with the other treatments. The number of GH pulses/24 h was similar for all doses of GRF. In a second experiment with Holstein steers, administration of 3·6 mg GRF/day for 5 days increased serum GH concentrations throughout the duration of the treatment without altering the temporal GH secretory pattern. The GH response to GRF did not diminish from days 1 to 5 of treatment suggesting that there was no pituitary desensitization.

J. Endocr. (1985) 104, 433–439
Characterization of profiles of salivary progesterone concentrations during the luteal phase of fertile and subfertile women
Authors: Walker R. F. , Wilson D. W. , Truran P. L. , Read G. F. , Richards G. , Walker S. M. , Riad-Fahmy D.
Published: December 2008

Salivary progesterone concentrations were measured in daily samples collected between 08.00 and 09.00 h throughout the menstrual cycle of women with a history of fertility. The luteal-phase salivary progesterone profiles in these normally menstruating, healthy women were characterized using a computer program based on a cumulative sum procedure. This method of statistical analysis led to the development of a 'progesterone boundary diagram', the inner and outer domains of which distinguished between the profiles of salivary progesterone considered compatible with fertility, and those observed in subfertile women attending an infertility clinic.

J. Endocr. (1985) 104, 441–446
Characterization of thyroid-stimulating immunoglobulin-induced cyclic AMP accumulation in the rat thyroid cell strain FRTL-5: potentiation by forskolin and calibration against reference preparations of thyrotrophin
Authors: Bidey S. P. , Emmerson J. M. , Marshall N. J. , Ekins R. P.
Published: December 2008

A clonal strain of rat thyroid cells (FRTL-5) has been used to investigate the biological activity of a Research Standard preparation of long-acting thyroid stimulator (LATS-B). Using the accumulation of intracellular cyclic AMP as a response parameter, significant stimulation was attained at a LATS-B dose of 0·75 mu./ml. The inter-bioassay coefficient of variation in response to a fixed dose of LATS-B (1·25 mu./ml) was 20·5%, as determined using eight sequential subcultures. Cells cultured directly from frozen stocks responded to both bovine TSH and LATS-B in a manner indistinguishable from cells subjected to regular subculturing. Cyclic AMP responses to incremental doses of LATS-B were potentiated after the inclusion of a low dose of forskolin (0·1 μmol/l). However, forskolin addition had no effect on the time-course of LATS-B-stimulated cyclic AMP accumulation, half-maximal responses being attained after 60 min in either the presence or absence of the diterpene. In the presence of 0·1 μmol forskolin/l, intracellular cyclic AMP responses to LATS-B were demonstrably parallel with those to human TSH (Second International Reference Preparation, 80/558), whilst parallel incremental cyclic AMP responses were also observed in respect of TSH and serial dilutions of a potent thyroid-stimulating immunoglobulin (TSIg) preparation, indicating that for this particular Graves' disease patient, TSIg bioactivity may be expressed in terms of a convenient and reproducible standard, as TSH microunit equivalents.

J. Endocr. (1985) 105, 7–15
The production and characterization of monoclonal antibodies to the human thyroid microsome
Authors: Weetman A. P. , Gunn C. A. , Rennie D. P. , Hall R. , McGregor A. M.
Published: December 2008

By suitable immunization of mice and fusion of their spleen cells with a non-secretor mouse myeloma line, monoclonal antibodies have been produced which react with the human thyroid microsomal (M) antigen. These monoclonal antibodies showed no reactivity by enzyme-linked immunoassay with liver microsomes or thyroglobulin and their specificity was confirmed by immunolocalization studies, in which they showed the staining characteristics of human M antibodies. All four monoclonal antibodies tested were immunoglobulin M; three were cytotoxic to thyroid cell monolayers. The lack of cytotoxicity with the fourth monoclonal supports the concept that certain epitopes of the M antigen may be partially or completely absent at the thyroid cell surface. These monoclonal antibodies should permit further characterization of the thyroid M antigen in view of their absence of cross-reactivity with thyroglobulin.

