bluuebunny/crossref_metadata_2025 huggingface dataset:
Adrenal status during the first month of life in mature and premature human infants
Authors: Wallace A. M. , Beesley J. , Thomson M. , Giles C. A. , Ross A. M. , Taylor N. F.
Published: December 2008

Measurements of (a) 17-hydroxyprogesterone (17-OHP) in blood collected onto filter paper after heel puncture by lancet and (b) steroid metabolites in random collections of urine, were made in human infants born from 25 weeks of gestation onwards. The concentration of 17-OHP in blood eluted from filter paper samples was inversely related to both gestational age and birth weight. In mature infants, 17-OHP concentrations fell rapidly soon after birth, whereas concentrations remained high over the first month of life in infants born earlier than 33 weeks of gestation. Sulphated urinary steroids were identified as having a 3β-hydroxy-5-ene structure and although the pattern of excretion was similar in mature and premature infants, significantly higher concentrations were found in the premature group. Steroid metabolites normally present when concentrations of circulating 17-OHP are increased due to 21-hydroxylase deficiency were not detectable in urine samples collected from infants born prematurely. Where direct comparison of 17-OHP in blood spots and urinary steroid metabolites was possible, the concentrations of 17-OHP in blood samples paralleled 3β-hydroxy-5-ene steroid metabolites in urine. The results suggest that a circulating cross-reacting 3β-hydroxy-5-ene steroid may be responsible for increased concentrations of 17-OHP in infants born prematurely. Increased concentrations of both 17-OHP in blood spots and steroid sulphates in urine were associated with stress in premature, but not in more mature, infants suggesting that in infants born prematurely postnatal stress may delay adrenal maturation.

J. Endocr. (1987) 112, 473–480
STEROIDAL PURE ANTIOESTROGENS
Authors: Wakeling A.E. , Bowler J.
Published: December 2008

The effects of some novel 7α-alkyl amide analogues of oestradiol on the rat and mouse uterus have been measured. The compound ICI 164,384 [N-n-butyl-N-methyl-11-(3,17β-dihydroxyoestra-1,3,5(10)-trien-7αyl) undecamide] was entirely devoid of oestrogenic activity in the rat and mouse uterus but completely blocked the uterine stimulatory effects of oestradiol and of tamoxifen. Biological activity was confined to 7α-isomers. The affinity of ICI 164,384 for the rat uterus oestrogen receptor (0.19) was substantially greater than that of tamoxifen (0.025 c.f. oestradiol=l). The compound inhibited oestradiol-induced growth of ZR-71-1 cells in a dose-dependent manner in vitro. ICI 164,384 thus has the characteristics of a pure antagonist of oestrogen action.
Failure of the synthetic androgen 17β-hydroxy-17α-methylestra-4,9,11-triene-3-one (methyltrienolone, R1881) to duplicate the activational effect of testosterone on mating in castrated male rats
Authors: Baum M. J. , Kingsbury P. A. , Erskine M. S.
Published: December 2008

Administration of the synthetic steroid, 17β-hydroxy-17α-methyl-estra-4,9,11-triene-3-one (methyltrienolone, R1881), which is an androgen receptor agonist not metabolized in vivo, at doses of 400, 800 or 2400 μg/kg s.c. in propylene glycol stimulated mounting and ejaculation only slightly in sexually experienced castrated rats. A similar low level of mating was observed in a group of castrated rats given testosterone at doses of 400 followed by 800 μg/kg. However, when treated with a higher dose of testosterone (2400 μg/kg) these castrated rats displayed significantly higher levels of mounting and ejaculation than rats treated with any of the doses of R1881. Also, when this higher dosage of testosterone was substituted for each dose of R1881, significant increments in mounting and ejaculation occurred in all groups. These findings show that R1881 is only marginally effective in restoring sexual behaviour in castrated rats, suggesting that the activation of neural androgen receptors cannot by itself account for the activational effect of testosterone on mating behaviour in gonadally intact male rats.

J. Endocr. (1987) 113,15–20
Effects of catecholaminergic blockade by haloperidol or propranolol at different stages of the oestrous cycle on ovulation and gonadotrophin levels in the rat
Authors: Domínguez R. , Gaitán C. M. , Méndez S. A. , Ulloa-Aguirre A.
Published: December 2008

Rats with a 4-day oestrous cycle were injected with 2·5 mg haloperidol/kg, a dopaminergic blocker, or with 2·0 mg propranolol/kg, a β1- and β2-receptor blocker, at 13.00 h on oestrus, dioestrous day 1, diestrous day 2 or pro-oestrus. Animals were autopsied on the next expected day of oestrus. Haloperidol blocked ovulation when injected on oestrus, dioestrous day 1 or pro-oestrus and was less effective when injected on dioestrous day 2. Propranolol caused a decrease in the number of ova shed when injected on dioestrous day 2 or pro-oestrus. Serum concentrations of FSH at oestrus were below the control values in those animals in which ovulation was blocked by haloperidol. No significant changes in serum concentrations of LH were observed. The normal gonadotrophin peak which occurs during the afternoon of pro-oestrus was blocked by administration of haloperidol on oestrus or dioestrous day 1. Administration of gonadotrophin-releasing hormone (GnRH) to haloperidol-treated animals on oestrus or dioestrous day 1 did not restore ovulation or increase serum FSH levels. When the same dose of GnRH was given to rats treated with haloperidol on pro-oestrus, they all ovulated and their FSH levels rose normally. Treatment with both FSH and LH of rats given haloperidol at oestrus restored ovulation in 50% of the animals, whereas it was ineffective in animals treated on dioestrous day 1. Fifty per cent of the animals treated with haloperidol on oestrus or dioestrous day 1 ovulated when oestradiol benzoate was injected on dioestrous day 2.

