bluuebunny/crossref_metadata_2025 huggingface dataset:
FEEDBACK CONTROL OF FOLLICLE-STIMULATING HORMONE IN PRE-AND POSTPUBERTAL RAMS AS REVEALED BY HEMICASTRATION
Authors: WALTON J. S. , EVINS JANET D. , WAITES G. M. H.
Published: December 2008

The levels of FSH, LH and testosterone in the plasma were measured in cross-bred male lambs which were bilaterally castrated, hemicastrated or left entire at 1 week of age. Removal of one testis caused the level of FSH in the circulation to increase to a value midway between the levels found in entire and castrated lambs up to 12 weeks of age. The concentrations of LH and testosterone in the plasma were similar in the control and hemicastrated lambs. The concentration of FSH in the plasma of the hemicastrated lambs fell at 12–14 weeks of age, the expected time of puberty, to the level found in control animals of the same age. Although the possibility of increased release of LH cannot be excluded, the increase in the secretion of FSH is believed to account for the compensatory hypertrophy of the remaining testis observed in the hemicastrated lambs.

Removal of one testis from mature Soay rams in spring (May) caused a small selective increase in the concentration of FSH in the plasma, compared with entire animals. This difference was maintained until July when there was a marked increase in the levels of FSH and LH in the hemicastrated rams such that an exaggeration of the normal seasonal changes in these hormones was observed. Compensatory hypertrophy of the remaining testis was observed in the hemicastrated animals.
CHANGES IN THE OVARIES OF RATS AFTER IMMUNIZATION AGAINST LUTEINIZING HORMONE RELEASING HORMONE
Authors: FRASER H. M. , BAKER T. G.
Published: December 2008

Rats were immunized against luteinizing hormone releasing hormone (LH-RH) and ovulation and follicular development were studied 12, 24 and 48 weeks later. The abolition of regular cyclic patterns of vaginal smears and the absence of luteal tissue in all but one of 32 rats showed that the immunization was effective in blocking ovulation. Follicular growth varied between rats and appeared to be dependent on whether the inhibition of LH-RH had been sufficient to affect the secretion of basal levels of gonadotrophins. Low levels of gonadotrophins were associated with poor follicular development, uterine atrophy and leucocytic vaginal smears, whereas levels of gonadotrophins similar to those in the dioestrous controls led to adequate follicular growth in the absence of ovulation, the production of cystic follicles, uterine stimulation and persistent vaginal oestrus. A group of rats was ovariectomized 12 weeks after immunization against LH-RH; animals with low antibody titres and large follicles responded with increases in the levels of LH and FSH in the blood, whereas in those with high antibody titres and little follicular development the concentrations of gonadotrophins remained low. The reproductive capacity of rats immunized against LH-RH was tested by caging them with normal male rats from 3 weeks after immunization. Although mating occurred in three rats during the first month, no offspring were produced. No matings occurred in the remaining 41 weeks.
PRESENCE AND SYNTHESIS OF VASOTOCIN IN THE PINEAL GLAND OF BRATTLEBORO RATS
Authors: COCULESCU M. , MATULEVIČIUS V. , GOLDSTEIN R. , PAVEL S.
Published: December 2008

Institute of Endocrinology and Faculty of Medicine, Bucharest, Romania

(Received 20 September 1977)

The pineal gland of all mammals so far investigated contains arginine-vasotocin (AVT; Pavel & Petrescu, 1966) or lysine-vasotocin (Pavel, 1965), except that of the homozygous Brattleboro rat with hereditary hypothalamic diabetes insipidus, in which apparently no radioimmunoassayable vasotocin could be detected (Rosenbloom & Fisher, 1975). Since it has been demonstrated recently that the pineal glands of normal rat foetuses contain (Pavel, Goldstein & Calb, 1975) and synthesize (Pavel, Goldstein, Ghinea & Calb, 1977) relatively large amounts of AVT, we investigated the possible occurrence and synthesis of AVT in the pineal glands of foetal homozygous Brattleboro rats. We also studied the pineal glands of adult homozygous Brattleboro rats to test for the presence of AVT.

The methods of assay used have been described previously (Pavel, 1965) and included rat antidiuretic, rat uterine and frog (Rana temporaria) bladder assays.
RESPONSE OF ANTIDIURETIC HORMONE TO ACUTE EXPOSURE TO MILD AND SEVERE HYPOXIA IN MAN
Authors: CLAYBAUGH J. R. , HANSEN J. E. , WOZNIAK D. B.
Published: December 2008

Eight men, 19-35 years of age, breathed 20·9% (normal oxygen), 13·9% (mild hypoxia) or 11·1% (severe hypoxia) oxygen in nitrogen gas mixtures during three 20 min periods, which were separated by 1 h recovery periods. The order in which the gas mixtures were breathed was random. The partial pressure of oxygen decreased from a mean of 93·5 during exposure to normal oxygen to 53·9 and 36·7 mmHg during mild and severe hypoxia respectively. There were corresponding decreases in haemoglobin saturation. The partial pressure of carbon dioxide was lower and the pH higher during severe hypoxia than during exposure to normal oxygen. There were no changes in the plasma osmolality or in the concentrations of sodium or potassium in the plasma. There was a tendency for both the renin activity and the concentration of aldosterone in the plasma to decrease progressively as the percentage of oxygen breathed decreased. Unlike severe hypoxia, mild hypoxia suppressed the concentration of antidiuretic hormone (ADH) in the plasma of all subjects by about 59%; during severe hypoxia the reduction was not significant, being only about 33%. These data are consistent with the suggestion that the effect of hypoxia on the release of ADH is dependent on the level of hypoxia.
STEROIDOGENESIS IN PREOVULATORY FOLLICLES OF PATIENTS GIVEN HUMAN MENOPAUSAL AND CHORIONIC GONADOTROPHINS AS JUDGED BY THE RADIOIMMUNOASSAY OF STEROIDS IN FOLLICULAR FLUID
Authors: FOWLER R. E. , EDWARDS R. G. , WALTERS D. E. , CHAN S. T. H. , STEPTOE P. C.
Published: December 2008

