bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECTS OF TAMOXIFEN ON PLASMA CONCENTRATIONS OF TESTOSTERONE AND GONADOTROPHINS IN THE MALE RAT
Authors: BARTKE A. , MASON M. , DALTERIO S. , BEX F.
Published: December 2008

Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 01545, U.S.A.

(Received 2% March 1978)

Tamoxifen (trans 1-(p-β-dimethylaminoethoxyphenyl)-1,2-diphenylbut-1-ene; ICI 46,474) is both a potent antioestrogen and a weak oestrogen (Harper & Walpole, 1967) and is thought to act by inhibiting the binding of oestradiol to its cytoplasmic receptor (Jordan & Koerner, 1975). Chronic treatment with tamoxifen causes atrophy of the male accessory reproductive glands and the testicular germinal epithelium in the rat (Harper & Walpole, 1967) and the dog (M. Mason, unpublished data), as well as depression of the plasma concentration of testosterone in the latter species (M. Mason & A. Bartke, unpublished data). A direct inhibitory effect of tamoxifen on testicular steroidogenesis was suspected because treatment of female rats with tamoxifen increases, rather than decreases, the plasma concentration of luteinizing hormone (LH; Watson, Anderson, Alam, O'Grady & Heald, 1975). The possibility that an antioestrogen might act directly is of interest since
APPEARANCE OF OESTRONE SULPHATE IN THE ALLANTOIC FLUID OF THE COW
Authors: ROBERTSON H. A. , KING G. J. , CARNEGIE J. A.
Published: December 2008

Reproductive Physiology Program, Animal Research Institute, Ottawa, Ontario, Canada, K1A 0C6 and * Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada, N1G 2W1

(Received 15 May 1978)

The ability of the conceptus to synthesize oestrogens during the early stages of pregnancy has recently been receiving increasing attention. Among the domesticated species, the day 12 blastocyst of the pig has been shown to be capable of synthesizing oestrogens (Perry, Heap & Amoroso, 1973; Gadsby, Burton, Heap & Perry, 1976) and oestrone sulphate, synthesized as a product of conception, has been shown to be present in the peripheral plasma of the pregnant pig as early as day 17 (Robertson & King, 1974; Robertson, King & Dyck, 1978). In the pregnant ewe, oestrone sulphate has been shown to be the predominant oestrogen in allantoic fluid and to be present in measurable concentrations as early as day 30 (Carnegie & Robertson,
EFFECT OF GROWTH HORMONE ON THE METABOLISM OF 25-HYDROXYCHOLECALCIFEROL IN HYPOPHYSECTOMIZED RATS ON A DIET WITHOUT VITAMIN D AND LOW IN CALCIUM
Authors: PAVLOVITCH H. , FONTAINE O. , BALSAN S.
Published: December 2008

The metabolism of 25-hydroxycholecalciferol (25-(OH)D3) was investigated in rats fed a diet low in calcium and without vitamin D for 4 weeks after hypophysectomy. Compared with intact rats on the same diet these animals had a low serum phosphorus concentration, a less marked degree of hypocalcaemia and their parathyroid gland was not hypertrophied. Eighteen hours after i.p. injection of a single dose of tritiated 25-(OH)D3, chromatography of serum extracts on Sephadex LH-20 showed that the percentage of radioactivity corresponding to 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) was lower in hypophysectomized rats than in control rats. High-pressure liquid chromatography demonstrated that 81% of this material had the same elution profile as synthetic 1,25-(OH)2D3. The percentage of 1,25-(OH)2D3 in the serum of hypophysectomized rats could be increased to the level seen in the controls by chronic treatment with bovine growth hormone. This action of growth hormone was most probably independent of the parathyroid glands since the injection of parathyroid extract did not alter 25-(OH)D3 metabolism in hypophysectomized animals. These results suggest that the decrease in the conversion of 25-(OH)D3 to 1,25-(OH)2D3 after hypophysectomy may be related to the lack of growth hormone.
STIMULATION OF THE SHORT-CIRCUIT CURRENT (SODIUM TRANSPORT) ACROSS THE SKIN OF THE FROG (RANA PIPIENS) BY CORTICOSTEROIDS: STRUCTURE–ACTIVITY RELATIONSHIPS
Authors: YORIO T. , BENTLEY P. J.
Published: December 2008

Aldosterone, at a concentration of 10−8mol/l, increases the short-circuit current (scc, a measure of active sodium transport) across the skin of the frog (Rana pipiens). The other natural amphibian corticosteroid hormone, corticosterone, is about 100 times less potent. The structure–activity relationships of a number of corticosteroids were studied with respect to this response. An 11β-hydroxyl group was essential, whereas unsaturation at the C-1 to C-2 positions abolished activity. A 17-hydroxyl group did not enhance the response. Fluorination at the 9α-position increased the affinity of the steroid for the receptor. Synthetic corticosteroids which have a high ratio of glucocorticoid : mineralocorticoid action can increase the scc and one of these, dexamethasone, was even more potent than aldosterone. A methyl group at C-16 appeared to be an important constituent for this response but it had to be in the α-position. The effects of both aldosterone and dexamethasone were inhibited by spironolactone. The results are discussed in relation to the nature of the response and to corticosteroid receptors in the skin of amphibians.
REFRACTORINESS OF THE PITUITARY GLAND AFTER CONTINUOUS EXPOSURE TO LUTEINIZING HORMONE RELEASING HORMONE
Authors: DE KONING J. , VAN DIETEN J. A. M. J. , VAN REES G. P.
Published: December 2008

The refractoriness of LH release by pituitary glands from intact female rats was studied during stimulation by luteinizing hormone releasing hormone (LH-RH), monobutyryl cyclic AMP+theophylline or potassium in vitro. Various concentrations of LH-RH (0·1, 0·3 and 10 ng/ml) all caused refractoriness within 24 h. Subsequent exposure to a supramaximally active concentration of LH-RH for 6 h also resulted in a depressed response; the degree of inhibition depended on the concentration of LH-RH to which the glands had been exposed previously. Glands made refractory to LH-RH also showed a depressed response to monobutyryl cyclic AMP+theophylline, although these agents by themselves were unable to induce refractoriness. Incubation in medium containing a high concentration of potassium also resulted in the release of LH, which in all respects was similar to that caused by LH-RH. Glands made refractory to LH-RH showed a decreased response to potassium and, conversely, the release of LH in response to LH-RH was reduced after exposure of glands to potassium.

