bluuebunny/crossref_metadata_2025 huggingface dataset:
PITUITARY CONTENT OF OXYTOCIN, VASOPRESSIN AND α-MELANOCYTE-STIMULATING HORMONE IN THE FETUS OF THE RAT DURING LABOUR
Authors: BOER K. , DOGTEROM J. , PRONKER H. F.
Published: December 2008

The pituitary contents of oxytocin, vasopressin and α-MSH were measured in fetal and newborn rats to assess possible changes in their release during the process of labour. In the 24 h period during which delivery is likely to occur in the Wistar rat, both the oxytocin and vasopressin content of the fetal pituitary gland increased, whereas α-MSH content remained the same. During and/or just before labour, the oxytocin content was found to decrease by 30%, indicating an enhanced fetal release of the hormone at this stage. It was concluded that the expulsion of each fetus did not provide an extra stimulus for release of oxytocin by the fetus.

In addition, if the fetus remained in the uterus after decapitation of the mother, the oxytocin content of the fetal pituitary gland decreased a further 30%. Neither vasopressin nor 30%. content was altered by the process of labour or by the fetus remaining in the uterus after decapitation of the mother. The levels of vasopressin and α-MSH were, however, 20 times higher than the oxytocin content in the fetus and the newborn, which might have obscured the demonstration of a relatively small change in levels of these two hormones.
DEVELOPMENT OF A SPECIFIC EXTRACTED RADIOIMMUNOASSAY FOR METHIONINE ENKEPHALIN IN HUMAN PLASMA AND CEREBROSPINAL FLUID
Authors: CLEMENT-JONES VICKY , LOWRY P. J. , REES LESLEY H. , BESSER G. M.
Published: December 2008

A sensitive extracted radioimmunoassay for methionine enkephalin (met-enkephalin) has been developed which allows measurement of its concentration in human plasma and cerebrospinal fluid (CSF). The first evidence for the existence of met-enkephalin in the circulation of man is described and its presence in CSF confirmed. The susceptibility of the methionine residue in met-enkephalin to undergo oxidation to the methionine sulphoxide analogue was utilized. All extracted samples were oxidized by hydrogen peroxide before assay and this allowed measurement of total met-enkephalin. The assay had unique specificity with no cross-reaction with leucine enkephalin, purified human β-endorphin or β-lipotrophin (β-LPH). A purification method for radio-iodinated enkephalin has been developed with octadecasilyl-silica (ODS-silica) (10 μm) yielding a high-affinity monoiodinated tracer stable on storage for up to 3 months at 4 °C. A method to extract met-enkephalin from acidified plasma or CSF has been developed with larger particle size ODS-silica (35–70 μm) suitable for extracting repeated samples. Met-enkephalin immunoreactivity was detectable in plasma of all subjects tested and ranged from 14 to 140 pg/ml. In CSF, however, the range was 5–29 pg/ml. Met-enkephalin immunoreactivity was not generated by incubating exogenous or endogenous β-LPH and β-endorphin in plasma or CSF. Two hypopituitary subjects and one dexamethasone-suppressed subject, all with undetectable immunoreactive plasma adrenocorticotrophic hormone and NH2- and CO2H-terminal β-LPH, had measurable met-enkephalin in their plasma suggesting met-enkephalin was not of pituitary origin nor a breakdown product of secreted β-LPH or β-endorphin.
EFFECTS OF NEONATAL TREATMENT WITH OESTROGEN AFTER OVARIECTOMY ON DIURNAL PERIODICITIES IN PLASMA LEVELS OF PROLACTIN, THYROTROPHIN AND CORTICOSTERONE IN ADULT RATS
Authors: KÜHN E. R. , NOUWEN E. J. , NIEUWBORG L. , HEYNS W. , BERTIAU F.
Published: December 2008

Rats were ovariectomized 2–4 h post partum and injected with oil or 100 μg oestradiol benzoate (OB). At 65 days of age, they were decapitated at various times and circadian plasma levels of prolactin, TSH and corticosterone were measured. Rats injected with OB had a significantly raised mean concentration of plasma prolactin, whereas levels of TSH and corticosterone did not differ from those of control rats. Plasma levels of corticosterone and prolactin were positively correlated both in oil-treated controls and oestrogenized rats. A small but not significant negative correlation existed between the levels of TSH and corticosterone in oil-treated control rats. This correlation became positive in rats neonatally injected with OB. Prolactin and TSH were positively correlated in oestrogenized rats but no correlation was found in control animals. It was possible to fit the diurnal variations of all hormones in oil-treated control and OB-injected rats to a significant sinusoidal curve. The acrophase for prolactin, but not for TSH and corticosterone, shifted significantly from 22·30 h in control rats to 14·69 h in oestrogenized rats. In oil-treated control rats, the acrophases of prolactin and corticosterone differed significantly by about 12 h from the TSH peak. In rats injected neonatally with OB, however, no difference between the acrophases of the hormones was seen.

It was, therefore, possible that the shift in prolactin release and the high plasma levels were both mediated by mechanisms which are common to TSH and prolactin and whose increased susceptibility is oestrogen-dependent. The role of this abnormal phasing relationship between prolactin, corticosterone and TSH which occurred in the oestrogenized rats is discussed in relation to the high incidence of various spontaneous or induced tumours which occur during later life in these rats.
INCUBATION IN MALLARDS (ANAS PLATYRHYNCHOS): CHANGES IN PLASMA LEVELS OF PROLACTIN AND LUTEINIZING HORMONE
Authors: GOLDSMITH A. R. , WILLIAMS D. M.
Published: December 2008