J. Endocr. (1985) 105, 47–52
Peripheral androgen levels in the male brush-tail possum (Trichosurus vulpecula)
Authors: Curlewis J. D. , Stone G. M.
Published: December 2008

Radioimmunoassays were established for the measurement of total androgens and the specific measurement of testosterone and 5α-dihydrotestosterone in peripheral plasma of the brush-tail possum. Androgen concentrations were measured in blood collected from indwelling jugular cannulae (i) to determine whether the normal pattern of androgen secretion in this species was episodic and (ii) to attempt to relate total androgen and the pattern of testosterone secretion to the changes previously reported in prostatic, but not epididymal, weight in the breeding season. Blood was collected from restrained animals at varying time-intervals during daylight hours and darkness. Despite an apparent good adaptation to the sampling procedure there was generally a progressive decline in plasma androgen level during the collection period. This was true for animals bled during or out of the breeding season. There was no significant seasonal effect on the androgen concentration in the initial blood sample. When less restraint was used, two of three animals showed fluctuations in androgen levels over the 7-h sampling period. Testosterone levels in blood obtained by cardiac puncture were four- to nine-fold higher than those of 5α-dihydrotestosterone but levels of these androgens in samples obtained during the breeding season were not significantly different from those obtained out of season. The results do not argue for a pulsatile release of testosterone in the possum but do demonstrate a marked capacity for changes in the peripheral androgen concentration. There was a poor correlation between testosterone and 5α-dihydrotestosterone levels and prostatic weight.

J. Endocr. (1985) 105, 63–70
Supraoptic neurones in Brattleboro rats respond normally to changes in plasma osmotic pressure
Authors: Dyball R. E. J. , Leng G.
Published: December 2008

Brattleboro rats homozygous for hypothalamic diabetes insipidus (DI rats) were anaesthetized with urethane. Extracellular recordings were made from antidromically identified neurones of the supraoptic nucleus. About half (77 out of 153) of the neurones recorded in DI rats showed phasic patterns of discharge activity similar to those which are characteristic of vasopressin-secreting neurones in normal rats during hyperosmotic stimulation. Significantly fewer neurones showed phasic activity in DI rats which had been pretreated with vasopressin tannate at a dose which significantly reduced urine volume, water intake and plasma osmolality. Acute systemic hyperosmotic stimulation, induced by an i.p. injection of 1 ml 1·5 m-NaCl, increased the discharge rate of each of 14 neurones from DI rats by 1–5 spikes/s. Hypo-osmotic stimulation, induced by an intragastric injection of 10 ml tap water, reduced the discharge rate of each of four neurones from DI rats by 50% or more.

We conclude that supraoptic neurones in DI rats respond normally to acute systemic osmotic stimuli despite the total absence of vasopressin in these rats and despite their chronically disturbed water balance. This implies that the osmoreceptor mechanism which drives the supraoptic nucleus does not adapt substantially during prolonged disturbance of water balance and functions outside the normal physiological range of plasma osmolality, and that the reported alteration of noradrenergic innervation of the neurones in DI rats does not affect their osmotic responsiveness.

J. Endocr. (1985) 105, 87–90
Stimulation of androgen and oestrogen concentrations in plasma of cows after administration of a synthetic glucocorticoid (flumethasone) at the end of gestation
Authors: Möstl E. , Choi H. S. , Bamberg E.
Published: December 2008

Administration of flumethasone (3·5 mg i.m.) to six cows on day 260 of pregnancy induced parturition in only one animal. In the other five cows circulating concentrations of epitestosterone and conjugated oestrogens increased to reach maximum values (epitestosterone, 13·73 ± 2·81 nmol/l; conjugated oestrogens, 33·59 ± 6·87 nmol/l) 2–3 days after treatment. Concentrations of these steroids were raised as long as the synthetic glucocorticoid was present in the circulation (as judged by depression of cortisol concentrations). After clearance of the drug, concentrations of these steroids declined to values present in the control group. Concentrations of unconjugated oestrogens were only slightly raised after flumethasone.

In contrast to the effect observed after administration on day 260, treatment on day 270 induced parturition in four of six treated animals. In these cows, mean circulating concentrations of epitestosterone, unconjugated and conjugated oestrogens increased to 9·50 ± 2·96, 9·62 ± 1·48 and 36·51 ± 4·8 nmol/l respectively to reach concentrations observed in the control group at parturition. After parturition the concentrations of epitestosterone and oestrogens declined rapidly in all groups.