It is concluded that the LH releasing activity of LH-RH, which is mimicked by potassium, deteriorates during continuous exposure to the secretagogue.
GENERATION OF SOMATOMEDIN ACTIVITY IN RESPONSE TO GROWTH HORMONE AND INSULIN FROM ISOLATED PERFUSED LIVERS OF NORMAL AND PROTEINMALNOURISHED RATS
Authors: SHAPIRO B. , WALIGORA K. , PIMSTONE B. L.
Published: December 2008

The generation of somatomedin activity by isolated perfused livers was examined in protein-malnourished (4% casein diet) and well-nourished (controls, 20% casein diet) rats. There was significantly less somatomedin activity (measured by the porcine costal cartilage bioassay), after perfusion for 2 h, in the perfusates from the livers of malnourished rats both in hormone-free perfusates and perfusates containing hormones (10 μg GH/ml, 1000 μu. insulin/ml or a combination of the two). A reduction in the somatomedin activity generated by the liver may be the mechanism responsible for the low serum level of somatomedin (in spite of raised or normal levels of growth hormone) in human or experimental protein malnutrition.
SEX RATIO IN UTERO AND THE PLASMA CONCENTRATION OF TESTOSTERONE IN MALE AND FEMALE RAT FOETUSES
Authors: SLOB A. K. , OOMS M. P. , VREEBURG J. T. M.
Published: December 2008

Department of Endocrinology, Growth and Reproduction, Faculty of Medicine, Erasmus University, P.O. Box 1738, Rotterdam, The Netherlands

(Received 14 June 1978)

Prenatal morphological and behavioural masculinization of female foetuses through exposure to androgen from the testes of male foetuses was first suggested by Clemens (1974). It was reported that female foetuses next to male foetuses in the uterus had a larger ano-genital distance at birth and displayed more (but not statistically significant) mounting behaviour in response to administration of testosterone in adult life than did female foetuses that had not been in such close proximity to foetal male rats. More recently, Gandelman, vom Saal & Reinisch (1977) also reported that in mice, the positions of the female foetuses in the uterus relative to the male foetuses determined the extent to which the female rat was masculinized in terms of both morphology (ano-genital distance at birth) and behaviour (testosterone-induced fighting in
SCREENING OF ABSTRACTS FOR THE FIFTH INTERNATIONAL CONGRESS OF ENDOCRINOLOGY 1976
Authors: SACHS GÜNTHER , VOIGT KLAUS-DIETER , BECK J. C.
Published: December 2008

Letzter Hasenpfad 63, 6000 Frankfurt 70 a.M., Federal Republic of Germany, * Medical University Clinic, Department of Clinical Chemistry, Martinistrasse 52, 2000 Hamburg 20, Federal Republic of Germany, and † The Robert Wood Johnson Foundation, Suite 310, Parnassus Heights Medical Buildings, 350 Parnassus Avenue, San Francisco, California 94117, U.S.A.

The increase in size of national and international scientific meetings has posed challenges to their efficient and effective organization. In planning the scientific programme, particularly when a process of abstract selection involves the judgement of multiple referees, new procedures should facilitate administration and reduce overall costs. The International Congress of Endocrinology held in Hamburg, Germany, in 1976, utilized a computer-assisted series of steps in handling abstracts and this paper summarizes the observations arising from the processing of over 1500 abstracts. We believe this experience will be valuable to future Congress organizers.

The objective of the process was the preparation of a
SEX DIFFERENCES IN THE CONCENTRATIONS OF GLUCOCORTICOID RECEPTORS IN RAT LIVER AND THYMUS
Authors: ENDRES D. B. , MILHOLLAND R. J. , ROSEN F.
Published: December 2008

The effects in rats of adrenalectomy, hypophysectomy, ovariectomy or combinations of these operations on the concentrations of glucocorticoid receptors in the cytosol of liver and thymus were measured. The concentrations of glucocorticoid receptors were lower in cytosols from liver and thymus of female than of male rats. After adrenalectomy, there was a significant increase in the concentrations of receptors measured in the cytoplasm from the liver and thymus of female rats and from the liver of male rats. After adrenalectomy or hypophysectomy, there was no sex difference in the concentrations of glucocorticoid receptors in cytosols of liver or thymus. After ovariectomy, the concentration of receptors in cytosols from the thymus, but not from the liver, increased. Ovariectomized rats responded to adrenalectomy in the same way as intact male rats. The different responses shown by male and female rats to endocrine manipulation probably depend upon associated changes in plasma corticosterone concentrations which are influenced by the ovary. Differences in response between the liver and thymus probably reflect a preferential distribution of corticosterone to the liver rather than to the thymus.
REDUCTION OF NON-SPECIFIC SERUM RESPONSES IN HUMAN PITUITARY GONADOTROPHIN RADIOIMMUNOASSAYS
Authors: HUNTER W. M. , BENNIE J. G.
Published: December 2008

Serum and plasma from human and domestic animals contain variable amounts of non-specific material(s) which may be mistaken for hormone in assays for human LH and FSH, based upon antisera of high sensitivity and hormonal monospecificity. The non-specific response curves are generally, but not invariably, less steep than those of the hormone standards and endogenous homologous hormones. The levels of non-specific intrusion can be of sufficient magnitude to obscure specific estimations seriously, particularly at low hormone levels, unless the assays are designed to minimize this effect.