The administration of human menopausal gonadotrophin (HMG) followed by human chorionic gonadotrophin (HCG) stimulated the development of various numbers of follicles in patients treated for infertility. Graafian follicles from these patients were aspirated 32–33 h after the injection of HCG and the levels of steroids in the follicular fluid and matching serum samples were measured by radioimmunoassay. The follicles could not be grouped into two distinct clusters as found in patients given HCG during the menstrual cycle but a broad classification of follicles into four groups was indicated from the dendrogram. Two of the groups were similar to the ovulatory and non-ovulatory groups found previously, whereas the other two groups of follicles were more intermediate in nature. The use of a discriminant analysis showed that these two groups had clearly been stimulated by the HMG and HCG, although they were not yet fully ovulatory.

Our data indicate that the number of developing follicles is considerably increased by treatment with HMG and HCG but there is asynchrony in follicular development because the pattern of steroid synthesis differs in many follicles. The effects of this asynchronous development on oocyte maturation and disorders of the luteal phase are discussed.
EFFECTS OF CASTRATION AND ANDROGEN REPLACEMENT ON ACID PHOSPHATASE ACTIVITY IN THE ADULT RAT PROSTATE GLAND
Authors: TENNISWOOD M. P. , ABRAHAMS PAMELA P. , BIRD C. E. , CLARK A. F.
Published: December 2008

Acid phosphatase (EC 3.1.3.2) activity was examined for its possible utilization as a biochemical marker for the profound changes that occur in the prostate gland after castration. Tissue filtrates were prepared from the prostate glands of mature male rats at various times after castration. The acid phosphatase activity was characterized by polyacrylamide gel electrophoresis and the percentage inhibition in the presence of tartrate. Prostatic acid phosphatase from mature rats has been shown to have two bands of activity, a lysosomal acid phosphatase and a secretory acid phosphatase. After castration, there was a loss of the secretory acid phosphatase from gel electrophoresis patterns by day 5 and a corresponding rise in the percentage inhibition by tartrate from the normal value of 43·2% to a maximum of 55·4% on day 7. Between days 7 and 15 there was a linear decrease in the percentage inhibition by tartrate, but after day 15 the value did not change significantly from 31·1% After castration, the specific activity of the uninhibited enzyme increased from a normal basal level of 2·16 μmol h−1 mg protein−1 to a maximum on day 7 of 8·10 μmol h−1 mg protein−1. After this time, the specific activity decreased slowly until it reached a normal level on day 21. Intraperitoneal administration of testosterone, 5α-dihydrotestosterone or 5α-androstane-3α,17β-diol at a dose of 2 mg/day and starting immediately after castration prevented the changes in percentage inhibition by tartrate and the loss of the secretory band of acid phosphatase. Administration of these androgens from day 7 after castration led to a decrease in the percentage inhibition from 50·1% to a minimum of 31·5% before the level returned to the normal value found in the mature rat. The secretory band of acid phosphatase, which was not present in gels at day 7, reappeared after 8–11 days of treatment with androgens. Of the androgens used,5α- androstane-3α,17β-diol was the most potent.
ENDOCRINE CONTROL OF ENERGY METABOLISM IN THE COW: COMPARISON OF THE LEVELS OF HORMONES (PROLACTIN, GROWTH HORMONE, INSULIN AND THYROXINE) AND METABOLITES IN THE PLASMA OF HIGH- AND LOW-YIELDING CATTLE AT VARIOUS STAGES OF LACTATION
Authors: HART I. C. , BINES J. A. , MORANT S. V. , RIDLEY J. L.
Published: December 2008

To obtain information on the physiological mechanisms controlling the partition of dietary energy between body weight and milk production in lactating cattle, the concentrations of hormones (prolactin, growth hormone, insulin and thyroxine) and metabolites (glucose, non-esterified fatty acids, β-hydroxybutyric acid and l-lactic acid) in plasma obtained from eight high-yielding and seven low-yielding cows, matched for diet and stage of lactation, were compared. Blood samples were taken via a jugular catheter, throughout four 48 h periods at various times during lactation (days 40, 80, 120 and 180) and also when the animals were dry.

The milk yield rose for 7 weeks after parturition, reaching peak values of 24·8 and 10·1 kg/day in the high- and low-yielding groups respectively. The body weights of the low-yielding animals rose steadily, whereas cows in the high-yielding group lost weight up to week 14 of lactation and thereafter gradually gained weight. No differences were found between the groups in the digestibility of the diets, although analysis of the rumen fluid indicated small differences in the proportions of volatile fatty acids. Milk analysis suggested that the protein content of milk obtained from low-yielding cows was greater than that of milk from high-yielding animals.

Throughout lactation, the concentrations of growth hormone (P < 0·001), non-esterified fatty acids (P < 0·01) and β-hydroxybutyric acid (P < 0·05) were higher in the high-yielding than in the low-yielding group, whereas the concentration of insulin was higher (P < 0·01) in the low-yielding animals. The level of thyroxine was higher (P < 0·05) in the low-yielding group when the animals were dry. A comparison of peak lactation (days 40 and 80) with the dry period demonstrated that the concentration of prolactin was higher in both groups high-yielding, P < 0·01; low-yielding, P < 0·001) when the animals were dry and the concentration of thyroxine in the low-yielding cows was higher (P < 0·01) when the animals were dry. Significant reductions in the concentrations of growth hormone (P < 0·001) and non-esterified fatty acids (P < 0·001) were accompanied by an increase in the concentration of glucose (P < 0·01) when the high-yielding animals were dry.
CONCENTRATIONS OF PROSTAGLANDINS F2α AND E2 IN THE ENDOMETRIUM THROUGHOUT THE HUMAN MENSTRUAL CYCLE, AFTER THE ADMINISTRATION OF CLOMIPHENE OR AN OESTROGEN–PROGESTOGEN PILL AND IN EARLY PREGNANCY
Authors: MAATHUIS J. B. , KELLY R. W.
Published: December 2008

The concentrations of prostaglandins F2α (PGF) and E2 (PGE) were measured by gas chromatography–mass spectrometry in endometrial tissue obtained from 45 normal women at various stages of the menstrual cycle. During the proliferative stages, the concentration of PGF in the endometrium was correlated with the concentration of oestradiol in the plasma. The concentration of PGF during the mid-secretory stage (mean, 2·047, range, 0·549–4·344 μg/g fresh endometrial tissue) was significantly higher than the concentrations during the late proliferative and late secretory stages. The endometrial concentration of PGE did not show a cyclic variation.

