bluuebunny/crossref_metadata_2025 huggingface dataset:
HYDROGEN PEROXIDE FORMATION IN THE RAT UTERUS UNDER HORMONE-INDUCED CONDITIONS
Authors: JOHRI R. K. , DASGUPTA P. R.
Published: December 2008

The production of hydrogen peroxide was quantitated in the uterus of cyclic, ovariectomized (treated with hormones) and pregnant (days 1–6 post coitum) rats. This phenomenon was found to be dependent on oestrogen. The uterine responsiveness to hydrogen peroxide was correlated with peroxidase-catalysed inactivation of oestrogens in this target organ.
GONADO-PITUITARY RELATIONSHIPS IN THE FETAL MOUSE AT VARIOUS TIMES DURING SEXUAL DIFFERENTIATION
Authors: POINTIS G. , LATREILLE M.-T. , CEDARD L.
Published: December 2008

Levels of testosterone in plasma and concentrations of LH in both plasma and pituitary glands of fetal mice aged 14, 16 and 18 days were measured by radioimmunoassays in a representative number of fetuses. During this period levels of testosterone in the plasma of male mice were significantly higher than those in the females. Levels of testosterone in plasma of male mice increased from day 14 to day 16 of gestation and decreased on day 1 before parturition. Plasma concentrations of LH remained undetectable in male and female fetuses until day 16 of gestation. Levels of LH rose slightly in both sexes in later gestation, but still remained significantly lower in the plasma of male fetuses on days 17–18. In contrast, higher but not significantly different concentrations of LH were observed in pituitary glands from days 14 to 18 in male compared with female mice. These observations suggest that the high levels of testosterone in the plasma of male fetal mice might be responsible for feedback inhibition of LH secretion during the last days of gestation.
DEMONSTRATION OF PROLACTIN-RELEASING ACTIVITY IN THE PIGEON
Authors: SHANI J. , GOLDHABER G. , GIVANT Y. , KOCH Y.
Published: December 2008

The capacity of the pigeon pituitary gland to release prolactin was investigated in vivo, to evaluate its hypothalamic regulation and to establish the dominant hypothalamic factor for prolactin secretion. After 3 days of systemic administration of some physiological and pharmacological agents, followed by 2 consecutive days of local intradermal injections of prolactin into their crop sacs, the crop mucosa was scraped, dried and weighed. The substances tested were: oestradiol and tamoxifen (antioestrogen), thyrotrophin-releasing hormone (TRH) and anti-TRH serum, perphenazine (releases prolactin in mammals) and bromocriptine (suppresses prolactin in mammals). Prolactin and anti-prolactin serum were tested as controls.

While prolactin markedly proliferated and anti-prolactin serum significantly inhibited the mucosal weight, oestradiol, TRH and perphenazine dramatically depressed proliferation of the mucosa, suggesting that prolactin secretion was inhibited. Tamoxifen, anti-TRH serum and bromocriptine significantly increased the proliferation of the crop mucosa, indicating an increase in the endogenous release of prolactin. Since the effect of these substances on prolactin release in the pigeon is the opposite from their well-established effects in mammals, these results suggest, in a specific and homologous model, that the dominating regulator for prolactin in the pigeon is contrary to that in the mammal, namely prolactin-releasing factor, and that TRH may play a significant role in the physiological regulation of prolactin secretion.
PRENATAL AND EARLY POSTNATAL SEX DIFFERENCES IN PLASMA AND GONADAL TESTOSTERONE AND PLASMA LUTEINIZING HORMONE IN FEMALE AND MALE RATS
Authors: SLOB A. K. , OOMS M. P. , VREEBURG J. T. M.
Published: December 2008

Plasma levels of testosterone and LH were estimated in female and male rats at gestational ages of 19, 20 and 21 days and at 1, 3, 6, 12, 18 and 24 h after birth. Concentrations of testosterone in the gonads were also estimated in 20-day-old fetuses and at various times after birth.

Before birth female fetuses had significantly lower levels of testosterone and higher levels of LH than had male fetuses. During the first 24 h after birth female rats also had lower levels of testosterone and higher levels of LH than male rats. The pattern of levels of testosterone in the hours after birth was significantly different between female and male rats in that high levels were observed 1 and 3 h after birth in male rats (3·0 and 2·2 ng/ml respectively). This finding, as well as the relatively high levels of testosterone in female fetuses (about 50% of the levels found in male womb-mates) is discussed.
EFFECTS OF ADRENALINE AND AMINO ACIDS ON THE RELEASE OF INSULIN IN THE SHEEP FETUS
Authors: FOWDEN ABIGAIL L.
Published: December 2008

The effects of adrenaline and amino acids on β-cell function have been investigated in chronically catheterized fetal sheep. Infusion of adrenaline (1 μg/min) abolished the normal β-cell response to both glucose and arginine. The adrenaline infusion also caused hyperglycaemia and a reduction in the basal plasma insulin concentration in the fetus in the period before the infusion of glucose or arginine was given. Infusion of amino acids increased the speed and the magnitude of the β-cell response to glucose. The maximum increment in the fetal insulin level in response to glucose was 68·5 ± 13·5 (s.e.m.) μu./ml (n = 5) during amino acid infusion which was significantly greater than the value of 16·1 ± 3·4 μu./ml observed in the control experiments. The observations are discussed in relation to the regulation of insulin release in utero.
STIMULATION BY β2-ADRENERGIC RECEPTORS OF THE PRODUCTION OF CYCLIC AMP AND PROGESTERONE IN RAT OVARIAN TISSUE
Authors: RATNER ALBERT , WEISS G. K. , SANBORN CAROLYN R.
Published: December 2008