These results suggest that the dopaminergic and adrenergic systems have different roles in the regulation of the oestrous cycle and ovulation. The decrease in the number of ova shed induced by propranolol may be related to the blockade of receptors at the level of the ovary. The sensitivity of the dopaminergic systems involved in gonadotrophin control seems to vary depending on the day of the oestrous cycle. It is possible that when the dopaminergic system is blocked at the beginning of the cycle, an alteration in oestrogen secretion might be produced, initiating a chain of events at the hypothalamic-pituitary-ovarian axis which will ultimately inhibit ovulation. Since dopaminergic blockade induces an increase in prolactin secretion, and prolactin enhances dopamine turnover at the median eminence and blocks oestrogen secretion at the level of the ovary, the present results might also reflect the effects of haloperidol at two different levels, i.e. increased dopamine turnover at the median eminence and decreased secretion of oestrogens.

J. Endocr. (1987) 113, 37–44
Somatostatin-like immunoreactivity in duck plasma, hypothalamus and neural lobe during post-hatch growth: comparison with plasma and pituitary growth hormone concentrations
Authors: Foltzer Ch. , Harvey S. , Mialhe P.
Published: December 2008

Variations in the concentrations of plasma and pituitary GH were determined in ducks for 66 and 87 days after hatch, and compared with somatostatin-like immunoreactivity (SLI) in the plasma, hypothalamus and neural lobe. Plasma GH levels gradually decreased during growth, while pituitary GH content increased. The concentration of pituitary GH increased during the first 3 weeks of age and remained relatively constant thereafter. The decline in plasma GH concentration was paralleled by a similar fall in the level of plasma SLI. While the content of hypothalamic SLI increased during development, the SLI concentration was maximal at 14 days of age and lowest in adults. The content and concentration of SLI in the neural lobe, in contrast, increased progressively during development. Gel filtration of hypothalamic and neural lobe extracts demonstrated that both young and older birds had two main peaks of SLI, corresponding to somatostatin-14 and somatostatin-28, and a third, larger form. The elution pattern of plasma SLI was similar in young and older birds and was principally composed of a large molecular species ('big' somatostatin), although an additional small peak eluting between somatostatin-28 and somatostatin-14 was eluted from a large pool of plasma from 90-day-old ducks. These results suggest that increased plasma GH levels in young birds do not result from a hypothalamic somatostatin deficiency nor from variations in molecular forms of SLI, and that the age-related decline in plasma GH concentration is not due to a deficiency in pituitary GH content. The decline in the circulating GH level during growth is probably due to an increase in hypothalamic somatostatin release.

J. Endocr. (1987) 113, 57–63
The contribution of corticosterone and testosterone to the suppression of serum LH in hyperprolactinaemic adult male rats with pituitary transplants
Authors: Weber R. F. A. , Ooms M. P. , Vreeburg J. T. M.
Published: December 2008

The effects of hyperprolactinaemia on serum levels of LH were investigated in adult male rats of the R × U strain. Hyperprolactinaemia was induced by three pituitary grafts under the kidney capsule, transplanted on day 0 of each experiment. Special attention was paid to the contribution of prolactin-stimulated testes, adrenals and corticosterone.

In experiment 1, hyperprolactinaemia significantly reduced the serum concentrations of LH in intact rats. In spite of a significant increase in the serum levels of corticosterone, serum testosterone was not significantly affected by hyperprolactinaemia. The weights of both the adrenals and accessory sex glands were significantly increased at autopsy. In experiment 2, treatment with 10 mg corticosterone s.c. daily from day 14 to day 28 after pituitary grafting significantly reduced serum levels of both LH and testosterone. The suppression of testosterone in the hyperprolactinaemic corticosterone-treated animals was significantly less than in the corticosterone-treated control animals. The weights of the accessory sex glands were significantly increased in the hyperprolactinaemic animals. In experiment 3, rats were adrenalectomized and half of them were substituted with corticosterone. Serum testosterone levels significantly increased in both hyperprolactinaemic adrenalectomized rats and in adrenalectomized corticosterone-treated animals without any significant effect on serum LH. Again the weights of the accessory sex glands were significantly increased in the hyperprolactinaemic animals. In experiment 4, rats were adrenalectomized, gonadectomized and corticosterone treated on day 0 and then implanted with a 2, 1·5 or 1 cm silicone elastomer capsule containing testosterone. On day 28 after pituitary grafting, LH levels were significantly suppressed in animals with a 2 or 1·5 cm testosterone implant. The weights of the accessory sex glands were not increased in the hyperprolactinaemic animals.

These results show that in the male rat the inhibitory effects of hyperprolactinaemia on serum LH levels may be due to (1) increased sensitivity of the hypothalamic-pituitary axis to the negative feedback action of testosterone by prolactin and by the prolactin-stimulated corticosterone secretion and (2) stimulation of testicular testosterone secretion by prolactin, which can also explain the increased weights of the accessory sex glands. Even in the presence of high serum concentrations of corticosterone, stimulation of testicular testosterone secretion by prolactin was observed.

J. Endocr. (1987) 113,111–116
Autoradiographic localization of binding sites for oxytocin and vasopressin in the rat kidney
Authors: Stoeckel M. E. , Freund-Mercier M. J. , Palacios J. M. , Richard Ph. , Porte A.
Published: December 2008

The distribution of [3H]vasopressin- and [3H]oxytocin-binding sites was examined, using an autoradiographical technique, in the kidney of Long–Evans and Brattleboro rats. Two types of binding sites with affinities in the nanomolar range were detected: one, located on glomeruli, bound both vasopressin and oxytocin; the other, on collecting ducts, bound vasopressin selectively. In the presence of 10 μmol oxytocin/1, [3H]vasopressin labelling was abolished in glomeruli, but only reduced in collecting ducts; [3H]oxytocin labelling was completely abolished by 10 μmol vasopressin/1. These observations are discussed in relation to known effects of neurohypophysial hormones on renal physiology.

