bluuebunny/crossref_metadata_2025 huggingface dataset:
INHIBITION OF THYROTROPHIN-RELEASING HORMONE RESPONSIVENESS BY PHYSIOLOGICAL CONCENTRATIONS OF THYROID HORMONES IN THE CULTURED RAT PITUITARY GLAND
Authors: LEWIS M. , YEO P. P. B. , GREEN E. , EVERED D. C.
Published: December 2008

Diced quarter anterior pituitaries from mature female Wistar rats were cultured in synthetic medium with or without added serum. Using each culture as its own control, the thyrotrophin-releasing hormone (TRH) dose–thyrotrophin (TSH) response characteristics of both media were similar; significant TSH secretion being stimulated at TRH doses around 1·5 × 10−9 mol/l. During days 1–3 of culture, basal TSH secretion fell significantly but TRH responsiveness was unchanged. Neither tri-iodothyronine (T3) nor thyroxine (T4) influenced basal TSH secretion.

In both culture media inhibition of TRH responsiveness was demonstrated with concentrations of T3 and T4 within the ranges 1·5 × 10−12 to 1·5 × 10−9 mol/l for T3 and 6·5 × 10−10 to 6·5 × 10−7 mol/l for T4. Equivalent inhibition was accompanied by similar T3 concentrations whether T3 or T4 supplements were used, suggesting that T4 itself has no feedback action. The similar concentrations of T3 required to inhibit TRH responsiveness in media either with or without serum suggest that the pituitary is responsive not only to free but also to total thyroid hormone concentrations, since serum-free medium contains no thyroid hormone-binding protein.
EFFECT OF DIBUTYRYL CYCLIC AMP AND OESTRADIOL ON INCORPORATION OF [3H]LEUCINE INTO THE PROTEINS OF LUMINAL FLUID OF THE RAT UTERUS
Authors: SURANI M. A. H. , WEBB F. T. G.
Published: December 2008

An injection of 12·5 nmol dibutyryl cyclic AMP (dbcAMP) into each uterine horn of ovariectomized rats maintained on progesterone alone, enhanced incorporation of [3H]leucine into uterine luminal proteins. A value of 11·73 × 103 c.p.m. [3H]leucine incorporated/ rat was found after injection of dbcAMP compared with 3·69 × 103 c.p.m./rat after injection of saline. An injection of 1·0 μg oestradiol, in contrast, gave 58·05 × 103 c.p.m./rat. Electrophoretic analysis showed that the radioactively labelled proteins found after an injection of dbcAMP or oestradiol were qualitatively similar to those detected on day 5 of pregnancy, the day of blastocyst implantation. The nucleotide thus apparently elicits a uterine response similar to that observed after an injection of oestradiol.
PHYSIOLOGICAL ACTIONS OF HUMAN FOLLICLE-STIMULATING HORMONE AND ITS β-SUBUNIT IN REPTILES
Authors: LICHT PAUL , GALLO ANTONELLA BONA , HARTREE ANNE STOCKELL , SHOWNKEEN RATNA C.
Published: December 2008

The actions of human follicle-stimulating hormone (hFSH) and its β-subunit were examined in several assays in reptiles, including effects on lizard testicular activity (growth and androgen production) in vivo, and stimulation of androgen production by snake testes and competition for binding of 125I-labelled hFSH in lizards and snakes in vitro. Binding was also examined with mammalian tissues.

The hFSH was highly steroidogenic in the snake and lizard; otherwise results were similar to those observed in mammals. In all cases, the potency of the β-subunit was only a few per cent of the intact hormone. The potency of hFSH in vivo compared with NIH-FSH ovine standards was several 100 times greater than in vitro. Results for stimulation of androgen production in vivo closely paralleled those for binding assays in both reptiles and mammals. In contrast to previous results for ovine FSH β-subunit, human FSH β-subunit has little if any FSH biological activity in reptiles.
VARIATIONS IN STORED AND PLASMA CONCENTRATIONS OF ANDROGENS AND LUTEINIZING HORMONE DURING SEXUAL DEVELOPMENT IN THE COCKEREL
Authors: SHARP P. J. , CULBERT J. , WELLS J. W.
Published: December 2008

The concentrations of luteinizing hormone (LH) and testosterone in the plasma and the stored levels of LH, testosterone and androstenedione were measured in cockerels aged 8–29 weeks. The onset of puberty occurred between 16 and 24 weeks of age, when the testes entered a phase of rapid growth and spermatogenesis was completed. The following sequence of endocrine events was found to be associated with the onset of puberty: a fall in the amount of androstenedione in the testes before any evidence of increased testicular growth; an increase in the total amount of LH in the pituitary gland as the testes started to enlarge; an increase in the total amount of testosterone in the testes and in the concentration of LH in the plasma; an increase in the concentration of testosterone in the plasma. An increase in the rate of growth of the comb and testes preceded a detectable increase in the levels of LH and testosterone in the plasma. The increase in the amount of testosterone in the plasma which occurred after the initial increase in the concentration of LH was associated with the final stages of spermatogenesis, a decrease in the rate of body growth and a temporary reduction in the amount of LH secreted.
EFFECTS OF CERTAIN ANALOGUES OF SYNTHETIC LUTEINIZING HORMONE RELEASING HORMONE ON THE RELEASE OF LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE IN THE ANOESTROUS EWE
Authors: SIDDALL BRENDA , CRIGHTON D. B.
Published: December 2008