The concentrations of PGF and PGE in samples of endometrium collected after the administration of clomiphene were significantly lower than the concentrations observed in endometrial tissue obtained from normally menstruating women in the mid-proliferative period. The administration of an oestrogen–progestogen pill resulted in higher endometrial concentrations of PGE than were measured in the mid-secretory phase. The concentrations of PGF and PGE in decidual tissue (conceptual age 3–10 weeks) were lower than those measured at any stage of the normal menstrual cycle. During the human menstrual cycle, high levels of oestradiol and progesterone are related to high endometrial levels of PGF but not PGE. The presence of a conceptus apparently blocks the effect of high concentrations of ovarian steroids on the synthesis or catabolism of prostaglandins.
SOMATOSTATIN IMMUNOREACTIVE PEPTIDES OF HIGHER MOLECULAR WEIGHT IN OVINE HYPOTHALAMIC EXTRACTS
Authors: MILLAR R. P.
Published: December 2008

U.C.T./M.R.C. Protein Research Unit, Department of Chemical Pathology, Medical School, Observatory 7925, Cape Town, Republic of South Africa

(Received 26 January 1978)

Higher molecular weight (HMW) immunoreactive forms of somatostatin have been reported in extracts of ovine hypothalami (Vale, Ling, Rivier, Villarreal, Rivier, Douglas & Brown, 1976), rat pancreas and stomach (Arimura, Sato, Dupont, Nishi & Schally, 1975) and human pancreatic somatostatinoma (Larsson, Hirsch, Holst, Ingemansson, Kühl, Jensen, Lundquist & Rehfeld, 1977). However, the possibility that the HMW immunoreactive substances were oligomers of somatostatin or somatostatin bound to larger molecules was not excluded. The present study was undertaken to establish that authentic HMW immunoreactive somatostatin is present in the ovine hypothalamus and to glean information on the structural relationship of the HMW species with somatostatin.

Sheep hypothalami were extracted and subjected to gel permeation chromatography as described previously by Millar, Aehnelt & Rossier (1977). Fractions were assayed for somatostatin immunoreactivity
RELATIONSHIP BETWEEN THE PITUITARY GLAND AND GONADAL STEROIDS: INVOLVEMENT OF A HYPOPHYSIAL FACTOR IN REDUCED α2u-GLOBULIN AND INCREASED TRANSCORTIN CONCENTRATIONS IN RAT SERUM
Authors: VANDOREN G. , VAN BAELEN H. , VERHOEVEN G. , DE MOOR P.
Published: December 2008

Evidence is presented that the level of α2u-globulin in the serum of male rats depends, at least in part, on neonatal androgens. After castration of adult animals the concentration of this protein falls but remains measurable, whereas in intact or ovariectomized female rats α2u-globulin cannot be detected. Moreover, α2u-globulin is found in adult male and female rats gonadectomized at birth and treated with a single injection of testosterone propionate immediately thereafter. The mechanism by which neonatal androgens increase the concentration of α2u-globulin has been investigated.

Transplantation of a supplementary pituitary gland under the renal capsule of male rats resulted in reduced levels of α2u-globulin and increased levels of transcortin. The changes discussed here were observed only in those animals in which the transplant was functional and they were amplified or reversed by modulators of prolactin secretion such as oestrogens or bromocriptine respectively. The hypothesis is advanced that neonatal androgens stimulate the production of a hypothalamic inhibitory factor that controls the secretion of prolactin, or another hypophysial hormone subjected to similar neuroendocrine control. Measurements in gonadectomized animals and in rats receiving both oestradiol benzoate and bromocriptine indicate that, besides these pituitary-mediated effects, both oestrogens and androgens exert direct effects on the level of α2u-globulin.
A RAPID SIMPLIFIED BIOASSAY FOR SOMATOMEDIN
Authors: SPENCER G. S. G. , TAYLOR A. M.
Published: December 2008

A simplified, more rapid bioassay for the estimation of somatomedin activity, based on the porcine costal cartilage bioassay, is described. A micro-scale system based on the porcine costal cartilage assay is also described. These assay systems showed no decrease in sensitivity or precision, compared with other methods, as a result of the modifications. The assays have been used for routine hospital laboratory determinations, for the estimation of somatomedin activity in normal adolescent children of both sexes and in clinical studies of scoliotic, acromegalic and hypopituitary patients.
DEMONSTRATION OF A CYTOPLASMIC RECEPTOR PROTEIN FOR OESTROGEN IN THE CANINE PROSTATE GLAND
Authors: CHAISIRI N. , VALOTAIRE Y. , EVANS BRONWEN A. J. , PIERREPOINT C. G.
Published: December 2008

A receptor protein that selectively binds oestrogens has been demonstrated in the cytosol of the canine prostate gland. The steroid–receptor complex was found to have a sedimentation coefficient of 4–5 S with respect to bovine serum albumin after sucrose density-gradient centrifugation. The high affinity and low capacity of the protein for oestrogens was indicated by displacement studies, which gave a value of 3·8 ± 1·53 (s.d.) × 10−10 mol/l for the dissociation constant. A metastasizing prostatic tumour was also shown to possess this receptor, with binding properties similar to those exhibited by the receptor in normal prostatic cytosol. The implications of these findings are discussed with regard to normal prostatic function in the dog and the virtually inevitable advent of prostatic hyperplasia with age in this species.
GONADOTROPHIC ACTIVITY IN PITUITARY EXTRACTS FROM AN ELASMOBRANCH (SQUALUS ACANTHIAS L.)
Authors: LANCE V. , CALLARD I. P.
Published: December 2008

Department of Biology, Boston University, Boston, Massachusetts 02215, U.S.A.