J. Endocr. (1987) 113, 179–182
Peripheral plasma concentrations of pregnenolone sulphate, pregnenolone, progesterone and 20α-hydroxy-4-pregnen-3-one in ewes throughout the oestrous cycle
Authors: McKay S. A. , Jenkin G. , Thorburn G. D.
Published: December 2008

Pregnenolone sulphate, pregnenolone, progesterone and 20α-hydroxy-4-pregnen-3-one concentrations in peripheral plasma of normal cyclic ewes were measured by radioimmunoassay. The concentrations of these steroids were correlated with that of progesterone. The concentrations of all the steroids measured in peripheral plasma varied in a cyclic manner and showed a significant (P <0·05) positive correlation with the concentration of progesterone.

Peripheral plasma concentrations of these steroids in ovariectomized and ovariectomized, dexamethasone-treated ewes were also determined. The plasma concentration of progesterone in ovariectomized ewes was undetectable but the concentrations of pregnenolone sulphate, pregnenolone and 20α-hydroxy-4-pregnen-3-one remained similar to those observed at oestrus. Administration of dexamethasone to ovariectomized ewes had no effect on pregnenolone sulphate or pregnenolone concentrations but 20α-hydroxy-4-pregnen-3-one concentrations, which were already very low, decreased further.

It is proposed that the ovary, probably the corpus luteum, secretes pregnenolone sulphate, pregnenolone and 20α-hydroxy-4-pregnen-3-one; however, pregnenolone sulphate and 20α-hydroxy-4-pregnen-3-one may also arise from the metabolism of circulating pregnenolone and progesterone.

J. Endocr. (1987) 113, 231–237.
Stimulation of intestinal epithelial cell proliferation in culture by growth factors in human and ruminant mammary secretions
Authors: Corps A. N. , Brown K. D.
Published: December 2008

Samples of human and ruminant mammary secretions stimulated the proliferation of rat intestinal epithelial (RIE-1) cells in culture. The stimulation was dose-dependent, and samples taken prepartum had greater potency than those taken after parturition. When various hormones and growth factors known to be present in milk were tested, only epidermal growth factor (EGF), insulin and insulin-like growth factor I (IGF-I) stimulated the proliferation of RIE-1 cells. IGF-I was effective at lower concentrations than insulin, and the maximal stimulation induced by each of these two polypeptides was greater than that induced by EGF. The maximal stimulation induced by samples of mammary secretions was similar to that induced by insulin or IGF-I.

J. Endocr. (1987) 113, 285–290
Specific binding sites for LH/chorionic gonadotrophin, low-density lipoprotein, prolactin and FSH in homogenates of human corpus luteum. I: Validation of methods
Authors: Bramley T. A. , Stirling D. , Swanston I. A. , Menzies G. S. , Baird D. T.
Published: December 2008

The specific binding of 125I-labelled human chorionic gonadotrophin (hCG), human low-density lipoprotein (hLDL), human FSH (hFSH) and human prolactin (hPRL) to homogenates of human corpus luteum tissue was measured.

Specific binding of 125I-labelled hCG was dependent on the temperature and duration of incubation, was inhibited by divalent metal ions or chelating agents, and increased linearly with homogenate concentration. Recovery of bound hormone was more effective using Millipore filtration or polyethylene glycol precipitation compared with centrifugation alone. Binding of 125I-labelled hCG was inhibited specifically by low levels of hCG and human LH (hLH) but not by ovine LH or bovine LH. Incubation of human luteal tissue with ice-cold citrate buffer (pH 3) released more than 90% of specifically bound 125I-labelled hCG within 5 min. This treatment inactivated LH receptors, but did not affect the immunoactivity of hLH released, enabling the measurement of released hormone by radioimmunoassay.

Scatchard plots of binding of 125I-labelled LDL to human corpus luteum demonstrated a single class of binding sites. Binding was saturable, increased linearly with increasing concentration of homogenate, and was displaceable by low concentrations of unlabelled LDL.

Binding of 125I-labelled hPRL to human luteal homogenates was increased by Mg2+ and was specific for lactogenic hormones (human prolactin, human growth hormone and ovine prolactin). Binding of 125I-labelled hFSH was not dependent on divalent metal ion concentration (in marked contrast to hFSH binding to immature pig granulosa cell receptors) and was displaced by hFSH preparations but not by hPRL, ovine LH or hCG at 1 μg/ml.

These results establish optimal conditions and hormone specificities for the measurement of human luteal gonadotrophin and LDL receptors, and methods for the estimation of hLH/hCG endogenously bound to human corpus luteum tissue.

J. Endocr. (1987) 113, 305–315
Influence of bromocriptine and oestrogen on prolactin synthesis, secretion and tumour growth in vivo in rats
Authors: Vrontakis M. E. , Thliveris J. A. , Friesen H. G.
Published: December 2008

The effects of diethylstilboestrol implants and bromocriptine administration on serum prolactin concentrations, prolactin messenger RNA (mRNA) and pituitary tumour weight were examined. Intact female Fischer 344 rats were implanted s.c. with 10 mg diethylstilboestrol (DES) under light anaesthesia. All animals except the control group carried the implant for 7 weeks at which time the rats were subdivided into five groups: A, control; B, DES for 7 weeks; C, DES for 7 weeks followed by withdrawal of DES for 1 week; D, DES for 7 weeks followed by withdrawal of DES and administration of bromocriptine for 1 week; E, DES for 8 weeks with concurrent administration of bromocriptine during the last week. Serum concentrations of prolactin were measured by radioimmunoassay, prolactin mRNA concentrations were measured by dot-blot hybridization and sodium dodecylsulphate–polyacrylamide gel electrophoresis of the in-vitro translated mRNA. Pituitary growth was estimated by changes in pituitary weight and assessed by light and electron microscopic examination.