The ability of eight nonapeptide analogues of synthetic luteinizing hormone releasing hormone (LH-RH) to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in the anoestrous ewe was studied and compared with the activity of synthetic LH-RH. In all the analogues, the glycineamide residue in position 10 was replaced with ethylamine; seven of them also had various substituents in positions 6 and/or 7. In a screening experiment using a single i.v. dose, the majority of the analogues were more potent than synthetic LH-RH in terms of the total amounts of LH and FSH released. The most potent overall was [d-Ser(But)6] Des Gly-NH210 LH-RH ethylamide which produced LH and FSH responses in terms of peak height, duration and area within the physiological range of the natural preovulatory peak. The dose–response relationships of this analogue and synthetic LH-RH were also compared. Deviations from parallelism were observed when all the aspects of the LH and FSH responses were considered, and with the FSH response deviations from linearity were also seen. These facts precluded the computation of a potency estimate using conventional statistical methods for the analysis of six-point biological assays, although it was clear that the analogue was substantially more potent than synthetic LH-RH. It was calculated that the administration of a single i.v. dose of between 6 and 30 μg of the analogue to anoestrous ewes would result in peaks in the concentrations of LH and FSH similar in all respects to those occurring naturally at oestrus, a situation previously found impossible to mimic with single injections of synthetic LH-RH.
HOMOLOGOUS RADIOIMMUNOASSAY FOR CANINE PROLACTIN AND ITS APPLICATION IN VARIOUS PHYSIOLOGICAL STATES
Authors: GRÄF K.-J. , FRIEDREICH E. , MATTHES S. , HASAN S. H.
Published: December 2008

The purification of canine prolactin and the development of an homologous radioimmunoassay including several physiological studies in the Beagle dog are described. The assay measured immunoreactive canine prolactin with a sensitivity limit of 0·6 ng/ml. Purified canine luteinizing hormone gave no significant inhibition in the assay whereas purified canine growth hormone inhibited the binding of 125I-labelled canine prolactin to antiserum only at very high dose levels. In Beagle dogs, basal serum prolactin concentrations were in the range 1–2 ng/ml in normal male, normal female (metoestrus and anoestrus) and oophorectomized–hysterectomized female dogs. The prolactin concentration in one sample of amniotic fluid was in the same range, while in hypophysectomized male dogs no serum prolactin could be detected by our assay system. Serum prolactin concentrations tended to increase during late pregnancy and parturition, remaining high during the first 9 days of lactation. In consequence, a negative correlation was suggested between serum prolactin and serum progesterone concentrations.
VENOUS DRAINAGE AND FUNCTIONAL CONTROL OF THE CANINE PROSTATE GLAND
Authors: DHABUWALA C. B. , PIERREPOINT C. G.
Published: December 2008

The venous drainage of the canine prostate gland has been studied in nine dogs after post-mortem intravenous injection of a coloured suspension of latex. A submucosal cavernous plexus of the prostatic urethra continuous with that of the penis, and a previously unnamed vessel that drains this plexus into the prostatico-vesical vein are described. The eferential vein was found to open variably, but always into the prostatic venous system. The data support the concept that a very small retrograde blood flow would take androgenrich blood from the deferential vein into the prostate gland.
EFFECT OF HUMAN CHORIONIC GONADOTROPHIN ON ADENYLATE CYCLASE ACTIVITY AND TESTOSTERONE CONTENT IN RAT TESTICULAR MITOCHONDRIA
Authors: SULIMOVICI SOREL , ROGINSKY M. S.
Published: December 2008

The adenylate cyclase activity and the concentration of testosterone in testicular mitochondria from immature rats were measured after administration of human chorionic gonadotrophin (HCG) or dibutyryl cyclic AMP in vivo or in vitro. Intratesticular injection of HCG produced an increase in adenylate cyclase activity which preceded the rise in the level of testosterone, whereas addition of the trophic hormone in vitro resulted in simultaneous increases. Administration of dibutyryl cyclic AMP in vivo enhanced the testosterone content of the mitochondria. However, the cyclic nucleotide added in vitro at concentrations up to 5 mmol/l had no effect. Cycloheximide injected intraperitoneally before the administration of HCG abolished the stimulatory effect of the trophic hormone on the level of testosterone in the mitochondria, whereas chloramphenicol had no effect.

These results, although they confirm the role of cyclic AMP as an intermediate in the stimulatory effect of HCG on the concentration of testosterone in rat testis, do not support a role for mitochondrial adenylate cyclase in this action. A protein regulator(s) formed extramitochondrially appears to be involved in the stimulatory effect of gonadotrophins on steroidogenesis.
CHANGES IN CONCENTRATIONS OF FOLLICLE-STIMULATING HORMONE, LUTEINIZING HORMONE, PROLACTIN AND PROGESTERONE IN THE PLASMA OF EWES DURING THE TRANSITION FROM ANOESTRUS TO BREEDING ACTIVITY
Authors: WALTON J. S. , McNEILLY JUDITH R. , McNEILLY A. S. , CUNNINGHAM F. J.
Published: December 2008

The plasma concentrations of FSH, LH, prolactin and progesterone were measured throughout anoestrus and during the resumption of cyclic activity in two groups of ewes. Group A was maintained under conditions of natural daylength throughout the experiment, whereas Group B was exposed to 6 h of light and 18 h of darkness, the change being made abruptly on the longest day. In those ewes kept on short days, oestrus and ovulation occurred 18·3 days (P < 0·05) and 23·4 days (P < 0·001) earlier than in the ewes under conditions of natural daylength. Ovulation preceded oestrus by 18·6 days and 23·1 days in Groups A and B respectively.

The occurrence of ovulation was detected by the determination of plasma progesterone concentrations. In all ewes, progesterone levels were basal until the first ovulation when the pattern of secretion was typical of that seen during the oestrous cycle. In the 4 days before ovulation, the plasma progesterone concentration increased slowly to reach a maximum of 0·66 ± 0·12 (s.e.m.) ng/ml on day − 1. The first ovulation was associated with a substantial surge of LH. Similar release of LH, thought to be related to the increased progesterone secretion, was also observed on day −5. Sporadic release of LH was also found before this time in some animals.