(Received 9 January 1978)

Selective ablation of portions of the pituitary gland (Dodd, Evennett & Goddard, 1960) and indirect evidence from heterologous immunohistochemical (Mellinger & Dubois, 1973) or radioimmunoassay (Scanes, Follett & Goos, 1972) data has indicated that the anatomically discrete ventral lobe of the elasmobranch pituitary gland may be the sole source of gonadotrophins in these fishes. Bioassay studies have, however, given conflicting results. With a bioassay involving the uptake of 32P by the testes of 1-day-old chicks, Scanes, Dobson, Follett & Dodd (1972) found gonadotrophic activity only in the ventral lobe, whereas Firth & Vollrath (1973) showed gonadotrophic activity in both the ventral and median lobes of the pituitary gland of Scyliorhinus canicula when using the Xenopus oocyte meiosis assay. Thus there is still no agreement as to the nature and source of the gonadotrophin(s) in elasmobranchs.

The dispersed
EVALUATION OF A RADIOIMMUNOASSAY FOR PLASMA ADRENOCORTICOTROPHIN
Authors: MARTON J. , STARK E. , MERÉTEY KATALIN , SCHULSTER D.
Published: December 2008

A radioimmunoassay for plasma ACTH has been described and evaluated. Rabbit antiserum produced by immunization with Asp25, Ala26, Gly27,]-αh-corticotrophin-(1–28)-octacosa-peptide (a sequence analogue of αh1-28-ACTH) bovine gamma globulin conjugate was used. The antiserum is specific for the NH2-terminal portion of the ACTH molecule and cross-reactivity of human, porcine and rat ACTH in the system has been demonstrated. Reasonable agreement was found between estimates obtained by bioassay and radioimmunoassay of the ACTH content of rat pituitary gland incubation media, indicating a close relationship between the sequence of ACTH recognized by the antibodies and the sequence possessing the steroidogenic activity. Measurement of the amount of ACTH in the plasma required the preliminary extraction and concentration of the hormone. Over a range of concentrations between 3·5 and 3600 pg/ml, extraction recovery was independent of the initial concentration of ACTH in the plasma. Extraction gave rise to no changes in the immunological properties of standard ACTH. The concentration of immunoreactive ACTH in rat plasma was 48 ± 3·6 (s.e.m.) pg/ml in the morning and 106 ± 9·9 pg/ml in the afternoon. Exposure to ether for 5 min and subsequent laparotomy gave rise to a significant increase in the concentration of immunoreactive ACTH in the plasma. The resting level of ACTH and the ACTH response to stress were both significantly higher 1 and 7 days after adrenalectomy. Intravenous injection of a hypothalamic extract elicited a considerable rise in the concentration of immunoreactive ACTH in the plasma, but no response was seen after oral administration of this partially purified extract. The sensitivity, precision and specificity of this ACTH radioimmunoassay make it a useful tool for studying pituitary– adrenal physiology.
INITIATION OF PARTURITION IN THE GOAT: EVIDENCE FOR CONTROL BY FOETAL GLUCOCORTICOID THROUGH ACTIVATION OF PLACENTAL C21-STEROID 17α-HYDROXYLASE
Authors: FLINT A. P. F. , KINGSTON E. J. , ROBINSON J. S. , THORBURN G. D.
Published: December 2008

Infusion of dexamethasone into chronically catheterized foetal kids induced delivery in 41–65 h. Changes in the concentrations of placental and ovarian steroids in the maternal circulation at dexamethasone-induced delivery mimicked those preceding spontaneous kidding at term; in both instances the peripheral concentration of progesterone fell and the concentration of oestradiol-17β rose. The concentration of cortisol in the foetus was low at dexamethasone-induced delivery. Metabolism of pregnenolone, progesterone, 17α-hydroxyprogesterone and androst-4-ene-3,17-dione by extracts of foetal placenta was investigated in late pregnancy, after premature parturition induced with dexamethasone or prostaglandins and after spontaneous parturition at term. In placentae obtained before the onset of labour (or from animals induced to kid by administration of prostaglandins), the main product of progesterone metabolism was a 5β-pregnane-3,20-diol. In contrast, placentae from animals in which the foetal level of glucocorticoid had been raised (after spontaneous parturition or by administration of dexamethasone to the foetus) were able to 17α-hydroxylate and progesterone was metabolized to 5β-pregnane-3α/3β,17α,20α-triols and 17α,20α-dihydroxypregn-4-en-3-one. The appearance of placental 17α-hydroxylase was correlated with raised maternal concentrations of 17α,20α-dihydroxypregn-4-en-3-one and androstenedione. The induction or activation of placental 17α-hydroxylase may represent the mechanism by which foetal glucocorticoid controls the onset of labour in the goat.
EFFECT OF LOW PHOSPHORUS DIETS ON INTESTINAL CALCIUM ABSORPTION AND THE CONCENTRATION OF CALCIUM-BINDING PROTEIN IN INTACT AND PARATHYROIDECTOMIZED PIGS
Authors: FOX J. , PICKARD D. W. , CARE A. D. , MURRAY T. M.
Published: December 2008