The concentrations of prolactin and LH were measured in the plasma of male and female mallards (Anasplatyrhynchos) during the breeding season. The concentration of prolactin in the female birds was low before and during egg-laying, increased threefold (P < 0·001 ) during incubation and returned to basal levels immediately after the young were hatched. The drakes, which do not participate in incubation in this species, had fairly low prolactin levels throughout the breeding period; levels being slightly higher during the incubation phase than at other times but still much lower (P < 0·001) than in the incubating females. Concentrations of LH in the females were high during egg-laying but declined at the onset of incubation. In the drakes levels of LH remained high for much longer and did not appear to decline at a fixed time relative to the reproductive cycle of the female birds. These observations support the view that prolactin is associated with incubation in birds, though the data do not permit a conclusion as to whether an increase in prolactin secretion causes incubation behaviour or is stimulated by it.
AGE-RELATED CHANGES IN THE DEGRADATION OF THYROTROPHIN RELEASING HORMONE BY HUMAN AND RAT SERUM
Authors: WHITE NICKI , GRIFFITHS E. C. , JEFFCOATE S. L. , MILNER R. D. G. , PREECE M. A.
Published: December 2008

Changes in the rate of in-vitro degradation of thyrotrophin releasing hormone (TRH) in serum as related to age have been investigated in the rat and man. In rats, no inactivation was found up to the age of 15 days but thereafter an age-related increase in inactivation was detected with approximately 75% inactivation in 60 min at 40 days and reaching a maximum of 88–93% inactivation in adult male and female animals. The human serum samples studied (both male and female) showed a similar but less clear-cut pattern of inactivation of TRH compared with that found in the rat. A physiological role for these age-related changes in the degradation of TRH remains to be established but it has been concluded that the changes observed in both rat and man may be associated with growth and development, possibly by facilitating feedback control of thyrotrophin secretion through the degradation of TRH.
CONVERSION OF PROGESTERONE TO 5α- AND 5β-REDUCED METABOLITES IN THE BRAIN OF THE HEN AND ITS POTENTIAL ROLE IN THE INDUCTION OF THE PREOVULATORY RELEASE OF LUTEINIZING HORMONE
Authors: SHARP P. J. , MASSA R.
Published: December 2008

In the laying hen, progesterone was shown to be converted in vitro in the pituitary gland and the hypothalamus to 5β-pregnane-3,20-dione (5β-DHP), 5β-pregnan-3α-ol-20-one (5β,3α-ol) and 5α-pregnane-3,20-dione (5α-DHP) and in the hyperstriatum dorsale to 5β-DHP and 5β,3α-ol. The conversion of progesterone to 5β-reduced metabolites was greater in the hyperstriatum dorsale than in the hypothalamus (P<0·001) and greater in the hypothalamus than in the pituitary gland (P <0·01). The conversion of progesterone to 5β-reduced metabolites was greater than its conversion to 5α-DHP in the pituitary gland (P <0·01) and the hypothalamus (P < 0·001).

The possibility was investigated that 5α-DHP and 5β-DHP may act as metabolic intermediaries in the mechanism by which progesterone exerts a positive feedback effect on LH release. Progesterone, 5α-DHP and 5β-DHP were injected into laying hens at doses of 0·05,0·25 and 1·25 mg/kg and the changes in the concentration of plasma LH were followed for 4 h thereafter. Secretion of LH was stimulated after treatment with progesterone or 5α-DHP but not 5β-DHP. Progesterone stimulated LH release more effectively than did 5α-DHP, since an increase in the concentration of plasma LH was observed after 0·25 mg progesterone/kg but not after the same dose of 5α-DHP. It was concluded that in the hen 5α-DHP is unlikely to play a role in the induction of the preovulatory release of LH.
PLASMA CONCENTRATION OF TESTOSTERONE IN YOUNG BULLS IN RELATION TO AGE, RATE OF WEIGHT GAIN AND STIMULATION WITH HUMAN CHORIONIC GONADOTROPHIN
Authors: SUNDBY ANNE , VELLE WEIERT
Published: December 2008

In 86 bulls ranging in age between 3 and 11 months, the maximal plasma testosterone concentration (n = 7) well as the mean concentration (n = 7, same samples) were found to increase with age to peak values at 7–8 months with a subsequent decrease.

The multiple correlation coefficient for monthly gain as a function of testosterone concentration and age was 0·85 (P <0·001), for monthly gain as a function of age 0·84 (P <0·001) and for monthly gain as a function of testosteroneconcentration 0·44 (P <0·001).

The deviation in levels of measured plasma testosterone from the curve expressed by multiple regression analyses of testosterone concentration as a function of age was correlated with the average daily weight gain during the testing period of 9 months and found to be not significant (r = 0·21).

The difference between concentrations of plasma testosterone after stimulation with human chorionic gonadotrophin (HCG) and the spontaneous maximal concentration of this hormone was not significant. High correlation coefficients were found between maximal (r = 0·8) and mean (r = 0·6) concentrations of plasma testosterone before and after an injection of HCG (P <0·001).
EFFECT OF SPIRONOLACTONE ON ANDROGEN-DEPENDENT PROTEINS IN THE VENTRAL PROSTATE OF THE RAT
Authors: CARTER D. B. , SILVERBERG A. B. , HARRIS S. E.
Published: December 2008

The effect of spironolactone on five androgen-dependent proteins in the ventral prostate of the rat was investigated by two-dimensional gel electrophoresis. Spironolactone was given to intact male, castrated and androgen-stimulated castrated rats. It has been shown that spironolactone had no influence on the synthesis or accumulation of the androgen-dependent proteins in intact animals. However, spironolactone suppressed the restoration of the major androgen-dependent protein of low molecular weight in castrated rats given testosterone. The mechanism by which spironolactone exerts its anti-androgenic activity was shown to be unrelated to its capacity to inhibit the synthesis or accumulation of the five androgen-dependent proteins studied in this investigation.
PERMISSIVE ROLE OF l-THYROXINE IN INDUCTION OF PANCREATIC AMYLASE BY CORTISOL IN NEONATAL RATS
Authors: KUMEGAWA MASAYOSHI , MAEDA NORIHIKO , YAJIMA TOSHIHIKO , TAKUMA TAISHIN , IKEDA EIKO , HANAI HIROSHI
Published: December 2008

