bluuebunny/crossref_metadata_2025 huggingface dataset:
OESTROGEN, PROGESTERONE AND CORTICOSTEROID CONCENTRATIONS IN PERIPHERAL PLASMA OF SOWS DURING PREGNANCY, PARTURITION, LACTATION AND AFTER WEANING
Authors: ASH R. W. , HEAP R. B.
Published: December 2008

Steroid hormone concentrations in plasma have been measured in blood samples taken from conscious sows with ear vein catheters. In late pregnancy, the plasma progesterone concentration ranged from 6 to 12 ng/ml and it decreased in all animals before the onset of parturition. Total unconjugated oestrogens increased to high values of up to about 3 ng/ml in late pregnancy and then declined after the onset of parturition. Oestrone was the predominant unconjugated oestrogen measured. Plasma corticosteroid (mainly cortisol) concentration was about 33 ng/ml and showed no consistent change at the time of parturition.

During lactational anoestrum the plasma concentration of progesterone and total unconjugated oestrogens was very low, while that of corticosteroids was 21 ng/ml. When the piglets were weaned at 26–31 days, sows came into oestrus 4–12 days later, and this was preceded, or accompanied by, an increase in plasma oestrogens. In the luteal phase, plasma progesterone concentrations rose to 20–35 ng/ml. A sow whose piglets were removed at birth, showed signs of oestrus (vulval enlargement and a lordosis response), but a lack of receptivity to the boar associated with no detectable changes in the plasma oestrogen concentration; however, ovulation probably occurred since plasma progesterone values increased in a manner comparable to that found after the formation of normal corpora lutea in other sows. After a second non-receptive cycle, the sow was mated and became pregnant at the third post-weaning oestrus.

At parturition the concentration of progesterone and total unconjugated oestrogens was greater in placental venous plasma than in maternal jugular plasma, which indicates placental synthesis of these hormones. A greater concentration of plasma corticosteroids in foetal blood than in placental venous or maternal jugular plasma suggests foetal synthesis in late pregnancy.
THE PITUITARY-ADRENAL SYSTEM OF THE GENETICALLY OBESE (ob/ob) MOUSE
Authors: EDWARDSON J. A. , HOUGH C. A. M.
Published: December 2008

Adult genetically obese (ob/ob) mice which are characterized by adrenal hypertrophy and increased secretion of corticosteroids have considerably increased levels of ACTH in the pituitary gland. At 5 weeks of age there is no difference in the pituitary ACTH content of lean and obese animals and dietary restriction, sufficient to maintain body weight at normal values, reduces the pituitary ACTH content of adult obese mice from 14 times the level found in lean litter-mate controls to almost normal values. Using an in-vitro perifusion system, the release of ACTH from isolated pituitary glands was studied. Pituitaries from lean and obese mice responded similarly to stimulation with a crude extract of hypothalamic tissue containing corticotrophin releasing factor (CRF). The CRF content of the hypothalamus in both groups appears to be similar. In contrast with the high pituitary content, plasma values for ACTH in unstressed obese mice are not increased. The results are discussed in relation to other evidence for a hypothalamic disorder in ob/ob mice.
LIPIDS IN THE MOUSE UTERUS DURING EARLY PREGNANCY
Authors: HALL KATHLEEN
Published: December 2008

Lipids in the uterine endometrium of mice during early pregnancy were investigated by histochemical techniques. Three groups of animals were studied: (1) on days 1–8 inclusive of the first pregnancy, (2) on days 1–9 after mating at the post-partum oestrus and suckling seven or eight young from their first pregnancy, (3) on days 1–6 after delivery of the first litter but with no access to males. Day 1 was that on which a seminal plug appeared in the vagina or (group 3) after birth of a litter during the previous night. In post-partum mice, only the areas between the former implantation sites were studied.

Epithelial lipids are sparse during the first 24 h. On day 2 and early day 3 in nulliparous mice, and for a longer period in post-partum mice, the presence of lipid in epithelium and stroma seems mainly a degenerative phenomenon associated with cell breakdown and consequent tissue disruption. During late day 3 and on day 4 the increase in lipid droplets giving staining reactions characteristic for triglycerides may represent the storage in this form of fatty acids no longer needed for phospholipid synthesis or as energy sources, once the intense mitotic proliferation of these cells dies down. Triglycerides also predominated in the necks of the glands, but in the deeper parts, the sparse droplets often gave staining reactions for acidic lipids. In differentiating decidual cells during day 5 and early day 6 in nulliparous mice, histochemical reactions suggest that fatty acids accumulate. Some of these are probably utilized in synthesis of the increasing amounts of phospholipids which were particularly prominent later on day 6 and during day 7, while others appeared to be temporarily stored during that period as triglycerides. The phased deposition and removal of triglyceride proceeds centrifugally through the decidua and is slightly in advance of glycogen deposition and removal in the same cells; its time-course correlated well with that which other workers have described from chemical assay. Histochemical tests appeared to reveal activity of a lipase-esterase (fatty acid ester hydrolase) which strengthened and spread through the decidua in parallel with the disappearance of lipid droplets. In lactating mice, as long as the blastocysts remained in diapause, epithelial lipid resembled that on day 4; in the stromal cells, lipid droplets were plentiful in areas close to the former placental sites but were few or absent elsewhere. Once the delayed implantation had started no abnormalities were detected. Alterations in lipids are discussed in the context of the known changes in the levels of ovarian hormones. Lipids within uterine macrophages are also discussed.
MATERNAL AND FOETAL CORTICOSTERONE LEVELS DURING LATE PREGNANCY IN RATS
Authors: DUPOUY J. P. , COFFIGNY H. , MAGRE S.
Published: December 2008

Adrenal and plasma corticosterone levels were determined in rat foetuses and in intact or adrenalectomized mothers during late pregnancy. Foetal adrenal and plasma corticosterone concentrations reached a peak on day 19 of pregnancy, while maternal plasma corticosterone increased on day 18 and remained high until parturition. From day 18, mothers adrenalectomized on day 14 had corticosterone levels similar to those of intact pregnant rats. At every stage of gestation (except day 21) plasma corticosterone levels were higher in the foetuses than in the mothers. The corticosterone concentration in the maternal plasma correlated with the number of live foetuses during the last 3 days of gestation.