Ovarian tissue from immature rats treated with pregnant mare serum gonadotrophin (PMSG) or PMSG and human chorionic gonadotrophin was incubated in Medium 199. Stimulation of the formation of cyclic AMP in follicular and luteal tissue by terbutaline (10−5 mol/l), a selective β2-agonist, was blocked by butoxamine (10−5 mol/l), a selective β2-antagonist, whereas practolol (10−5 mol/l), a selective β1-antagonist, was ineffective. Propranolol (10−5 mol/l), a non-selective β-antagonist, butoxamine nor practolol affected the increase in cyclic AMP promoted by the addition of 1 μg LH. Stimulation of the production of progesterone in both follicular and luteal tissue by terbutaline was blocked by butoxamine, but not by practolol. These findings indicated that β-adrenergic stimulation of ovarian cyclic AMP and progesterone is mediated by β2-adrenergic receptors.
SUPPRESSION BY ORGANOCHLORINES OF THE RESPONSE TO ADRENOCORTICOTROPHIN OF THE INTERRENAL TISSUE IN SAROTHERODON AUREUS (TELEOSTEI)
Authors: ILAN Z. , YARON Z.
Published: December 2008

Superfused interrenal tissue of Sarotherodon aureus responded to ACTH with increased release of cortisol. The response to ACTH of interrenal tissue taken from fish treated with the organochlorine insecticide 1,1-dichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl) ethane (o,p-DDD; 50 mg/kg) in vivo was almost totally abolished. Lower doses were less effective. The response was also suppressed by exposure in vitro of the interrenal tissue to the organochlorine; there seemed to be a dose–response to o,p-DDD over the range of 0·023 to 1 mg/l. Also 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p′-DDE) was effective in suppressing the response to ACTH at concentrations of 50–150 mg/l; 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane (p,p′-DDT) or the polychlorinated biphenyl, Aroclor 1254, were ineffective at 50 mg/l.

No suppressive effect of o,p-DDD on output of cortisol could be detected in superfusion when N6,O2′-dibutyryl cyclic AMP (20 mmol/l) was substituted for ACTH. This may indicate that the interference of o,p-DDD with the interrenal response to ACTH results from an interruption in the generation of cyclic AMP.
CONSUMPTION OF FOOD, BODY WEIGHT, PERINEAL COLOUR AND LEVELS OF PROGESTERONE IN THE SERUM OF CYCLIC FEMALE CHINCHILLAS
Authors: BROOKHYSER KAREN M. , AULERICH R. J.
Published: December 2008

Venous blood of eight cyclic female chinchillas (Chinchilla laniger) was collected twice weekly during all stages of the oestrous cycle and levels of progesterone were determined by radioimmunoassay. Consumption of food, body weight and perineal colour were also monitored in 25 cyclic female chinchillas. Cyclic trends were significant for feed consumption (P<0·01), colour of the perineum (P<0·001) and body weight (P<0·001). Analysis of data used a standardized cycle of 36 days which was arranged according to vaginal perforation. This was subdivided into six periods with 6 days in each. Values of progesterone in the serum ranged from 0·07 to 6·27 ng/ml (n = 64 samples, each in duplicate), and the period of 6 days with the lowest mean progesterone value was that which included the first day of vaginal perforation. The pattern of fluctuations of progesterone resembled that of another hystricomorph rodent, the guinea-pig.
DOSE REGIMENS OF HUMAN GROWTH HORMONE: EFFECTS OF CONTINUOUS INFUSION AND OF A GELATIN VEHICLE ON GROWTH IN RATS AND RATE OF ABSORPTION IN RABBITS
Authors: MARY COTES P. , BARTLETT W. A. , GAINES DAS ROSE E. , FLECKNELL P. , TERMEER R.
Published: December 2008

Different methods for administration of human growth hormone (hGH) have been examined with a view to efficient use of the limited amounts of hGH at present available for clinical use.

We found that in hypophysectomized rats (1) hGH administered by continuous subcutaneous infusion induced a greater increase in body weight (referred to throughout as growth) than hGH administered by intermittent (daily) injection and (2) intermittent injections of hGH dissolved in 16% gelatin induced more growth than hGH dissolved in a glycine buffer.

It was further found that (1) hGH dissolved in 16% gelatin compared with hGH dissolved in a glycine buffer induced lower maximal levels of immunoreactive plasma hGH and between 7 and 9 h after treatment higher plasma levels when injected subcutaneously in rabbits, (2) 125I-labelled hGH added as a tracer to hGH in gelatin was removed more slowly from subcutaneous injection sites in rabbits than 125I-labelled hGH given with hGH in glycine buffer and (3) changes in the ratio of hGH to gelatin had little effect on the time-course of plasma levels of hGH in the rabbit. Addition of the protease inhibitors aprotinin or 6-aminohexanoic acid, to injection of hGH in gelatin or glycine did not induce any consistent increase in plasma levels of hGH.
DECREASE IN HUMAN PLASMA PROLACTIN LEVELS BY ORAL PROSTAGLANDIN E2 IN EARLY PUERPERIUM
Authors: CAMINITI F. , DE MURTAS M. , PARODO G. , LECCA U. , NASI A.
Published: December 2008

Eight milligrams of prostaglandin E2 (PGE2; 2 mg every 30 min) were given orally to 12 puerperal women on day 4 after delivery. Plasma levels of prolactin showed a significant decrease in comparison with basal levels and with those of controls sampled over a similar period. The same dose of PGE2 was ineffective in modifying the plasma prolactin levels in four puerperal women on day 30 after delivery and in four non-pregnant women with normal levels of prolactin. It is suggested that a PGE2-induced decrease in prolactin could be mediated by hypothalamic dopaminergic neurones.
ANDROGENS IN THE FETAL GUINEA-PIG AFTER MATERNAL INFUSION OF RADIOACTIVE TESTOSTERONE
Authors: VREEBURG J. T. M. , WOUTERSEN P. J. A. , OOMS M. P. , VAN DER WERFF TEN BOSCH J. J.
Published: December 2008