The effect of l-thyroxine (T4) on amylase activity in the developing rat pancreas has been investigated. Administration of T4 (0·2 μg/g body wt) alone to intact rats on days 5–10 after birth did not induce pancreatic amylase but the enzyme was induced significantly by daily injection of cortisol (10 μg/g body wt) alone into intact rats over the same period. In thyroidectomized, adrenalectomized rats pancreatic amylase was not induced by the injection of cortisol alone but it was induced by the administration of cortisol plus T4. Increase in enzyme activity was much less in thyroidectomized animals than in intact animals. These results suggested that T4 does not have a direct effect in increasing pancreatic amylase activity but plays a permissive role in increasing enzyme activity.
A NEURAL BASIS FOR CENTRAL INHIBITION OF MILK EJECTION IN THE RABBIT
Authors: TINDAL J. S. , BLAKE LAURA A.
Published: December 2008

Discrete, transverse stereotaxic cuts in the forebrain of the anaesthetized lactating rabbit caused spontaneous milk-ejection responses repeated at intervals of 1–5 min. The region of the brain in which cuts were effective included the diagonal band of Broca, the entire rostrocaudal extent of the dorsal medial septum, part of the cingulum and part of the hippocampal fimbria. It is proposed that severance of a septo-hippocampal pathway frees the hippocampus from inhibition and allows oxytocin release to occur. It remains to be determined whether the hippocampus itself is directly responsible for periodic activation of neurosecretory cells.
PROLACTIN RECEPTORS IN THE RAT KIDNEY
Authors: MOUNTJOY K. , COWDEN E. A. , DOBBIE J. W. , RATCLIFFE J. G.
Published: December 2008

Specific binding of 125I-labelled ovine prolactin iodinated by a lactoperoxidase method was demonstrated in crude membrane preparations of kidneys and adrenals of male Sprague–Dawley rats and livers from female rats. Membrane preparations derived from the 100 000 g fractions of tissue homogenates contained most of the specific prolactin binding. Kinetic and affinity characteristics of prolactin binding to kidney membranes were examined in detail. Maximal specific binding occurred after incubation for 30 h at room temperature. Scatchard analysis indicated that prolactin binding to kidney membranes was of high affinity (dissociation constant = 1·4 × 10−10 mol/l) and similar to that for liver membranes, although kidney membranes from male rats bound approximately sixfold less prolactin/mg membrane protein than did liver membranes from female rats. Specific prolactin binding was demonstrated in both renal medulla and cortex. Autoradiography showed maximal prolactin binding activity in the epithelial cells of the proximal tubule and faint activity in the tubular cells throughout the nephron. Specificity of uptake by proximal tubular cells was indicated by the gross reduction in prolactin activity when excess ovine prolactin was administered simultaneously. The demonstration of specific binding sites for prolactin localized primarily in the proximal tubules was consistent with renal action of prolactin, predominantly on sodium metabolism.
PROGESTERONE PRODUCTION BY DISPERSED CELLS FROM HUMAN CORPUS LUTEUM: STIMULATION BY GONADOTROPHINS AND PROSTAGLANDIN F2α; LACK OF RESPONSE TO ADRENALINE AND ISOPRENALINE
Authors: RICHARDSON M. C. , MASSON G. M.
Published: December 2008

Progesterone production was assessed following short-term incubations of luteal cell suspensions prepared from tissue samples of human corpora lutea obtained at specific times throughout the luteal phase of the menstrual cycle. Luteal cells responded rapidly and sensitively to human chorionic gonadotrophin (HCG; concentration required for 50% maximum response, 0·1–1·0 i.u./ml) with a maximum level of response (five- to tenfold higher than basal production) similar to that elicited by human LH or N6,02-dibutyryl cyclic AMP. In the absence of gonadotrophin or in the presence of sub-maximal (but not maximal) concentrations of HCG, progesterone production by mid-luteal phase cells was stimulated by prostaglandin F2α (1 μmol/l), an effect not observed during the late-luteal phase. l-Adrenaline and l-isoprenaline failed to elicit significant increases in the level of progesterone production.
EFFECTS OF TRI-IODOTHYRONINE, THYROXINE AND ISOPROPYL-DI-IODOTHYRONINE ON THYROID-STIMULATING HORMONE IN SERUM AND PITUITARY GLAND AND ON PITUITARY CONCENTRATIONS OF PROLACTIN, GROWTH HORMONE, LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE IN HYPOTHYROID RATS
Authors: WONG C. C. , DÖHLER K. -D. , VON ZUR MÜHLEN A.
Published: December 2008

Replacement of the 3′-halogen of the tri-iodothyronine (T3) molecule by a propyl-group produces a thyromimetic analogue, 3′-isopropyl-3,5-di-iodo-l-thyronine (T2iPr), with high biological potency. A serum thyroid-stimulating hormone (TSH) suppression test with one single intraperitoneal injection of 3 or 30 nm-T3 or T2iPr or with 30 or 300 nm-thyroxine (T4) per kg body weight was performed on 56 adult male Lewis rats which were maintained for 3 weeks on an iodine-deficient diet containing 0·2% 6n-propyl-2-thiouracil (PTU). Blood was withdrawn from each rat by cardiac puncture 24 h before and 3, 7, 24 and 48 h after application of the iodothyronines.