Plasma concentrations of FSH fluctuated randomly throughout anoestrus and during the transition to established oestrous cycles. These changes were not apparently related to ovulation. Throughout anoestrus, prolactin concentrations were raised but always declined before the time of ovulation. The fall in prolactin concentrations occurred sooner in the ewes on short days, pointing to a relationship with the decreased daylength.

These data suggest that the return to oestrous cycles may be brought about by the removal of an antigonadotrophic effect exerted by high concentrations of prolactin in the blood during anoestrus.
METABOLISM OF ANDROGENS IN VITRO BY THE SUBMAXILLARY SALIVARY GLAND OF THE MATURE DOMESTIC BOAR
Authors: BOOTH W. D.
Published: December 2008

Homogenates of the submaxillary glands of mature domestic boars were incubated with radioactively labelled C19 steroids. The metabolism of [7α-3H]dehydroepiandrosterone and [7α-3H]androstenedione was primarily to the end products 5α-androstane-3,17-dione and androsterone, but some testosterone, 5α-dihydrotestosterone and 5α-androstane-3α,17β-diol were also formed. When [7α-3H]5-androstene-3β,17β-diol was used as a substrate, the major metabolite was testosterone. Both [7α-3H]5-androstene-3β,17β-diol and [1α,2α-3H]-testosterone were converted to 5α-dihydrotestosterone and high yields of 5α-androstane-3α,17β-diol, but only small yields of 5α-androstane-3β,17β-diol and androsterone were obtained. High yields of 5α-androstane-3α,17β-diol and to a lesser extent 5α-androstane-3β,17β-diol were formed from the substrate [1α,2α-3H]5α-dihydrotestosterone. Conversely, when both 3H-labelled androstanediols were used as substrates, 5α-dihydrotestosterone was formed in equal amounts together with a large yield of 5α-androstane-3α,17β-diol from the 3β-epimer. There was no evidence for steroid sulphatase or aromatase activity in these incubations. These findings support the prohormone concept that precursor steroids of testosterone, known to be present in boar testis, could act as an additional source of potent androgens in peripheral target organs to androgens in this species.

In a number of incubations with [1α,2α-3H]testosterone, free oestradiol-17β and oestrone, but not oestrone sulphate enhanced the formation of androstenedione, but reduced the formation of 5α-dihydrotestosterone. However, both free and conjugated oestrogen reduced the formation of 5α-androstane-3α,17β-diol. These findings are discussed in relation to the high levels of oestrogen found in male pigs.
SELECTIVE RELEASE OF FOLLICLE-STIMULATING HORMONE DURING THE PERIOD OF OVULATION INDUCED BY HUMAN CHORIONIC GONADOTROPHIN IN DIOESTROUS RATS
Authors: SASAMOTO SHUJI , HARADA SHIGEO , TAYA KAZUYOSHI
Published: December 2008

Laboratory of Veterinary Physiology, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183, Japan

(Received 2 May 1977)

When an amount of human chorionic gonadotrophin (HCG) sufficient to cause ovulation is given to 4-day cyclic rats on the day of dioestrus, premature ovulation is induced the next morning (Eto & Imamichi, 1955). The pattern of release of follicle-stimulating hormone (FSH) responsible for the initiation of follicular maturation of the next set of follicles (Schwartz, 1969; Welschen & Dullaart, 1976) after HCG-induced ovulation has not been previously evaluated. The present communication is concerned with this problem and indicates that a large amount of FSH is released within 12 h of administration of HCG, with only a small concomitant rise in the concentration of luteinizing hormone (LH).

Adult female Wistar rats were maintained under a 14 h light : 10 h darkness schedule (lights on 05.00 h), and those showing three or
INTRACELLULAR DISTRIBUTION OF CATHEPSIN D IN RAT CORPORA LUTEA IN RELATION TO REPRODUCTIVE STATE AND THE ACTION OF PROSTAGLANDIN F2α AND PROLACTIN
Authors: LAHAV MICHAL , MEIDAN RINA , AMSTERDAM A. , GEBAUER H. , LINDNER H. R.
Published: December 2008

To examine whether lysosomal enzymes play a part in the involution of corpora lutea, cathepsin D was assayed in both the lysosomal fraction ('bound' cathepsin D) and the postlysosomal supernatant fluid ('free' enzyme), by measuring the increment in absorbance at 280 nm caused by acid-soluble material released from haemoglobin. From these data the release ratio (free: bound specific activity) was calculated. In corpora lutea on days 5 and 15 of pregnancy, the values for lysosome-bound specific activity (units of E280/h/mg protein) were 4·76 ± 0·51 and 5·00 ± 0·29 (s.e.m.), and the release ratios were 0·12 ± 0·02 and 0·11 ± 0·01 respectively. Similar values were obtained in newly formed corpora lutea of dioestrous and pro-oestrous rats, but on the day of oestrus the level of cathepsin D bound to lysosomes decreased to 2·66 ± 0·36 and the release ratio increased to 0·36± 0·03. On day 5 of prolactin-induced pseudopregnancy, the activities of cathepsin D in both cellular fractions resembled those of pregnancy. An even higher level of lysosome-bound cathepsin D (7·11 ± 0·47) with a relatively low level of free activity (release ratio 0·18 ± 0·02) was observed in lactating rats (day 7 of lactation), in the persistent corpora lutea of pregnancy. Administration of prostaglandin F2α (PGF2α) on days 4, 5 and 6 of lactation significantly decreased the level of lysosome-bound cathepsin D measured on day 7 in the persistent corpora lutea of pregnancy (3·81 ± 0·24) and increased the release ratio (0·40 ± 0·05). The intracellular distribution of acid phosphatase did not show a consistent relationship with the reproductive state. It appears that a decrease in the amount of lysosome-bound cathepsin D is associated with incipient luteolysis, that prolactin inhibits release of cathepsin D from the lysosomes and that PGF2α counteracts this action of prolactin.
INTRAOCULAR OVARIAN ISOGRAFTS IN MALE MICE AND THEIR RESPONSE TO HUMAN PLACENTAL LACTOGEN
Authors: TALAMANTES F. , GUZMAN R. , LOPEZ J.
Published: December 2008

Division of Natural Sciences and Oakes College, Thimann Laboratories, University of California, Santa Cruz, California 95064, U.S.A.