Testosterone was measured in plasma pools from male and female fetal guinea-pigs between the ages of 30 and 55 days of pregnancy. Between days 33 and 36 the testosterone concentration in the plasma of males (1·4 ng/ml) was several times higher than that found at other ages or that measured in female fetuses. After infusion of tritiated testosterone for 2 h into pregnant guinea-pigs at day 36 of pregnancy, high levels of testosterone and androstenedione were found in maternal plasma. Nevertheless, tritiated testosterone and androstenedione could hardly be shown in the fetuses. Similar large differences in plasma progesterone levels appeared to exist between the maternal and the fetal circulation. Therefore, only a very small fraction of these steroids can penetrate from the maternal circulation into that of the fetus. This finding might be explained by the large difference in androgen-binding capacity between maternal and fetal plasma, as was shown by equilibrium dialysis.
LUTEINIZING HORMONE RELEASING HORMONE-INDUCED RELEASE OF LUTEINIZING HORMONE FROM PITUITARY EXPLANTS OF COWS KILLED BEFORE OR AFTER OESTRADIOL TREATMENT
Authors: CONVEY E. M. , KESNER J. S. , PADMANABHAN V. , CARRUTHERS T. D. , BECK T. W.
Published: December 2008

In ovariectomized heifers, oestradiol decreases concentrations of LH in serum for approximately 12 h after which LH is released in a surge comparable in size and duration to the preovulatory surge. Using this model, we measured LH release induced by LH releasing hormone (LH-RH) from pituitary explants taken from ovariectomized heifers before or after an oestradiol-induced LH surge. These changes were related to changes in LH concentrations in serum and pituitary glands and hypothalamic LH-RH content.

Twenty Holstein heifers were randomly assigned to one of four treatment groups to be killed 0, 6, 12, or 24 h after the injection of 500 μg oestradiol-17β. Jugular blood was collected at −2, −1 and 0 h then at intervals of 2 h until slaughter. Pituitary glands were collected and ≃2 mm3 explants were exposed to 4 ng LH-RH/ml medium for 30 min (superfusion) or 4 ng LH-RH/ml medium for 2 h in Erlenmeyer flasks. Levels of LH were measured in the medium. Hypothalami, collected at autopsy, were assayed for LH-RH content. To determine pituitary LH content, an additional 15 ovariectomized heifers were killed, five each at 0, 12 and 24 h after the injection of 500 μg oestradiol. In both groups of heifers, oestradiol reduced serum LH concentrations to ≃ 1 ng/ml, a level which persisted for 12 h, when LH was released in a surge. Pituitary sensitivity to LH-RH was increased at 6 and 12 h after the injection of oestradiol, but was markedly decreased at 24 h, i.e. after the LH surge. Despite this twofold increase in capacity of the pituitary gland to release LH in response to LH-RH, pituitary LH content did not change during 12 h after oestradiol treatment. However, LH content decreased after the LH surge and this decrease was associated with a decrease in pituitary responsiveness to LH-RH. Hypothalamic LH-RH content was not altered by these treatments.

We have interpreted our results as evidence that oestradiol exerts a positive feedback effect on the pituitary gland of ovariectomized heifers such that pituitary sensitivity to LH-RH is increased twofold by the time the LH surge is initiated. In addition, oestradiol causes a transitory inhibition of LH-RH release as shown by the fact that serum LH concentrations remained low during the interval from injection of oestradiol until the beginning of the LH surge despite the fact that pituitary sensitivity to LH-RH is increased at this time. Depletion of a readily releasable pool of pituitary LH may be the mechanism by which the LH surge is terminated.
EFFECT OF PORTACAVAL ANASTOMOSIS AND CHRONIC UNDERFEEDING ON THE HYPOTHALAMIC-PITUITARY-GONADAL AXIS IN THE RAT
Authors: MILLIGAN S. R. , SARNA G. S.
Published: December 2008

Portacaval anastomosis (PCA) in the rat may be a useful experimental model for examining endocrine changes that occur during cirrhosis of the liver. A marked reduction in diet intake and body weight occurs in rats after establishing the shunt and studies were undertaken to determine the relationship of these effects to the testicular atrophy that also follows PCA. Control, sham-operated animals, experiencing a reduction in food intake similar to that of the animals with a PCA, showed reduced plasma levels of LH and testosterone but also exhibited a marked testicular response to LH. This was consistent with increased sensitivity of the hypothalamic-pituitary axis to the negative feedback of gonadal steroids in chronically underfed animals. Male rats with a PCA exhibited similarly reduced levels of LH and testosterone, but showed poor secretory responses of the pituitary gland to LH releasing hormone (LH-RH) and of the testis to LH. Testicular atrophy and cessation of spermatogenesis occurred in the animals with a PCA. These results suggested that the effects of PCA on the pituitary-gonadal axis cannot simply be explained as a consequence of the restricted intake of diet. This was confirmed by the responses to castration. In both fed and underfed sham-operated rats, castration resulted in a rapid and sustained increase in plasma LH and both groups showed a marked LH secretory response to LH-RH. In contrast, in animals with a PCA castration had little effect on plasma LH and the pituitary response to LH-RH was still poor. The effects of PCA cannot be simply explained by impeded metabolism of gonadal steroids causing increased negative feedback on the hypothalamic-pituitary axis.
RACEMIZATION EFFECTS ON MELANOCYTE-STIMULATING HORMONES AND RELATED PEPTIDES
Authors: BOOL A. M. , GRAY G. H. , HADLEY M. E. , HEWARD C. B. , HRUBY V. J. , SAWYER T. K. , YANG Y. C. S.
Published: December 2008