These results suggest that corticosterone can cross the placenta from foetus to mother as early as day 18 and that the foetus contributes to the maternal corticosterone pool after day 18.
MAMMARY NUCLEIC ACIDS AND PITUITARY PROLACTIN SECRETION DURING PROLONGED LACTATION IN MICE
Authors: NAGASAWA H. , YANAI R.
Published: December 2008

Lactation was prolonged until 61 days by repeated renewal of litters every week after day 12 in primiparous C3H/He strain mice. On days 12, 19, 40 and 61 of lactation, litters were removed for 5 h and after 1 h of resuckling the synthesis of DNA and RNA in the mammary gland was estimated by the incorporation of [3H]thymidine and [14C]uridine into mammary DNA and RNA in vitro respectively. Mammary nucleic acid content and pituitary and plasma levels of prolactin were also assayed. Nulliparous mice were similarly treated on day 19 of pregnancy.

The percentage gain in litter weight per week was highest between days 5 and 12 of lactation, declined until days 26–33 and became steady thereafter. Mammary DNA synthesis was extremely high on day 19 of pregnancy, decreased on day 12 of lactation to less than one-fifteenth of that on day 19 of pregnancy and increased linearly thereafter. Changes in mammary DNA content were not so marked, but DNA content was high on days 12 and 19 of lactation. RNA synthesis was highest on day 19 of pregnancy, abruptly decreased on days 12 and 19 of lactation and increased again with the advance of lactation. Mammary RNA content, RNA:DNA and 14C:3H ratios increased from day 19 of pregnancy to days 12–19 of lactation and decreased on days 40 and 61. While the pituitary levels of prolactin were almost constant during lactation, they were significantly higher than those on day 19 of pregnancy. There were only slight differences in plasma prolactin levels at any stage.
EFFECT OF BILATERAL ADRENALECTOMY AND CORTICOSTEROID THERAPY ON THE SECRETION OF CORTICOTROPHIN-RELEASING FACTOR ACTIVITY FROM THE HYPOTHALAMUS OF THE RAT IN VITRO
Authors: HILLHOUSE E. W. , JONES M. T.
Published: December 2008

The rat hypothalamus in vitro preparation was used to investigate the effect of bilateral adrenalectomy, with and without replacement therapy, on the release of corticotrophin-releasing factor (CRF). Corticotrophin-releasing factor was estimated using 48 h basal hypothalamic lesioned assay rats and corticosterone production of excised adrenals was used as the end point.

Bilateral adrenalectomy resulted in depletion of hypothalamic CRF content within the first 2 h after the operation but this effect was prevented by replacement therapy with corticosterone. Thereafter, the hypothalamic CRF content returned to values not significantly different from the intact control level. Bilateral adrenalectomy caused an increase in both basal and acetylcholine-induced release of CRF and it is suggested that corticosteroids exert a negative feedback effect on the hypothalamus.
PREGNANT MARE SERUM GONADOTROPHIN: RATIO OF FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE ACTIVITIES MEASURED BY RADIORECEPTOR ASSAY
Authors: STEWART FRANCESCA , ALLEN W. R. , MOOR R. M.
Published: December 2008

Specific radioreceptor assays for FSH and LH, which employ tissue receptors from rat testis and highly purified human FSH (LER 1575-C) and LH (Hartree IRC-2, 24/6/69) as standards, have been developed to determine the FSH-like and LH-like activities in pregnant mare serum gonadotrophin (PMSG). Measurements of FSH and LH concentrations in the serum of six pregnant Pony mares showed that the ratio of these two activities did not vary significantly between mares and remained constant between days 40 and 80 of gestation with a value of 1·45 ± 0·04 (s.e.m.). The FSH:LH ratio of PMSG produced by cultured equine trophoblast cells was found to be 0·72 ± 0·03 (s.e.m.) and that of partially purified serum extracts of PMSG 1·08 (range 0·87–1·30).
SEXUAL BEHAVIOUR OF NEONATALLY CASTRATED RATS INJECTED DURING INFANCY WITH OESTROGEN AND DIHYDROTESTOSTERONE
Authors: BOOTH JANET E.
Published: December 2008

Male rats were castrated on the day of birth (day 1) and injected with either testosterone, dihydrotestosterone, a synthetic oestrogen (RU 2858), RU 2858 + dihydrotestosterone, or oil from days 1 to 5. The aromatizable androgen, testosterone, and RU 2858 suppressed both cyclic gonadotrophin secretion, indicated by the absence of corpora lutea from implanted ovarian grafts, and the behavioural response to oestradiol benzoate + progesterone injections in adulthood. The 5α-reduced androgen, dihydrotestosterone alone did not affect gonadotrophin secretion or female receptive behaviour, but like testosterone, it increased penis development in response to testosterone propionate, and this was positively correlated with copulatory efficiency, i.e. the ratio of intromission to mount frequencies. Nevertheless, ejaculation only occurred among animals that had received testosterone or RU 2858 + dihydrotestosterone. The results support the concept that during the perinatal period, neural conversion of androgens to oestrogens is important both for the suppression of female gonadotrophin secretion and behaviour patterns as well as for the organization of male behaviour patterns. The 5α-reduction of unsaturated C19-steroids to dihydrotestosterone in peripheral tissues is also required to complete the development of the male genital tract.
STRUCTURE–ACTIVITY RELATIONSHIPS OF CORTICOSTEROID FEEDBACK AT THE HYPOTHALAMIC LEVEL
Authors: JONES M. T. , HILLHOUSE E. W. , BURDEN J. L.
Published: December 2008

Structure–activity studies on the corticosteroid fast and delayed feedback receptor mechanisms controlling the secretion of corticotrophin releasing factor (CRF) were carried out with the rat hypothalamus in vitro. The secretion of CRF was induced by acetylcholine (3 pg/ml).