J. Endocr. (1985) 105, 121–126
The genetic background of circadian and ultradian rhythm patterns of 17-hydroxycorticosteroids: a cross-twin study
Authors: Reinberg A. , Touitou Y. , Restoin A. , Migraine C. , Levi F. , Montagner H.
Published: December 2008

Circadian and ultradian rhythms in urinary excretion of 17-hydroxycorticosteroids were documented individually during an 8-day span in two pairs of young male twins. Studies were performed once at the age of 6 years for dizygotic twins and twice at the ages of 4·3 and 10·3 years for monozygotic twins. Four different methods were used for time-series analyses: chronograms (raw data), best-fitting curves resulting from cosinor analyses, power spectra and correlations of time-qualified data. Estimates of rhythm parameters (prominent periods, acrophases, etc.) as well as shapes of curves were closer in mono- than in dizygotic twins. Both similarities and small differences in rhythm characteristics of monozygotic twins were detected at both ages considered.

J. Endocr. (1985) 105, 247–253
Vasopressin-neurophysin II gene expression in the ovary: studies in Sprague–Dawley, Long–Evans and Brattleboro rats
Authors: Fuller P. J. , Clements J. A. , Tregear G. W. , Nikolaidis I. , Whitfeld P. L. , Funder J. W.
Published: December 2008

The neurohypophysial hormones oxytocin and arginine vasopressin (AVP) have been identified on immunological criteria in the ovary. Confirmation of extraneuronal synthesis requires the demonstration in the tissue of the specific messenger RNA (mRNA) for the preprohormone. Using a synthetic pentadecamer nucleotide probe, highly specific for the 5′ region of rat neurophysin II (NPII), we have demonstrated the presence of AVP-NPII mRNA in the ovary of Sprague–Dawley, Long–Evans and Brattleboro rats, with an apparent molecular weight identical to that seen for hypothalamus. These findings, together with the presence of immunoreactive AVP in the ovaries but not hypothalami of Brattleboro rats, suggest that tissue-specific differences in AVP-NP II gene expression occur at the translational as well as transcriptional level.

J. Endocr. (1985) 105, 317–321
Antibiotics attenuate experimental hypertension in rats
Authors: Honour J. W. , Borriello S. P. , Ganten U. , Honour P.
Published: December 2008

Hypertension was produced in Sprague–Dawley rats by intramuscular injections of either corticosterone or ACTH. Lower increases in blood pressure to these challenges were observed in Sprague–Dawley rats pretreated with neomycin or vancomycin which alone had no effect on blood pressure or growth. The development of high blood pressure in spontaneously hypertensive rats of a stroke-prone substrain was also attenuated by oral administration of neomycin. These results suggest that experimental hypertension can be modulated by the administration of antibiotics.

J. Endocr. (1985) 105, 347–350
Gonadotrophin excretion in fertile women: effect of age and the onset of the menopausal transition
Authors: Metcalf M. G. , Livesey J. H.
Published: December 2008

In normal women the menopausal transition starts typically with a sudden break in regular menstrual cyclicity: gonadotrophin levels escape from the cyclical pattern characteristic of fertile women and increasingly rise into the postmenopausal range. An investigation was undertaken to determine whether this rise precedes the first appearance of ovarian dysfunction.

Weekly urine samples for the measurement of FSH, LH and pregnanediol were collected from 100 women, all of whom had regular 20- to 35-day menstrual cycles (504 samples from 48 women aged 20–39 years and 620 samples from 52 women aged 40–48 years; 96·8% of these cycles were shown to be ovulatory).

Excretion rates of FSH in excess of 5 i.u./24 h occurred more often in women aged ≥ 40 years than in younger women (incidence, 31·5 cf. 19·5%; P < 0·001). The difference was greatest at the time of the perimenstruum (7-day incidence, 32·5 cf. 13·9%) and declined to insignificance during the mid-cycle gonadotrophin surge (7-day incidence, 44·2 cf. 34·8%). Examination of the rank correlation between age and gonadotrophin excretion confirmed the age-related rise in FSH and identified a lesser but significant perimenstrual rise in LH. For both FSH and LH these changes were small compared with the increases observed in nine women presumed to have reached the menopausal transition during the trial (incidence FSH ≥ 5 i.u./24 h, 60·6%; incidence LH ≥ 5 i.u./24 h, 48·6%).