The effect of changing the dietary concentration of phosphorus on the intestinal absorption of calcium has been studied in conscious pigs each prepared with a Thiry–Vella loop of jejunum. A reduction in the percentage of phosphorus in the diet from 0·7 to 0·3% caused an increase in the efficiency of absorption of calcium from the fluid used to perfuse the jejunal loop in both intact and parathyroidectomized animals. There was a marked increase in the amount of calcium-binding protein (CaBP) in the small intestine of pigs fed the low phosphorus diet. Parathyroidectomy did not affect the amount of CaBP in the small intestine when either the normal or the low phosphorus diets were fed.
ACTIVITY OF TESTOSTERONE 5α-REDUCTASE IN THE HAIR FOLLICLES OF WOMEN WITH POLYCYSTIC OVARIES
Authors: MIYAZAKI MASATOSHI , TAKAYASU SUSUMU , KARAKAWA TAKEHISA , AONO TOSHIHIRO , KURACHI KEIICHI , MATSUMOTO KEISHI
Published: December 2008

Departments of *Obstetrics and Gynecology and †Dermatology and ‡Institute for Cancer Research, Osaka University Medical School, Fukushima-ku, Osaka 553, Japan

(Received 23 February 1978)

Hirsutism is often seen in patients with polycystic ovaries and it has been suggested that it may be caused by excessive production of androgens or raised concentrations of androgens in the plasma (Kirschner & Bardin, 1972; Kuttenn, Mowszovicz, Schaison & Mauvais-Jarvis, 1977). Hirsutism may also be attributable to altered androgen metabolism in the skin since human skin and its appendages, such as sebaceous glands and hair follicles, are capable of converting testosterone to 17β-hydroxy-5α-androstan-3-one (dihydrotestosterone, DHT) and are considered to be target tissues for androgens (Sansonne & Reisner, 1971; Takayasu & Adachi, 1972; Kuttenn & Mauvais-Jarvis, 1975).

In the present study, the concentration of testosterone in the plasma and the activity of 5α-reductase in the hair follicles of seven patients with polycystic ovaries and definite hirsutism
EVIDENCE FOR THE COMMON IDENTITY OF RABBIT OVARIAN 20α- AND 17β-HYDROXYSTEROID DEHYDROGENASES
Authors: RODWAY R. G. , RAHMAN S. S.
Published: December 2008

Department of Reproductive Biology, Case Western Reserve University, Cleveland, Ohio 44106, U.S.A.

(Received 21 April 1978)

In recent years, there has been disagreement over the possibility that the activities of the 20α- and 17β-hydroxysteroid dehydrogenases in various endocrine tissues may depend on the same enzymic protein. Contradictory results have been obtained with human placental tissue. The results of Purdy, Halla & Little (1964) and Jarabak & Sack (1969) suggest that the two activities are dependent on the same protein, whereas the data of Karavolas & Engel (1971) suggest that they are not. This paper reports our findings on the problem using rabbit ovarian tissue.

Ovaries containing corpora lutea at random stages of development or regression were obtained from rabbits undergoing ovariectomy in a separate experiment. The complete ovaries were homogenized in 12 ml 0·25 m-sucrose and centrifuged for 30 min at 105 000 g. The supernatant fractions were used for
EFFECTS OF 5α-ANDROSTANE-3β,17β-DIOL AND 5β-DIHYDROTESTOSTERONE ON ACID PHOSPHATASE ACTIVITY IN THE PROSTATE GLAND OF THE CASTRATED ADULT RAT
Authors: TENNISWOOD M. P. , ABRAHAMS PAMELA P. , BIRD C. E. , CLARK A. F.
Published: December 2008

Polyacrylamide gel electrophoresis of filtrates from adult rat prostatic tissue showed two bands of acid phosphatase activity. These corresponded to the lysosomal and secretory acid phosphatases. After castration the secretory acid phosphatase disappeared. The specific activity of the enzyme increased from the time of castration to a maximum on day 7 before declining steadily, while the percentage inhibition by tartrate of acid phosphatase increased from control levels to a maximum on day 7 and then decreased to a new steady state by day 15. When 5α-androstane-3β,17β-diol was administered i.p. at a dose of 2 mg/day, starting immediately after castration, the secretory acid phosphatase was retained but the percentage inhibition and the specific activity were both raised above control levels. When this steroid was administered daily starting 7 days after castration the secretory acid phosphatase band on the gels returned more rapidly than with the classical androgens, but the percentage inhibition and specific activity were once again raised.

Intraperitoneal administration of 5β-dihydrotestosterone, at a dose of 2 mg/day, did not maintain the secretory acid phosphatase activity which disappeared by day 5. However, the specific activity of acid phosphatase and the percentage inhibition by tartrate were both raised throughout the experiment. If this steroid was given 7 days after castration, the percentage inhibition by tartrate did not respond and fell to the level seen in castrated rats. The specific activity, however, remained significantly above the level found in castrated control rats.
SYNCHRONOUS EPISODIC RELEASE OF CORTISOL IN THE SHEEP
Authors: FULKERSON W. J.
Published: December 2008

Department of Animal Science and Production, University of Western Australia, Nedlands, Western Australia 6009, Australia

(Received 13 March 1978)

The activity of the adrenal gland is believed to be governed by the secretion of corticotrophin (ACTH) in a positive stimulus/negative feedback equilibrium. There is increasing evidence that in man, the secretion of corticosteroids never actually reaches a steady-state condition and that the circadian rhythm displayed by these hormones in the circulation is therefore the result of a number of secretory episodes over a 24 h period (Hellman, Nakada, Curti, Weitzman, Kream, Roffwarg, Ellman, Fukushima & Gallagher, 1970; Weitzman, Fukushima, Nogeire, Roffwarg, Gallagher & Hellman, 1971). Data presented by McNatty, Cashmore & Young (1972) also raise the possibility that a similar pattern of hormone release may exist in the sheep. However, McNatty et al. (1972) collected samples relatively infrequently and it is hard to define peaks in cortisol concentration. With more
PLASMA CONCENTRATIONS OF GROWTH HORMONE DURING GROWTH IN NORMAL AND TESTOSTERONE-TREATED CHICKENS
Authors: HARVEY S. , SCANES C. G.
Published: December 2008

Department of Zoology, University of Hull, Hull, HU6 7RX and * Department of Physiology, Rutgers University, New Brunswick, New Jersey 08903, U.S.A.