The fast feedback receptor appears highly specific, and the structure essential for efficacy involves an 11β-hydroxyl group and an unblocked 21-hydroxyl group. Several steroids showed antagonism and so the binding site is not very specific. 18-Hydroxy,11-deoxycorticosterone, progesterone, 17α-hydroxyprogesterone and 11-deoxycorticosterone were antagonists of fast feedback.

The delayed feedback receptor required either an 11β- or a 21-hydroxyl group for efficacy. The binding site required a 17-hydroxyl group when the 11β- or 21-hydroxyl groups were absent. Binding also involved the 3-oxo,4,5-ene structure since steroids in which these are absent were inactive.
INTERFERENCE OF GESTAGENS AND ANDROGENS WITH RAT UTERINE OESTROGEN RECEPTORS
Authors: DI CARLO F. , CONTI G. , REBOANI C.
Published: December 2008

The inhibitory effect of some gestagens and calusterone on the binding of oestradiol-17β to its specific uterine receptors has been investigated in intact rats. Progesterone, medrogestone, clogestone, medroxyprogesterone acetate and calusterone reduce the specific oestradiol– receptor interaction in vitro; this effect is dose-dependent and does not differ significantly from one drug to the other. A more relevant decrease in the amount of oestradiol-17β bound to specific receptors has been observed with calusterone. Progesterone, clogestone, medrogestone, medroxyprogesterone acetate and calusterone given orally induce a marked decrease (between 30 and 70% depending on the dose) in the binding capacity of oestradiol-17β to specific uterine receptors in vivo. Results from a Scatchard plot analysis suggest that the interference with the binding of oestradiol-17β caused by both progestogens and calusterone is due to a non-competitive interaction.
CONTROL OF THE PREOVULATORY SURGE OF LUTEINIZING HORMONE IN THE HEN (GALLUS DOMESTICUS): THE ROLE OF PROGESTERONE AND ANDROGENS
Authors: WILLIAMS J. B. , SHARP P. J.
Published: December 2008

Peripheral blood samples were taken from laying hens at frequent intervals during various periods of the ovulatory cycle in order to detect small changes in the concentrations of progesterone and androgen which might be important in initiating the preovulatory release of LH.

Blood samples were taken from seven hens at 1 h intervals for 3 h when the ovary contained a mature (C1) follicle and on another occasion, when the largest ovarian follicle was immature. The concentrations of progesterone and androgens in the plasma were 30% higher when there was a mature C1 follicle present in the ovary than when there was not, but this increase was significant (P < 0·05) only for progesterone.

The concentrations of progesterone and androgens were also measured in blood samples taken at 30 min intervals during the 3 h before and after the initiation of the first preovulatory LH surge of a sequence. The hens were kept on a lighting schedule of 14 h light/day and the first LH surge of a sequence was initiated at the beginning of the dark period. Just after the onset of darkness there was a small increase in the concentration of LH in the plasma and a subsequent, larger preovulatory release of LH. The first increase in the level of LH was associated with a small rise in the concentrations of androgens and progesterone in the plasma while the preovulatory release of LH was accompanied by a much larger increase in the secretion of these steroids.

It is proposed that the increase in the level of LH in the plasma at the onset of darkness stimulates the maturing ovarian follicles to secrete progesterone and androgens and that the quantities of these steroids secreted (particularly of progesterone) depends on the maturity of the largest ovarian follicle. If the largest ovarian follicle is mature, then the increase in the level of LH in the plasma associated with the onset of darkness stimulates the secretion of a quantity of progesterone sufficient to cause the preovulatory surge of LH. A diurnal increase in the concentration of LH in the plasma could, therefore, be responsible for timing the preovulatory surges of LH so that they are only initiated at night.
STRESS-INDUCED DECREASES IN THE SERUM CONCENTRATION OF PROGESTERONE IN THE PREGNANT BABOON
Authors: ALBRECHT E. D. , NIGHTINGALE M. S. , TOWNSLEY J. D.
Published: December 2008

Pregnancy Research Branch, NICHD, National Institutes of Health, Bethesda, Maryland 20014, U.S.A.

(Received 4 January 1978)

During preliminary studies on the rate of production of progesterone in pregnant baboons, an apparent decline was noted in the serum concentration of progesterone during ketamine sedation. Ketamine (Elvidge, Challis, Robinson, Roper & Thorburn, 1976) and phencyclidine (Setchell, Shackleton & Himsworth, 1975) reduce the plasma concentration of cortisol in rhesus monkeys. The present study determined the effect of no sedation, sedation with ketamine or phencyclidine and tranquillization with chlordiazepoxide on the serum concentrations of progesterone and cortisol during serial bleeding of pregnant baboons.

Nine pregnant baboons (Papiopapio) were mated and maintained as described previously (Townsley, 1974) and studied between days 60 and 172 of gestation (term = 184 days). Between 11.00 and 13.00 h baboons were restrained in a squeeze cage and bled (4 ml) via a 21-gauge needle from the saphenous vein; the
ACTIVE IMMUNIZATION OF EWES AGAINST LUTEINIZING HORMONE RELEASING HORMONE, AND ITS EFFECTS ON OVULATION AND GONADOTROPHIN, PROLACTIN AND OVARIAN STEROID SECRETION
Authors: CLARKE I. J. , FRASER H. M. , McNEILLY A. S.
Published: December 2008

Three Scottish Blackface ewes were immunized against luteinizing hormone releasing hormone (LH-RH) conjugated to bovine serum albumin (BSA) and three control ewes were immunized against BSA alone. When the antibody titre to LH-RH became raised the treated animals failed to show oestrus or ovulate; they had significantly lower levels of plasma luteinizing hormone (LH) and higher levels of prolactin than the controls, whereas the levels of follicle-stimulating hormone (FSH) were unaltered.