Treatment with DES dramatically increased serum prolactin concentrations and prolactin mRNA and induced pituitary tumour formation as shown by histological changes. Withdrawal of DES for 1 week did not lead to a decrease in pituitary tumour weight but was accompanied by a decrease in serum prolactin concentrations and prolactin mRNA from peak concentrations although they remained significantly increased above controls. Treatment with bromocriptine after DES implants were removed led to a significant reduction in pituitary tumour weight and a decrease in serum prolactin concentrations and prolactin mRNA. Histology of the pituitary tumour after the bromocriptine treatment showed pituitary cells similar to those from normal animals. In group E, when bromocriptine was administered in the presence of DES implants, no reduction in pituitary tumour weight occurred but serum prolactin concentrations and prolactin mRNA decreased almost to normal concentrations. Histology of the pituitary showed most cells remaining hypertrophied and similar in appearance to those seen in animals treated with DES alone. These results suggest that the mechanisms by which oestrogen and bromocriptine control prolactin synthesis and secretion are independent from those which influence pituitary tumour growth and regression.

J. Endocr. (1987) 113, 383–388
Diurnal variations in plasma concentrations of cortisol, prolactin, growth hormone and glucose in the fetal sheep and pregnant ewe during late gestation
Authors: McMillen I. C. , Thorburn G. D. , Walker D. W.
Published: December 2008

We have measured fetal and maternal plasma concentrations of cortisol, prolactin, GH and glucose in samples collected during a 24-h period in 14 animals between 127 and 142 days of gestation. There was a significant increase in both the mean daily plasma cortisol concentration and mean daily coefficient of variation (C.V.) of plasma cortisol concentrations after 135 days of gestation. There was also a significant variation in the fetal plasma cortisol concentrations with a peak occurring at 19.00 h. There was a significant sinusoidal diurnal rhythm in the plasma prolactin concentrations in both the fetal sheep and pregnant ewe and the maximal prolactin concentrations occurred between 19.00 and 23.00 h (fetal) and 21.00 and 01.00 h (maternal). Although no significant diurnal variation was detected in fetal plasma GH concentrations, there was a significant sinusoidal diurnal rhythm in the plasma GH concentrations of the pregnant ewe and the maximal maternal GH concentrations occurred between 21.00 and 01.00 h. Both the fetal and maternal plasma glucose concentrations showed a significant sinusoidal diurnal rhythm. The maximal maternal and fetal glucose concentrations were measured between 21.00 and 01.00 h and between 23.00 and 03.00 h respectively. We have therefore established that diurnal variations in plasma cortisol and prolactin concentrations exist prenatally. Whether the presence of such hormonal rhythms reflects the activity of an endogenous fetal circadian pacemaker remains to be established.

J. Endocr. (1987) 114, 65–72
Plasma Met-enkephalin and catecholamine responses to insulin-induced hypoglycaemia in greyhounds
Authors: Medbak S. , Mason D. F. J. , Rees L. H.
Published: December 2008

The involvement of endogenous opioid peptides in the stress response was investigated by measuring plasma concentrations of Met-enkephalin-like immunoreactivity (MLI), adrenaline and noradrenaline during insulin-induced hypoglycaemia in conscious greyhounds. Moreover, the molecular forms of circulating MLI were characterized using gel filtration chromatography.

In the first group of animals, i.v. administration of insulin (0·3 units/kg) provoked marked hypoglycaemia (blood glucose concentrations fell from 4·4 ± 0·1 to 1·5 ±0·2 mmol/l; mean ± s.e.m.) which was associated with significant (P< 0·001) rises in plasma MLI concentrations from a basal concentration of 45 ± 8 to a peak of 189 ±39 ng/l.

A within-subject study comparing five different insulin doses ranging from 0·004 to 0·3 units/kg showed dose-related effects on blood glucose with nadir concentrations of 4·1 ± 0·6 mmol/l (after the smallest dose of insulin) and 0·8 ± 0·1 mmol/l (after the largest dose of insulin). This was associated with dose-related rises in plasma MLI with peak concentrations of 56±17 and 558 ± 35 ng/l, plasma adrenaline with peak concentrations of 0·45± 0·06 and 15·76±1·33 nmol/l and plasma noradrenaline with peak concentrations of 0·49 ± 0·07 and 2·27 ± 0·45 nmol/l following the smallest and largest doses of insulin respectively. These results are the first demonstration of raised plasma MLI concentrations following hypoglycaemia. Moreover, they show that the hormonal responses vary with the degree of hypoglycaemia achieved. Together with reports by other investigators these findings might suggest opioid modulation of the responses of the sympathoadrenal system to hypoglycaemia. These responses were, however, not modified by the opioid antagonist naloxone.

Gel filtration chromatography of neat (unextracted) plasma revealed the predominance of large molecular weight enkephalin-containing peptides, with approximate molecular weights of 18 000 and 8000, both basally and following stimulation by hypoglycaemia.