The non-specific effects could be minimized (but not abolished) by careful optimization of the assays which involved making the response curve as sensitive as possible and incorporating the serum at a final dilution of 1: 2, since further dilution increased the relative contribution of the non-specific substance(s). The optimized assays require only 48 h of total incubation and show a sevenfold increase in the mean concentration of LH between sera from prepubertal children and adults accompanied by a mean threefold difference in the concentration of FSH.
BIOASSAY OF INHIBIN-LIKE ACTIVITY USING PITUITARY CELLS IN VITRO
Authors: DE JONG F. H. , SMITH S. D. , VAN DER MOLEN H. J.
Published: December 2008

The secretion of follicle-stimulating hormone (FSH) by the pituitary gland appears to be partially regulated by a protein hormone, inhibin, which is produced in the Sertoli cells of the testis and is also present in ovarian follicular fluid (FF). The aim of the present study was to develop a sensitive method for the detection and estimation of inhibin-like activity, using dispersed pituitary cells in culture.

Pituitary cells from adult male rats were dispersed and precultured for 3 days. After renewal of the medium (2 ml), samples to be tested for inhibin-like activity were added and culture was continued for a further 3 days. A dose-dependent suppression of the concentration of FSH in the medium (λ = 0·17–0·22) was observed after addition of FF (0·05–1 μl) or Sertoli cell culture medium (SCCM, 0·05–1 ml). Luteinizing hormone (LH) concentrations were not affected with these doses of FF, but SCCM and higher doses of FF caused a significant increase in the concentration of LH in the medium. During an additional 6 h of culture in the presence of luteinizing hormone releasing hormone (LH-RH), FF and SCCM suppressed the release of both FSH (λ = 0·07–0·11) and LH in a dose-dependent way. Cellular content of FSH, but not of LH, was decreased after these treatments. These results could not be explained by damage to the pituitary cells, by degradation of FSH or LH-RH, or by effects of steroids.

It is concluded that this pituitary cell culture system can be used as a sensitive method for the estimation of inhibin-like activity in FF and SCCM.
SERUM CONCENTRATIONS OF TESTOSTERONE, OESTROGENS, LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE IN MALE AND FEMALE RATS DURING THE CRITICAL PERIOD OF NEURAL SEXUAL DIFFERENTIATION
Authors: PANG S. F. , CAGGIULA A. R. , GAY V. L. , GOODMAN R. L. , PANG C. S. F.
Published: December 2008

Untreated male and female rat pups were killed 1–5 days post partum and the serum concentrations of testosterone, oestrogens, LH and FSH were determined by radioimmunoassay. At all five sampling times, the serum concentrations of testosterone in male rats were about three times higher than those in female rats, but serum levels of oestrogens did not differ between the sexes. Serum concentrations of LH and FSH were lower in male than in female pups. In another study, rats were decapitated 1–10 days after birth and serum concentrations of testosterone were determined with a different radioimmunoassay. Again, at all four sampling times, the concentration of testosterone was significantly higher in the male than in the female pups.
A FEMALE-LIKE RISE IN LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE AFTER GONADECTOMY IN MALE RATS INDUCED BY OESTRADIOL PRETREATMENT
Authors: JUSTO S. N. , NEGRO-VILAR A.
Published: December 2008

A marked sexual difference in the rise of serum gonadotrophin concentrations after gonadectomy has been described in the rat. Gonadectomy in males induced a rapid rise in the concentrations of both LH and FSH within 8 to 12 h, whereas ovariectomy invoked a rapid increase in the concentration of FSH while the response by LH was delayed for several days. To determine whether these differences could be explained, at least in part, by the different steroid milieu at the time of gonadectomy, a series of experiments were performed to analyse the rise in both LH and FSH serum concentrations in control male and female rats and in male rats that had been pretreated with oestradiol-17β. Adult male rats received an s.c. implant of a silicone elastomer capsule filled with crystalline oestradiol-17 β. Controls received empty capsules. Twenty-four hours later, the oestradiol-implanted rats were castrated and control animals were sham-operated. Both LH and FSH levels remained within control levels after castration in the oestradiol-implanted rats, indicating that the oestradiol implant was preventing any rise of either gonadotrophin. On day 5 after implantation, the capsules were removed, sham-implanted animals were castrated and LH and FSH levels at 12, 24, 48 and 72 h were measured and compared with those of ovariectomized rats at similar intervals. The control male rats displayed the pattern of gonadotrophin increments normally found after castration, with both LH and FSH concentrations rising significantly by 12 h after castration and with further increments at later periods. Oestradiol-treated rats showed a female-like gonadotrophin pattern. FSH levels started to rise significantly at 24 h compared with values from intact rats and increased further at 48 and 72 h. During the first 48 h, FSH levels in both oestradiol-treated, castrated rats and female gonadectomized rats were significantly lower than in castrated animals. LH levels, on the other hand, remained low in both groups during the first 48 h, starting to rise significantly above control levels by 72 h. These results indicate that the different pattern of response to gonadectomy in rats of both sexes may be altered by changes in steroid environment and, therefore, may not be genetically predetermined.
SEASONAL FLUCTUATIONS IN THE PLASMA CONCENTRATIONS OF PROGESTERONE AND OESTRADIOL-17β IN THE FEMALE SNAPPING TURTLE (CHELYDRA SERPENTINA)
Authors: LEWIS JAMES , MAHMOUD I. Y. , KLICKA JOHN
Published: December 2008