Heat–alkali treatment of synthetic α- and β-melanocyte-stimulating hormones (MSH), known to cause racemization of amino acids within the peptides, results in prolongation of the darkening (melanophore dispersion) effect of these hormones on frog and lizard skins in vitro. Skins remain darkened for hours or even days if supramaximal concentrations of the racemized hormones are used. This response can be partially reversed by melatonin or noradrenaline. Heat–alkali treatment of α-MSH at either 60 or 97 °C results in a retardation of the response of the skins to the racemized peptides. In contrast, the response of frog skins to heat–alkali-treated β-MSH is immediately enhanced and potentiated. Heat–alkali treatment also prolongs and potentiates the activity of synthetic [des-acetyl]-α-MSH (in contrast to the retardation effect on the natural acetylated peptide). These data suggest a role for the N-acetyl group in the retardation phenomenon. The activity of synthetic [2-d-tyrosine]-α-MSH is much lower than that of α-MSH itself, indicating that heat–alkali treatment of the hormone may produce either potentiation or partial inactivation of the peptide, depending on the site of racemization.
THE INFLUENCE OF ENERGY INTAKE ON THE METABOLISM OF 3,5,3′-TRI-IODOTHYRONINE AND 3,3′,5′-TRI-IODOTHYRONINE IN YOUNG PIGS
Authors: INGRAM D. L. , RAMSDEN D. B.
Published: December 2008

The disappearance rates of radioactive 3,5,3′-tri-iodothyronine (T3) and 3,3′,5′-tri-iodothyronine (reverse T3) from plasma were investigated in young pigs receiving various levels of food intake. The rate of utilization of reverse T3 decreased when intake was decreased to zero, whilst the rate of utilization of T3 was unaffected.
CELL REPLICATION IN THE ISLETS OF LANGERHANS OF ADULT RATS: EFFECTS OF PREGNANCY, OVARIECTOMY AND TREATMENT WITH STEROID HORMONES
Authors: GREEN I. C. , EL SEIFI S. , PERRIN D. , HOWELL S. L.
Published: December 2008

It was possible to vary the replication rate of cells in the islets of Langerhans of adult rats. The rate of incorporation of [3H]thymidine into islet DNA was increased at 12 days of pregnancy to 2·3-fold and at 19 days of pregnancy to 1·3-fold that in control rats. Ovariectomy, which leads to lowered plasma levels of ovarian steroids, induced a significant and unexpected increase in the rate of thymidine incorporation into islets; treatment of ovariectomized rats with 2 μg oestradiol/rat per day for 3 days reversed this upward trend. When islets from normal rats were cultured with certain combinations of steroid hormones including progesterone and oestradiol or with insulin secretagogues, with the exception of glucose, a decreased rate of DNA synthesis was usually found compared with that in control rats.

Since treatment with steroid hormones inhibited incorporation of [3H]thymidine into islets from ovariectomized rats and directly reduced incorporation into tissue-cultured islets from normal rats in vitro, it was concluded that increased levels of steroid hormones were not responsible for the higher rate of regeneration of islet cells in pregnant rats. However, a striking correlation between levels of blood glucose in vivo and DNA synthesis in islets in vitro has been observed.
FATE OF PROGESTERONE IN THE PLASMA AND VARIOUS TISSUES OF ANAESTHETIZED RABBITS
Authors: VERMA URMILA , LAUMAS K. R.
Published: December 2008

Studies on the metabolism of progesterone in rabbit plasma and tissues during constant infusion of [3H]progesterone revealed a gradual increase in the concentration of progesterone in plasma until a state of equilibrium was attained about 2 h after the start of infusion. The metabolic clearance rate of progesterone was 0·116 l/min and the turn-over time was 0·006 min/ml plasma. Under conditions of equilibrium, the concentration of radioactivity as well as that of labelled progesterone was higher in the tissues than in plasma. On a unit–weight basis, myometrium localized 6·6 nCi, Fallopian tube 5·5 nCi and vagina 6·1 nCi [3H]progesterone/g tissue. A higher concentration of progesterone, 16·5 nCi, was localized in the mammary gland tissue. Skin localized only 0·9 nCi progesterone and the lowest amount (0·34 nCi/ml) was found in plasma.

The metabolism of progesterone in tissues differed from that in plasma. In plasma only 5·6% of the infused steroid was recovered as unconverted progesterone and the major amount was metabolized to polar compounds with smaller amounts of 5α-pregnane-3,20-dione, 5α-pregnan-3β-ol-20-one and 20α-hydroxypregn-4-en-3-one. In the myometrium and Fallopian tubes the major metabolites were 5α-pregnan-3β-ol-20-one and 5α-pregnane-3,20-dione respectively. In the vagina, like the myometrium, 5α-pregnan-3β-ol,20-one was the major metabolite. 20α-Hydroxypregn-4-en-3-one was the major identified metabolite of mammary gland tissue.
BRAIN ADRENOCORTICOTROPHIN AFTER ADRENALECTOMY AND SHAM-OPERATION OF RATS
Authors: VAN DIJK A. M. A. , VAN WIMERSMA GREIDANUS TJ. B. , BURBACH J. P. H. , DE KLOET E. R. , DE WIED D.
Published: December 2008

The influence of adrenalectomy on the level of immunoreactive 18–24 ACTH extracted from hypothalamus, hippocampus and pituitary gland of rats was investigated. Brain ACTH was further characterized by fractionation by gel-permeation chromatography. Porcine 1–39 ACTH was exposed to synaptic plasma membranes in vitro in order to evaluate the role of metabolic conversion in changes of brain ACTH content.

Removal of the adrenals, when compared with sham-adrenalectomy, resulted in a transient depletion of ACTH content in the anterior pituitary gland and the hippocampus, but not in the hypothalamus and the neurointermediate lobe. However, sham-adrenalectomy caused a transient reduction in levels of ACTH when compared with levels before operation in all tissues studied.