J. Endocr. (1987) 114,81–87
Insulin-modulated interleukin-2 production by murine splenocytes and a T-cell hybridoma
Authors: Pavelić K. , Bernacki R. J. , Vuk-Pavlović S.
Published: December 2008

Murine interleukin-2 (IL-2)-producing AOFS 21 T-cell hybridoma cells and normal murine splenocytes were stimulated in serum-free media by 16 potential mitogens/growth factors. Only insulin, concanavalin A (Con A), peptidoglycan monomer and a tumour-derived insulinoid stimulated [3H]thymidine incorporation by AOFS 21 cells and splenocytes. Supernatants of these stimulated cultures were tested for IL-2 activity which generally followed the pattern of growth stimulation. Both the mitogenicity and stimulation of IL-2 secretion by insulin were second only to the effects of Con A.

J. Endocr. (1987) 114, 89–94
Effect of prolactin, progesterone, pregnancy and lactation on DNA synthesis and DNA polymerase activities in rabbit mammary gland
Authors: Zwierzchowski L. , Niedbalski W. , Kleczkowska D.
Published: December 2008

DNA synthesis and DNA polymerase-α, -β and -γ activities in the rabbit mammary gland were studied during hormone-directed cellular growth. It was found that during pregnancy, early lactation and after injection of prolactin, changes in the activity of DNA polymerase-α paralleled the rate of mammary gland DNA synthesis. It was also found that the amount of polymerase-α activity bound to isolated chromatin depended on the physiological state of the animal. During pregnancy and early lactation changes in the activity of chromatin-bound enzyme correlated directly with the rate of DNA synthesis (r = 0·83). Moreover, in virgin rabbits treated with prolactin the activity of chromatin-bound DNA polymerase-α increased markedly at the same time as the DNA-synthetic rate increased. No correlation of the DNA-synthetic rate was found with the activity of soluble (cytosolic) DNA polymerase-α or with the activity of soluble or chromatin-bound DNA polymerases-β and -γ.

On the basis of these results it is suggested that in the developing mammary gland both the activity and cellular distribution of DNA polymerase-α might be subject to hormonal regulation.

J. Endocr. (1987) 114, 139–145
Effect of age on renal responsiveness to parathyroid hormone and calcitonin in rats
Authors: Armbrecht H. J. , Wongsurawat N. , Paschal R. E.
Published: December 2008

The purpose of these studies was to determine whether the responsiveness of the kidney to parathyroid hormone (PTH) and calcitonin changed with age. Experiments were performed in young (3 months old), adult (12–14 months old) and old (22–24 months old) male Fischer 344 rats fed normal diets and thyroparathyroidectomized. Parathyroid hormone was administered i.p. at 24, 12 and 2 h before death and calcitonin was given i.p. at 12 and 2 h before death. Parathyroid hormone significantly increased the conversion of 25-hydroxyvitamin D3 to 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) by renal slices from young but not adult or old animals. A similar age-related decline in the capacity of PTH to raise serum 1,25-dihydroxyvitamin D (1,25-(OH)2D) levels was also seen. Parathyroid hormone significantly decreased tubular reabsorption of phosphorus, increased concentrations of urinary cyclic AMP (cAMP) and increased serum concentrations of calcium in all age groups. In contrast, calcitonin significantly increased 1,25-(OH)2D3 production by renal slices from both young and adult animals. Calcitonin decreased serum concentrations of calcium in young but not in adult rats. These results suggest that there are maturational changes in the PTH- and cAMP-dependent pathways in the kidney but not in the calcitonin- and cAMP-independent pathways. The changes in the PTH- and cAMP-dependent pathways affect the stimulation of 1,25-(OH)2D production but not the inhibition of phosphate transport.

J. Endocr. (1987) 114, 173–178
Effects of chronic infusion of porcine relaxin on oxytocin release in lactating rats
Authors: Jones S. A. , Summerlee A. J. S.
Published: December 2008

The effects of chronic infusion of porcine relaxin on oxytocin release were studied in lactating rats. Infusion of relaxin (4·2 μg/h for either 4 or 6 days) suppressed reflex milk ejection and reduced litter weight gain for 48 h compared with saline-infused controls. After 2 days, neither the rate of growth nor the frequency of milk ejection were significantly different from controls. For 24 h after the infusion of relaxin ended, litters gained weight more quickly than controls but there was no difference seen in the frequency of milk ejection. The effects on oxytocin release of stopping an infusion of relaxin after 3 days were investigated. There was a significant (P <0·01) rise in plasma oxytocin (up to 90 pmol/l) 30 min after the infusion was stopped, followed by a sustained rise in intramammary pressure. Treatment of relaxin-infused rats with naloxone (0·1 mg/kg) when the infusion was halted caused a more rapid release of oxytocin (within 2 min), a greater release of oxytocin (up to 140 pmol/l) and a prolonged rise in intramammary pressure.

J. Endocr. (1987) 114, 241–246
Monoclonal antibodies against human, bovine and rat prolactin: epitope mapping of human prolactin and development of a two-site immunoradiometric assay
Authors: Staindl B. , Berger P. , Kofler R. , Wick G.
Published: December 2008

Nine mouse hybridoma cell lines producing monoclonal antibodies (MCA) against human prolactin (hPRL), 19 cell lines against bovine prolactin (bPRL) and one MCA against rat prolactin (rPRL) were established. The MCA were characterized by one- and two-site radioimmunoassays (RIA) as well as indirect immunofluorescence (IIF) and used for epitope mapping of hPRL and immunoradiometric assays (IRMA).