The integrity of the hypothalamus-pituitary-gonadal system of these animals was then challenged by the injection of a highly active analogue of LH-RH and by ovariectomy. An i.v. injection of 5 μg d-serine-t-butyl6 des-glycine-NH210 LH-RH ethylamide raised plasma LH and FSH. Ovariectomy caused an eight- and ninefold rise in plasma levels of LH and FSH respectively in controls, but failed to increase plasma levels of LH and FSH in the LH-RH-immunized ewes. Plasma prolactin concentrations in the LH-RH-immunized ewes were significantly reduced by ovariectomy.
RATE OF TESTICULAR MATURATION, IN RELATION TO GONADOTROPHIN AND TESTOSTERONE LEVELS, IN QUAIL EXPOSED TO VARIOUS ARTIFICIAL PHOTOPERIODS AND TO NATURAL DAYLENGTHS
Authors: FOLLETT B. K. , MAUNG S. L.
Published: December 2008

Rates of testicular growth and plasma levels of FSH, LH and testosterone were determined in Japanese quail exposed to various fixed photoperiods (number of hours of light: number of hours of darkness): 12L: 12D, 13L: 11D, 14L: 10D, 16L: 8D and 20L: 4D and to natural daylengths. All five artificial photoperiods stimulated spermatogenesis, with the testes reaching maturity after 30–40 days. Maximum rates of testicular growth occurred with 14L: 10D, 16L: 8D or 20L: 4D but the rate was reduced by 50% in birds exposed to 12L: 12D. This reduction was due to decreased growth in the seminiferous tubule epithelium (and hence in tubule diameter); the duration of spermatogenesis hardly being affected. Near maximum growth rates occurred with 13L: 11D.

The hormone profiles offer an explanation for the differential rates of testicular growth. In the three longest photoperiods, FSH rose from 20 ng/ml to peak levels of 300–400 ng/ml after 10 days. As the testes matured, so the level of FSH decreased to 50–100 ng/ml. This pattern was not seen under 12L: 12D; the level of FSH rose slowly to about 100 ng/ml and showed no peak of secretion. With 13L: 11D a small peak was found, which decreased at maturity. In quail with testes > 1500 mg, the level of FSH was invariably about 100 ng/ml. Patterns of LH secretion were rather similar with all treatments, but testosterone was affected by photoperiod; lower levels were found under 12L: 12D than 20L: 4D. The rate of photoperiodically induced testicular growth was proportional to the levels of FSH, and possibly also testosterone, in the circulation.

Outdoors, testicular growth began when daylengths reached about 12 h. Maturity occurred within the next 40 days. The levels of FSH rose steadily but did not show a peak of secretion. In general, the highest levels of hormone were found in July just before gonadal regression which occurred when the daylengths were still quite long.
PARTIAL ALLEVIATION OF THE ANTITESTICULAR EFFECT OF PIPECOLINOMETHYLHYDROXYINDANE BY ZINC IN RATS
Authors: FANG V. S. , FURUHASHI N.
Published: December 2008

Department of Medicine, The University of Chicago, Chicago, Illinois 60637, U.S.A.

(Received 31 May 1978)

Zinc deficiency in childhood may result in retardation of growth and hypogonadism, since affected adolescent boys show increased growth and sexual maturation after zinc replacement therapy (Sandstead, Prasad, Schulert, Farid, Miale, Bassilly & Darby, 1967; Halsted, Ronaghy, Abadi, Haghshenass, Amirhakemi, Barakat & Reinhold, 1972). Testicular dysfunction has been found after zinc deficiency due to chronic haemodialysis for uraemia and can be reversed by zinc supplements (Antoniou, Shalhoub, Sudhakar & Smith, 1977). Furthermore, oligospermic men, after treatment with zinc, showed increased plasma concentrations of androgens and raised sperm counts (Hartoma, Nahoul & Netter, 1977). The present study investigated the preventative effects of zinc on rats treated with dl-6-(N-α-pipecolinomethyl)-5-hydroxyindane maleate (PMHI), a potent and specific antitesticular agent whose mechanism of action has yet to be determined (Boris, DeMartino & Trmal, 1974).

Three groups of 28-day-old male Sprague–Dawley
SPECIFIC INTERACTION OF CORTICOSTEROIDS WITH BINDING SITES IN THE PLASMA MEMBRANES OF THE RAT ANTERIOR PITUITARY GLAND
Authors: KOCH B. , LUTZ-BUCHER B. , BRIAUD B. , MIALHE C.
Published: December 2008

The binding of glucocorticoids to a crude fraction of rat pituitary plasma membranes and to solubilized membrane proteins was measured. The binding characteristics were similar to those exhibited by transcortin: radioactive corticosterone was bound to a greater extent than radioactive dexamethasone and labelled corticosterone, but not labelled dexamethasone, was displaced by unlabelled corticosterone, deoxycorticosterone and progesterone. A Scatchard plot of the binding data revealed the presence of a binding material with a dissociation constant of about 3·2 nmol/l, which sedimented at 4S after sucrose density-gradient centrifugation. It was found that the number of binding sites was inversely related to the concentration of corticosterone in the circulation and was increased after long-term adrenalectomy. These data suggest that a material similar to transcortin is complexed to the plasma membrane of rat pituitary cells.
INHIBITION OF STEROID 5α-REDUCTASE IN VIVO: EFFECT ON SUPPRESSION OF LUTEINIZING HORMONE AND STIMULATION OF ACCESSORY SEX ORGANS BY TESTOSTERONE IN THE ORCHIDECTOMIZED RAT
Authors: KAO LIDIA WEI LIU , WEISZ JUDITH
Published: December 2008