The effects of adrenalectomy on hippocampal ACTH content persisted in hypophysectomized rats. Treatment of adrenalectomized rats with corticosterone failed to restore the reduced ACTH content when it was administered in doses that completely suppressed the release of pituitary ACTH. Adrenal steroids, however, may exert a direct effect on the metabolism of ACTH in the brain as judged from the in-vitro studies with porcine 1–39 ACTH exposed to a synaptosomal plasma membrane fraction of hippocampal tissue. The present study suggests that control of brain ACTH occurs independently of the control of pituitary ACTH release.
RELATIONSHIPS BETWEEN OESTRADIOL-17β, TESTOSTERONE, DIHYDROTESTOSTERONE AND 5α-ANDROSTANE-3α,17β-DIOL IN HUMAN BENIGN HYPERTROPHY AND CARCINOMA OF THE PROSTATE
Authors: GHANADIAN R. , PUAH C. M.
Published: December 2008

The relationship between the concentrations of oestradiol, testosterone, dihydrotestosterone (DHT) and 5α-androstane-3α,17β-diol in circulating blood and prostatic tissues was studied in patients with benign prostatic hypertrophy (BPH) and carcinoma of the prostate. All steroids were measured by radioimmunoassay. In patients with BPH the tissue concentrations of oestradiol, testosterone, DHT and 5α-androstane-3α,17β-diol expressed per kg wet weight were 228·6 ± 7·4 (s.e.m.) pmol, 1·29 ± 0·06 nmol, 25·61 ± 1·15 nmol and 1·43 ± 0·10 nmol respectively. The corresponding values for carcinomatous tissues were 380·1 ± 19·4 pmol, 7·20 ± 1·10 nmol, 12·32 ± 1·56 nmol and 1·99 ± 0·32 nmol. Significant differences (t-test) were found between the mean concentrations of oestradiol (P <0·001), testosterone (P <0·001), DHT (P <0·001) and 5α-androstane-3α,17β-diol (P <0·05) in prostatic tissues of these two groups of patients. Significant negative correlations were observed between the tissue concentrations of oestradiol and DHT (r = −0·49, P <0·05) and between oestradiol and 5α-androstane-3α,17β-diol (r = −0·44, P <0·05) in BPH but not in malignant tissues. The plasma concentrations of oestradiol, testosterone, DHT and 5α-androstane-3α,17β-diol in patients with BPH were 147·4 ± 6·9 pmol/l,18·4 ± 1·2 nmol/l,2·6 ± 0·2 nmol/l and 0·84 ± 0·04 nmol/l respectively. The corresponding values for patients with carcinoma of the prostate were 145·5 ± 17·0 pmol/l, 17·3 ± 2·4 nmol/l, 2·0 ± 0·3 nmol/l and 0·56 ± 0·06 nmol/l respectively. The mean plasma 5α-androstane-3α,17β-diol was found to be significantly higher in patients with BPH (P <0·01) than with carcinoma. No significant correlations were found between the tissue concentrations of these steroids and the corresponding plasma values, which suggested that their metabolism and accumulation in prostatic tumours are independent of their plasma concentrations.
GONADOTROPHIN RELEASE IN VITRO, IN THE PRESENCE AND ABSENCE OF LUTEINIZING HORMONE RELEASING HORMONE, BY PITUITARY GLANDS FROM OVARIECTOMIZED AND SHAM-OPERATED IMMATURE FEMALE RATS OF VARIOUS AGES
Authors: DULLAART J.
Published: December 2008

Hemipituitary glands of immature female rats, aged 10, 15, 20, 25, 30 and 35 days and either ovariectomized or sham-operated 5 days earlier, were incubated for 2 h in vitro with or without LH releasing hormone. Concentrations of LH and FSH were determined at the end of the incubations in the incubation media and in the hemipituitary glands, and also in the sera collected at the beginning of the incubation experiments.

Results showed that in many instances gonadotrophin release was higher after incubation of glands of ovariectomized rats than with glands of control animals. However, these effects of ovariectomy were much smaller than those observed in vivo and were generally absent in rats of less than 20 days of age. It was concluded that ovariectomy may change the secretory characteristics of the gonadotrophic cells of immature rats but that such changes were largely restricted to immature rats older than 20 days.
METABOLISM OF ANDROGENS BY THE ACTIVE AND INACTIVE PROSTATE GLAND, AND THE SEASONAL CHANGES IN SYSTEMIC ANDROGEN LEVELS IN THE GREY SQUIRREL (SCIURUS CAROLINENSIS GMELIN)
Authors: SIWELA A. A. , TAM W. H.
Published: December 2008

The nuclear and cytoplasmic fractions derived from the actively secretory and inactive prostate of adult grey squirrels were incubated with radioactive testosterone and androstenedione. Testosterone was metabolized first to 5α-dihydrotestosterone and then 5 α-androstane-3α(β), 17β-diols. Testosterone could also be transformed into androstenedione and then to androsterone, but no 5α-dihydrotestosterone or diols could be synthesized from this pathway. Neither subcellular fraction of the inactive, non-secretory prostate could produce 5α-androstane-3α(β),17β-diols from testosterone either in the absence or presence of exogenous NADPH. The synthesis of androstenedione and 5α-dihydrotestosterone by the nuclear and cytoplasmic fractions of the inactive gland were significantly increased compared to that in fractions of the active prostate. The increase was unaffected by exogenous NADPH. The concentration of androgen (testosterone plus 5α-dihydrotestosterone) in systemic plasma was highest in December, the beginning of the breeding season. For the remainder of the breeding season, the androgen level was similar to that found in the non-breeding season. It is suggested that formation of 5α-androstane-3α(β),17β-diols was associated with the secretory activity of the prostate. The failure of the inactive prostate to synthesize these diols during sexual quiescence might be a means of ensuring the inactivity of the prostate.
EVIDENCE THAT A PLACENTAL FACTOR OTHER THAN ANDROSTERONE OR DIHYDROTESTOSTERONE INHIBITS OESTROGEN-INDUCED LORDOSIS BEHAVIOUR IN PREGNANT RATS
Authors: DE GREEF W. J. , SCHENCK P. E. , VREEBURG J. T. M. , VAN DER VAART P. D. M. , BAUM M. J.
Published: December 2008

Daily administration of oestradiol benzoate, beginning 10 days after mating, stimulates lordosis behaviour in deciduomata-bearing pseudopregnant rats, but not in pregnant rats. The inhibition of this behaviour during pregnancy was not prevented by reducing the number of conceptuses to two, by removing the fetuses while leaving the placentas in utero, or by removing the ovaries and administering progesterone to prevent abortion. Removal of the uterus or fetuses and placentas on day 12, however, led to high levels of lordosis behaviour. Thus, it is likely that the placenta produces a factor which inhibits the behavioural responsiveness to oestrogen.