Interspecies cross-reactivity studies by RIA revealed two groups of anti-hPRL MCA: seven which reacted only with hPRL and two additionally recognizing bPRL and ovine prolactin (oPRL). The anti-bPRL MCA, which were tested on pituitary sections by IIF could be divided into 17 MCA cross-reacting with the closely related oPRL, and two MCA which showed additional cross-reactions with equine prolactin. The anti-rPRL antibody reacted exclusively with rPRL in direct binding RIA studies. No intraspecies cross-reactions with the closely related protein hormones placental lactogen and GH were detected.

To elucidate the antigenic surface of hPRL all MCA directed against hPRL were then used for two-site epitope mapping studies in which pairs of MCA were assessed for simultaneous reaction with the same antigen. The native hormone was incubated with the first, solid-phase bound, so called 'capture MCA', and this complex treated with a second, 125I-labelled 'detection MCA'. Based on the results of these combinations, at least three sterically non-overlapping and (taking RIA cross-reaction studies into consideration) two additional epitopes could be defined. Two antibodies (code numbers INN-hPRL-1 and INN-hPRL-9) recognizing different antigenic determinants were selected and used to elaborate a two-site IRMA with an operating range wider and a reaction time shorter than those obtained with a conventional one-site RIA.

J. Endocr. (1987) 114,311–318
Thyrotrophin-releasing hormone in human ejaculate
Authors: Rui H. , Welinder B. S. , Purvis K. , Dolva Ø.
Published: December 2008

Immunoassayable TRH in human ejaculate was eluted from a gel column in a form with a molecular weight larger than that of the native peptide. With reverse-phase high-performance liquid chromatography (HPLC) the same activity co-eluted with standard TRH. Incubation of ejaculates at room temperature for 8 h was associated with a time-related increase in the total immunoassayable TRH. Analysis by HPLC of ejaculates after 12 h of incubation at room temperature indicated that, whereas the levels of the peptide co-eluting with native TRH declined with time, there was a concomitant increase in the concentration of a molecular species which also cross-reacted with the TRH antiserum, but which was more hydrophobic. The latter species is presumably identical to the tetrapeptide recently described by others and which may arise from the proteolytic degradation of secretory macromolecules. Although immunological activity was present in all six fractions of split ejaculates, the bulk of the peptide was associated with the later portions, implying a major vesicular contribution. However, secretions isolated from surgical preparations of the seminal vesicles contained undetectable levels of peptide, suggesting that the ejaculation process may represent a stimulus for its appearance in the semen. This study is further support for a local involvement of TRH in male reproductive function.

J. Endocr. (1987) 114, 329–334
Disparate effects of ACTH(1–24) and corticosterone on lipoprotein lipase in rat adipose tissue
Authors: Baggen M. G. A. , Jansen H. , Lammers R. , Verschoor L. , Birkenhäger J. C.
Published: December 2008

The effects of corticosterone and ACTH(1–24) on lipoprotein lipase (LPL) activity of rat epididymal fat tissue were studied. Hypercorticism induced by s.c. administration of 10 mg corticosterone acetate for 3 days led to a decrease in LPL activity. This decrease could be prevented by treatment of the rats simultaneously with synthetic ACTH(1–24). Adrenalectomy also reduced LPL activity. Corticosterone and ACTH(1–24) treatment had a similar effect on LPL activity in adrenalectomized and intact rats.

These results indicate that ACTH(1–24) may affect adipose tissue LPL in the rat by a mechanism in which corticosterone is not involved.

J. Endocr. (1987) 114, 369–372
Effects of the anabolic steroid stanozolol on growth and protein metabolism in the rat
Authors: Bates P. C. , Chew L. F. , Millward D. J.
Published: December 2008

The effects of the anabolic steroid stanozolol on whole body and muscle growth and protein metabolism in the rat have been examined. No responses could be found in normal well-fed male rats. Female rats responded to 1 mg/kg per day with an increased body and skeletal muscle growth rate and an increase in muscle protein synthesis. The anabolic action on muscle protein synthesis was due to increased RNA concentration with no change in the rate of protein synthesis per unit RNA (KRNA). Investigation of any anticatabolic effects of stanozolol treatment in male rats deprived of food for 24 h indicated no response of protein balance and turnover. However, rats treated with catabolic doses of corticosterone (50 mg/kg per day) did respond to stanozolol with decreased muscle growth inhibition due to better-maintained muscle protein synthesis. The latter response was due to a reversal of the corticosterone-induced reduction of KRNA, but with no effect on RNA concentration. Thus there appear to be at least two effects of stanozolol; an anabolic action evident only in female rats, involving increased muscle RNA concentrations, and an anticatabolic action involving inhibition of the corticosterone-induced fall in muscle RNA activity. In both cases, stanozolol influenced muscle protein synthesis with no evident effects on protein degradation.

J. Endocr. (1987) 114, 373–381
Failure of fasting and changes in plasma metabolites to affect spontaneous fluctuations in plasma concentrations of ovine placental lactogen
Authors: Butler W. R. , Huyler S. E. , Grandis A. S. , Handwerger S.
Published: December 2008

The relationships between plasma concentrations of energy substrates and placental lactogen (PL) were investigated in pregnant ewes. In successive hourly samples of plasma PL, concentrations varied by ± 30% but were not related to general activity or feeding of the ewes or the time of day. Fasting ewes for 72 h did not alter the pattern or the mean PL titres. Insulin-induced acute hypoglycaemia, hyperglycaemia and decreases or increases in free fatty acids (FFA) all failed to alter PL levels significantly during 5-h post-treatment periods. These experiments demonstrate that PL secretion in the ewe fluctuates markedly and is unaffected by changes in plasma glucose or FFA concentrations.

