bluuebunny/crossref_metadata_2025 huggingface dataset:
CHANGES IN THE WEIGHT OF THE ADRENAL GLANDS AND IN THE CONCENTRATION OF PLASMA CORTICOSTERONE IN PERINATAL RATS AFTER PRENATAL TREATMENT WITH OESTRADIOL BENZOATE
Authors: EGUCHI Y. , ARISHIMA K. , MORIKAWA Y. , HASHIMOTO Y.
Published: December 2008

On day 20 of gestation, foetal rats received a subcutaneous injection of 0·01 mg oestradiol benzoate dissolved in 0·05 ml sesame oil; foetuses in other litters were given sesame oil alone. Autopsy was performed on day 22 of gestation, at delivery or at various times after birth. Gravimetric and histological observations of the adrenals from oestradiol-treated, oil-treated and intact litter-mate control foetal and neonatal rats were performed together with determination of plasma corticosterone concentrations. Activity of 3β-ol dehydrogenase was also examined histochemically in the adrenals from these animals.

The results indicated that oestradiol benzoate when given prenatally prevented the neonatal decline of adrenal weight and adrenocortical cell size. In normal or oil-treated rats, plasma corticosterone concentration was greatly increased during delivery and 2 h after birth, declining up to 12 h after birth. Oestradiol benzoate prevented this perinatal increase and suppressed the activity of 3β-ol dehydrogenase in the perinatal adrenal cortices.
PLACENTAL LACTOGEN (CHORIONIC MAMMOTROPHIN) IN THE FIELD VOLE, MICROTUS AGRESTIS, AND THE BANK VOLE, CLETHRIONOMYS GLAREOLUS
Authors: FORSYTH ISABEL A. , BLAKE LAURA A.
Published: December 2008

Placental lactogen has been detected in the field vole, Microtus agrestis, and the bank vole, Clethrionomys glareolus, using a co-culture technique. In field voles this activity could be detected from about day 8 of pregnancy to shortly before term, and stimulated both mouse and vole mammary gland to secrete in vitro. Partial immunological cross-reaction was detected in a radioimmunoassay system between rat prolactin and either extracts of vole pituitaries or media on which vole pituitaries had been cultured; vole placental lactogen showed no cross-reaction with rat prolactin. One site of origin for this hormone is probably the trophoblastic giant cells.
EFFECT OF INTRA-UTERINE FOREIGN BODIES AND OF PROSTAGLANDIN ADMINISTRATION ON PROGESTERONE SECRETION DURING THE OESTROUS CYCLE OF THE GUINEA-PIG
Authors: BLATCHLEY F. R. , DONOVAN B. T.
Published: December 2008

The response of the guinea-pig corpus luteum to the luteolytic influence of glass beads placed in the uterus, or to prostaglandin administration, was followed by assay of the progesterone content of blood samples collected daily. Following the introduction of glass beads into the uterus early in the cycle, the secretion of progesterone was curtailed. Treatment with prostaglandin F2α over days 4–6 or 6–8 of the cycle temporarily depressed progesterone release without shortening the life of the corpora lutea. When the drug was administered over days 8–10, 10–12 or 12–14 the depression in progesterone was not followed by any recovery.

These observations indicate that the response of the corpora lutea to a luteolytic influence changes during the oestrous cycle.
RENIN, CORTISOL AND PLASMA VOLUME IN MARINE TELEOST FISHES ADAPTED TO DILUTE MEDIA
Authors: NISHIMURA HIROKO , SAWYER W. H. , NIGRELLI R. F.
Published: December 2008