An inhibitor of 5α-reductase, the 17β-carboxylic acid derivative of testosterone (testosterone-17βCA), has been used to evaluate the importance of the 5α-reduction of testosterone in its action on the suppression of LH secretion in male rats. The potential of testosterone-17βCA to inhibit the formation of 5α-dihydrotestosterone (DHT) was first demonstrated in vitro. When homogenates of hypothalami or anterior pituitary glands were incubated with [3H]testosterone in the presence of a 50-fold excess of testosterone-17βCA, the formation of labelled DHT was inhibited by more than 80%. Adult male rats that had been castrated for 1–2 months were fitted with chronic intravenous catheters and implanted with silicone elastomer sheets: one group received one sheet, 0·5–2·0 cm2 in size containing 1·6% testosterone, a second group received one 50 cm2 sheet containing 1·6% testosterone-17βCA and a third group received two sheets, one sheet 50 cm2 in size containing 1·6% testosterone-17βCA and the second ranging in size from 0·5 to 2·0 cm2 and containing 1·6% testosterone. Blood was withdrawn daily from each rat over a 4–5 day period after implantation of the steroids and the level of LH in the plasma was measured by radioimmunoassay. The seminal vesicles and the ventral prostate gland were removed at autopsy on day 4 or 5; the weights of these organs were shown to have increased progressively as the size of the implant of testosterone increased. In contrast, the level of LH in the plasma was suppressed to a comparable extent by implants of testosterone between 0·6 and 2 cm2, whereas a 0·5 cm2 implant of testosterone had no effect. Implants of testosterone-17βCA alone did not influence the weight of the accessory organs or the level of LH. When testosterone-17βCA and testosterone were implanted together, the growth-promoting effect of the latter on the accessory sex organs was significantly reduced. The effectiveness of testosterone in suppressing the level of LH in the plasma of these animals was not influenced by the presence of testosterone-17βCA and in certain instances the level was raised.
SECRETION OF ALDOSTERONE IN RESPONSE TO HISTAMINE IN HYPOPHYSECTOMIZED-NEPHRECTOMIZED DOGS
Authors: AIKAWA TADAOMI , HIROSE TAEKO , MATSUMOTO ITSURO , SUZUKI TATUZI
Published: December 2008

In hypophysectomized-nephrectomized dogs after intravenous injection of histamine, a marked increase was observed in the rate of secretion of aldosterone, although it was smaller than that in intact dogs. Hypophysectomy plus bilateral nephrectomy greatly impaired the secretion of corticosterone and cortisol in the dog in response to histamine. However, a small yet significant increase in corticosterone and cortisol secretion was observed in hypophysectomized-nephrectomized dogs after intravenous injection of histamine. Additional experiments showed that plasma concentrations of potassium and sodium in hypophysectomized-nephrectomized dogs remained unchanged after intravenous injection of histamine. These results suggest that histamine stimulates aldosterone secretion in the dog partly by a direct effect on the adrenal cortical cells, whereas the effect of histamine on corticosterone and cortisol secretion is mediated mainly, but not totally, by pituitary release of ACTH.
SYNTHESIS OF PROLACTIN BY HUMAN DECIDUA IN VITRO
Authors: GOLANDER AVRAHAM , HURLEY THOMAS , BARRETT JANET , HANDWERGER STUART
Published: December 2008

To determine whether human decidua and/or chorion synthesizes and secretes prolactin, explants of decidua obtained at Caesarian section and explants of chorion from the membranes separating dizygotic twins were cultured for periods of up to 6 days. The decidual explants released 366 ± 37 ng prolactin/100 mg tissue (mean ± s.d.) during each day in culture and incorporated 3H-labelled amino acids into immunoprecipitable prolactin. In the radioimmunoassay for prolactin, serial dilutions of incubation medium displaced 125I-labelled prolactin parallel to the displacement by pituitary prolactin and the prolactin in the medium eluted from Sephadex G-150 in a position identical to that of pituitary prolactin. Chorionic explants released prolactin into the incubation medium during day 1 of culture only and did not incorporate 3H-labelled amino acids into prolactin. These results demonstrate that prolactin is synthesized by the decidua and not by the chorion and suggest that the decidua is the source of prolactin in amniotic fluid.
STEROID AND PROSTAGLANDIN SECRETION BY THE CORPUS LUTEUM, ENDOMETRIUM AND EMBRYOS OF CYCLIC AND PREGNANT PIGS
Authors: WATSON J. , PATEK C. E.
Published: December 2008

Prostaglandin F2α (PGF2α) secreted by the reproductive tissues of the pig in vitro was measured and it was found that the levels secreted by the corpus luteum and endometrium of early pregnant sows were significantly lower than those secreted by tissues during the late stage of the oestrous cycle. They were, however, comparable to levels secreted by tissues from the mid-stage of the oestrous cycle. Embryos also secreted significant amounts of PGF2α. Secretion of progesterone and oestradiol by the corpora lutea of both cyclic and pregnant pigs fell within accepted limits but embryos were also found to secrete significant amounts of oestradiol. The results suggest that luteal maintenance in the early pregnant pig is unlikely to be directly due to reduced synthesis of PGF2α.
ALTERATIONS IN LEVELS OF THYROTROPHIN RELEASING HORMONE AND RATES OF HORMONE DEGRADATION IN HYPOTHALAMIC TISSUE OF THE DEVELOPING RAT
Authors: PEASE KATHLEEN , SHEN HIRAM , ACRES G. S. , RUPNOW J. H. , DIXON J. E.
Published: December 2008