Plasma levels of progesterone, androsterone and dihydrotestosterone were higher during the second half of pregnancy than in the second half of pseudopregnancy prolonged by uterine decidualization. The possible involvement of these steroids in the inhibition of lordosis behaviour was investigated by increasing their levels in deciduomata-bearing pseudopregnant rats and determining the effect on oestrogen-induced lordosis behaviour. Little suppression of this behaviour was seen when the pseudopregnant rats were treated with progesterone or androsterone whereas treatment with dihydrotestosterone resulted in a significant inhibition of lordosis behaviour. However, the dose of dihydrotestosterone required to do so resulted in high, non-physiological plasma levels of this steroid. No inhibition of lordosis behaviour was observed when dihydrotestosterone levels were approximately threefold those normally present in pregnant rats. It is concluded that none of these three steroids is primarily responsible for the suppression of lordosis behaviour during pregnancy.
SERUM LEVELS OF OESTRADIOL-17β AND PROGESTERONE IN RELATION TO SEXUAL RECEPTIVITY IN INTACT AND OVARIECTOMIZED RATS
Authors: SÖDERSTEN P. , ENEROTH P.
Published: December 2008

Serum levels of oestradiol-17β fluctuated markedly during the oestrous cycle of rats. The onset of sexual receptivity occurred in close correlation with increasing serum levels of progesterone. The serum levels of oestradiol and progesterone in ovariectomized rats implanted with constant-release implants filled with oestradiol or progesterone were related to the amount of hormone in the implants. Constant low serum levels of oestradiol stimulated sexual behaviour in ovariectomized rats, but progesterone stimulation was required for maximum behavioural responses. Peak levels of progesterone in the serum during the oestrous cycle were much higher than those needed for induction of the behaviour in ovariectomized, oestradiol-treated rats. Progesterone, administered in physiological doses, inhibited the induction of sexual receptivity caused by oestradiol and progesterone and the inhibition depended on the strength of the stimulation with oestradiol.
CONSTANT LIGHT BLOCKS DIURNAL BUT NOT PULSATILE RELEASE OF LUTEINIZING HORMONE IN THE OVARIECTOMIZED RAT
Authors: WATTS A. G. , FINK G.
Published: December 2008

We have investigated the effects of constant light on the patterns of LH release in long-term ovariectomized rats. Some animals were implanted with a silicone elastomer capsule containing oestradiol-17β. Plasma samples in anaesthetized animals were taken from the external jugular vein and in conscious animals from an indwelling intra-atrial catheter. The pulsatile release of LH that occurred in animals not treated with oestrogen was unaffected by constant light or the steroid anaesthetic alphaxalone plus alphadolone acetate (Althesin), but was abolished by sodium pentobarbitone. However, the diurnal release of LH produced by increasing the concentrations of plasma oestradiol in conscious animals was blocked by constant light. Thus, these two rhythms of LH release are controlled by different neural pathways; the one concerned with diurnal LH release being suppressed by exposure to constant light.
IMPORTANCE OF VARIATIONS IN BEHAVIOURAL AND FEEDBACK ACTIONS OF OESTRADIOL TO THE CONTROL OF SEASONAL BREEDING IN THE EWE
Authors: GOODMAN R. L. , LEGAN S. J. , RYAN K. D. , FOSTER D. L. , KARSCH F. J.
Published: December 2008

Seasonal variations in the behavioural and feedback actions of oestradiol in the ewe were examined by determining the ability of various physiological oestradiol concentrations to elicit oestrous behaviour, induce an LH surge, and suppress tonic LH secretion at four times of the year. These tests were performed in acutely ovariectomized animals pretreated with oestradiol and progesterone to minimize seasonal differences in their endocrine status. Although smaller amplitude LH surges were observed in anoestrus, the dose–response curves for the induction of LH surges were virtually identical at all times of the year. Oestradiol was slightly less effective in eliciting oestrous behaviour in anoestrus and during the transition to the breeding season than at other times. This seasonal variation was, however, observed only with relatively low oestradiol concentrations; serum oestradiol levels of 3 pg/ml or greater induced oestrus in almost all ewes regardless of season. In contrast, there was a marked seasonal change in the negative feedback action of oestradiol. In anoestrus, basal oestradiol levels of 1–3 pg/ml suppressed LH to low levels (0·3 ng/ml), whereas in the breeding season, even peak oestradiol concentrations of 10 pg/ml were not able to produce this degree of inhibition. These results thus support the hypothesis that the annual breeding cycle of the ewe is governed primarily by shifts in the extent to which oestradiol can suppress tonic LH secretion.
OESTROGEN RECEPTORS AND METABOLIC ACTIVITY IN THE GENITAL TRACT AFTER OVARIECTOMY OF EWES WITH PERMANENT INFERTILITY CAUSED BY EXPOSURE TO PHYTO-OESTROGENS
Authors: TANG B. Y. , ADAMS N. R.
Published: December 2008

Characteristics of the uterus and cervix after ovariectomy of ewes with permanent phyto-oestrogenic infertility (PPI) were compared with controls. Ewes with PPI had more oestrogen-binding sites in the cervix, but not in the uterus. There was no difference between the two groups of ewes in the binding affinity constant of receptors from the uterus or cervix. There were more keratinized cells in the vaginal epithelium of ewes with PPI, and the rates of protein and glycoprotein synthesis in the uterus and cervix were higher in ewes with PPI. These results offer further evidence that PPI in adult ewes is similar to the 'persistent oestrus' syndrome in rodents oestrogenized neonatally.
EFFECT OF REDUCED EXTRACELLULAR SODIUM CONCENTRATION ON THE FUNCTION OF ADRENAL ZONA GLOMERULOSA: STUDIES ON ISOLATED GLOMERULOSA CELLS FROM THE RAT
Authors: ENYEDI P. , SPÄT A.
Published: December 2008