The renin–angiotensin system has been found in teleost fishes from both marine and freshwater environments. In an attempt to define whether activity of the renin–angiotensin system is related to sodium balance in fishes, we transferred two euryhaline teleosts from seawater to hypo-osmotic media. Plasma renin activity decreased in American eels, Anguilla rostrata, after they were transferred from seawater to fresh water, and it did not change in the aglomerular toadfish, Opsanus tau, after transfer from 50% seawater to 5% seawater. Plasma sodium concentrations decreased significantly in toadfish in 5% seawater and in one group of eels in fresh water. Plasma levels of cortisol, a major mineralocorticoid in teleosts, and plasma volume, measured in eels, remained relatively constant. There are no clear correlations between plasma renin levels and those of plasma sodium or plasma cortisol. These results provide no evidence that the need of these fishes to conserve sodium when in hypo-osmotic media stimulates the renin–angiotensin system.
EFFECT OF A SKELETON PHOTOPERIOD ON THE DAYLENGTH-DEPENDENT RESPONSE TO OESTROGEN IN CANARIES (SERINUS CANARIUS)
Authors: STEEL ELIZABETH , HINDE R. A.
Published: December 2008

Previous studies have shown that ovariectomized canaries, injected with 50 μg oestradiol benzoate thrice weekly, show more oestrogen-induced nest-building on a long day than on a short day. In this study the same effect was obtained with castrated canaries.

The influence of time available for building was assessed first by comparing castrated males on skeleton long days with birds on short days, the total number of light hours being equal. More birds in the skeleton long-day group placed material in the nest, and did so with a shorter latency, than birds in the short-day group. Thus the differences between short- and long-day birds are unlikely to be due entirely to differences in the time available. However, some of the long-day birds were no more active than the short-day ones suggesting that the skeleton long-day schedule does impose some constraint.

In a third experiment photorefractory females (whose ovaries do not secrete oestrogen in response to long days) kept on a long skeleton-day scored similarly on all measures of building as birds kept on a full 14 h day and significantly more than birds on a short day.

The results also indicate that the birds are measuring daylength by means of a diurnal rhythm of photosensitivity, an effect comparable to that of longer photoperiods on gonadal growth.
ADVANCEMENT OF OVULATION IN THE GUINEA-PIG WITH EXOGENOUS PROGESTERONE AND RELATED EFFECTS ON LENGTH OF THE OESTROUS CYCLE AND LIFE SPAN OF THE CORPUS LUTEUM
Authors: JOSLYN W. D. , WALLEN K. , GOY R. W.
Published: December 2008

A single subcutaneous injection of progesterone (0·4 mg) was given to intact female guinea-pigs on either day 1, 7, 12, 13, 14, 15, or 16 of the behavioural oestrous cycle (day of oestrus is day 0). Injections given on either day 1 or day 7 had little effect, although there was a suggestion that injection on day 7 produced a lengthening of the cycle. Animals injected on either day 12 or day 13 underwent cycles of 16·9 and 18·1 days average length, respectively, which were significantly longer than the mean of 15·8 days for uninjected control females.

Injection of progesterone on days 14, 15, or 16 was associated with one of three distinct sequelae: (1) simple prolongation of the cycle associated with a return to spontaneous oestrus 4–7 days later; (2) advancement of ovulation, formation of abnormal corpora lutea, and return to spontaneous oestrus 9–13 days later, and (3) return to spontaneous oestrus 14–16 days after the progesterone injection. These findings suggest that progesterone can cause the release of ovulatory amounts of gonadotrophin following a period of endogenous oestrogen conditioning of the gonadotrophic system. If progesterone is administered before oestrogen conditioning is complete, then it inhibits or delays the conditioning process, and spontaneous oestrus and ovulation are postponed.
PRODUCTION OF ANTISERA AGAINST HIGHLY PURIFIED HUMAN FOLLICLE-STIMULATING HORMONE, LUTEINIZING HORMONE AND THYROID-STIMULATING HORMONE
Authors: THORELL J. I. , HOLMSTRÖM B.
Published: December 2008

Antisera were produced in rabbits against highly purified preparations of human LH (2000 or 10000 i.u./mg), human FSH (5500 i.u./mg), and human TSH (7·5 i.u./mg). Most rabbits produced antisera of high titre and high avidity. Cross-reactions were minimal between human TSH and human chorionic gonadotrophin (HCG) and between human FSH and HCG but marked between human LH and HCG. TSH and FSH also showed a constant but relatively weak cross-reaction. LH cross-reacted with FSH to a higher degree than did HCG. The avidity of the antisera was high. It was concluded that much of the lack of specificity recorded for glycoprotein antisera are effects of impure immunogens. Some of the true cross-reactions are probably explained by shared antigenic determinants of the β-subunits. Unadsorbed antisera could be used for assay of FSH and TSH in plasma from pregnant women.
IMMUNOREACTIVE LUTEINIZING HORMONE RELEASING FACTOR IN PITUITARY STALK BLOOD FROM FEMALE RATS: SEX STEROID MODULATION OF RESPONSE TO ELECTRICAL STIMULATION OF PREOPTIC AREA OR MEDIAN EMINENCE
Authors: SHERWOOD NANCY M. , CHIAPPA SHARON A. , FINK G.
Published: December 2008