(Received 6 May 1977)

The luteotrophic activity of human placental lactogen (HPL) in non-primates was demonstrated by its ability to maintain the induced decidual reaction in hypophysectomized pseudopregnant rats (Josimovich, Atwood & Goss, 1963). In the mouse, HPL has been reported to induce hyperaemia of corpora lutea of ovulation in non-parous mice (Kavocic, 1968). However, because of the design of the study, it was not possible to determine the duration of hyperaemia in those HPL-induced corpora lutea.

Ovarian isografts in male mice develop mature follicles that only rarely luteinize spontaneously. Such follicles luteinize upon the administration of luteinizing hormone (LH) and the resultant corpora lutea only show hyperaemia of function if a luteotrophic hormone is then given (Browning, 1968). The present investigation was undertaken to examine the hyperaemic response of ovarian isografts in
CHANGES IN CATECHOLAMINE CONTENT OF THE MEDIAN EMINENCE PRECEDE THE PRO-OESTROUS SURGES OF LUTEINIZING HORMONE AND PROLACTIN
Authors: NEGRO-VILAR A. , CHIOCCHIO SARA R. , TRAMEZZANI J. H.
Published: December 2008

Instituto de Neurobiologia, Serrano 665, Buenos Aires, Argentina

(Received 9 June 1977)

Changes in the levels of catecholamines in the hypothalamus during the oestrous cycle have been reported by Donoso, Stefano & Biscardi (1966) and Stefano & Donoso (1967). Shaar & Clements (1974) found that lower concentrations of dopamine and noradrenaline than those found in the hypothalamus can inhibit the release of prolactin from the rat pituitary gland. We have studied the levels of noradrenaline and dopamine in the median eminence around the time of the spontaneous preovulatory release of hormones.

Adult female Holtzman rats showing at least three consecutive 4 day cycles, were killed by decapitation at 09.30, 13.00 and 17.30 h on the days of dioestrus I and pro-oestrus. After decapitation, blood was collected into centrifuge tubes and the brains were immediately removed and frozen on solid CO2. Serum was separated by centrifugation and stored at −20 °C
FAILURE OF NEUROHYPOPHYSIAL NEUROSECRETORY GRANULE LYSATE TO LIBERATE ARGININE-VASOPRESSIN FROM SYNTHETIC MODEL PROHORMONES SIMULATING COVALENT ATTACHMENT OF ARGININE-VASOPRESSIN TO NEUROPHYSIN
Authors: MOORE G. J. , SWANN R. W. , LEDERIS KARL
Published: December 2008

Division of Pharmacology and Therapeutics, Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada

(Received 13 June 1977)

Several lines of circumstantial evidence suggest that the neurohypophysial hormones may be biosynthesized in the form of larger peptides (prohormones) which are degraded to the free hormones during passage of the neurosecretory granules from the hypothalamus to the neurohypophysis (Vogt, 1953; Sachs & Takabatake, 1964; Pickering, Jones & Burford, 1971). Furthermore, it has been suggested that the hormone carrier proteins, the neurophysins, may at some stage in the biosynthesis, form part of the putative prohormones (Hope & Pickup, 1974).

In cattle, arginine-vasopressin (AVP) is associated with bovine neurophysin II (Dean, Hope & Kazič, 1968), the complete amino acid sequence of which has been elucidated by Schlesinger, Capra & Walter (1974) and Wuu & Crumm (1976). In the present study, two dodecapeptide analogues of AVP in which the peptide chain was elongated
EFFECTS OF TESTOSTERONE ON HEPATIC LIPID METABOLISM IN THE MATURE FEMALE DOMESTIC FOWL
Authors: PEARCE J.
Published: December 2008

Department of Agricultural and Food Chemistry, The Queen's University of Belfast, Newforge Lane, Belfast, BT9 5PX, and Department of Agriculture, Northern Ireland

(Received 1 July 1977)

Before the onset of egg laying in the domestic fowl, there are increases in the lipid content of the plasma and liver (Chaikoff, Lorenz & Entenman, 1941; Heald & Badman, 1963). These changes are the result of oestrogen secretion by the ovary (Sturkie, 1965). Hepatic lipogenic enzymes also increase in activity during the onset of sexual maturity and their specific activities are greater in the laying hen than in the mature cockerel (Pearce, 1971); similar changes in the activities of hepatic lipogenic enzymes have been observed in oestrogen-treated immature pullets (Balnave & Pearce, 1974). The synthesis of yolk proteins in the liver is also induced by the administration of oestrogen to immature pullets and cockerels (Gruber, 1972). The action of oestrogen is antagonized by
METABOLISM OF TESTOSTERONE IN THE ANTERIOR PITUITARY GLAND AND THE CENTRAL NERVOUS SYSTEM OF THE EUROPEAN STARLING (STURNUS VULGARIS)
Authors: MASSA R. , CRESTI L. , MARTINI L.
Published: December 2008

The metabolism of testosterone was studied in vitro in anterior pituitary, hypothalamic and hyperstriatal tissues taken from male European starlings in the autumn. In all the tissues studied, testosterone was converted into 5α-androstan-17β-ol-3-one (5α-DHT), 5β-androstan-17β-ol-3-one (5β-DHT), 5β-androstane-3α,17β-diol (5β-THT), 5β-androstane-3,-17-dione and androst-4-ene-3,17-dione.