Plasma concentrations of progesterone and oestradiol-17β were determined by radioimmunoassay procedures in the sexually mature female snapping turtle at four different stages of the annual ovarian cycle. The highest level of progesterone in the peripheral plasma was detected during the luteal stage (June), whereas the concentration of oestradiol was highest (280 pg/ml) in May, immediately before ovulation.
DIFFERENTIAL CONTROL OF LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE BY LUTEINIZING HORMONE RELEASING HORMONE IN THE RAM
Authors: LINCOLN G. A.
Published: December 2008

Adult Soay rams with low concentrations of gonadotrophins in the circulation as a result of 12 weeks of exposure to long daylengths (16 h light: 8 h darkness) were given small doses (100 ng) of synthetic luteinizing hormone releasing hormone (LH-RH) into the jugular vein two, four or seven times/day for 10 days.

Each injection of LH-RH induced a transitory increase in the concentration of LH and testosterone in the plasma, whereas the concentration of FSH showed little immediate change, After repeated treatment with pulses of LH-RH, the responses of LH and testosterone became slightly enhanced and the plasma concentration of FSH became permanently raised; these changes were most conspicuous in the animals receiving the most frequent injections.

At the end of the study when the injections of LH-RH were stopped, the concentrations of LH and testosterone remained low but the concentrations of FSH continued to be maintained at a high level for at least 24 h.
EFFECT OF TREATMENT WITH AN AGONIST OF LUTEINIZING HORMONE RELEASING HORMONE ON EARLY MATURATIONAL CHANGES IN PITUITARY AND TESTICULAR FUNCTION IN THE RAT
Authors: SHARPE R. M. , FRASER H. M. , SANDOW J.
Published: December 2008

Male rats aged 30 days were injected once daily for between 1 and 7 days with 50 ng (d-serine t-butyl6, des-glycine-NH210) luteinizing hormone releasing hormone ethylamide (LH-RH agonist), and pituitary and testicular function were assessed. Treatment for 7 days significantly (P < 0·02) inhibited maturational increases in the pituitary content and serum concentration of gonadotrophins, testicular luteinizing hormone (LH)-receptor concentration and the testicular capacity to secrete testosterone; the pituitary content and serum concentration of prolactin, the hypothalamic content of LH-RH and testicular weight were unaffected. In rats treated with LH-RH agonist, the initial (2 to 3 days) reduction in testicular LH-receptors and the capacity to secrete testosterone probably resulted from acutely raised levels of LH in the blood, whilst later effects may have resulted from the apparently chronic reduction in serum gonadotrophin levels. The latter may reflect a decrease in pituitary responsiveness to repeated stimulation with LH-RH agonist. Despite the extensive loss of testicular LH-receptors and diminished responsiveness, the concentration of HCG which significantly (P < 0·05) increased testosterone secretion by the testis in vitro was the same (2 pmol/l) as that for testes from control rats.
EFFECTS OF GONADAL STEROIDS ON OUTPUT OF LUTEINIZING HORMONE RELEASING FACTOR INTO PITUITARY STALK BLOOD IN THE FEMALE RAT
Authors: SARKAR D. K. , FINK G.
Published: December 2008

The concentration of immunoreactive luteinizing hormone releasing factor (LH-RF) was measured in pituitary stalk blood collected in the afternoon of expected pro-oestrus from rats ovariectomized and given oil, oestradiol benzoate (OB) or progesterone on the morning of dioestrus. Compared with the values in intact rats, LH-RF concentrations were reduced in ovariectomized animals treated with oil or progesterone but not with OB. Administration of progesterone at 12.30 h of expected pro-oestrus reduced the LH-RF concentrations in OB-treated rats; 5α-pregnan-3β-ol-20-one was not as effective as progesterone. The apparent inhibitory effect of progesterone, which was dose-dependent, was not found in long-term adrenalectomized rats, suggesting that it may be due to the production of an inhibitory substance by the adrenal consequent upon steroid administration. These and other data show that oestradiol triggers the spontaneous LH surge by stimulating the release of LH-RF as well as by enhancing pituitary responsiveness. A different mechanism may underlie the reflex surge of LH in rats exposed to constant light for, in these animals, progesterone was found to stimulate LH-RF release.
PRODUCTION OF TESTOSTERONE, 5α-ANDROSTANE-3α,17β-DIOL AND ANDROSTERONE BY DISPERSED TESTICULAR INTERSTITIAL CELLS AND WHOLE TESTES IN VITRO
Authors: MOGER W. H.
Published: December 2008

The production of 5α-androstane-3α,17β-diol (androstanediol), androsterone and testosterone by whole rat testes and testicular interstitial cells dispersed with collagenase was studied in vitro. Luteinizing hormone stimulated the production of each of the androgens by cells prepared from 31- to 34-day-old rats. Half maximum stimulation of the production of each androgen occurred with approximately 3·5 ng NIH-LH-B9/ml medium. Androstanediol was the predominant product then androsterone and then testosterone. Luteinizing hormone stimulated the production of testosterone, but not androstanediol or androsterone by dispersed interstitial cells from 200-day-old rats. The time-course of production and the effect of the concentration of cells on the production of these androgens suggested that in dispersed testicular interstitial cells from immature animals androstanediol and androsterone are formed, at least partially, by the metabolism of testosterone. In these experiments LH-stimulated testosterone production increased during incubation for 15–60 min and then remained constant up to 180 min. The concentrations of androstanediol and androsterone increased in a linear manner during incubation for 60–180 min. Varying the number of cells incubated yielded a positive correlation between cell concentration and the ratio 5α-reduced androgen: testosterone produced. Luteinizing hormone stimulated production of each androgen by whole testes obtained from rats at 30–175 days of age. The serum concentration of testosterone in these rats increased abruptly at 50 days of age. Significant changes in androgen production in vitro also observed at this age included: (1) increased production of the three steroids when incubated in either the presence or absence of LH and (2) testosterone production, either in the presence or absence of LH, which represented a greater percentage of the total production of the three androgens.
ALTERATIONS IN ADRENAL GROWTH AND CORTICOSTEROID CONTENT IN FOETAL AND NEONATAL RATS DEVELOPING AT HIGH ALTITUDE
Authors: GARVEY D. , AKANA S. , WEISMAN A. , TIMIRAS P. S.
Published: December 2008