The effects of sex steroid hormones on the responsiveness of the neural mechanism responsible for the secretion of LH-RF have been examined in the female rat. Responsiveness was determined at pro-oestrus by measuring the increments in immunoreactive LH-RF of pituitary stalk blood produced by electrical stimulation of the medial preoptic area or median eminence. Ovariectomy on the morning of dioestrus reduced the LH-RF response to preoptic stimulation while oestradiol benzoate (OB) or testosterone propionate (TP) administered immediately after ovariectomy significantly augmented the response. The facilitatory effect of TP was possibly due to its conversion to an aromatized derivative since 5α-dihydrotestosterone monobenzoate was ineffective. Progesterone did not facilitate preoptic responsiveness, and, when administered to animals ovariectomized at 12.00 h of pro-oestrus, reduced the LH-RF response at 18.00 h the same day. Stimulation of the median eminence produced a significantly greater increment in LH-RF than stimulation of the preoptic area. The facilitatory action of OB on the LH-RF response was less marked for median eminence compared with preoptic stimulation. The administration of ICI 46474 at 17.00 h of dioestrus did not reduce preoptic responsiveness on the morning of the next day, suggesting that this compound does not act as an 'antioestrogen' at the level of the preoptic area.
PROSTATIC DISTRIBUTION OF SEX HORMONE-BINDING GLOBULIN AND CORTISOL-BINDING GLOBULIN IN BENIGN HYPERPLASIA
Authors: COWAN R. A. , COWAN SHEILA K. , GILES C. A. , GRANT J. K.
Published: December 2008

Sex hormone-binding globulin-(SHBG) and cortisol-binding globulin-(CBG) like proteins have been demonstrated in prostatic tissue surgically removed from patients with benign prostatic hyperplasia. These proteins are not easily removed by superfusion of tissue slices. Epithelial tissue was separated from stroma and found not to contain the SHBG- or CBG-like proteins. Substantial amounts of these proteins, however, remained associated with the stroma. It is suggested that they may be constituents of interstitial fluid in this tissue compartment. The possible significance of this in benign prostatic hyperplasia is discussed.
PARATHYROID HORMONE AND EGGSHELL CALCIFICATION IN JAPANESE QUAIL
Authors: DACKE C. G.
Published: December 2008

The effect of parathyroid hormone (PTH) on egg-shell calcification has been investigated in egg-laying Japanese quail. Lilly parathyroid extract (PTE) when injected into quail within 2–6 h of oviposition caused a significantly increased deposition of a chronic 45Ca label into the sequential egg-shell compared with the previous egg in the clutch, indicating increased mobilization of bone Ca and its subsequent incorporation into the egg-shell. At the same time egg-shell weight/unit area and egg-shell Ca/unit area were significantly decreased. Parathyroid extract injected 12–16 h after oviposition had none of these effects. Purified PTH also caused a significant decrease in egg-shell weight/unit area if injected within 2–6 h of oviposition. This result indicated an action of PTH either directly or indirectly on the avian oviduct limiting egg-shell calcification. The loss of responses in the 12–16 h treated birds may reflect high endogenous PTH levels with subsequent saturation of target organ receptors.
DIURNAL VARIATION AND THE EPISODIC RELEASE OF PLASMA GONADOTROPHINS IN JAPANESE QUAIL DURING A PHOTOPERIODICALLY INDUCED GONADAL CYCLE
Authors: GLEDHILL B. , FOLLETT B. K.
Published: December 2008

Blood samples were taken every 3 h, over a 27 h period, from (1) a group of 12 intact male quail on short days (lights on 09.00–17.00 h) and during the 2nd, 15th and 36th day of photostimulation (lights on 09.00–05.00 h); (2) 12 castrated male quail on the 2nd, 20th and 43rd long day, and (3) 12 intact male quail on the 12th long day. Plasma LH was measured in all samples and FSH in the 43rd long day castrate and 12th long day intact male samples. Although there was considerable variation in the levels of LH and FSH, both between birds and between samples taken from the same bird, statistical analyses failed to reveal any diurnal (or circadian) rhythm at any time. There was a marked correlation between the LH and FSH levels in all samples.