J. Endocr. (1987) 114, 391–397
Retardation of preovulatory desensitization to negative oestrogen feedback: mechanism of the effect of progesterone in 5-day cyclic rats
Authors: Döcke F. , Rohde W. , Chaoui R. , Stürzebecher J. , Dörner G.
Published: December 2008

Recent studies have shown that oestrogen can induce desensitization to its own gonadotrophin-inhibiting effect in female rats by an action on the medial preoptic area (MPOA). Probably as a consequence of this action, sensitivity to the negative oestrogen feedback declines markedly between metoestrus and dioestrus of the 4-day ovarian cycle.

To study this desensitization process in 5-day cyclic rats, females exhibiting regular 5-day vaginal cyclicity were ovariectomized on consecutive days of the cycle, injected with oestradiol benzoate (OB) or oil on the day of ovariectomy and autopsied 24 h after the injection. Estimation of the serum concentration of LH revealed that desensitization to negative oestrogen feedback occurred only between day 2 of dioestrus and pro-oestrus, i.e. 2 days later than in females with a 4-day cycle. In the latter animals, an injection of progesterone in metoestrus or early dioestrus, which induced lengthening of the ovarian cycle for 1 day, delayed the onset of desensitization to a degree similar to that found in spontaneously 5-day cyclic rats. In acutely ovariectomized females, progesterone implants placed in the MPOA, but not those located in the mediobasal hypothalamus, increased the LH-inhibiting effect of low doses of OB.

The results suggest that the prolonged secretion of progesterone recorded in 5-day cyclic rats retards follicle maturation and delays the forthcoming ovulation by acting, at least partly, on the MPOA and antagonizing the desensitizing effect of oestrogen. In this way, inhibition of gonadotrophin secretion by oestrogen is enhanced and the increase in tonic LH secretion necessary for the completion of follicle maturation is retarded.

J. Endocr. (1987) 114, 409–414
Opiate suppression of LH secretion involves central receptors different from those mediating opiate effects on prolactin secretion
Authors: Pfeiffer D. G. , Pfeiffer A. , Almeida O. F. X. , Herz A.
Published: December 2008

The involvement of μ- and κ-opiate receptors in the regulation of LH and prolactin secretion was investigated in long-term ovariectomized rats using selective opiate receptor agonists and antagonists. The μ-agonists morphine and [d-Ala2,MePhe4,Gly5-ol]-enkephalin (DAGO) suppressed LH levels in a dose-related manner. The benzomorphane (−)-5,9-dimethyl-2′-hydroxy-2-(tetrahydrofurfuryl)-6,7-benzomorphan tartrate (MR 2034; a designated κ-agonist) also suppressed LH levels, whereas another benzomorphane κ-agonist (−)-5,9-dimethyl-2′-hydroxy-2-(2-methoxy-propyl)-6,7-benzomorphan hydrobromide (MRZ 2549) had no effect on the levels of this hormone. Pretreatment with the highly selective μ-antagonist β-funaltrexamine (β-FNA), the fumarate methyl ester derivative of naltrexone, blocked the actions of both μ-agonists and MR 2034, indicating that opiate suppression of LH secretion is mediated by μ-receptors. This was further confirmed by in-vitro studies: the KCl-induced release of LHRH from perifused hypothalami obtained from ovariectomized rats was significantly reduced by DAGO but not by MRZ 2549.

Prolactin secretion was stimulated in a dose-dependent manner by both μ- and κ-agonists. The stimulation caused by morphine and DAGO was antagonized by β-FNA, whereas that caused by the κ-agonists MR 2034 and MZR 2549 was resistant to blockade by β-FNA but not by naloxone (an antagonist which blocks all classes of opiate receptors when given in high doses). Thus prolactin secretion seems to be regulated by both μ- and κ-opiate receptors, whereas the effects on LH secretion seem to involve μ-receptors only.

J. Endocr. (1987) 114, 469–476
Relationship between maternal and fetal corticotrophin-releasing hormone-41 and ACTH levels in human mid-trimester pregnancy
Authors: Economides D. , Linton E. , Nicolaides K. , Rodeck C. H. , Lowry P. J. , Chard T.
Published: December 2008

Samples of maternal blood, amniotic fluid and umbilical arterial and venous blood were collected from 11 women at 16–24 weeks of pregnancy. Corticotrophin-releasing hormone-41 (CRH-41) and ACTH were measured by immunoradiometric assay. The mean levels of ACTH were 11 pmol/l in maternal plasma, 12 pmol/l in fetal plasma and 9·7 pmol/l in amniotic fluid. The mean levels of CRH-41 were 1·6 pmol/l in maternal plasma and 0·7 pmol/l in fetal plasma. There was a positive correlation between maternal and fetal plasma CRH-41 and between maternal CRH-41 and ACTH. In fetal plasma there was a weak inverse correlation between CRH-41 and ACTH. This is the first demonstration of CRH-41 in the circulation of the mid-trimester human fetus, but on the basis of the present findings it is not possible to specify the exact source (fetal, placental or maternal).