Developmental changes in levels of hypothalamic thyrotrophin releasing hormone (TRH) and the role that hypothalamic degrading enzymes may play in these alterations were investigated. Levels of TRH in male and female fetal rats and in male neonatal rats were measured by radioimmunoassay. The hormone content of the hypothalamus was shown to increase from less than 1 ng at 1–4 days of age to approximately 10 ng at 20 days of age. Thereafter, the content of TRH declined to the adult level of about 5 ng. The ability of fractionated hypothalamic homogenates to degrade TRH was measured over the same time. The 27 000 g supernatant fraction contained a degrading activity that yielded only radiolabelled deamido-TRH upon incubation with [l-proline 2,3-3H]TRH. The corresponding particulate fraction contained at least two distinct TRH degrading activities as determined by the number of metabolites present. Changes in rates of degradation were not large enough to account for the differences observed in levels of TRH.
CONTROL OF GONADOTROPHIN SECRETION IN THE FEMALE TAMMAR WALLABY (MACROPUS EUGENII)
Authors: EVANS SUSAN M. , TYNDALE-BISCOE C. H. , SUTHERLAND R. L.
Published: December 2008

A heterologous radioimmunoassay for tammar wallaby FSH, using an ovine FSH antiserum and a human FSH tracer, is described. With this assay concentrations of FSH in plasma of intact female tammars are not detectable except rarely at the time of oestrus. However the assay has proved useful in studies of the control of gonadotrophin secretion in intact male and in ovariectomized tammars.

In the female tammar, concentrations of LH and FSH in plasma rose within a few days of bilateral ovariectomy. Ovariectomized tammars respond to a luteinizing hormone releasing hormone stimulus (10 μg, i.v.) with a prompt release of LH, peak levels of 16·9 ± 1·4 ng NIH-LH-S19/ml plasma (n = 12) being reached within 25 min of injection. Concentrations of LH and FSH in plasma were reduced to preoperative values in ovariectomized tammars when lutein tissue developed in ovarian cortex grafts autotransplanted under the pouch skin. Ovarian interstitial tissue was not necessary for this effect.

After lutectomy during quiescence, the female tammar ovulates again in about 14 days. Injections of progesterone (700 μg/kg per day, i.m.) for 7 days after the operation did not delay this response, but follicular development and ovulation appeared to be retarded in animals given oestradiol-17β (5 μg/kg per day, i.m.) with or without progesterone.
EFFECTS OF SYNTHETIC MAMMALIAN GONADOTROPHIN RELEASING HORMONE AND DOGFISH HYPOTHALAMIC EXTRACTS ON LEVELS OF ANDROGENS AND OESTRADIOL IN THE CIRCULATION OF THE DOGFISH (SCYLIORHINUS CANICULA L.)
Authors: JENKINS N. , DODD J. M.
Published: December 2008

Intravenous injection of synthetic mammalian gonadotrophin releasing hormone (GnRH; 5 μg per fish) induced a significant increase in androgen levels in the circulation of male dogfish within 4 h. Female dogfish injected with 10 μg GnRH in November showed significantly raised plasma levels of androgens and oestradiol-17β after 90 min as well as an increase in the rate of oviposition. Twice this dose of GnRH failed to produce significant increases in plasma levels of oestradiol in female dogfish in February and the androgen response in these animals was less than that seen after injection of GnRH in November.

Injection of an acid extract of dogfish hypothalamus significantly increased plasma levels of androgen and oestradiol in female fish when they were compared with control fish injected with extracts of dogfish cerebellum and the latency of response was similar to that encountered when GnRH was injected. It was concluded that the dogfish hypothalamus contains a factor capable of increasing plasma sex steroid levels in the same species and which is similar in its effects to mammalian GnRH.
PLACENTAL TRANSFER OF ALDOSTERONE IN THE SHEEP
Authors: WINTOUR E. M. , COGHLAN J. P. , HARDY K. J. , LINGWOOD B. E. , RAYNER M. , SCOGGINS B. A.
Published: December 2008

To determine the percentage of the maternal secretion of aldosterone which crosses the placenta the blood clearance rate (BCR) of aldosterone was measured in pregnant sheep and in chronically cannulated fetuses by the constant infusion of [3H]aldosterone alternately into the maternal and fetal compartments. When equilibrium had been reached the concentration of [3H]aldosterone was measured in both maternal and fetal compartments. Aldosterone BCR in eight pregnant ewes was 98 ± 5 (s.e.m.) litres/h which was not significantly different from that of ten non-pregnant ewes at 95 ± 5 litres/h. The BCR of aldosterone in seven fetuses was 24 ± 2 litres/h. A small percentage (4·4 ± 0·3; n = 7) of the maternal production rate was transferred to the fetus, whilst 29 ± 4% (n = 8) of the fetal production rate was transferred to the maternal compartment.

When aldosterone was measured in maternal and fetal blood samples collected simultaneously from sodium-replete sheep more than 80% of the aldosterone in fetal blood was of fetal origin if the actual fetal concentration of aldosterone was greater than 1·5 ng/dl.
INFLUENCE OF STRESS ON THE SECRETION OF CORTICOSTERONE IN THE DUCK (ANAS PLATYRHYNCHOS)
Authors: HARVEY S. , MERRY B. J. , PHILLIPS J. G.
Published: December 2008

The influence of stress on the secretion of corticosterone has been investigated by radioimmunoassay in domestic ducks (Anas platyrhynchos) of 6–8 weeks of age. Intravenous and i.m. injections of synthetic ACTH (Synacthen, 25 i.u./bird and Synacthen Depot, 100 i.u./bird respectively) markedly increased (2·7- to 10-fold) basal concentrations of corticosterone in plasma (3–6 ng/ml) in comparison with those in birds injected with 0·9% saline (1 ml/bird). Maximum levels of 30–40 ng/ml plasma were reached after 30 min and 5 h respectively. Increased levels of corticosterone in plasma were also seen within 5 min of i.v. administration of saline and remained as high as those in birds treated with Synacthen for at least 20 min after injection. Blood sampling (from the brachial vein) was, by itself, sufficient to increase levels of corticosterone in plasma; a large (twofold) rise being observed as soon as 1 min after initial handling and bleeding, with concentrations of 30–40 ng/ml being found in birds bled 15 times during a period of 14 min. However, in a flock of birds, the alarm created in unhandled birds while others were being bled had no effect on concentrations of corticosterone in plasma. Deprivation of food or water for 24 h also enhanced levels of corticosterone in plasma, as did 24 h of adaptation to 0·2 m-NaCl drinking water. These results have demonstrated the lability of the secretion of corticosterone in response to stress and demonstrated its usefulness as a physiological indicator of stress in ducks.
INDUCTION OF SEXUAL RECEPTIVITY IN OVARIECTOMIZED RATS BY PULSE ADMINISTRATION OF OESTRADIOL-17β
Authors: SÖDERSTEN P. , ENEROTH P. , HANSEN S.
Published: December 2008