Raised serum levels of TSH, due to the treatment with PTU, were significantly reduced within 3 h of treatment with 30 nm-T3, 300 nm-T4, 3 or 30 nm-T2iPr and they remained low throughout the observation period. Treatment with 3 nm-T3 or 30 nm-T4 per kg body weight was less effective. Pituitary concentrations of growth hormone, TSH, prolactin and FSH were significantly reduced by the treatment with PTU. There was also a slight, but insignificant reduction of pituitary concentrations of LH. Treatment with T3, T4 or T2iPr stimulated the reaccumulation of growth hormone, TSH, prolactin, LH and FSH in the pituitary gland.
ACTIVATION OF SEXUAL BEHAVIOUR IN CASTRATED RATS WITH THE SYNTHETIC ANDROGEN 17β-HYDROXY-17α-METHYL-ESTRA-4,9,11-TRIENE-3-ONE (R 1881)
Authors: SÖDERSTEN P. , GUSTAFSSON J. -Å.
Published: December 2008

Castrated sexually inactive rats were treated with the synthetic androgen 17β-hydroxy-17α-methyl-estra-4,9,11-triene-3-one (methyltrienolone, R 1881), testosterone benzoate (TB), 5α-dihydrotestosterone benzoate (DHTB) or oestradiol benzoate (OB) and tested for sexual behaviour. The synthetic androgen, R 1881, was as potent as TB in stimulating sexual behaviour and OB stimulated all aspects of copulatory behaviour but DHTB had no significant effect. The synthetic androgen, R 1881, is not metabolized by target cells and rapid metabolism could explain the failure of DHTB to stimulate sexual behaviour.
STEROID METABOLISM IN THE YOLK SAC PLACENTA AND ENDOMETRIUM OF THE TAMMAR WALLABY, MACROPUS EUGENII
Authors: HEAP R. B. , RENFREE M. B. , BURTON R. D.
Published: December 2008

Yolk sac and endometrial tissue were obtained from tammar wallabies between 11 and 25 days after the removal of pouch young. Tissues were examined histologically and steroid-metabolizing enzymes were identified by incubation for 3 h at 37 °C in Medium 199 containing labelled steroid precursors. Yolk sac membrane (YSM) incubated with labelled pregnenolone produced a small amount of progesterone and pregnanediols; 80·5 ± 8·4 (s.e.m.) % of the original substrate remained unmetabolized. Labelled androstenedione was metabolized to 5α-androstane-3,17-dione and androsterone, and only 5·8 ± 3·8% of the original substrate remained at the end of incubation. Incorporation of androstenedione or dehydroepiandrosterone (DHA) into phenolic compounds was low (0·5 ± 0·1%). There was no evidence for the enzymes, arylsulphatase or sulphotransferase, in YSM. Endometrial tissue from the same animals metabolized pregnenolone, DHA and androstenedione, converted progesterone to androstenedione, and produced aqueous-soluble steroid conjugates. The results demonstrated that YSM contains enzymes associated predominantly with steroid catabolism and with incipient progesterone synthesis. The findings are discussed in relation to the histological appearance of the tissues and compared with placental steroid synthesis in eutherian mammals.
ALTERATIONS INDUCED BY CLOMIPHENE IN THE CONCENTRATIONS OF OESTROGEN RECEPTORS IN THE UTERUS, PITUITARY GLAND AND HYPOTHALAMUS OF FEMALE RATS
Authors: ADASHI E. Y. , HSUEH A. J. W. , YEN S. S. C.
Published: December 2008

Alterations in the concentrations of oestrogen receptors in the uterus, pituitary gland and hypothalamus during the 2 weeks following a single administration of clomiphene citrate (Clomid) to immature, bilaterally ovariectomized rats were investigated. Examination of the uterine wet weight at 1, 7 and 14 days following a single injection of Clomid (100 μg, 250 μg or 10 mg) indicated significant time- and dose-related increments from a control value of 45 ± 2 (s.e.m.) mg to a maximum of 123 ± 3 mg (250 μg dose at 14 days). In contrast, a single injection of oestradiol led to a transient increase in the uterine weight on day 1 to 94 ± 6 mg, but was without effect by days 7 and 14. Analysis of the uterine DNA content 7 and 14 days after treatment with Clomid revealed significant increments from control values of 390 ± 10 μg to a high level of 558 ± 8 μg (10 mg dose at 7 days). There was a transient retention of nuclear oestrogen receptors and rapid replenishment of cytoplasmic oestrogen receptors in less than 24 h in the uteri of animals treated with oestradiol (25 μg), but determinations of receptor content in Clomid-treated animals revealed prolonged retention of nuclear receptors and delayed replenishment of cytoplasmic receptors. The duration and extent of retention of nuclear receptors and depletion of cytoplasmic receptors after treatment with Clomid were found to be dose-dependent. Fourteen days after Clomid treatment, levels of oestrogen receptors in nuclei from the uterus were still raised in all treatment groups, whereas replenishment of cytoplasmic receptors was complete in animals treated with the lower doses (100 and 250 μg) of Clomid.

A single injection of Clomid (250 μg) induced similar prolonged retention of nuclear receptors and delayed depletion of cytoplasmic receptors in pituitary tissue. In contrast, changes in the content of oestrogen receptors in the hypothalamus following Clomid treatment were minimal. The limited effect of Clomid on hypothalamic tissue may mean that the pituitary gland is a more important target for this compound than is the hypothalamus. The findings have confirmed earlier reports on the long-term uterotrophic effect of Clomid and have suggested that under these long-term, in-vivo conditions, Clomid acts in the uterus and pituitary gland as a long-acting oestrogen characterized by prolonged retention of oestrogen receptors in the nucleus and delayed, but otherwise effective, replenishment of the oestrogen receptors in the cytoplasm.
NEGATIVE FEEDBACK OF SECRETION OF FOLLICLE-STIMULATING HORMONE BY THE PITUITARY GLAND OF DEVELOPING MALE RATS
Authors: SHETH A. R. , VANAGE GEETA R. , VAZE A. Y. , THAKUR A. N.
Published: December 2008