Aldosterone production by isolated adrenal glomerulosa cells from the rat was estimated in the presence of varying concentrations of sodium ion. The reduction of sodium concentration by 5–20 mmol/l, with or without osmotic changes, did not influence the rate of aldosterone production. Aldosterone response to angiotensin II was not modified by varying the sodium concentration.
ACUTE EFFECTS OF AN ANTISERUM TO LUTEINIZING HORMONE ON OVARIAN STEROIDOGENESIS IN THE PREGNANT RAT
Authors: TERRANOVA P. F. , GREENWALD G. S.
Published: December 2008

Pregnant rats were injected s.c. at 09.00 h on day 8 of pregnancy (day 1 = sperm-positive vaginal smear) with either 0·2 or 0·5 ml equine antiserum to bovine LH (anti-LH) while control rats were injected with 0·5 ml normal horse serum (NHS). Rats were decapitated 1,3,6, 24 and 48 h later and serum was saved for radioimmunoassay of progesterone, androstenedione, testosterone, oestrone and oestradiol. One ovary was kept for histology, and from the other, corpora lutea (three/animal) and the non-luteal ovary (ovarian remnant from which all corpora lutea were removed) were saved for steroid determinations. The production rate of steroids by the luteal and non-luteal ovarian compartment was assessed by incubation in Krebs–Ringer bicarbonate buffer for 2 h.

A significant decrease in the serum concentrations of all steroid hormones was induced by 6 h after treatment with anti-LH; progesterone being the first hormone to be consistently reduced (by 3 h). The steroid concentrations remained lower than those in control rats on days 9 and 10. A single injection of anti-LH reduced the number of healthy antral follicles by 3 h but there were always two to four normal antral follicles per ovary on days 8–10.

The initial hormonal changes in the non-luteal ovary after LH deprivation were decreases in the concentration and production rates of the androgens and oestrogens. The initial concentration of non-luteal progesterone was lower 3 and 6 h after anti-LH than in control rats.

Although anti-LH induced a decrease in the serum concentration of progesterone 24 and 48 h later, the corpora lutea contained more progesterone on day 8 and produced in vitro more progesterone than controls on day 8 after 0·2 and 0·5 ml anti-LH and on day 9 when only 0·5 ml was given. The increase in the initial concentration of progesterone on day 8 probably represents accumulation resulting from inhibition of luteal progesterone release. It appears, therefore, that the initial alteration after LH deprivation is inhibition of the release of luteal progesterone and this alone is sufficient to account for the interruption of pregnancy.

The in-vitro increase in luteal steroidogenesis following LH deprivation was observed to some extent with androstenedione but testosterone was unaffected. Luteal aromatizing enzymes appeared to be very sensitive to LH deprivation on day 8 since the concentration and production of oestrogen decreased without concomitant decreases in androgen.

Progesterone (4 mg) administered along with 0·2 ml anti-LH on day 8 prevented luteal regression and the corpora lutea synthesized progesterone and androgens similarly to NHS-treated controls; however, the corpora lutea of the progesterone-treated group contained and produced less oestrogen than controls.
EFFECT OF α-MELANOCYTE-STIMULATING HORMONE AND OVARIAN STEROIDS ON PREPUTIAL GLAND FUNCTION IN THE FEMALE RAT
Authors: DONOHOE S. M. , THODY A. J. , SHUSTER S.
Published: December 2008

Sexually experienced male rats were used to test the attractiveness of preputial gland odours of female rats. The male rats showed a clear preference for the preputial gland odours of hypophysectomized females given oestradiol benzoate (OB) for 3 or 8 days to those of control rats. Progesterone treatment had no effect on the attractiveness of the preputial gland odours of OB-treated hypophysectomized female rats. Administration of α-MSH for either 3 or 8 days, on the other hand, increased the attractiveness to male rats of preputial gland odours of OB-treated hypophysectomized females and the presence of progesterone produced no further change. When administered alone α-MSH had no effect on the attractiveness of the preputial gland odours. Other pituitary hormones, such as ACTH and prolactin, had no effect on the attractiveness of preputial gland odours of OB-treated hypophysectomized rats when administered for 3[unk]days.

An increase in preputial gland size was only seen when OB, progesterone and α-MSH were administered together. It would appear that no relationship exists between the size of the preputial glands and their ability to attract male rats. It is concluded that, while α-MSH and progesterone may be important in controlling growth of the preputial glands, an interaction between α-MSH and oestrogen is more important for regulating the production of sex attractants by the preputial glands.
CARTILAGE RESPONSE TO PLASMA AND PLASMA SOMATOMEDIN ACTIVITY IN RATS RELATED TO GROWTH BEFORE AND AFTER BIRTH
Authors: HILL D. J. , ANDREWS S. J. , MILNER R. D. G.
Published: December 2008

Cartilage response to plasma, plasma somatomedin activity, body weight and length were measured in rats from 15 days of fetal age to 37 days postnatally. The metabolic activity of costal cartilage was assessed by the incorporation of [35S]sulphate in basal medium and after stimulation by plasma.

It was found that (a) A significant stimulation of isotope uptake above basal levels occurred in the presence of 15% standard adult rat plasma at every age studied. (b) The degree of stimulation, a measure of cartilage sensitivity to plasma growth factors, increased through the latter part of fetal life but fell after birth. A high degree of cartilage stimulation was seen on day 6 of postnatal life. (c) The changes in cartilage sensitivity and in the stimulated isotope uptake, resembled the changes observed in growth rate for body weight, nose–rump length and tail length. (d) Plasma somatomedin activity measured by the pig costal cartilage assay was low in the fetus and neonate but rose to adult values 9 days after birth. However, plasma from fetal or neonatal rats tested on cartilage from rats of the same age was equipotent to adult rat plasma. (e) Plasma from hypophysectomized adult rats had a low potency in stimulating isotope uptake by neonatal rat cartilage but was equipotent to normal adult rat plasma in its action on fetal cartilage. (f) The action of plasma from hypophysectomized rats on fetal cartilage was unaffected by dialysis but was destroyed by incubation with trypsin.
PLACENTAL PRODUCTION OF 5β-PREGNANE-3α,20α-DIOL IN GOATS
Authors: SHELDRICK E. L. , RICKETTS A. P. , FLINT A. P. F.
Published: December 2008