To study the effects of chronic maternal hypoxia on the growth and functional development of foetal and neonatal adrenal glands, Long–Evans rats were acclimatized to high altitude (3800 m) before mating and were maintained at this height throughout gestation. The body growth of the progeny at high altitude was essentially normal during the perinatal period, but adrenal weight and adrenocortical function showed marked differences from those of control rats maintained at sea level. The adrenal glands were larger in foetuses but smaller in neonates, compared with the adrenal glands of control animals maintained at sea level. Differences in the protein content of the adrenal glands between the two groups paralleled differences in adrenal weight. The concentration and content of corticosterone in the adrenal glands of both foetuses and neonates kept at high altitude were markedly lower than values in animals kept at sea level. The lower adrenal corticosterone content was not reflected in the concentration of the hormone in the peripheral plasma, since this was essentially the same at high altitude and at sea level in both mothers and perinatal animals. The reduction in the adrenal corticosterone content was accompanied by and may have resulted from, a reduction in the concentration of cytochrome P-450 in the adrenal tissue of foetuses maintained at high altitude. Possible explanations for the dichotomous results are discussed.
INTERNAL QUALITY CONTROL OF RADIOIMMUNOASSAYS: MONITORING OF ERROR
Authors: WILSON D. W. , GRIFFITHS K. , KEMP K. W. , NIX A. B. J. , ROWLANDS R. J.
Published: December 2008

A cumulative sum technique has been specially designed to monitor the error between replicate determinations made on quality control plasma for consecutive batches of assays. This procedure has played a vital role in assessing assay performance. Special consideration has been given to small sample sizes (n = 2 or 3) which is generally the rule rather than the exception in many situations. This technique has been applied to numerous steroid radioimmunoassays and has ensured that both the mean value and the standard error of hormone levels of a quality control pool were under control. Data from routine assays of oestriol and testosterone in plasma from women are presented. Since this technique provides a sensitive measure of monitoring error, it assists the endocrinologist in elucidating statistical inferences which are a manifestation of assay performance.
EFFECT OF THE TIMING OF PERPHENAZINE ADMINISTRATION ON PREGNANCY IN THE RAT
Authors: SHANI J. , AMIT M. , GIVANT Y.
Published: December 2008

Perphenazine in doses of 10–50 mg kg−1 day−1 given at the early stages of pregnancy delayed nidation up to day 8 of pregnancy. Once nidation had occurred the length of the rest of the gestation period was normal. Doses of up to 20 mg perphenazine kg−1 day−1, injected on days 1–7, prolonged gestation but the mothers and young were apparently normal; lower doses were effective only when treatment commenced soon after copulation. The delay in implantation of the ovum caused by perphenazine was corrected and implantation was brought about immediately, by injection of 0·1 μg oestradiol together with perphenazine. It is suggested that perphenazine delays and prevents implantation in rats by counteracting oestrogen release from the ovaries.
EFFECT OF PREGNANCY ON THE COLLAGEN CONTENT OF THE OVIDUCT IN THE LIZARD
Authors: AL-ZAID N. S. , BOU-RESLI M. N.
Published: December 2008

It was shown experimentally that both the growth and total collagen content of the oviduct in the lizard Acanthodactylus scutellatus hardyi are mainly dependent on the number of eggs present. There was rapid formation of collagen if more than two eggs were present.
REGULATION OF PROLACTIN BINDING SITES IN THE SEMINAL VESICLE, PROSTATE GLAND, TESTIS AND LIVER OF INTACT AND CASTRATED ADULT RATS: EFFECT OF ADMINISTRATION OF TESTOSTERONE, 2-BROMO-α-ERGOCRYPTINE AND FLUPHENAZINE
Authors: BARKEY R. J. , SHANI J. , BARZILAI D.
Published: December 2008

The effect of hormonal manipulations on prolactin binding to its specific binding sites in the seminal vesicle, prostate gland, testis and liver of adult male rats was studied. Castration significantly reduced prolactin binding to the seminal vesicle and prostate, whereas it greatly increased its binding to the liver. Testosterone replacement therapy restored the reduced level of binding to that found in the liver of intact rats, whereas binding to the seminal vesicle and the prostate was raised to the high levels found in the testosterone-treated intact rats. In contrast, testosterone administration to intact rats significantly reduced the binding of prolactin to the testicular homogenate. The administration of 2-bromo-α-ergocryptine (CB 154) to either intact or testosterone-treated castrated rats caused no significant change in binding of prolactin to any of the organs tested. Fluphenazine enanthate or CB 154 +ovine prolactin increased the binding of prolactin to the liver, when compared with untreated rats, whereas in the testis these treatments resulted in a minor decrease as compared with untreated rats. In the testosterone-treated castrated rats, fluphenazine caused no apparent effect on the binding of prolactin to any of the organs tested. In conclusion, testosterone is essential for the maintenance of prolactin binding sites in the seminal vesicle and prostate of the adult rat. Prolactin, however, does not appear to regulate its own receptor in the accessory sex glands, neither alone nor in synergism with testosterone. In the testis, exogenous testosterone exerted a negative effect on prolactin binding, as did raised serum prolactin levels. In the liver of the male rat, testosterone seemed to be the major cause of the low level of prolactin binding sites, while prolactin was capable of inducing its own sites in that organ.
A BIOASSAY FOR INHIBIN USING PITUITARY CELL CULTURES
Authors: EDDIE L. W. , BAKER H. W. G. , HIGGINSON R. E. , HUDSON B.
Published: December 2008