Rabbit antiserum to human seminal plasma inhibin (hSPI) was administered subcutaneously to developing male rats of 5, 10, 14, 17 and 24 days of age and the size of the endogenous FSH rise in serum was measured. The FSH levels were threefold higher on day 9 and 1·5-fold higher on days 14 and 18 when compared with levels in control rats treated with normal rabbit serum. Furthermore, the in-vitro binding capacity of pituitary plasma membrane to 125I-labelled hSPI declined with increase in age of the rats. Thus, the results of the present study suggest that the sensitivity of the testicular inhibin–FSH feedback relationship is related to age-dependent changes in pituitary binding of inhibin.
PERMISSIVE ROLE OF l-THYROXINE IN THE INDUCTION OF STOMACH PEPSINOGEN BY CORTISOL IN NEONATAL RATS
Authors: KUMEGAWA MASAYOSHI , YAJIMA TOSHIHIKO , MAEDA NORIHIKO , TAKUMA TAISHIN , HOSODA SATOKO
Published: December 2008

Subcutaneous injection of cortisol (10 μg/g body wt daily for 5 days) into normal neonatal rats increased the activity of stomach pepsinogen after day 5. l-Thyroxine (T4; 0·2 μg/g body wt daily for 5 days) alone did not affect the activity but it somewhat enhanced the effect of cortisol. Even before day 5, when no effect of cortisol alone was observed, T4 plus cortisol increased pepsinogen activity. In adrenalectomized, thyroidectomized neonatal rats, injection of cortisol alone did not induce enzyme activity but cortisol together with T4 did induce it. Moreover, the increase in pepsinogen activity was depressed in rats thyroidectomized on day 10 but not in those thyroidectomized on day 15. These results suggest that T4 does not have a direct effect on the stomach but plays an important role in making the stomach responsive to glucocorticoids, resulting in increased pepsinogen activity.
ROLE OF TESTOSTERONE IN THE SEXUAL DIMORPHISM OF ADRENAL ACTIVITY AT PUBERTY IN THE GUINEA-PIG
Authors: EL HANI A. , DALLE M. , DELOST P.
Published: December 2008

Sexual dimorphism in adrenal activity appeared during the pubertal period of the guinea-pig with plasma levels and binding of cortisol lower in male guinea-pigs compared with female, and metabolic clearance rate (MCR) of cortisol higher in male than in female animals. Gonadectomy of female guinea-pigs did not change the values of the parameters regulating adrenal activity. Castration of male guinea-pigs caused a rise in plasma cortisol levels by increasing the binding capacity of transcortin for cortisol and by decreasing cortisol MCR. Treatment of females with testosterone from day 24 produced a drop on day 50 in plasma cortisol levels following a decreased binding capacity of transcortin for cortisol and at the same time as cortisol MCR increased. Furthermore, the adrenal response to stress was higher in castrated than in control males and lower in testosterone-treated females compared with control females. Testosterone appeared to be the hormone responsible for sexual dimorphism in adrenal activity in the pubertal guinea-pig.
EFFECT OF SUPPRESSION OF THE SURGE OF FOLLICLE-STIMULATING HORMONE WITH PORCINE FOLLICULAR FLUID ON FOLLICULAR DEVELOPMENT IN THE RAT
Authors: HIRSHFIELD ANNE N. , DE PAOLO L. V.
Published: December 2008

To examine the manner in which the FSH surge of one oestrous cycle recruits follicles for ovulation in the subsequent cycle, porcine follicular fluid (PFF) was used to alter the pattern of endogenous FSH secretion during the periovulatory period. Ovaries of animals killed at oestrus or metoestrus were examined histologically for the presence of large follicles (greater than 400 μm in diameter) after treatment. Large follicles were absent in ovaries of all PFF-treated animals at oestrus, while control rats had an average of 2·7 large follicles per ovary. By metoestrus, however, ovaries of rats treated with PFF contained several large, healthy follicles. Only when PFF treatment was continued throughout the evening of oestrus was the appearance of large follicles prevented at metoestrus.

Our results suggest that the prolonged oestrous portion of the FSH surge, rather than the pro-oestrous portion, is responsible for follicular recruitment during the normal oestrous cycle in the rat. They also indicate that compensatory follicular development occurs in response to the FSH rebound which has been shown to follow FSH suppression.
ENDOCRINE PANCREAS IN THE OFFSPRING OF RATS WITH EXPERIMENTALLY INDUCED DIABETES
Authors: AERTS L. , VAN ASSCHE F. A.
Published: December 2008

At birth newborn rats from mothers with experimentally induced diabetes show hypertrophy and degranulation of the pancreatic islets. With birth the maternal hyperglycaemic stimulus is removed and during the lactation period the overstimulated B cells can restore their normal secretory activity. The increase of B-cell mass, however, remains retarded for several weeks. By adulthood the endocrine pancreas of offspring from mildly diabetic mothers seems to have recovered from the influence of the abnormal intra-uterine milieu, at least as judged by morphometric examination. In offspring from severely diabetic mothers an increased secretory activity of the individual B cells might be responsible for their sustained hypoglycaemia.
CHANGES IN SECRETION OF LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE INDUCED BY HYPOVOLAEMIA IN RATS
Authors: LEE V. W. K. , DE KRETSER D. M.
Published: December 2008

Changes in levels of LH and FSH in the circulation were examined during repeated blood sampling in untreated rats and gonadectomized male and female rats treated with oestrogen, progesterone and thyroxine. Blood depletion induced a significant increase in levels of LH in steroid-treated rats but the increase was abolished when the depleted blood volume was replaced with egg albumen. The rise in LH was less dramatic in male than in female animals. In untreated rats, levels of LH either decreased or did not change with repeated phlebotomy. In contrast, the levels of FSH either did not alter or were lowered in all situations.
FATE OF NEUROHYPOPHYSIAL GRANULE MEMBRANES AFTER SECRETION IN THE RAT: GENERATION OF A NEW APPARENT ORGANELLE BY FREEZING AND THAWING SECRETORY GRANULES
Authors: LACEY JEAN H. , PICKERING B. T.
Published: December 2008