It is concluded that in fertile women there is evidence of an age-related rise in FSH which is distinct from the changes occurring at the start of the menopausal transition.

J. Endocr. (1985) 105, 357–362)
Vitamin D metabolites regulate osteocalcin synthesis and proliferation of human bone cells in vitro
Authors: Skjødt H. , Gallagher J. A. , Beresford J. N. , Couch M. , Poser J. W. , Russell R. G. G.
Published: December 2008

The effects of six natural vitamin D metabolites of potential biological and therapeutic interest, 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3), 25-hydroxyvitamin D3 (25-OH-D3), 24R,25-dihydroxyvitamin D3 (24R,25-(OH)2D3), 1,24R,25-trihydroxyvitamin D3 (1,24R,25-(OH)3D3), 25S,26-dihydroxyvitamin D3 (25S,26-(OH)2D3) and 1,25S,26-trihydroxyvitamin D3 (1,25S,26-(OH)3D3) on cell replication and expression of the osteoblastic phenotype in terms of osteocalcin production were examined in cultured human bone cells. At a dose of 5 × 10−12 mol/l, 1,25-(OH)2D3 stimulated cell proliferation, whereas at higher doses (5 × 10−9−5 × 10 −6 mol/l) cell growth was inhibited in a dose-dependent manner. The same pattern of effects was seen for the other metabolites in a rank order of potency: 1,25-(OH)2D3> 1,25S,26-(OH)3D3 = 1,24R,25-(OH)3D3>25S,26-(OH)2D3 = 24R,25-(OH)2D3 = 25-OH-D3. Synthesis of osteocalcin was induced by 1,25-(OH)2D3 in doses similar to those required to inhibit cell proliferation. Biphasic responses were observed for some of the metabolites in terms of osteocalcin synthesis, inhibitory effects becoming apparent at 5 × 10−6 mol/l. The cells did not secrete osteocalcin spontaneously. These results indicate that vitamin D metabolites may regulate growth and expression of differentiated functions of normal human osteoblasts.

J. Endocr. (1985) 105, 391–396
EVIDENCE FOR A NOVEL INHIBITION OF CALCIUM UPTAKE INTO CHICK BONE IN RESPONSE TO BOVINE PARATHYROID HORMONE (1-34) OR 16, 16-DIMETHYL PROSTAGLANDIN E2 IN VIVO
Authors: Shaw A.J. , Dacke C.G.
Published: December 2008

Mechanisms of initial hypercalcaemic responses to parathyroid hormone (PTH) and 16, 16-dimethyl prostaglandin (PG) E2 have been investigated in 10-to 12-day-old chicks in vivo using a combination of acute 45Ca injection and microwave fixation to stabilize tissue isotope levels.

Single i.v. injection of 16, 16-dimethyl PGE2 (20 μg/100 g body wt) caused an approximately 100% increase in soft tissue 45Ca levels compared with vehicle control injected chicks at 30 min. 45Ca levels were lowered in calvarium by 26% and in femur by 60% with this treatment. Bovine PTH (1-34) (3.3 μg/100 g body wt) had no effect on soft tissue 45Ca levels, but in calvarium it had a similar effect to the PG. In femur this dose of PTH lowered 45Ca by 19%. When expressed on an absolute basis (c.p.m./ 100 mg tissue wt), responses to the PG in soft tissue were only 3 and 10% respectively of those in femur and calvarium.

The duration of inhibitory responses in bone were examined and those to PTH found to be transient (< 45 min) compared with the responses to the PG (> 135 min). Dose-response curves for PTH- and PG-induced inhibition of 45Ca uptake into femur at 15 min were essentially parallel and indicated that the lowest doses of PTH and PG used (0.74 μg and 1.1 μg/100 body wt respectively) produced significant responses.

In a separate experiment it was found that inhibition of 45Ca uptake into femur was evident as early as 3 min following PTH or PG injection.

The experiments described in this paper collectively indicate a higherto unrecognized action of PTH and PGE in the regulation of Ca metabolism in chicks which is to inhibit entry of Ca into bone.