Possible episodic LH secretion was investigated by taking blood samples every 15 min for between 3 and 6 h from six intact male quail and six laying females on long days. Samples were obtained from each bird at three time-periods which were arranged so as to overlap and cover the first 12 h of the daily photoperiod. Statistical analysis suggested that episodes of secretion occurred 6–10 times/day in males, and 4–8 times/day in females. The pulses appeared to occur at random.
EFFECT OF α-MELANOCYTE-STIMULATING HORMONE AND TESTOSTERONE ON CUTANEOUS AND MODIFIED SEBACEOUS GLANDS IN THE RAT
Authors: THODY A. J. , COOPER MARY F. , BOWDEN P. E. , MEDDIS D. , SHUSTER S.
Published: December 2008

The effects of α-MSH and testosterone propionate on sebum secretion, sebaceous gland volume, dermal lipogenesis, and preputial gland weight and lipogenesis were examined in hypophysectomized rats. Hypophysectomy reduced sebum secretion, sebaceous and preputial gland size, and dermal and preputial gland lipogenesis. The greatest effects were seen on the biosynthesis of wax esters and squalene. Testosterone propionate (TP) increased sebum secretion, sebaceous gland volume and preputial gland weight and lipogenic activity, but had no significant effect on the pattern of lipid labelling. α-MSH had no effect on sebaceous or preputial gland size, but increased sebum secretion and dermal lipogenesis, especially wax ester biosynthesis. When given together TP and α-MSH had a synergistic effect on sebum secretion and on dermal and preputial gland lipogenesis, and the pattern of lipid labelling was shifted towards normal. TP and α-MSH also showed synergism in increasing preputial gland weight, but together they had no greater effect on sebaceous gland volume than that achieved with TP alone.

These results suggest that TP and α-MSH have different actions on the sebaceous glands with α-MSH acting predominantly on lipogenesis and TP on cellular proliferation and turnover leading to an increase in gland size. Preputial glands differ from cutaneous sebaceous glands in their response to α-MSH and androgen which could be a reflection of their more specialized function.
CHANGES IN BRAIN, PITUITARY AND UTERINE CYTOPLASMIC OESTROGEN RECEPTORS INDUCED BY OESTRADIOL-17β IN THE OVARIECTOMIZED RAT
Authors: MORRIS I. D.
Published: December 2008

The oestrogen specific, high-affinity cytosol receptor (HAR) from amygdala, anterior, middle and posterior hypothalamus, pituitary and uterus was studied in the ovariectomized rat. A single in-vivo injection of oestradiol-17β produced significant changes in both the tissue HAR concentrations and the apparent dissociation constants (Kd) determined in vitro. Four hours after oestradiol-17β treatment (20 μg/kg), the HAR concentration was depleted in all tissues except the posterior hypothalamus. A lower dose of oestradiol-17β (4 μg/kg) produced similar changes in HAR concentration with the exception of those in the amygdala and posterior hypothalamus. Twenty-four hours after oestradiol-17β, HAR concentrations had returned to pre-injection levels in all tissues except the uterus. The uterine HAR concentrations were raised after both doses of oestradiol-17β. The apparent tissue cytosol Kd values were decreased by both doses of oestradiol-17β. The results suggest that brain, pituitary and uterine oestrogen cytosol HARs react to plasma oestrogen in a manner predictable by the steroid receptor hypothesis. The oestradiol-17β-induced differential effects upon the tissue cytosol concentration may contribute to the overall spectrum of action of oestrogen in the central and peripheral reproductive processes.
EFFECT OF ADRENERGIC BLOCKADE AND DEXAMETHASONE ON THE ALDOSTERONE RESPONSE TO BRAIN STIMULATION IN THE RHESUS MONKEY
Authors: JENKINS J. S. , FRANKEL R. J. , WRIGHT J. J. , KHAN M. U. A.
Published: December 2008