The contents and membranes of the secretory granules in the rat neurohypophysis were labelled in vivo with [35S]cysteine and [3H]choline respectively. Density-gradient centrifugation of the labelled granules showed the membrane label to be distributed largely between two peaks: one associated with intact granules and one with the characteristics of empty granule envelopes. Stimulation of hormone release in vitro led to the movement of membrane label from the intact granule fraction to the other one, consistent with the recapture of membrane as large vesicles. Freezing and thawing the crude granule fraction, ostensibly to aid osmotic fracture, produced a single membrane component with a density intermediate between the two original fractions.
SPECIFIC BINDING OF THYROID-STIMULATING HORMONE BY HUMAN SERUM GLOBULINS
Authors: BÍRÓ J.
Published: December 2008

Globulin preparations (41) from patients with Graves's disease (positive to thyroid stimulating immunoglobulins; TSI) and 12 from healthy persons (TSI-negative) were tested for their specific thyrotrophin (TSH)-binding properties. Globulins from both groups possessed binding sites for 131I-labelled TSH. The mean dissociation constant (Kd) was 6·8 pmol/l per mg globulin and the maximum specific binding (Bmax) was 3·0 pmol/mg globulin per 1 for the TSI-negative control group. Twenty-four (58·5%) globulin preparations from the TSI-positive group had similar TSH-binding characteristics with mean Kd of 7·2 pmol/l per mg globulin and Bmax of 3·6 pmol/mg globulin per 1 (A-type binding) but the remaining 17 (41·5%) bound TSH in a different fashion with Kd of 71·5 pmol/l per mg globulin and Bmax of 13·6 pmol/mg globulin per 1 (B-type binding).

Both types of specific TSH binding reached the maximal level within 1 h of incubation and had an optimum pH of 7–8. There was a linear correlation between the amount of bound TSH and the globulin content of the samples. Both types of binding were reversible by the addition of an excess of TSH and gonadotrophins, ACTH, prolactin and insulin competed with TSH for the binding sites only when in relatively high concentrations. The binding sites were associated with macromolecules; they emerged with the void volume after chromatography on Sephadex G-200 and migrated with immunoglobulin G (IgG) on paper electrophoresis. The binding capacity of the globulin preparations could be decreased by preincubation with antiserum to human IgG or with human thyroid membranes.
EFFECTS OF CORTISOL ON CELL PROLIFERATION AND PROTEOGLYCAN SYNTHESIS AND DEGRADATION IN CARTILAGE ZONES OF THE CALF COSTOCHONDRAL GROWTH PLATE IN VITRO WITH AND WITHOUT RAT PLASMA SOMATOMEDIN ACTIVITY
Authors: HILL D. J.
Published: December 2008

The actions of cortisol were investigated in vitro on separated zones of cartilage from the calf costochondral junction, and from the structural costal cartilage. Cortisol had no direct effect in plasma-free medium on the uptake of [3H]thymidine, [3H]leucine or [35S]sulphate in any zone of growth plate or structural cartilage until pharmacological concentrations (10−4–10−3 mol/l) were present, when the incorporation of all three isotopes was significantly reduced. In the presence of a somatomedin stimulus of normal rat plasma the addition of cortisol at supraphysiological concentrations (10−8–10−6 mol/l) had no effect on the incorporation of any isotope in structural cartilage, but significantly reduced the uptake of [3H]thymidine in the growth plate region of proliferating chondrocytes, and at a concentration of 10−6 mol/l appeared to increase the uptake of [35S]sulphate in the region of maturing chondrocytes. This was not accompanied by a general increase in protein synthesis as assessed by [3H]leucine incorporation, and could reflect the decreased rate of proteoglycan degradation in the presence of cortisol. It could not be proven in the present experiments that the actions of cortisol at supraphysiological levels were dependent on the presence of growth hormone dependent somatomedin.
TIMING AND LOCALIZATION OF THE STIMULATORY EFFECT OF FOLLICLE-STIMULATING HORMONE ON URIDINE INCORPORATION IN THE MOUSE TESTIS IN VIVO
Authors: DAVIES A. G. , LAWRENCE N. R.
Published: December 2008

Human pituitary FSH increased the incorporation of [5-3H]uridine into RNA in vivo in the testes of intact 9-day-old mice and of hypophysectomized adults. In both groups the effect was greatest 8 h after administration of 5–7·5 i.u. FSH. Autoradiographs were prepared from the testes of hypophysectomized adult mice given subcutaneous injections of FSH or of 0·9% saline 6 h, and [5-3H]uridine 1·5 h, before death. Treatment with FSH caused statistically significant increases in the density of silver grains over the nuclei of Sertoli cells, type A and intermediate spermatogonia, and preleptotene and mid-pachytene primary spermatocytes. It was concluded that FSH has a generalized stimulatory action on RNA synthesis in the nuclei of Sertoli cells and those types of germinal cell which synthesize RNA most actively.
PROGESTERONE AND INSULIN-RESISTANCE: STUDIES OF PROGESTERONE ACTION ON GLUCOSE TRANSPORT, LIPOGENESIS AND LIPOLYSIS IN ISOLATED FAT CELLS OF THE FEMALE RAT
Authors: SUTTER-DUB M.-TH. , DAZEY B. , HAMDAN E. , VERGNAUD M.-TH.
Published: December 2008

The effects of progesterone on isolated rat adipocytes were studied in vitro during various steps of glucose metabolism, transport, lipogenesis and lipolysis. Progesterone decreased the phosphorylation of glucose into glucose-6-phosphate as assessed by measuring the uptake of 2-deoxyglucose but it had no effect on transmembrane transport of glucose as determined by measuring the entry of 3-0-methylglucose into the cell. As glucose phosphorylation is a rate-limiting step of the pentose-phosphate pathway, these data could explain the inhibition of lipogenesis and the enhancement of lipolysis observed when progesterone is present in incubation medium. Progesterone might thus modulate a regulatory step of glucose metabolism and antagonize insulin action in the fat cell.
A ROLE FOR PROSTAGLANDINS IN DECIDUALIZATION OF THE RAT UTERUS
Authors: SANANÈS NICOLE , BAULIEU ETIENNE-EMILE , LE GOASCOGNE CLAUDE
Published: December 2008