The 5α-DHT was produced in significantly greater amounts by the pituitary gland than by the hypothalamus and hyperstriatum. The amount of 5α-DHT produced, however, was very low in comparison with the amounts of 5β-reduced metabolites. The amount of 5β-reductase was also higher in the pituitary gland than in the two nervous tissues. The ratios between the production of 5β-DHT, 5β-THT and 5β-androstane-3,17-dione were, however, different in the three tissues: 5β-DHT was produced in the greatest quantities by the hyperstriatum, while the production of 5β-THT, 5β-androstane-3,17-dione and androst-4-ene-3,17-dione was greatest in pituitary tissue.

The role of 5α- and 5β-reduced metabolites in the pituitary gland and in the brain of birds is unknown, but some possibilities arising from the present results are discussed.
FORMATION OF STEROID HORMONES IN VITRO BY DEVELOPING CORPORA LUTEA OF THE RABBIT
Authors: SUZUKI AKIRA , MORI TAKAHIDE , NISHIMURA TOSHIO
Published: December 2008

Rabbits were injected with human chorionic gonadotrophin (HCG), and slices of developing corpora lutea taken from the ovaries 15, 18, 24, 48, 72 and 96 h after injection were incubated with [1-14C]sodium acetate at 37 °C for 3 h. The incorporation of labelled acetate into ten steroids, including progestagens, androgens and oestrogens, was analysed.

In the initial step of corpus luteal formation, the specific incorporation (incorporation of [1-14C]acetate/100 mg tissue) increased sharply. The major steroidal products were progesterone, 17-hydroxyprogesterone and 20α-hydroxypregn-4-en-3-one. Between 18 and 48 h, the increase in specific incorporation was more gradual than in the initial step. Although the pattern was also dominated by progestagens, a temporary increase in the incorporation of acetate into androgens and oestrogens was observed. In the final step, a sharp rise in the total incorporation (incorporation of [1-14C]acetate/corpus luteum) was found, whereas the specific incorporation increased only slightly. The principal steroids produced were progesterone, pregnenolone and 20α-hydroxypregn-4-en-3-one. Incorporation into C19 steroids declined markedly and that into C18 steroids could not be detected. This profile of steroidogenesis 96 h after injection of HCG was similar to that of the corpus luteum in pregnancy.

Thus marked quantitative and qualitative changes have been demonstrated during the period of formation of corpora lutea in the rabbit.
PLASMA CALCITONIN LEVELS IN PREGNANT AND NEWBORN RATS
Authors: GAREL JEAN-MICHEL , JULLIENNE ANNICK
Published: December 2008

A radioimmunoassay for rat calcitonin was developed, which used a heterologous system that involved labelled human calcitonin, an antibody developed against purified human calcitonin and purified or synthetic rat calcitonin as a standard. The sensitivity of the assay was 0·3 ng rat calcitonin/ml plasma. The levels of calcitonin in the plasma of pregnant rats were studied in the last week of gestation and compared with the levels found in the plasma of control virgin female rats. The level of calcitonin in the plasma after 17·5 days of gestation was already higher than that in the control rats, it increased further up to 19·5 days and decreased at 21·5 days. Infusion of calcium into pregnant rats for 1 h after 21·5 days of gestation induced a sixfold increase in the level of calcitonin in the plasma after 30 min, and a threefold increase after 1 h.

The level of calcitonin in the plasma of fed and unfed newborn rats was measured 2, 6, 12 and 16 h after birth. At each stage, the concentration of calcitonin was higher in fed than in unfed animals. Stomach gavage of fat (triglycerides) in fasted rats born 2 h earlier stimulated secretion of calcitonin; administration of pentagastrin or glucagon had no effect on the level of calcitonin in the plasma. Subcutaneous injection of a calcium load to fasted newborn rats (2 hours old) increased the level of calcitonin in the plasma after 30 min.

These results demonstrate that during gestation calcitonin has a comparable role in rats to that already found in ruminants. They also substantiate the part played by the fat present in milk as a stimulus (through some unknown gastrointestinal hormones) for secretion of calcitonin during suckling, and the involvement of calcitonin secretion in the regulation of nutrient absorption in the newborn rat.
CONCENTRATION OF TRANSCORTIN IN THE PREGNANT RAT AND ITS FOETUSES
Authors: VAN BAELEN H. , VANDOREN G. , DE MOOR P.
Published: December 2008

The concentration of transcortin in serum from foetal, neonatal, pregnant and lactating rats was measured by a single radial immunodiffusion method. A decrease in transcortin concentration in sera from foetuses and pregnant rats occurred starting on days 19 and 20 of pregnancy respectively. A more pronounced fall in transcortin concentration in foetal and maternal serum was observed after treating pregnant rats with dexamethasone. These results suggest that corticosterone may be responsible for the observed changes in transcortin concentration.
PROGESTERONE METABOLISM IN THE FEMALE GORILLA
Authors: YOUNGLAI E. V. , COLLINS D. C. , GRAHAM C. E.
Published: December 2008

Department of Obstetrics and Gynecology, McMaster University Medical Centre, Hamilton, Ontario, Canada, L8S 4J9, *Department of Medicine, Emory School of Medicine, Atlanta, Georgia 30303, U.S.A. and †Yerkes Regional Primate Center, Atlanta, Georgia 30322, U.S.A.