The increase in aldosterone and plasma renin activity (PRA) observed after stimulation of extrahypothalamic sites within the brain of the rhesus monkey was prevented by the prior administration of the β-adrenergic blocking agent propranolol. α-Adrenergic blockade by phentolamine had no inhibiting effect. Propranolol only partially reduced the response of aldosterone to lateral hypothalamic stimulation in spite of inhibition of PRA; a partial reduction in aldosterone was also obtained from this site after dexamethasone treatment without any effect on PRA. It was concluded that the increase in aldosterone observed after extra-hypothalamic stimulation was mediated mainly through the renin-angiotensin mechanism whereas in the case of the hypothalamus, release of ACTH was also a contributory factor.
ONSET OF OESTROGEN-INDUCED PROLACTIN SECRETION AND DNA SYNTHESIS BY THE RAT PITUITARY GLAND
Authors: JACOBI JOAN , LLOYD H. M. , MEARES J. D.
Published: December 2008

The times of onset of oestrogen-induced prolactin secretion and DNA synthesis were studied in the pituitary gland of the male rat. At intervals from 3 to 96 h after injection of 10 mg diethylstilboestrol dipropionate, serum and pituitary prolactin concentrations were measured by radioimmunoassay and pituitary DNA synthesis by incorporation of [3H]thymidine in vitro. Serum prolactin was raised significantly from 6 h onwards and DNA synthesis was increased from 30 h onwards. Pituitary prolactin concentration began to increase at 30 h. Significant correlations were obtained between serum prolactin and DNA synthesis from 24 to 72 h but not during the period of prolactin secretion from 6 to 24 h.
HORMONAL EFFECTS ON CANINE PROSTATIC EXPLANTS IN ORGAN CULTURE
Authors: SINOWATZ F. , PIERREPOINT C. G.
Published: December 2008

Explants of canine prostate were cultured in a defined medium for periods of up to 5 days with and without added steroids. Testosterone and 5α-dihydrotestosterone failed to maintain their histological integrity and induced a greatly increased formation of stromal elements. Epitestosterone and 5α-dihydroepitestosterone were partially successful in maintaining epithelial height although secretory activity was not preserved. The only steroid that sustained epithelial height and secretory activity whilst keeping stromal growth at a minimum was 5α-androstane-3α, 17α-diol. The three other epimeric androstanediols were ineffective.
LIGHT AND ELECTRON MICROSCOPIC STUDIES OF THYROTROPHIN RELEASING HORMONE-INDUCED GROWTH HORMONE AND PROLACTIN RELEASE IN HYPOPHYSECTOMIZED RATS BEARING AN ECTOPIC PITUITARY GLAND
Authors: ROSSI G. L. , PROBST DOROTHEA , PANERAI A. E. , GIL-AD IRIT , COCCHI DANIELA , MÜLLER E. E.
Published: December 2008

A light microscopic and ultrastructural study of anterior pituitary glands transplanted under the kidney capsule of hypophysectomized rats was performed, in basal conditions and after stimulation with thyrotrophin releasing hormone, at various intervals (24 h–2 months) after transplantation. Confirming previous biochemical findings, the results suggest that with time, somatotrophs acquire sensitivity to thyrotrophin releasing hormone and respond with increased exocytosis at doses that were found ineffective in pituitary glands in situ. Thryotrophin releasing hormone stimulation did not seem to influence the morphology of prolactin cells, which were already highly active under basal conditions at all time intervals.
EVIDENCE FOR DOPAMINERGIC CONTROL OF THYROTROPHIN SECRETION IN THE RAT
Authors: RANTA TAPIO , MÄNNISTÖ PEKKA , TUOMISTO JOUKO
Published: December 2008