Constant-release implants filled with oestradiol-17β induced sexual receptivity in ovariectomized rats in response to progesterone treatment if they were implanted 32 h before behavioural testing. A 20 h period of exposure to oestradiol, by implantation 32 h before testing and removal of the implants 20 h later, was sufficient for induction of the behaviour. The exposure time necessary for behavioural responses could be further reduced to two 4 h periods, between 32 and 28 h and between 16 and 12 h, before testing. Serum levels of oestradiol were raised within 1 h of oestradiol implantation and declined rapidly after implant removal. A single injection of oestradiol benzoate was much more potent than a single injection of oestradiol in inducing sexual receptivity in ovariectomized rats, but this difference in potency was reversed if two appropriately timed injections were given. Oestrone- or oestriol-filled implants were relatively ineffective in inducing sexual receptivity. It is suggested that oestradiol has to be present at crucial time points to prepare an ovariectomized rat to respond behaviourally to progesterone treatment and that oestradiol is the principal oestrogen in the stimulation of sexual behaviour in female rats.
EVIDENCE THAT CHANGES IN LUTEINIZING HORMONE SECRETION REGULATE THE GROWTH OF THE PREOVULATORY FOLLICLE IN THE EWE
Authors: McNATTY K. P. , GIBB MARION , DOBSON CAROLYN , THURLEY D. C.
Published: December 2008

The aim of the present study was to gain evidence that the level of LH secretion preceding the preovulatory LH surge is an important determinant of follicular maturation and corpus luteum function in the ewe. In addition it was hoped to establish whether the pattern of LH delivery to the ovary (pulsatile v. constant) is a critical factor in the maturation of a preovulatory follicle.

To accomplish this, progesterone-primed anoestrous ewes were repeatedly injected i.v. with LH or luteinizing hormone-releasing hormone (LH-RH), or given an i.v. infusion of LH, over a 72 h period. These animals, together with the appropriate controls, were exposed to a sexually active ram so that oestrous activity could be recorded. All ewes were subjected to intensive blood sampling regimes so that the plasma levels of LH and progesterone could be determined and compared to those which occurred in the same breed of sheep during the oestrous cycle.

Collectively the data suggest that the plasma levels of LH preceding the preovulatory LH surge are an important determinant of follicular maturation as judged by subsequent corpus luteum function. Moreover, they show that follicular maturation can be achieved with widely differing patterns of LH delivery to the ovary during the preovulatory period and that a strict pulsatile delivery of LH may not be an absolute requirement.
ANDROGEN AND OESTROGEN BINDING IN CYTOSOLS OF HUMAN OVARIAN TUMOURS
Authors: HAMILTON T. C. , DAVIES P. , GRIFFITHS K.
Published: December 2008

The specific retention of androgens and oestrogens by cytoplasmic components of human ovarian tumours was investigated. High-affinity, low-capacity binding of androgens was observed in 88% of tumour specimens and oestrogen binding in 32%. Retention of oestrogens did not occur in the absence of androgen binding. The androgen-binding component, of sedimentation coefficient 7·5–8·5S, showed specificity for 5α-dihydrotestosterone and 17β-hydroxy-17α-methyl-estra-4,9,11-trien-3-one (R1881). In some instances, competition for R1881-binding sites indicated the presence of progesterone receptor-like binding. The data presented suggest strongly the existence of androgen and oestrogen receptors in some ovarian tumours and may be relevant to histopathological classification and therapeutic rationales.
RESPONSE OF LUTEINIZING HORMONE FROM COLUMNS OF DISPERSED RAT PITUITARY CELLS TO A HIGHLY POTENT ANALOGUE OF LUTEINIZING HORMONE RELEASING HORMONE
Authors: YEO T. , GROSSMAN A. , BELCHETZ P. , BESSER G. M.
Published: December 2008

The response of LH from a perfused column of dispersed rat anterior pituitary cells to LH releasing hormone (LH-RH) and the analogue, d-Ser(But)6-desGly10-Proethylamide9-LH-RH (Hoe 766), was investigated. Dose–response curves showed non-parallelism between LH-RH and the analogue, but it was evident that the analogue was considerably more potent. After a single pulse of LH-RH, LH output returned to basal values in 8 min; this was prolonged to 20 min in the case of the analogue. During this 20 min the cells were refractory to pulses of LH-RH but pulses of the analogue maintained output of LH. During constant-dose perfusion with either synthetic LH-RH or the analogue, output of LH rapidly reached a peak and then gradually fell over several hours to approach baseline values. However, a pulse of 50 mmol potassium chloride/l was still able to release LH at this time. The data are consistent with the view that this analogue of LH-RH is highly potent and is strongly bound by the LH-RH receptor. Furthermore, since it desensitizes the LH-RH receptor, it appears that continued turnover of either LH-RH or the analogue at the receptor is necessary for output of LH to be maintained.
ADRENOCORTICAL RESPONSES AND CHANGES DURING THE OESTROUS CYCLE IN MICE: EFFECTS OF MALE PRESENCE, MALE URINE AND HOUSING CONDITIONS
Authors: NICHOLS D. J. , CHEVINS P. F. D.
Published: December 2008