A bioassay for inhibin based on the suppression of gonadotrophin releasing hormone (Gn-RH)-stimulated secretion of FSH by primary monolayer cultures of rat anterior pituitary cells is described. The cultures were exposed to standard or test materials for 3 days. The levels of FSH in the media were measured by radioimmunoassay after exposure for 6 h to a maximally stimulating concentration of Gn-RH (10 nmol/l). The standard was prepared from ovine testicular lymph. Several preparations of proteins from gonadal tissues or secretions suppressed the levels of FSH in parallel with the standard. The levels of LH were also reduced but higher doses of active material were required. Non-specificity from cell damage and inactivation of Gn-RH have been excluded. The secretion of gonadotrophins by the pituitary cells was also inhibited by androgens, but not in parallel with the standard and secretion of LH was affected more than that of FSH. Control lymph protein preparations from castrated sheep had no detectable activity. The assay was sensitive and had adequate precision and practicability. It has proved useful for monitoring preliminary steps in the purification of inhibin.
SUPPRESSION OF THE LUTEINIZING HORMONE RELEASING EFFECT OF LUTEINIZING HORMONE RELEASING HORMONE BY ARGININE-VASOTOCIN
Authors: YAMASHITA K. , MIENO M. , YAMASHITA ER.
Published: December 2008

The concentrations of 17-oxosteroids in the spermatic venous blood of anaesthetized dogs were used as an index of LH release to assess the effects of arginine-vasotocin on the response of the canine pituitary gland to exogenous luteinizing hormone releasing hormone (LH-RH). When injected into the carotid artery, arginine-vasotocin (1·0 μg/kg body wt) caused no significant alterations in the testicular output of 17-oxosteroids. The administration of LH-RH (5 μg/kg body wt, a standard dose) into the carotid artery produced typical stimulation of testicular 17-oxosteroid secretion. Administration of arginine-vasotocin (0·01, 0·1 or 1·0 μg/kg body wt) into the carotid artery 3 h before the administration of a standard dose of LH-RH inhibited the testicular secretion of 17-oxosteroids normally induced by LH-RH. However, pretreatment with arginine-vasotocin (1·0 μg/kg body wt) did not affect the testicular response to i.v. administration of human chorionic gonadotrophin (5 i.u./kg body wt). These results indicate that in the dog, arginine-vasotocin inhibits the LH-RH-induced release of LH by acting directly on the anterior pituitary gland.
EFFECT OF STORAGE ON THE BIOACTIVITY OF TWO INTERNATIONAL REFERENCE PREPARATIONS OF HUMAN PITUITARY LUTEINIZING HORMONE IN VITRO
Authors: ROBERTSON D. M. , FRÖYSA BERIT
Published: December 2008

There was no loss of biological activity in vitro when the 1st International Reference Preparation (IRP) for human pituitary gonadotrophins [FSH and LH/interstitial cell stimulating hormone (ICSH) for bioassay] code no. 69/104 and the 1st IRP for human pituitary LH/ICSH [for immunoassay] code no. 68/40 were stored for 1 year at −70 °C in a buffered 0·8% saline solution containing 1% bovine plasma albumin (BPA). However, storage of the 69/104 preparation at −20 °C in either 0·1 or 1% BPA, or at −70 °C in the presence of 0·1% BPA showed a small but significant decrease (∼ 10%) in activity over the same period. It is, therefore, advantageous to store these reference preparations at −70 °C in the presence of 1% BPA.
FURTHER EVIDENCE THAT MELATONIN REPRESENTS THE RELEASING HORMONE FOR PINEAL VASOTOCIN
Authors: PAVEL S. , GOLDSTEIN R.
Published: December 2008

As deduced from the antidiuretic and hydro-osmotic activities, intracarotid injection of 10 μg melatonin into urethane-anaesthetized cats significantly decreased the pineal argininevasotocin (AVT) content and increased its level in cerebrospinal fluid (CSF) between 5 and 60 min after the injection. No AVT was detectable in the plasma of cats between 5 and 60 min after the intracarotid injection of melatonin. However, between 60 and 90 min, when AVT disappeared from the CSF, a significant amount of AVT was detectable in plasma. The intracarotid injection of 10 μg serotonin was unable to induce the release of AVT into CSF or plasma, or to affect the pineal AVT content. Although intracarotid injection of 10 ng melatonin was unable to induce the release of AVT during the daylight hours, the same amount of melatonin was highly potent in inducing the release of AVT into the CSF during the night in the dark. The sensitivity of AVT to melatonin appears to be induced by darkness because the same amount (10 ng) of melatonin was ineffective when injected into animals maintained with the light on during the night. Since it was necessary to administer 5 μg melatonin during the hours of daylight to match the effects of 10 ng melatonin given at night, it appears that melatonin is about 500 times more potent in inducing AVT release during the night in the dark. The present results further consolidate the concept that melatonin represents the releasing hormone for pineal AVT and at the same time strongly suggest that AVT is first released into the CSF and reaches the blood only secondarily after its absorption from the CSF.
PLASMA OXYTOCIN AND STEROID CONCENTRATIONS DURING LATE PREGNANCY, PARTURITION AND LACTATION IN THE MINIATURE PIG
Authors: FORSLING M. L. , TAVERNE M. A. M. , PARVIZI N. , ELSAESSER F. , SMIDT D. , ELLENDORFF F.
Published: December 2008

Plasma oxytocin concentrations were measured during late pregnancy, parturition and lactation in the miniature pig. Measurements were made of plasma oestradiol, oestrone and progesterone to determine whether there was any relationship between the concentrations of oxytocin and these steroids in the circulation.