The effects of two dopamine agonists (apomorphine and bromocriptine) and a dopamine antagonist (pimozide) on cold- or thyrotrophin releasing hormone (TRH)-induced TSH secretion were studied in normal male rats. Apomorphine given in various doses (0·5–10 mg/kg body wt) 10 min before exposure to cold significantly depressed TSH secretion. Large doses of bromocriptine (5–10 mg/kg body wt) given 1 h before exposure to cold, also blocked this response whereas a smaller dose (2·5 mg/kg body wt) given 30 min, 1, 3 or 6 h before cold exposure or repeated doses (0·1–2·5 mg/kg body wt) for 3 days did not modify cold-induced TSH secretion. Pimozide given in various doses (0·25–2·5 mg/kg body wt) 1 h before exposure to cold did not alter the cold response, but 2·5 mg/kg reversed the inhibition caused by apomorphine or bromocriptine. None of these drugs affected TRH-induced TSH secretion. These results suggest that there are no dopaminergic receptors on the pituitary thyrotrophs, but that dopamine might be an inhibitory transmitter in the brain involved in the regulation of TSH secretion in the rat.
THE HYPOTHALAMIC CENTRES INVOLVED IN THE CONTROL OF PRODUCTION AND RELEASE OF PROLACTIN IN SHEEP
Authors: WOLIŃSKA EWA , POLKOWSKA JOLANTA , DOMAŃSKI E.
Published: December 2008

Lesions made in the anterior medial basal hypothalamus (MBH) in pregnant or lactating ewes caused lack of development of the mammary gland and depressed milk yield, a decrease in plasma prolactin concentration and structural changes in the prolactin cells as manifested by a lack of the expected degranulation (lack of the hormone release) or by atrophic changes and diminished cell granulation (or granule synthesis). Lesions made in the caudal MBH during pregnancy advanced development of the mammary gland, induced a rapid increase in the plasma prolactin concentration and caused extensive degranulation of prolactin cells. These results indicate that at least two functional systems controlling the secretion and production of prolactin exist in the hypothalamus of sheep: an anterior system which is stimulatory and a caudal which is inhibitory.
PROSTAGLANDIN A2 AT LOW RATES OF INFUSION RESTORES THE ANTIDIURETIC EFFECT OF VASOPRESSIN IN LITHIUM-TREATED RATS
Authors: MTABAJI J. P. , ROBINSON C. J. , MANKU M. S. , CRONIN D. , HORROBIN D. F.
Published: December 2008

To test the effect of prostaglandin A2 (PGA2) on renal function, infusions of PGA2 (0·7 ng/ kg/min), arginine-vasopressin (AVP) (1·25 ng/kg/min) and PGA2 plus AVP were administered to male rats made resistant to the antidiuretic effect of AVP by pre-treatment with lithium. In non-lithium-treated control rats, AVP had its expected antidiuretic action but in lithium-treated rats neither urinary volume nor osmolarity was changed. Prostaglandin A2 alone had no effect on urine output in lithium-treated rats; AVP plus PGA2 infused together evoked a near normal antidiuretic response. This antidiuretic action of PGA2 contrasts with the diuretic action reported by others. However, our infusion rates were 300–4000 times lower than those of other workers and it is suggested that PGs may have opposite actions on the kidney depending on their concentration.

The effect of indomethacin (a blocker of prostaglandin synthesis) on urine flow was tested in five groups of rats on different régimes of liquid intake. Urine flow was reduced in the three groups with the highest urine volumes before treatment, and increased in the two groups with the lowest urinary volumes, again indicating that PGs may have both diuretic and antidiuretic actions.
EFFECTS OF LUTEINIZING HORMONE RELEASING HORMONE ON PLASMA FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE LEVELS IN THE FERRET
Authors: DONOVAN B. T. , TER HAAR M. B.
Published: December 2008