(Received 9 May 1978)

Recent avian studies (Harvey, Godden & Scanes, 1977; Harvey, Scanes, Falconer, Bolton & Chadwick, 1977) have established a definite pattern of growth hormone (GH) secretion during growth, with high plasma concentrations in young growing birds and low levels in adults. These observations indicate that the concentration of immunoreactive GH in the circulation may be related to the rate of body growth. The aim of the present study was, therefore, to determine whether experimental modification of growth was accompanied by corresponding alterations in GH secretion. Since testosterone suppresses growth in cockerels (Visco, 1973), plasma concentrations of GH were determined during growth in control and testosterone-implanted birds.

Seven 2-week-old cockerels (Thornber 909 strain) were implanted subcutaneously with a testosterone pellet (Intervet, 100 mg) in the nape
EFFECTS OF HIGH ALTITUDE ON ENDOCRINE FUNCTION IN THE SHERPAS OF NEPAL
Authors: BANGHAM C. R. M. , HACKETT P. H.
Published: December 2008

*National Institute for Biological Standards and Control, Holly Hill, London, NW3 6RB and ‡Himalayan Rescue Association, P.O. Box 283, Kathmandu, Nepal

(Received 23 May 1978)

There is demographic evidence from studies in the Andes (James, 1966; Heer, 1967; Abelson, 1976) for lower fertility in high-altitude dwellers than in moderate- or low-altitude dwellers. In the Sherpas of Nepal, the completed fertility rate at high altitude (about 6·0) is appreciably less than that at lower altitudes (8·5; C. R. M. Bangham & J. M. Sacherer, unpublished observations). However, the physiological reasons (if any) for such a difference are obscure. The present study was carried out to test the hypothesis that such a fertility difference (between low- and high-altitude dwellers) is reflected in different serum concentrations of reproductive hormones.

Sampling was carried out at altitudes of 4240 m in Khumbu, 2670 m in Pharak (south of Khumbu) and 1460 m in Kathmandu; the
SECRETION OF PROGESTERONE DURING GESTATION IN THE RAT
Authors: SANYAL MRINAL K.
Published: December 2008

The concentrations of progesterone and 5α-pregnane-3,20-dione in ovarian and uterine venous plasma and in the systemic circulation were measured during gestation in the rat. The steroids were quantified by radioimmunoassay after separation on silicic acid microcolumns with the solvent system hexane: ethyl acetate (5: 2, v/v). The concentration of progesterone in the systemic circulation was highest on days 3–4 and 13–17 of pregnancy; throughout gestation, the concentration of 5α-pregnane-3,20-dione was low in relation to that of progesterone and showed no marked changes as gestation proceeded.

The level of progesterone in ovarian venous effluent was 10–20 times higher than that in the uterine vein and 20–50 times greater than that in the systemic circulation. The rate of secretion of progesterone by the ovary was highest during days 13–17 of gestation and ovariectomy during this period markedly reduced the levels of progesterone in the peripheral circulation. The concentration of progesterone in the uterine venous effluent was raised compared with the concentration in plasma from the abdominal aorta, especially on days 7 and 9 of pregnancy.

These results suggest that, in vivo, the rat placenta synthesizes small amounts of progesterone and secretes it into the maternal circulation. The ovary is the primary source of progesterone during pregnancy and the placental contribution is of secondary importance. Although 4-ene-5α-reductase enzyme(s) is present in the ovary and placenta, significant quantities of the reduced progestin 5α-pregnane-3,20-dione are not secreted into the systemic circulation during gestation in the rat.
CHANGES IN THE CONCENTRATION OF UTERINE CYTOPLASMIC OESTROGEN RECEPTORS INDUCED BY DOXORUBICIN AND METHOTREXATE
Authors: DI CARLO F. , REBOANI C. , CONTI G. , GENAZZANI E.
Published: December 2008

The effects of doxorubicin and methotrexate on the oestradiol-induced depletion, replenishment and subsequent increase beyond the normal value (overshoot) in the number of uterine cytoplasmic oestrogen receptors were investigated in intact rats. Injection of doxorubicin (0·5 mg/kg, i.v.) or methotrexate (1 mg/kg, i.m.) 5 min after a single i.p. injection of 10 ng oestradiol-17β (which is able to induce a 50% depletion in the number of oestrogen receptors) caused a significant increase in the oestradiol-induced depletion. Both drugs inhibited the replenishment and the overshoot phases until 48 h after treatment, although the effect was more marked with doxorubicin. Experiments in vitro showed that both methotrexate and doxorubicin affected the capacity of oestradiol-17β to bind to specific cytoplasmic receptors, inducing an increase in binding when used at low concentrations and a decrease at higher concentrations. The effects of doxorubicin and methotrexate on the depletion, replenishment and overshoot of oestrogen receptors seemed to be partly dependent on the inhibition of protein synthesis and partly due to direct action on the binding of oestradiol-17β to its receptors.
THE IMPORTANCE OF PROLACTIN FOR LACTATION IN THE EWE
Authors: HOOLEY R. D. , CAMPBELL JEANETTE J. , FINDLAY J. K.
Published: December 2008