(Received 26 April 1977)

It is becoming evident that rodents and rhesus monkeys are not suitable models for the study of all aspects of human reproductive endocrinology (Hobson, Coulston, Faiman, Winter & Reyes, 1976). Apes, on the other hand, closely resemble man in many aspects of their endocrinology (Graham, 1976). As part of a continuing study on progesterone metabolism among the great apes, we have found that the single most abundant urinary metabolite of progesterone is 5β-pregnane-3α,20α-diol (pregnanediol) in the adult female chimpanzee (YoungLai, Graham & Collins, 1975) and is similar to that in the immature chimpanzee (Romanoff, Grace, Sugarman & Pincus, 1963). This is in contrast to the macaques where androsterone is the major metabolite
PATHWAYS FOR THE BIOSYNTHESIS OF OESTRADIOL IN THE RABBIT OVARIAN FOLLICLE IN VITRO
Authors: PATWARDHAN V. V. , LANTHIER A.
Published: December 2008

Laboratoire d'Endocrinologie, Hópital-Notre-Dame et Département de Médecine, Université de Montréal, Montréal, Canada

(Received 8 June 1977)

In ovarian tissues, the synthesis of oestrogen from pregnenolone can proceed via progesterone and the 3-oxo-4-unsaturated steroid pathway or by way of dehydroisoandrosterone and the 5-unsaturated steroid pathway. In human ovaries, the follicle seems to prefer the 5-unsaturated pathway for formation of oestrogen (Ryan & Petro, 1966), whereas in the corpus luteum, the 4-unsaturated steroid pathway may be the only one that is operative (Ryan, 1963). The situation is not so clear in other species. In the rabbit, a reflex ovulator, ovarian follicles are known to secrete oestradiol (YoungLai, 1972). Furthermore, isolated follicles can form oestradiol, androgens and progesterone from endogenous (Mills, 1975) or exogenous (Mills & Savard, 1972) precursors in vitro. Mills & Savard (1972) incubated rabbit follicles with [1-14C]acetate and isolated labelled oestradiol and intermediates involved in the 4- and 5-unsaturated steroid
LEVELS OF TESTOSTERONE AND LUTEINIZING HORMONE IN THE PLASMA OF YOUNG POST-PUBERTAL BULLS AFTER INJECTION OF HUMAN CHORIONIC GONADOTROPHIN OR DEXAMETHASONE AND HUMAN CHORIONIC GONADOTROPHIN
Authors: THIBIER M. , ROLLAND O.
Published: December 2008

Institut National Agronomique Paris-Grignon, Centre de Grignon, Franceand *Laboratoire d'Hormonologie, U.N.C.E.L.A., 13 Rue Jouet, 94700 Maisons-Alfort, France

(Received 21 July 1977)

There is now very good evidence that in young or adult bulls, as in many species, the secretion of luteinizing hormone (LH) and testosterone is episodic (Katongole, Naftolin & Short, 1971; Thibier, 1975, 1976). Each individual discharge of LH can result in transient stimulation of the testes and hence in an associated increase in the level of testosterone. It has recently been shown that administration of dexamethasone dramatically reduces the level of testosterone in the plasma, with no fluctuations during the next 30h; simultaneously, the level of LH also tends to decrease (Thibier & Rolland, 1976). We have now examined the levels of testosterone and LH in the peripheral plasma of young post-pubertal bulls after treatment with human chorionic gonadotrophin (HCG) alone, or HCG and dexamethasone. Twelve French Friesian
CHARACTERIZATION AND ASSAY OF THE PROGESTERONE RECEPTOR IN RAT UTERINE NUCLEI
Authors: VU HAI M. T. , MILGROM E.
Published: December 2008

Rat uterine nuclei containing unlabelled progesterone–receptor complexes were incubated at 0 °C with the synthetic progestogen [3H]R5020 (17,21-dimethyl-19-norpregna-4,9-diene-3,20-dione). Complete exchange of steroid bound to the receptor was observed after 5–6 h. For longer times (up to 26 h) there was no further change in the concentration of steroid–receptor complexes, but the non-specific binding was increased. Saturation of nuclear receptors was obtained with a concentration of 5–10 nm-[3H]R5020. Competition with unlabelled steroids showed that only progestogens inhibited the binding of [3H]R5020 to nuclei. Optimum experimental conditions to reduce the non-specific binding to nuclei were established, and a method for the assay of nuclear progesterone–receptor complexes was devised, based on these characteristics. The concentration of nuclear receptors was low in oestradiol-primed ovariectomized rats; adrenalectomy gave rise to slightly lower values. Injection of the rats with progesterone resulted in a 5·5-fold increase in the number of nuclear receptors and a parallel decrease in the number of cytosol receptors. Similar injections of corticosterone and testosterone were without effect. Nuclear receptors were also shown to be stable in uteri kept in liquid nitrogen for up to 3 weeks. This assay may be used to study the correlation of a biological response to progesterone with the extent of receptor occupation in the nuclei.
EFFECTS OF OVARIECTOMY, PROGESTERONE AND OESTROGEN ON UTERINE CATECHOLAMINE CONCENTRATIONS IN RELATION TO PARTURITION IN RATS
Authors: MALTIER J. P. , CAVAILLÉ F.
Published: December 2008

In control rats, the concentrations of catecholamines in the uterus were markedly modified between days 21 and 22 of gestation, just before parturition; there was a considerable decrease in the concentration of adrenaline (−73%), whereas the level of noradrenaline increased significantly.

Of rats ovariectomized on day 19, 59% underwent abnormal parturition, and the uterine concentration of catecholamines remained constant; on day 22 of gestation, the concentration of adrenaline was twice as high as that in control rats. Injections of progesterone during late pregnancy resulted in prolonged pregnancies in 100% of those rats injected. Changes in the uterine concentrations of catecholamines observed in control rats did not take place in the injected animals, and on day 22 of gestation the concentration of adrenaline was three times that in control rats. Injections of oestrogen in late pregnancy advanced littering in rats which normally produced late litters. In the uterus, a considerable decrease in the concentration of adrenaline was observed and this was similar to that observed in control rats, except that the reduction occurred earlier.

Sham treatments (sham ovariectomies or injections of solvent in which oestrogen or progesterone were administered) had no effect on the timing of parturition or the uterine concentration of catecholamines, compared with control rats.