Heterologous radioimmunoassays for FSH and LH were employed to examine the effect of synthetic LH-RH upon gonadotrophin secretion in the ferret. Intravenous injection of 4 μg LH-RH induced a surge of FSH and of LH secretion in male and in female animals. In intact and in castrated males, the rise of LH was much more marked than that of FSH. The gonadotrophin response to LH-RH was greater in anoestrous than in oestrous females; FSH secretion was not enhanced during oestrus. Ovariectomized females behaved as anoestrous females with respect to LH secretion, while FSH secretion remained unchanged. Treatment of ovariectomized females with progesterone did not alter the pattern of response to LH-RH, but oestradiol treatment depressed the reaction to match that seen in oestrous females. Repetitive injections of LH-RH induced repetitive surges of FSH and LH in anoestrous females, but only of LH during oestrus: slow i.v. infusion of LH-RH induced a sustained elevation of plasma LH levels both in oestrous and in anoestrous females; again FSH levels rose only in anoestrous females. Injection of synthetic TRH did not alter gonadotrophin secretion in corresponding groups of male or female ferrets.
EARLY INCREASES IN RIBONUCLEIC ACID POLYMERASE ACTIVITIES OF DIMETHYLBENZANTHRACENE-INDUCED MAMMARY TUMOUR NUCLEI IN RESPONSE TO OESTRADIOL-17β AND TAMOXIFEN
Authors: NICHOLSON R. I. , DAVIES P. , GRIFFITHS K.
Published: December 2008

Studies on the mode of action of tamoxifen have shown that this compound ultimately causes regression of mammary tumours induced in female rats by 7,12-dimethylbenz(a)-anthracene, but induces preliminary effects similar to those produced by oestradiol-17β. Following a single intravenous injection of either substance, a sequence of events was observed which included depletion of cytoplasmic receptor, a concomitant increase in nuclear receptor and a subsequent replenishment of cytoplasmic receptor. Tamoxifen and oestradiol-17β induced a transient increase in RNA polymerase B activity, followed by increases in RNA polymerase A and, again, RNA polymerase B activity. Tamoxifen, unlike oestradiol-17β, could not maintain replenishment of cytoplasmic receptor, the increase in RNA polymerase A activity or the secondary rise in RNA polymerase B activity. The basic anti-oestrogenic properties of tamoxifen may be implicit in its inability to maintain oestrogenic stimulation, and may be linked to its retention time within the nuclei.
EFFECT OF CHRONIC ADMINISTRATION OF GONADOTROPHIN RELEASING HORMONE AND THYROTROPHIN RELEASING HORMONE TO PUBERTAL BULLS ON PLASMA LUTEINIZING HORMONE, PROLACTIN AND TESTOSTERONE CONCENTRATIONS, THE NUMBER OF EPIDIDYMAL SPERM AND BODY WEIGHT
Authors: HAYNES N. B. , HAFS H. D. , MANNS J. G.
Published: December 2008

The experiment was designed to determine whether chronic administration of gonadotrophin releasing hormone (GnRH) plus thyrotrophin releasing hormone (TRH) to pubertal bulls would hasten sexual maturation. Nine bulls, three each at 4, 5 and 6 months of age were given i.m. injections of GnRH (0·4 μg/kg) plus TRH (2 μg/kg) three times daily (09.00, 16.00 and 23.00 h) for 30 days. Equivalent animals were given 0·9% saline vehicle as controls. At the outset of injections the 6-, 5- and 4-month-old bulls weighed 201, 157 and 169 kg respectively; equivalent weights at the final injection were 222, 186 and 198 kg. Plasma levels of LH, prolactin and testosterone were determined weekly around the injection given at 09.00 h. Twenty-four-hour plasma testosterone and LH profiles were obtained immediately after the last injection. The animals were unilaterally castrated at the end of this 24 h period and the second testis was removed 60 days later to assess testicular weights and epididymal sperm numbers. Surges of LH, testosterone and prolactin occurred throughout the experimental period in response to GnRH/TRH injection. The LH surge in response to the first injection was nearly fivefold larger than those measured at subsequent weekly intervals but prolactin and testosterone responses did not decline during the 28-day experimental period. Induced LH and prolactin peaks were larger than those occurring in the control bulls, but control animals produced an equivalent amount of testosterone. These bulls produced quasi-adult levels of testosterone even at 4 months of age. Chronic GnRH/TRH administration resulted in a depression of plasma testosterone, and a disruption of the normal episodic release pattern during the 24 h after the final treatment, but normal patterns returned within 60 days. Testicular weights and epididymal sperm numbers were not increased by chronic GnRH/TRH treatment.
TWO-SITE ASSAY OF BOVINE PARATHYROID HORMONE
Authors: WOODHEAD J. S. , DAVIES S. JOYCE , LISTER D.
Published: December 2008