The deciduogenic action of various kinds of prostaglandin (PG), i.e. PGE1, PGE2, PGF2α and PGI2, methylated prostaglandins (15-met-PGE1, 15-met-PGE2 and 15-met-PGF2α), PGF2α-13-dehydro analogues (13-DH-PGF2α, ent-15-epi-13-DH-PGF2α), endoperoxide analogues (15S)-hydroxy-9α,11α-(epoxymethano)-prosta-5Z,13E-dienoic acid (U 44069) and (15S)-hydroxy-11α,9α-(epoxymethano)-prosta-5Z,13E-dienoic acid (U 46619), and of the prostaglandin precursor, arachidonic acid, has been demonstrated after intraluminal instillation of these compounds into the uterus of immature rats sensitized with progesterone alone. Under this minimal hormonal stimulation, in which a trauma (a scratch) of the endometrium is required to induce the decidual response, all these compounds elicited the formation of deciduomata, substantiating the suggestion that the scratch-induced decidual reaction is mediated through release of prostaglandin. Confirmation was obtained through the effect of indomethacin and cortisol, both of which decreased the decidual response brought on by a scratch or by arachidonic acid, whereas the effect of PGF2α was decreased by indomethacin but not by cortisol. Histamine, thromboxane B2, and oleic, palmitic and homo-γ-linolenic acids were not deciduogenic.

A dose-dependent inhibitory effect of indomethacin on deciduoma formation by instillation of oil into animals sensitized by progesterone plus oestradiol was also observed.

The results support the proposal that the decidual reaction involves prostaglandins and we suggest that the deciduoma is a valuable model for studying the action of prostaglandin-related compounds.
CONCENTRATIONS OF OESTRADIOL AND OESTRONE IN PLASMA, UTERUS AND OTHER TISSUES OF FETAL GUINEA-PIGS: THEIR RELATIONSHIP TO UPTAKE AND SPECIFIC BINDING OF [3H]OESTRADIOL
Authors: GELLY C. , SUMIDA C. , GULINO A. , PASQUALINI J. R.
Published: December 2008

The concentrations of unconjugated oestradiol-17β and oestrone have been measured by radioimmunoassay in the plasma of fetal, newborn and immature guinea-pigs. In fetal plasma, the values of oestradiol ranged from 15 to 50 pg/ml with no significant variations with gestational age except for an abrupt increase at the very end of gestation (148 pg/ml). Low concentrations of oestradiol were also found postnatally (from not detectable to 31 pg/ml) as well as in maternal plasma (22 pg/ml). The values of oestrone were consistently higher in all plasma regardless of age (43–164 pg/ml).

Oestrogen concentrations were also determined in the fetal uterus, lung, kidney and brain and were found to be as much as 60 times higher (per g tissue) than in plasma, especially in the fetal uterus which contained four to five times more than the other tissues. These data correlated well with a 20–90 times greater uptake of [3H]oestradiol by the fetal uterus compared with the other tissues after in-vivo administration of [3H]oestradiol to the fetuses. The selective retention of oestradiol was probably due to the presence of specific oestradiol binding in these fetal tissues, particularly in the uterus whose binding was 60–120 times higher than in the other fetal tissues. Thus, the levels of oestrogen in the circulation of fetal guinea-pigs are low, but the fetal uterus is capable of maintaining a higher concentration which may be important physiologically since oestradiol has been shown to evoke a biological response in the fetal guinea-pig uterus.
DIFFERENCES IN CONCENTRATIONS OF PLASMA CORTISOL IN THE TROUT AND THE EEL FOLLOWING ADAPTATION TO BLACK OR WHITE BACKGROUNDS
Authors: BAKER BRIDGET I. , RANCE THERESA A.
Published: December 2008

When rainbow trout (Salmo gairdneri) and eels (Anguilla anguilla) were kept in black tanks for 3—4 weeks, their plasma cortisol titres were about fourfold higher than in fish kept in white tanks. In trout, the difference was apparent only under a long photoperiod of 16 h light: 8 h darkness, but in eels the difference was clear under both a long or short photoperiod (9·5 h light: 14·5 h darkness). It is suggested that the increase in plasma cortisol seen in black-adapted fish is dependent on either ACTH or MSH secreted by the pars intermedia melanotrophs. No difference was seen either in the total cortisol-binding capacity of the plasma nor in interrenal histology in trout from black or white backgrounds.
ULTRASTRUCTURE AND IMMUNOCYTOCHEMISTRY OF THE PARS DISTALIS OF THE FEMALE RAT WHEN GRAFTED UNDER THE KIDNEY CAPSULE AND A PARALLEL STUDY OF THE PLASMA LEVELS OF PROLACTIN
Authors: AGUADO L. I. , ALVIAL G. S. , RODRÍGUEZ E. M.
Published: December 2008

Two hypophysial partes distales were grafted under the kidney capsule of intact female rats. The plasma prolactin levels 15, 45 and 90 days after the operation were determined. At the same postoperative intervals the grafted glands of some of the operated rats were processed for conventional light and electron microscopy and for the demonstration of prolactin, FSH and LH according to the unlabelled immunoperoxidase procedure. The ultrastructural characteristics of the transplanted secretory cells and the amount and distribution of the immunoreactive material within their cytoplasm were used to evaluate approximately the secretory activity of these cells.