The concentration of adrenaline in the uteri of pregnant rats was controlled by steroid hormones and it seems that a very low concentration was required for normal parturition.
HYPOTHALAMIC PARAVENTRICULAR UNIT ACTIVITY DURING LABOUR IN THE RAT
Authors: BOER K. , NOLTEN J. W. L.
Published: December 2008

The spike activity of 191 antidromically identified paraventricular units was recorded during labour and the oestrous cycle of rats under urethane anaesthesia. Accelerated bursts of neuronal activity, as reported to occur during suckling, were not observed and changes in firing rate were not correlated with individual uterine contractions. There was, however, an increase in the magnitude of the mean spontaneous firing rate of antidromically identified neurosecretory cells during labour, as compared with all stages of the oestrous cycle. This increase was mainly caused by (1) a marked reduction (>25%) in the percentage of totally silent cells and (2) an increase in the magnitude of the mean firing rate of the phasically firing units (1·58–3·44 spikes/s).

It was concluded from these increases in spike activity that the tonic release of neurohypophysial hormones is stimulated during labour, and that this may contribute to the induction and course of labour.
LORDOSIS BEHAVIOUR IN IMMATURE MALE RATS
Authors: SÖDERSTEN P.
Published: December 2008

Lordosis behaviour was induced in immature 20-day-old male rats by sequential treatment with oestradiol benzoate (OB) and progesterone, but prepubertal male rats were behaviourally less sensitive to the OB and progesterone treatment than were female rats. Thus, the sex difference in the lordosis response was present early during development. Castration at various times after birth showed that the capacity of immature rats to show lordosis is normally inhibited by an action of testicular secretions exerted during the first 10 days of life. Treatment of day 0 castrated rats with OB, either as a single injection given on the day of birth or as daily injections given on the first 10 days after birth, was much more effective in inhibiting the display of lordosis behaviour at 30 and 37 days of age than was treatment with testosterone benzoate (TB). Treatment with dihydrotestosterone benzoate neonatally had no inhibitory effect. Treatment of intact male rats or day 0 castrated OB-or TB-treated rats with the anti-oestrogen ethamoxytriphetol (MER-25) during the first 10 days of life antagonized the inhibitory effect of the testes and of the OB or TB treatment on the development of the lordosis response. It is suggested that during normal development oestradiol formed in the brain from testosterone in the circulation acts during the first 10 days of life to inhibit the capacity of male rats to show lordosis when adult.
EFFECTS OF CASTRATION AND TESTOSTERONE, DIHYDROTESTOSTERONE OR OESTRADIOL REPLACEMENT TREATMENT IN NEONATAL RATS ON MOUNTING BEHAVIOUR IN THE ADULT
Authors: SÖDERSTEN P. , HANSEN S.
Published: December 2008

Castration of rats on the day of birth abolished the capacity to ejaculate and reduced the capacity to show intromissions in response to testosterone propionate (TP) treatment in adults. Day 10 castrated rats treated daily with oil or day 0 castrated rats treated daily with testosterone benzoate (TB) during the first 10 days of life achieved intromissions and ejaculation after TP treatment in adulthood. Treatment of day 0 castrated rats with a high dose of TB during the first 10 days of life enhanced their capacity to ejaculate in response to TP treatment in adulthood to a level above that of day 10 castrated rats given oil in infancy and similarly treated with TP as adults.

Castration on the day of birth greatly reduced the increase in penis weight and the development of cornified papillae on the glans penis which were seen in day 10 castrated rats after TP treatment in adulthood. These peripheral effects of neonatal testicular secretions are reversed by neonatal treatment of day 0 castrated rats with TB.

Daily treatment of day 0 castrated rats with dihydrotestosterone benzoate (DHTB) during the first 10 days of life facilitated the increase in weight of the penis and the development of cornified papillae on the glans penis but did not enhance the capacity to ejaculate in response to TP treatment in adulthood. Daily treatment of day 0 castrated rats with oestradiol benzoate (OB) during the first 10 days of life facilitated ejaculation without increasing penis sensitivity to TP in adulthood. Combined treatment of the neonate with OB and DHTB was no more effective in facilitating ejaculation in the adult than was OB alone. Neonatal treatment with OB was considerably more potent than neonatal treatment with TB in enhancing ejaculatory behaviour in adulthood.

It is suggested that both the inhibition of the development of lordosis behaviour and the facilitation of the development of mounting behaviour by testicular secretions in newborn rats may be dependent upon, but variously sensitive to, the amount of oestradiol formed in the brain from testosterone in the blood during the first 10 days of life.
EFFECTS OF INHIBITION OF ADRENAL STEROIDOGENESIS ON COMPENSATION OF FLUID LOSS AND ON SURVIVAL AFTER LIMB ISCHAEMIA IN THE RAT
Authors: BARTON R. N. , LITTLE R. A.
Published: December 2008

In rats injected with a specific inhibitor of adrenal steroidogenesis, 4α,5-epoxy-17β-hydroxy-3-oxo-5α-androstane-2α-carbonitrile (WIN 24 540), the increase in the concentration of corticosterone in the plasma caused by bilateral hind-limb ischaemia was greatly reduced. The lethality of this injury was increased. Fluid loss into the hind limbs was unaltered but the compensatory movement of fluid into the plasma was impaired. The hyperglycaemia that occurred after the injury was markedly reduced by WIN 24 540, but this was probably unrelated to the poorer compensation of fluid loss as there was no corresponding fall in plasma osmolality. The effects of injecting WIN 24 540 could be completely reversed by the simultaneous injection of corticosterone, so as to restore the rise in its concentration in the plasma. We conclude that the adrenal cortex plays an active part in the early circulatory and metabolic responses to injury, in contrast to its reportedly permissive role in the later catabolic phase.
METABOLISM OF ANDROSTENEDIONE IN SKIN AND SERUM LEVELS OF GONADOTROPHINS AND ANDROGENS IN PREPUBERTAL BOYS WITH HYPOSPADIAS
Authors: SVENSSON JAN , ENEROTH PETER , GUSTAFSSON JAN-ÅKE , RITZÉN MARTIN , STENBERG ÅKE
Published: December 2008

The metabolism of 4-[1,2-3H]androstene-3,17-dione in the prepuce, axillary skin and skin from the arm was investigated in 27 boys operated for phimosis (controls) and 13 unselected boys with hypospadias (a congenital defect of the male urethra). In all types of skin investigated, androstenedione was metabolized to 5α-androstane-3,17-dione, 3α-hydroxy-5α-androstan-17-one, 3β-hydroxy-5α-androstan-17-one and testosterone. Conversion to testosterone was found in the prepuce of two out of 11 boys with hypospadias.