Plasma oxytocin concentrations were low or undetectable in late pregnancy. Rises of up to 68·8 μu./ml were seen at the time of delivery of the foetuses and at the expulsion of the placenta. The only steroid that seemed to relate to oxytocin release was progesterone. Oxytocin release was consistently seen when progesterone concentrations had fallen to below 10 ng/ml but no increase in concentration was observed while oestrone and oestradiol increased to their maximum concentrations of 3·86–11·6 and 0·43–0·70 ng/ml respectively.

During lactation, when both oestrogen and progesterone concentrations were low, suckling caused the levels of oxytocin to increase to 7·4 μu./ml. These increases were greater during the first 2 weeks of lactation than later.
EFFECTS OF GLUCOSE AND AMINO ACIDS ON INSULIN, GLUCAGON AND ZYMOGEN GRANULE SIZE OF FOETAL RAT PANCREAS GROWN IN ORGAN CULTURE
Authors: MILNER G. R. , DE GASPARO M. , KAY R. , MILNER R. D. G.
Published: December 2008

Foetal rat pancreatic rudiments explanted on day 14 of gestation were grown for 6 days in organ culture in medium containing glucose (5·5 (1G) or 16·5 (3G) mmol/l) and amino acids at the 'physiological' (1AA) or seven times the 'physiological' (7AA) concentration. Cultures were also performed in medium to which zinc sulphate had been added at 10−7 to 10−5 mol/l concentration. At the end of the period of culture the diameters of insulin, glucagon and zymogen granule profiles in the rudiments were compared with those in normal 20-day foetal pancreas by quantitative morphology. The β cell volume, the number of granules per β cell, the insulin granular volume fraction and the area of insulin granule core and halo were also measured under selected experimental conditions.

Zymogen granule profiles were largest in vivo, intermediate in diameter when grown in 1G × 7AA medium and smallest in 1G × 1AA medium. The mean diameter of glucagon granule profiles remained constant for growth in vivo, in 1G × 1AA medium or in 1G × 7AA medium. Insulin granule profiles were largest in 1G ×7AA medium, smallest in 3G × 1AA medium and of intermediate diameter in vivo. Amino-acid enrichment increased the diameter of insulin granules and glucose enrichment decreased it. The addition of zinc to the culture medium had no effect on insulin granule diameter. In 1G × 7AA cultures the β cells were of similar size to those in vivo, but there were 29% fewer insulin granules per cell. The increased size of the insulin granules in 1G × 7AA cultures resulted in the insulin granule volume fraction in 1G × 7AA being 17·6 compared with 10·8% in vivo. Insulin granule cores were made larger by amino-acid enrichment of the culture medium but they were unaffected by glucose. The haloes were larger in 7AA medium and smaller in 3G medium. Glucose and amino-acid enrichment had a significant interaction on halo area, the mean area in 3G × 7AA medium being less than would have been expected from the summation of the effects of the two conditions.
EFFECT OF CHICKEN HYPOTHALAMUS ON PROLACTIN AND GROWTH HORMONE SECRETION IN MALE CHICKENS
Authors: HARVEY S. , SCANES C. G. , CHADWICK A. , BORDER G. , BOLTON N. J.
Published: December 2008

The effects of a chicken hypothalamic extract (HE) on the secretion of prolactin and growth hormone (GH) in vivo have been investigated by radioimmunoassay in the domestic fowl. Different i.v. doses of HE (0·25–25 HE equivalents/kg body weight) had no effect on GH secretion in conscious or anaesthetized cockerels. In both groups of birds the concentration of plasma prolactin was significantly increased within 10 min of administration of the extract. Extracts of other brain tissues (cerebral cortex, cerebellum and medulla oblongata) had no stimulatory effect on prolactin or GH secretion. Release of both prolactin and GH by dispersed pituitary cells and by hemipituitary glands in vitro was enhanced following incubation with HE (5 hypothalami equivalents/ml) or with single whole hypothalami respectively. Other brain tissues (cerebellum, optic lobes and medulla oblongata) had no effect on the concentration of prolactin or GH released by incubated hemipituitary glands.
INFLUENCE OF IODINE ON THE FORMATION OF 27S AND LARGER IODOPROTEINS IN RAT THYROID FOLLICLES
Authors: SMEDS S. , EKHOLM R. , STUDER H.
Published: December 2008

The importance of the presence of iodine for the formation of iodoproteins larger than 19S thyroglobulin, i.e. 27S and larger iodoproteins (large-TG), was studied. Samples of colloid were collected in vivo by micropuncture of single rat thyroid follicles after treatment with a low iodine diet or potassium perchlorate. The protein composition of the colloid was analysed by microgel electrophoresis on polyacrylamide gels.

It was observed that the large-TG fractions were reduced by approximately 50% after treatment with a low iodine diet for 3 months. The large-TG fractions were almost absent after treatment with perchlorate for 3 weeks.

Administration of 5 or 10 μg potassium iodide to the animals on a low iodine diet resulted in a significant increase of the relative amount of the large-TG fractions in the colloid within approximately 2 h, the higher dose of KI producing a more pronounced accumulation of the large-TG fractions. Inhibition of protein synthesis by cycloheximide did not prevent the increase of large-TG proteins in animals on a low iodine diet after the administration of 5 μg KI. The administration of iodide to rats treated with potassium perchlorate did not result in the appearance of large-TG fractions.