Although levels of prolactin in the three experimental groups were significantly higher than those in control rats, a decrease in prolactin level was detected in 71% of the samples taken 45 days after operation. At day 15 the graft was completely surrounded by lymphoid cells whereas at day 45 these cells had invaded the whole graft. In the group sampled at day 90 the graft was free of lymphoid cells. When traced immunocytochemically the three types of cells followed different patterns of evolution after transplantation. Most prolactotrophs were hypertrophied in all groups but, in addition, they underwent a process leading to hyperplasia some time between days 45 and 90 after operation. Syncytial formations which probably correspond to multinucleated prolactotrophs were present only in the group sampled at day 90. The number of LH and FSH cells had decreased in the group at day 45 and by day 90 the former remained scarce but immunoreactive FSH cells were no longer found. At the ultrastructural level clear signs of involution of gonadotrophs and degradation by macrophages were seen in the graft 45 days after operation.

The relation between the morphology and hormone content of the graft and hormone content of the plasma is discussed, together with several questions raised by the results. Pituitary transplantation can be used as an experimental model only if the time-dependent changes described here are taken into account.
SERUM CONCENTRATIONS OF PROLACTIN, LUTEINIZING HORMONE, GROWTH HORMONE, CORTICOSTERONE, PROGESTERONE, TESTOSTERONE AND OESTRADIOL IN RELATION TO BROODINESS IN DOMESTIC TURKEYS (MELEAGRIS GALLOPAVO)
Authors: HARVEY S. , BEDRAK E. , CHADWICK A.
Published: December 2008

Variations in concentrations of LH, GH, prolactin, corticosterone, oestradiol, testosterone and progesterone in serum were followed over a 24 h period (14 h light: 10 h darkness) in laying and broody turkeys and in turkeys suspected of becoming broody (pre-broody hens). In laying hens marked variations in LH and gonadal steroid levels were observed in relation to the ovulatory cycle of the bird. These patterns of hormone secretion were not seen in either group of broody birds. Levels of GH in serum were very variable and showed no correlation with the egg-laying or light: darkness cycle and the concentrations did not differ between the respective physiological states. A nocturnal increase in the concentration of corticosterone in serum was observed in all three groups of turkeys and the concentration was occasionally higher in the pre-broody and broody birds than in the laying hens. The serum prolactin concentration in each group was also very variable and showed no obvious relationship with the ovulatory or photoperiodic cycle. The mean circulating prolactin concentration throughout the 24 h period did not differ significantly between the groups. These results suggest that broodiness in the domestic turkey is not initiated or maintained by enhanced prolactin secretion.
CONCENTRATIONS OF PITUITARY, GONADAL AND ADRENAL HORMONES IN SERUM OF LAYING AND BROODY WHITE ROCK HENS (GALLUS DOMESTICUS)
Authors: BEDRAK E. , HARVEY S. , CHADWICK A.
Published: December 2008

Diurnal variations in circulating concentrations of LH, GH, prolactin, corticosterone, oestradiol, progesterone and testosterone were followed in laying and broody White Rock domestic fowl. Throughout the 24 h study prolactin concentrations in serum were consistently (two- to fourfold) higher in broody than in laying birds, in which the prolactin level varied with the light: darkness or ovulatory cycles. Concentrations of GH in serum tended to be lower in broody birds but in both groups were very variable and showed no obvious relationship with either the lighting or ovulatory cycles. Broodiness was also characterized by low LH and gonadal steroid levels and by the absence of preovulatory peaks in the serum concentrations of these hormones. A diurnal rhythm in corticosterone was observed in both the laying and broody birds, with high levels during the period of darkness. Corticosterone concentrations were markedly higher in the broody birds than in laying birds during most of the 24 h study. No diurnal rhythm in the blood haematocrit level was observed in either group, although the level was generally lower in broody birds. This difference, however, was insufficient to account for the lower LH and gonadal steroid levels in the broody birds.

The results suggest that prolactin is involved in the initiation or maintenance of broodiness in the fowl and the possibility of an antigonadal role for the hormone is discussed.
SPECIFIC PROLACTIN BINDING IN THE RAT ADRENAL GLAND: ITS CHARACTERIZATION AND HORMONAL REGULATION
Authors: CALVO J. C. , FINOCCHIARO L. , LÜTHY I. , CHARREAU E. H. , CALANDRA R. S. , ENGSTRÖM B. , HANSSON V.
Published: December 2008

Rat adrenal prolactin receptors possess the same hormonal specificity as those in the prostate gland and liver, but are less stable during storage and after freezing. There is a gradual decrease in specific prolactin binding to the adrenal during sexual maturation in male rats; maximum binding capacity of 980 fmol/mg protein is at 25 days of age decreasing to approximately 100 fmol/mg protein at day 90. Prolactin receptors in the prostate are high at 25 days of age (700 fmol/mg protein), decrease sharply by day 30 (180 fmol/mg protein) and then gradually increase.

Ovariectomy resulted in a significant rise in total prolactin binding in the adrenal gland, while the administration of oestradiol or testosterone reduced the binding, the reverse of changes in prolactin binding in the liver. Only oestrogen increased serum levels of prolactin in female rats.

Ovine prolactin (500 μg) given to female rats resulted in a rapid increase over a period of 2–8 h in total prolactin receptors in the adrenal, and these then decreased to normal levels, indicating a possible positive regulation of prolactin receptors by homologous hormone.
DIURNAL CHANGES IN THE CONCENTRATION OF PROGESTERONE IN THE PLASMA OF WOMEN AT 34–35 WEEKS OF GESTATION
Authors: CHALLIS J. R. G. , WORKEWYCH J. V. , PATRICK J. E.
Published: December 2008

The concentration of progesterone has been measured in ten women at 34–35 weeks of gestation in blood samples taken at 30 or 60 min intervals during a 24 h study period. Plasma progesterone concentrations showed a distinct diurnal rhythm. Most values determined between 04.00 and 11.00 h were significantly lower than the peak concentrations measured between 13.00 and 01.00 h. The relation of these changes in plasma progesterone to those in plasma cortisol and oestrogens is discussed.