The effect of 2-bromo-α-ergocryptine (bromocriptine) on the induction, initiation and maintenance of milk secretion was studied in post-parturient ewes and in ovariectomized ewes artificially induced to lactate by treatment with oestrogen plus progesterone and then dexamethasone. Treatment with bromocriptine (about 0·4 mg/kg every 3 days) lowered and maintained the plasma concentration of prolactin at < 12 ng/ml. Ewes receiving bromocriptine concurrently with oestrogen plus progesterone during the priming phase had a significantly lower (P< 0·05) mean cumulative milk yield than control ewes, although the milk of the treated ewes contained normal amounts of fat, protein and lactose. Administration of bromocriptine during dexamethasone-induced lactogenesis had no significant effect on the mean cumulative milk yield but significantly (P<0·05) increased the milk fat and protein content. In established lactation, bromocriptine markedly reduced the milk yield in both intact and ovariectomized ewes. The concentration of protein was not significantly affected although the milk fat content was higher in the bromocriptine-treated than in the control ewes. The effects of bromocriptine on milk yield and composition during galactopoiesis could be reversed by concurrent infusion of prolactin and the results suggest that prolactin is an important hormone during mammogenesis and galactopoiesis in the sheep.
PARADOXICAL EFFECTS OF DRUGS ACTING ON THE CENTRAL NERVOUS SYSTEM ON THE PREOVULATORY RELEASE OF PITUITARY LUTEINIZING HORMONE IN PRO-OESTROUS RATS
Authors: BLAKE C. A.
Published: December 2008

There are many drugs which act on the central nervous system to block the spontaneous, preovulatory surge of LH in the plasma of the rat when administered just before the start of the LH surge at pro-oestrus. Several of these drugs have been tested for their ability to inhibit LH release after the start of the LH surge. Four day cyclic rats were each fitted with an indwelling right atrial cannula during the morning of pro-oestrus. Serial blood samples were collected through the cannula during the afternoon of pro-oestrus, starting at a time when the level of LH in the plasma was expected to be raised. Drugs were then administered at doses known to block the surge of LH. Additional blood samples were collected and subsequently the plasma concentration of LH was measured by radioimmunoassay. In rats with a raised level of LH, i.p. injection of phenobarbitone or pentobarbitone, s.c. injection of atropine or i.v. injection of ethanol caused the concentration of LH to fall rapidly starting within 15 min after the injection. The mean half-lives for the disappearance of LH from plasma ranged from 23·5 to 28·6 min over a 30 min period. In contrast, s.c. injection of nicotine, i.p. injection of urethane or continuous exposure to ether fumes resulted in a biphasic effect on the concentration of LH in the plasma. The value rose rapidly, reached a peak within 5–20 min and declined rapidly (range of mean half-lives 25·3– 28·6 min). Nicotine, urethane and ether caused a small, transient increase in the plasma level of LH when administered before the start of the spontaneous surge of LH. These results and the fact that luteinizing hormone releasing hormone (LH-RH) is far more effective at raising the concentration of LH in the plasma when given after the start of the LH surge than just before it, suggest that LH-RH must prime the pituitary gland before nicotine, urethane or ether can cause a substantial increase in the plasma level of LH in pro-oestrous rats.
EVIDENCE FOR SPECIFIC PROGESTERONE RECEPTORS IN RAT BRAIN CYTOSOL
Authors: GREENSTEIN B. D.
Published: December 2008

Cytosol prepared from rat brains perfused with saline possesses saturable macromolecular components which form unstable complexes with [3H]progesterone in vitro. The components can be distinguished from the serum protein corticosteroid-binding globulin (CBG) which also binds progesterone. Unlike CBG, the cytosol components did not bind corticosterone and were more unstable in the presence of Sephadex LH-20 than was CBG. Furthermore, the components were precipitated by a concentration of ammonium sulphate in which CBG is soluble. Unlabelled progesterone and testosterone competed equipotently with [3H]progesterone, and 5α-pregnane-3,20-dione and deoxycorticosterone competed to a lesser extent, whereas oestradiol, corticosterone and 11β-hydroxy-pregn-4-en-3,20-dione were not bound. Although present in all brain tissues examined and in uterine and anterior pituitary tissue, the saturable binding was not detectable in cytosols from the spleen or diaphragm.

Complete exchange occurred in the incubation at 0 °C between [3H]progesterone and unlabelled progesterone and the saturable binding sites and the reaction attained apparent equilibrium within 2 h at this temperature. An incubation temperature of 30 °C resulted in an almost complete loss of saturable binding. Scatchard plots obtained from binding isotherms were curvilinear and yielded at least three dissociation constants (Kd), two of higher affinity (Kd ≃ 10−8 mol/l) and one about sixty times lower.

From these results it is concluded that rat brain cytosol possesses progesterone-selective components which fulfil some of the criteria required for steroid hormone receptors.
A PIGEON CROP SAC RADIORECEPTOR ASSAY FOR PROLACTIN
Authors: FORSYTH ISABEL A. , BUNTIN J. D. , NICOLL C. S.
Published: December 2008

Ovine prolactin, labelled with 125I by either lactoperoxidase or a mild chloramine T method, bound to receptors from the pigeon crop sac mucosa cells of prolactin-injected pigeons. Binding was demonstrated in a crude homogenate of mucosal cells removed from the crop by scraping and in a subcellular fraction in which 5′-nucleotidase activity was enhanced two- to threefold. The binding was specific, dependent on time, temperature and the concentration of receptors and had a dissociation constant of 7 × 10−10 mol/l. The binding capacity of the crop tissue was 71 fmol/mg membrane protein. Nine purified preparations of prolactin from four species were assayed by local pigeon crop sac bioassay and by radioreceptor assay. The two methods were highly correlated (r = 0·934). The regression equation was radioreceptor assay = 1·22 bioassay–0·18 indicating a 1: 1 correspondence between the two methods for prolactin purified from sheep, rat, horse and pig anterior pituitary glands.
RADIOIMMUNOASSAY OF 3,3′-DI-IODOTHYRONINE IN UNEXTRACTED SERUM: THE EFFECT OF ENDOGENOUS TRI-IODOTHYRONINE
Authors: VISSER T. J. , KRIEGER-QUIST L. M. , DOCTER R. , HENNEMANN G.
Published: December 2008