It is concluded that the aggregation of thyroglobulin molecules occurs in the follicle lumen as a consequence of iodine administration. This formation of large-TG fractions does not require exocytosis of newly synthesized protein.
PROLONGED INTRAVENOUS INFUSION OF LABELLED IODOCOMPOUNDS IN THE RAT: [125I]THYROXINE AND [125I]TRI-IODOTHYRONINE METABOLISM AND EXTRATHYROIDAL CONVERSION OF THYROXINE TO TRI-IODOTHYRONINE
Authors: BOONNAMSIRI VIPA , KERMODE J. C. , THOMPSON B. D.
Published: December 2008

Extrathyroidal tissues of the rat were labelled to steady state by prolonged continuous intravenous infusion of 125I-labelled thyroxine (T4) or tri-iodothyronine (T3). Labelled iodocompounds extracted from various tissues were analysed by thin-layer chromatography.

Significant amounts of labelled T3 were found in all tissues examined after infusion of [125I]T4, confirming that conversion of T4 to T3 occurs in extrathyroidal tissues of the rat. Faecal excretion of labelled T3 after [125I]T4 infusion provided an assessment of the extent of extrathyroidal conversion: about a third of the T4 was metabolized by this pathway. Extrathyroidal conversion was independently estimated to account for about a third of the total production of T3.

The site of extrathyroidal conversion was established by comparing the distributions of labelled T3 after the two types of infusion: kidney and liver were both prominent sites of conversion of T4 to T3.
EVALUATION OF THE BOVINE TESTICULAR RADIORECEPTOR ASSAY FOR PITUITARY FOLLICLE-STIMULATING HORMONE
Authors: SAIRAM M. R.
Published: December 2008

A modified bovine testicular receptor was used to evaluate highly purified follicle-stimulating hormone (FSH) from a number of species. The particulate receptor obtained from adult bovine testes could be stored frozen or lyophilized for long periods without appreciable decrease in the binding of the ligand facility or in loss of specificity. The bovine testis receptor binds twice as much 125I-labelled ovine FSH as 125I-labelled human hormone. When FSH from different species was compared against NIH-FSH-S10, using various FSH ligands, the ovine hormone was clearly the most active, although many had comparable in-vivo biological potencies. The results suggest that there is probably some species specificity in the hormone–receptor interactions. As the ovine hormone is structurally closer to the bovine, from which the receptor was derived, it appears to have the highest activity in vitro. Marked differences in the biological activities of the different preparations between the human chorionic gonadotrophin-augmentation test and the in-vitro assays have been observed. In the in-vitro assays, all preparations, with the exception of the porcine hormone preparation, were less active and the ratio of bioassay/radioreceptor assay varied widely. In the radioreceptor assays, all FSH preparations except pregnant mare serum gonadotrophin (PMSG) showed parallel inhibition curves. The three different PMSG preparations examined gave inhibition lines that were parallel to each other.
INFLUENCE OF TESTICULAR SECRETIONS ON TISSUE WEIGHT AND ON METABOLIC AND ENZYME ACTIVITIES IN THE EPIDIDYMIS OF THE RAT
Authors: BROOKS D. E.
Published: December 2008

Preventing the entry of testicular secretions into the epididymis by ligating the efferent ducts resulted in reduced epididymal weight and an alteration in the distribution of carnitine throughout the segments. The metabolic activity of the distal regions of the duct was unaffected by ligation but some changes were apparent in more proximal regions, particularly in the initial segment. Inhibition of spermatogenesis by the administration of busulphan resulted in a loss of weight of the caput epididymidis similar to that caused by ligation of the efferent ducts, even though testicular fluid was not prevented from entering the epididymis. Treatment with busulphan also led to a reduction in androgen-binding protein (ABP) and to a lower activity of pyruvate carboxylase in the caput. Ligation of the efferent ducts in busulphan-treated animals prevented the entry of testicular fluid into the epididymis as judged by the absence of ABP. Despite the absence of ABP, and hence any androgens normally associated with it, there was no appreciable change in the activity of androgenregulated enzymes, indicating that sufficient androgen was reaching the epididymis by way of the peripheral circulation. However, the results suggest that, in addition to androgens, the testis normally produces some other component(s), possibly associated with spermatozoa, which are required for full maintenance of the weight of the epididymal duct and of metabolic activity in the more proximal regions.
EFFECTS OF THE METHOD OF EXSANGUINATION ON MEASUREMENTS OF DEVELOPMENTAL CHANGES IN SERUM CONCENTRATIONS OF FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE IN PREPUBERTAL AND ADULT MALE HOUSE MICE
Authors: BERKOWITZ A. S. , LLOYD J. A. , CHOWDHURY MRIDULA
Published: December 2008

The relationship between the method of exsanguination and the serum concentration of gonadotrophins was investigated in male house mice. Mice were killed 21–99 days post partum by ether anaesthesia and cardiac puncture, or by decapitation. Results of gonadotrophin radioimmunoassays indicated that titres of serum FSH were not affected by the method of exsanguination, while concentrations of serum LH were significantly raised when blood was collected by ether anaesthesia and cardiac puncture. Serum FSH in an inbred strain of mice peaked at 21 days post partum and declined steadily to a relatively constant pubertal and postpubertal level. Concentrations of serum LH were variable during the prepubertal period with a peak occurring 31–35 days post partum. Extremely high titres of FSH on days 21–35 post partum indicated that mice in this study might be relatively insensitive to FSH in the prepubertal period.