J. Endocr. (1987) 114, 497–501
Plasma vitamin D-binding protein and free 1,25-dihydroxyvitamin D3 index in pregnant ewes and their fetuses in the last month of gestation
Authors: Abbas S. K. , Care A. D. , Van Baelen H. , Bouillon R.
Published: December 2008

A radioimmunoassay for ovine vitamin D-binding protein (DBP) has been developed. This assay can also effectively measure DBP in goat plasma. A suitable ovine DBP antiserum raised in a rabbit produced a single monospecific line of precipitation when reacted against purified sheep DBP and sheep plasma. The preliminary purification of 125I-labelled ovine DBP was carried out using adsorption chromatography, and the final purification immediately before addition to the assay tubes was achieved by high-pressure liquid chromatography. Displacement of 125I-labelled ovine DBP by dilutions of sheep and goat plasma or standard DBP gave parallel curves, and only weak competition was observed with calf and pig plasma. The assay detected as little as 26 pmol DBP/1 with intra- and interassay coefficients of variation of 3 and 14% respectively. The mean plasma concentration of DBP in nine pregnant sheep (110–120 days of gestation) was 8·7 ± 0·3 (s.e.m.) μmol/l. These levels were significantly (P<0·02; paired t-test) higher than those in matched fetal plasma (6·7 ±0·4 μmol/l) obtained in utero through a catheter in a carotid artery. Plasma DBP concentrations in pregnant sheep were also significantly (P<0·02) higher than in five normal non-pregnant sheep (6·8 ± 0·5 μmol/l). The mean concentrations of total 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) in maternal and fetal plasma were 92·0 ±8·7 pmol/l and 152·5±18·0 pmol/l respectively (P<0·05). The free 1,25-(OH)2D3 index, a measure of the level of free 1,25-(OH)2D3 in plasma, was calculated as the ratio between the molar concentrations of total 1,25-(OH)2D3 and DBP. The mean value of the free 1,25-(OH)2D3 index in the fetus (2·3 × 10−5) was significantly (P<0·01) higher than that in the dam (1·1 × 10−5), thus indicating a gradient of free 1,25-(OH)2D3 during the latter part of ovine pregnancy with a mean fetal/maternal ratio of 2·1.

J. Endocr. (1987) 115, 7–12
Cyclic AMP-stimulated fluid transport in the thyroid: influence of thyroid stimulators, amiloride and acetazolamide on the dynamics of domes in monolayer cultures of porcine thyroid cells
Authors: Bourke J. R. , Matainaho T. , Huxham G. J. , Manley S. W.
Published: December 2008

Confluent monolayer cultures of porcine thyroid cells form dome-shaped elevations by local separation from the plastic culture dish. Formation of domes by epithelial cells in culture is generally considered to be evidence of fluid transport. A computer-controlled data acquisition system was developed to quantitate fluid transport in thyroid cultures by serial measurements of dome elevation. Thyrotrophin (10 mU/ml), prostaglandin E2 (PGE2; 0-01-1 μmol/l), forskolin (1 μmol/l), 8-(4-chlorophenylthio)adenosine 3′:5′-cyclic monophosphate (0.5 mmol/l) and 3-isobutyl-1-methyl-xanthine (0.5 mmol/l) promoted increases in dome height over 5–120 min. Dome growth in the presence of PGE2 (1 μmol/l) was inhibited by amiloride (0.1–100 μmol/l), ouabain (200 μmol/l), or by removal of bicarbonate and glucose from the medium. In media of reduced bicarbonate concentration (1 mmol/l compared with the control concentration of 10 mmol/l), dome growth was inhibited by acetazolamide (0.01– 1 mmol/l). These data are consistent with cyclic AMP-stimulated transport of fluid from apical to basal pole of the cells, dependent on sodium entry through the apical pole by an Na+/H+ exchanger.

J. Endocr. (1987) 115, 19-26
How large a hormone can be measured by microencapsulated antibody?
Authors: Duffy F. A. , Wallace A. M.
Published: December 2008

The size of molecules able to be measured in immunoassays where antibody is encapsulated within semipermeable microcapsules is restricted by the pore size of the membrane. This study was performed to determine the approximate molecular weight cut-off of this membrane. Permeability was assessed by measuring which labelled hormones were able to enter and bind their respective microencapsulated antibody. Hormones with molecular weights of less than 4000 (angiotensin II, thyroxine, 17-hydroxyprogesterone, progesterone, testosterone and androstenedione) passed freely through the pores but larger molecules, with molecular weights in excess of 10 000 (parathyroid hormone, human GH, TSH) could not. Insulin, with a molecular weight of 6000 (approximate minimum diameter 3·5 nm), had restricted entry while the next smallest hormone tested, the 1–34 amino acid portion of parathyroid hormone (molecular weight 4000; diameter 1·8 nm), was able to bind encapsulated antibody, suggesting that the pore diameter is between 1·8 and 3·5 nm. It can now be predicted that the method is able to measure compounds with a diameter within this range and with a molecular weight below 6000. Microcapsules may be useful for improving specificity of assays where a cross-reactant is too large to penetrate the membrane.

J. Endocr. (1987) 115, 47–51
Salivary oestriol and progesterone concentrations in women during late pregnancy, parturition and the puerperium
Authors: Lewis P. R. , Galvin P. M. , Short R. V.
Published: December 2008

Oestriol and progesterone concentrations were measured by specific radioimmunoassays in the saliva of six women on a daily basis during the last month of pregnancy, at frequent intervals during labour and daily during the puerperium. Salivary steroid concentrations are thought to reflect the circulating concentrations of the free hormone, and hence may be more biologically relevant than the total plasma concentration, or the urinary excretion of a metabolite.

There was no sign of a fall in salivary oestriol or progesterone concentrations before the onset of labour. During the first and second stages, the concentrations fluctuated widely, perhaps due to alterations in uterine blood flow. After delivery of the placenta, hormone concentrations declined abruptly. Oestriol reached undetectable levels of <0·1 nmol/l within a day, whereas progesterone concentrations declined somewhat more slowly, approaching follicular-phase values after 2–3 days. This slower decline in the concentration of progesterone may be due to a leaching-out of the hormone from body fat stores. The absence of any prepartum progesterone withdrawal presumably explains the characteristic postpartum delay in the onset of lactogenesis.

J. Endocr. (1987) 115, 177–181