The development of a highly sensitive and specific radioimmunoassay for 3,3′-di-iodothyronine (3,3′-T2) is described. The assay was applied to the measurement of 3,3′-T2 in unextracted human serum and used 8-anilino-l-naphthalene-sulphonic acid to inhibit the binding of 3,3′-T2 to serum transport proteins. The lower limit of detection of the assay was 2 fmol 3,3′-T2 per tube, which corresponded to 10 pmol 3,3′-T2/l serum. The mean concentration of 3,3′-T2 in normal serum was found to be 23 pmol/l, which is considerably lower than most values reported previously. Evidence is presented which suggests that the cross-reactivity of tri-iodothyronine with the antiserum to 3,3′-T2 is an important factor in the measurement of serum concentrations of 3,3′-T2 by radioimmunoassay.
BLOCKAGE OF THE ETHER-INDUCED SURGE OF PROLACTIN BY NALOXONE IN MALE RATS
Authors: SHIN S. H.
Published: December 2008

Department of Physiology, Abramsky Hall, Queen's University, Kingston, Ontario, Canada, K7L 3N6

(Received 17 July 1978)

It is well established that the stress of ether anaesthesia raises the level of prolactin in the circulation of the rat (Wakabayashi, Arimura & Schally, 1971; Krulich, Hefco, Illner & Read, 1974). Morphine or the endogenous morphine-like peptides, endorphins and enkephalins, can stimulate the secretion of prolactin in vivo (Ojeda, Harms & McCann, 1974; Martin, Audet & Saunders, 1975; Bruni, Van Vugt, Marshall & Meites, 1977; Rivier, Vale, Ling, Brown & Guillemin, 1977; Chihara, Arimura, Coy & Schally, 1978); naloxone, however, blocks the stimulatory effects of these substances (Bruni et al. 1977; Rivier et al. 1977). It was recently demonstrated that naloxone inhibits the secretion of prolactin induced by stress due to heat or immobilization (Van Vugt, Bruni & Meites, 1978). The restraintinduced stress produced an immediate increase in the concentration of prolactin
CIRCANNUAL AND CIRCADIAN RHYTHMS IN THE CONCENTRATION OF CORTICOSTERONE IN THE PLASMA OF THE EDIBLE FROG (RANA ESCULENTA L.)
Authors: DUPONT W. , BOURGEOIS P. , REINBERG A. , VAILLANT R.
Published: December 2008

For a period of 21 months between May 1974 and September 1976, circadian variations in the plasma concentration of corticosterone were studied by competitive protein-binding techniques in mature male and female edible frogs living in their natural environment. Blood samples were taken from 8 to 12 frogs six times daily and conventional and cosinor methods were used for statistical analysis.

Circadian rhythms were not detected during February and March (time of hibernation). Circannual rhythms were detected in three parameters of the circadian rhythm. The mean concentration of corticosterone over a 24 h period (24 h mean) reached a peak on 1 May (between 15 April and 15 May; 95% limits of confidence); the annual mean value of the 24 h means was 1·97 ± 0·25 (s.e.m.) μg/100 ml, with an amplitude of 0·66 μg/100 ml (0·53–0·79 μg/100 ml; 95% limits of confidence). Circadian variations in the concentration of corticosterone were largest in May (peak of reproductive activity). The time at which the peak concentration of corticosterone occurred showed circannual variations; peak values were detected around 24.00 h in May, 19.00 h in July and 08.00 h in November.

Both circadian and circannual variations have therefore been demonstrated in an endocrine function of an amphibian in its natural habitat.
EXTRACTION OF SMALL AMOUNTS OF OXYTOCIN FROM BIOLOGICAL FLUIDS BY MEANS OF AGAROSE-BOUND NEUROPHYSIN
Authors: ROBINSON I. C. A. F. , WALKER J. M.
Published: December 2008

The use of agarose-bound neurophysin for the extraction of oxytocin from biological fluids is described. Oxytocin can be extracted from plasma, urine and cerebrospinal fluid with a high rate of recovery and samples varying widely in volume and oxytocin concentration can be tested by the method.

Columns can be used to extract and concentrate dilute samples, or to help identify small amounts of neurohypophysial hormones by affinity chromatography. The oxytocin can be eluted from the column directly into the buffer used for subsequent bioassay. The composition of the final extract is constant and independent of the composition of the sample. The specificity of the binding is high. It is suggested that the method has many advantages over others in current use.
UNOCCUPIED BINDING SITES FOR OESTRADIOL IN NUCLEI FROM HUMAN BREAST CARCINOMATOUS TISSUE
Authors: GEIER A. , GINZBURG R. , STAUBER M. , LUNENFELD B.
Published: December 2008

The binding of oestradiol to a nuclear fraction extracted from human breast carcinomatous tissue was demonstrated. The material, which was extracted with KCl, sedimented at 3–4S and bound oestradiol with high affinity (dissociation constant ∼ 2 × 10−10 mol/l). Oestriol, diethylstilboestrol and 5α-dihydrotestosterone (100-fold excesses) competed with [3H]oestradiol for the binding sites (binding inhibited by 89 ± 8 (s.d.), 92 ± 6 and 57 ± 8% respectively), whereas progesterone and cortisol (100-fold excesses) did not (binding suppressed by 5 ± 5 and 2 ± 3% respectively). Similar competition patterns were found for cytoplasmic material which bound oestradiol. The binding occurred at 4 °C and was therefore considered to be a measure of the amount of binding material unoccupied by endogenous oestrogen.

Unoccupied binding sites for oestradiol in the nucleus and cytoplasm were measured in 35 samples of breast carcinomatous tissue using sucrose gradient centrifugation. In 17 out of 35 tumours, unoccupied nuclear and cytoplasmic 8S and 4S binding sites could be detected. Three out of 35 tumours contained unoccupied nuclear binding sites and 4S cytoplasmic binding sites. Nuclear binding sites only were found in two out of 35 tumours. Unoccupied nuclear binding sites were not detected in 13 out of 35 tumours and ten of these tumours also did not contain unoccupied cytoplasmic binding sites.