Mild forms of hypospadias in the age group 1–4 years had a higher level of 5α-reductase activity in the prepuce than controls in the same age group (P < 0·05); no such differences were found in the few severe cases of hypospadias in this group. No other differences in 5α-reductase activity were found between hypospadic boys and controls. The ratio of 5α-reductase activity in the prepuce: 5α-reductase activity in skin from the arm was significantly higher (P<0·05) in hypospadic boys than in controls in the age group 1–4 years.

Serum levels of LH and FSH were the same in normal and hypospadic boys but the concentration of prolactin in the serum was lower in boys with hypospadias compared with control subjects in the age group 1–4 years (P<0·005). No differences were found in serum concentrations of androstenedione, testosterone, oestradiol and testosterone-binding globulin.
EFFECTS OF MATING AND INJECTION OF LUTEINIZING HORMONE RELEASING HORMONE ON SERUM LUTEINIZING HORMONE AND TESTOSTERONE CONCENTRATIONS IN RABBITS
Authors: BLAKE C. A. , BLAKE PATRICIA K. , THORNEYCROFT NANCY K. , THORNEYCROFT I. H.
Published: December 2008

The effects of coitus and injection of luteinizing hormone releasing hormone (LH-RH) on serum concentrations of LH, testosterone and dihydrotestosterone (17β-hydroxy-5α-androstan-3-one; DHT) were tested in male rabbits. Before experimentation, male and female rabbits were housed in individual cages in the same room. Male rabbits were then bled by cardiac puncture before and after placement with female rabbits or intravenous injection of LH-RH. Serum LH, testosterone and DHT were measured by radioimmunoassay. Sexual excitement (sniffing, chasing and mounting), with or without intromission, caused a marked rise in serum testosterone and DHT concentrations in only some of the bucks. These increases were accompanied or preceded by a small, transient increase in serum LH. In the rest of the bucks, sexual excitement with or without intromission had either no effect on serum levels of all three hormones, or only serum testosterone and DHT decreased during the collection period. Similar responses were measured in bucks which were housed in a room without does for 2–4 weeks before experimentation. Injection of 10, 30 or 100 ng or 50 μg LH-RH caused serum LH, testosterone and DHT to rise in all bucks tested, but the magnitude of the rises in serum testosterone and DHT were not related to the magnitude of the LH rise. In both mated and LH-RH-injected bucks, the rises in serum testosterone and DHT were greatest in animals with low initial testosterone and DHT values. Under the conditions of this study, the data suggest that: (1) serum testosterone and DHT rise in only some male rabbits after sexual excitement (with or without intromission), (2) the rises in serum testosterone and DHT are dependent on a small transient increase in serum LH and (3) sexual excitement is less likely to cause release of LH-RH in bucks with raised serum testosterone and DHT concentrations.
CORRELATION BETWEEN THE EFFECTS OF NEUROLEPTICS ON PROLACTIN RELEASE, MAMMARY STIMULATION AND THE VAGINAL CYCLE IN RATS
Authors: LOTZ W. , KRAUSE R.
Published: December 2008

The correlation between hyperprolactinaemia induced by the administration of neuroleptic drugs, disturbances of the vaginal cycle and mammary gland stimulation in rats was investigated as a test model simulating the clinical syndrome of hyperprolactinaemia and amenorrhoea with anovulation. In acute experiments in which clozapine, sulpiride and chlorpromazine were administered orally to rats of both sexes, there were rapid increases in the level of prolactin in the serum with peak values between 15 and 60 min. The responses of female rats to various doses of sulpiride were consistently higher than those of male rats. Hyperprolactinaemia induced by sulpiride in dioestrous rats failed to desensitize the ovaries to the ovulatory effect of exogenous luteinizing hormone releasing hormone. Studies of these substances and of metoclopramide, haloperidol and thioridazine were then carried out in female rats by daily oral administration over a period of 13 days. The increases in the level of prolactin in the serum were paralleled by disruption of the vaginal cycle up to and including constant dioestrus and by mammary gland stimulation which, like the preceding phenomena, showed dose-dependence. The potencies of these six neuroleptics, as estimated from their effects on the mammary gland, appeared to be haloperidol⪢ sulpiride ≥ metoclopramide = thioridazine > chlorpromazine > clozapine.
EFFECT OF ALDOSTERONE ON URINE COMPOSITION IN THE CHRONICALLY CANNULATED OVINE FOETUS
Authors: LINGWOOD BARBARA , HARDY K. J. , COGHLAN J. P. , WINTOUR E. MARELYN
Published: December 2008

* Department of Physiology, University of Melbourne, Parkville, Victoria 3052, Australia, † Department of Surgery, Austin Hospital, Studley Road, Heidelberg, Victoria 3084, Australia, and ‡ Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Parkville, Victoria 3052, Australia

(Received 19 October 1977)

Aldosterone is present in the peripheral blood of ovine foetuses from at least 60 days until term at 147 ± 5 days (Wintour, Brown, Denton, Hardy, McDougall, Oddie & Whipp, 1975). To determine the biological significance of this steroid in the foetus, infusions of aldosterone were made into foetuses bearing chronic vascular and bladder cannulae and the urinary sodium: potassium Na+: K+) ratio was measured before, during and after infusion. Silastic cannulae (0·76 mm internal diameter, 1·65 mm outer diameter) were placed 6–8 cm into the left carotid arteries and right jugular veins of seven ovine foetuses between 86 and 120 days of gestation and a