Male urine applied daily to their bedding raised the basal levels of plasma corticosterone in individually housed, virgin female mice, when compared with females (grouped or individually housed) living with male mice or with group-housed females exposed daily to male urine. Values were not affected during ether-induced stress. A single application of male urine raised plasma levels 30 min later regardless of housing conditions; but after 4 and 24 h levels had fallen to normal. The results are discussed in terms of sensitization of the pituitary-adrenal system and of stress and reproductive pheromones. Male urine was less effective than male presence at inducing 4-day oestrous cycles. Length and type of cycle varied continuously under the influence of a spectrum of environmental signals.
RENIN AND ALDOSTERONE AT HIGH ALTITUDE IN MAN
Authors: KEYNES R. J. , SMITH G. W. , SLATER J. D. H. , BROWN M. M. , BROWN S. E. , PAYNE N. N. , JOWETT T. P. , MONGE C. C.
Published: December 2008

Measurements have been made of hormonal changes relevant to salt and water balance during prolonged exposure to hypoxia to improve our understanding of the syndrome of acute mountain sickness. We have attempted to delineate the detailed inter-relationships between the renin–aldosterone and the vasopressin systems by a metabolically controlled study, involving an orthostatic stress (45° head-up tilt) and an injection of a standard dose of ACTH to test adrenal responsiveness. Three Caucasian medical students underwent a 7-day equilibration at 150 m (Lima, Peru), followed by a 6-day sojourn at 4350 m (Cerro de Pasco, Peru) and a final 7 days at 150 m. Measurements were made of sodium and potassium balance, body weight and the 24-h renal excretion of vasopressin, cortisol and aldosterone 18-glucuronide. These variables showed little change, except for that of aldosterone 18-glucuronide, which fell sharply at altitude and rebounded even more sharply on return to sea level. At altitude, basal plasma levels of renin activity and aldosterone fell, and the response to orthostasis was attenuated, but the fall of plasma renin activity, as compared to plasma aldosterone, was delayed; on return to sea level this dissociation was exacerbated with the return of normal renin responsiveness lagging behind that of aldosterone. We suggest that unknown factors which dissociate the orthodox renin–aldosterone relationship, other than the activity of the angiotensin I-converting enzyme, are operative on exposure to hypoxia.
THYROID-STIMULATING ANTIBODIES IN GRAVES'S DISEASE AND THE EFFECT OF THYROTROPHIN-BINDING GLOBULINS ON THEIR DETERMINATION
Authors: BÍRÓ J.
Published: December 2008

Globulin preparations from the sera of 104 untreated patients with Graves's disease have been tested for their thyroid-stimulating antibody (TSAb) activities. Eighty-one of the samples (78%) were positive in the assay for the thyrotrophin-binding inhibitory immunoglobulins, 48 samples (46%) contained human thyroid adenyl cyclase stimulators (HTACS) and 71 (68%) contained human thyroid stimulators (HTS) measured as stimulation of colloid droplet formation in human thyroid slices. All 104 samples were positive in one or other of the assays, 29 (28%) were positive in all three assays and 38 (37%) in two.

All samples were tested for their specific TSH-binding characteristics, 40 (38%) possessed 'B-type' binding sites (previously characterized as TSH-binding sites with low affinity but high capacity for the ligand) but the remaining 64 samples (62%) were no different from normal control samples and had 'A-type' binding sites (high affinity but low capacity binding sites for TSH). Samples without detectable thyrotrophin-binding inhibitory immunoglobulin did not contain B-type TSH-binding globulins. Globulins exhibiting B-type binding were more active in the HTACS and HTS assays.

The B-type TSH-binding globulins have a characteristic, dose-dependent reducing effect on the human thyroid adenyl cyclase stimulation by TSH whereas A-type globulins do not. Globulins exhibiting B-type TSH-binding may therefore have a significant effect on assays for TSAb activities. The methods used to measure TSAb have been reviewed from this point of view.
HOURLY FLUCTUATIONS IN THE BLOOD LEVELS OF MELATONIN, PROLACTIN, LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE, TESTOSTERONE, TRI-IODOTHYRONINE, THYROXINE AND CORTISOL IN RAMS UNDER ARTIFICIAL PHOTOPERIODS, AND THE EFFECTS OF CRANIAL SYMPATHECTOMY
Authors: LINCOLN G. A. , ALMEIDA O. F. X. , KLANDORF H. , CUNNINGHAM R. A.
Published: December 2008

Eight adult Soay rams (four control and four cranially sympathectomized by removal of the superior cervical ganglia) were exposed to alternating 16-week periods of short days of 8 h light: 16 h darkness (8L : 16D) and long days (16L : 8D) for more than 3 years, and the changes in the diameter of the testes were recorded. Once during short days and once during long days blood samples were collected hourly for 28 h, and the concentrations of melatonin, prolactin, FSH, LH, testosterone, tri-iodothyronine (T3), thyroxine (T4) and cortisol were measured by radioimmunoassay.

In the control rams the testes were reduced in size during long days compared to short days, and the blood concentrations (24-h mean values) of FSH, LH and testosterone were decreased. The levels of prolactin were much increased, while there was no significant change in the mean levels of melatonin, T3, T4 and cortisol. During both photoperiods there was considerable hour-to-hour variation in all eight hormones indicative of episodic secretion, as well as a consistent variation related to the time of day which was most pronounced for melatonin and T3. There was a clear difference in the daily profile of plasma melatonin levels between short and long days.

In the superior cervical ganglionectomized rams there were no significant changes in the size of the testes or in the hormone titres between short and long days. Compared to the controls the plasma levels of LH, FSH, testosterone and prolactin were in the intermediate range. Some consistent diurnal variation was evident in the levels of all the hormones measured, with a pattern similar to the controls for a few of the hormones (e.g. T3) but quite different for others (e.g. melatonin).