A major product of progesterone metabolism by the goat placenta in vitro was found to be 5β-pregnane-3α,20α-diol. The concentration of this steroid has been measured by radioimmunoassay in the peripheral circulation during pregnancy. Peripheral plasma concentrations of 5β-pregnane-3α,20α-diol were low (less than 6 nmol/l) in anoestrous and non-pregnant ovariectomized goats, and during the first month of pregnancy but increased progressively after day 45 of pregnancy, reaching 78–94 nmol/l between days 112 and 142. Thereafter levels declined before term. Changes in the plasma concentration of 5β-pregnane-3α,20α-diol during pregnancy in the goat therefore resembled those of progesterone in the sheep. Plasma concentrations of 5β-pregnane-3α,20α-diol between day 70 and term were not influenced by repeated administration of medroxyprogesterone acetate from days 51 to 82 or by lutectomy in goats treated with medroxyprogesterone acetate. Secretion of 5β-pregnane-3α,20α-diol by the uterus and its contents was indicated by a positive venous–arterial difference across the uterus between days 128 and 141 in three ovariectomized pregnant goats receiving medroxyprogesterone acetate. Comparison of the rates of metabolism of progesterone by homogenates of placenta in vitro showed that the placental tissue from goats was three times more active in this respect than was tissue from sheep. The ratio of the plasma concentrations of 5β-pregnane-3α,20α-diol and progesterone in late pregnancy in ovariectomized or lutectomized goats exceeded by a factor of 10 that in sheep at a comparable stage of gestation. It is suggested that reductive metabolism of progesterone before it is secreted may account for the inability of the placenta to maintain pregnancy after ovariectomy in goats.
EFFECTS OF NEURAL STALK STIMULATION ON PHASIC DISCHARGE OF SUPRAOPTIC NEURONES IN BRATTLEBORO RATS DEVOID OF VASOPRESSIN
Authors: LENG G. , WIERSMA J.
Published: December 2008

Brattleboro rats, homozygous for diabetes insipidus, and Long–Evans rats were anaesthetized with urethane, and antidromically identified neurones were recorded from the supraoptic nucleus. Phasically firing neurones were studied during repeated electrical stimulation of the neural stalk, whereby most supraoptic neurones, but not the recorded neurone, were activated antidromically. Such stimulation consistently modified the discharge pattern of phasic neurones in Long–Evans rats, but was relatively ineffective in Brattleboro rats. These results suggest that the effects of neural stalk stimulation on discharge patterns in Long–Evans rats may be substantially mediated by the evoked release of vasopressin or neurophysin.
EFFECT OF PROGESTERONE ON LIPID METABOLISM IN THE INTACT RAT
Authors: SHIRLING D. , ASHBY J. P. , BAIRD J. D.
Published: December 2008

Female rats implanted with progesterone gained weight more rapidly than control animals and had an increased proportion of total body fat. Restriction of food intake to control levels demonstrated that the weight change was not dependent on increased energy intake. Serum concentrations of cholesterol, phospholipid and non-esterified fatty acid were raised in hormone-treated rats but triglyceride levels were normal. Endogenous production of triglyceride was also unchanged. Total postheparin lipoprotein lipase activity was increased in the plasma of progesterone-treated rats largely due to increased release of the extrahepatic protamine sulphate-labile fraction. The basal rate of lipogenesis was also increased in adipocytes isolated from hormone-treated rats as was the insulin-stimulated rate of oxidation of [1-14C]glucose. Basal and adrenaline-stimulated rates of fat cell lipolysis were, however, unchanged by treatment with progesterone.
ROLE OF SEROTONIN IN THE REGULATION OF GROWTH HORMONE AND PROLACTIN SECRETION IN THE DOMESTIC FOWL
Authors: RABII JAMSHID , BUONOMO F. , SCANES C. G.
Published: December 2008

Plasma levels of GH and prolactin were measured by radioimmunoassay in male domestic fowl treated with centrally active agents. p-Chlorophenylalanine (pCPA) did not have an effect on tonic levels of prolactin but led to a significant rise in circulating GH concentrations. The three serotonin receptor antagonists tested, methysergide, SQ-10631 and cyproheptadine, each resulted in a significant reduction in plasma prolactin while markedly increasing plasma GH levels. Administration of 5-hydroxytryptophan led to a rise in plasma prolactin and a drop in plasma GH levels in untreated birds or in animals pretreated with pCPA. The serotonin receptor agonist, quipazine, resulted in a marked increase in plasma prolactin and a marked reduction in plasma GH concentrations in untreated birds. In pCPA-pretreated animals quipazine was no longer effective in altering plasma prolactin levels but still caused a significant drop in circulating levels of GH. These results suggest that in the young male domestic fowl serotonin has a stimulatory role in the regulation of prolactin and an inhibitory role in the regulation of GH secretion.
DEVELOPMENT OF HYPOTHALAMIC–PITUITARY–ADRENAL RESPONSE TO STRESS IN RATS MADE HYPOTHYROID BY EXPOSURE TO THIOURACIL FROM CONCEPTION
Authors: MESERVE L. A. , LEATHEM J. H.
Published: December 2008

The functional maturation of the hypothalamic–pituitary–adrenal (HPA) axis has been studied in rats of 20–35 days of age made hypothyroid by the administration of thiouracil from conception. Basal concentrations of corticosterone in serum were normal in hypothyroid animals. Ether stress led to an increase in corticosterone content of the adrenal glands of hypothyroid and normal rats but not to a rise in serum corticosterone of hypothyroid rats until 30 days of age. Corticosterone secretion in response to ACTH administration was subnormal in hypothyroid rats. The hypothyroid state delays the development of the hypothalamic–pituitary–portion of the HPA axis until 30 days of age and causes a diminution in the adrenal response to ACTH beyond this time.