A two-site assay has been developed for bovine PTH. This technique involves reaction of the antigen with two antibody molecules with the purpose of increasing specificity. In practice the hormone was extracted from plasma samples on to plastic tubes coated with antibody specific for PTH (1–34). Uptake was then measured using 125I-labelled antibodies specific for PTH (53–84). In this way a sensitive assay was obtained for PTH (1–84) which did not recognize molecular fragments. This technique was used in conjunction with immunoradiometric assays specific for either NH2-terminal (1–34) or CO2H-terminal (53–84) molecular fragments to study the clearance of infused PTH in the cow. Preliminary results support the hypothesis that the intact molecule is rapidly degraded in the peripheral circulation with the preferential disappearance of an NH 2-terminal fragment. Studies on endogenous secretion during calcium and EDTA infusions indicated that there was little intact hormone present at the times when CO2H-terminal immunoreactivity was readily measured.
RELATIONSHIPS AMONG BIOASSAY, RADIOIMMUNOASSAY AND DISC ELECTROPHORETIC ASSAY METHODS OF MEASURING RAT PROLACTIN IN PITUITARY TISSUE AND INCUBATION MEDIUM
Authors: ASAWAROENGCHAI HANSA , NICOLL C. S.
Published: December 2008

Relationships among bioassay, radioimmunoassay (RIA) and disc electrophoretic assay methods of estimating rat prolactin in pituitary tissue and incubation medium were determined. Highly significant correlations were obtained between disc electrophoretic and RIA estimates of prolactin in tissue and between bioassay and RIA estimates of prolactin in medium. Less significant relationships were obtained between disc electrophoresis and RIA (medium) and between bioassay and disc electrophoresis (tissue and medium). The relationship between bioassay and RIA of prolactin in the incubated tissue was not significant.

Regression analysis disclosed the following: the RIA measured slightly more, and the bioassay detected substantially more prolactin in tissue and medium than did disc electrophoresis; the bioassay detected about five times more prolactin in medium than did the RIA. No significant relationships were found within or among the assays for depletion and release of prolactin. The results indicate that secreted prolactin has increased bioassay activity relative to its detectability by disc electrophoresis and RIA.
OVULATION IN PRENATALLY ANDROGENIZED EWES
Authors: CLARKE I. J. , SCARAMUZZI R. J. , SHORT R. V.
Published: December 2008

The ovarian activity of prenatally androgenized ewes was studied by measuring plasma progesterone concentrations in daily samples of peripheral blood, and by examining the ovaries at laparotomy.

Ewes that were exposed to testosterone between days 30 and 80, 50 and 100 or 70 and 120 of foetal life by implanting their mothers with 1 g testosterone, failed to show regular overt oestrous cycles, although some of them ovulated, whereas ewes exposed to testosterone between days 90 and 140 of foetal life had normal oestrous cycles. The incidence of ovulatory failure appeared to increase with age in ewes treated between days 50 and 100 or days 70 and 120 of foetal life.
EFFECT OF OESTRADIOL-17β EXPOSURE ON THE SPONTANEOUS SECRETION OF GONADOTROPHINS IN CHRONICALLY GONADECTOMIZED RATS
Authors: HENDERSON S. R. , BAKER CHRISTINE , FINK G.
Published: December 2008

The effect of oestradiol-17β (administered in Silastic capsules) on gonadotrophin secretion in long-term gonadectomized rats has been investigated. In female rats, a daily afternoon surge of LH occurred which could be blocked by administering sodium pentobarbitone at 13.00 h. This, together with the fact that there was no significant difference between the LH-response to LH-releasing factor in the morning compared with the afternoon, supports the view that the LH surges are due to a neural rhythm. There was no significant diurnal variation in plasma FSH concentration, but an apparent diurnal variation was disclosed by administering sodium pentobarbitone on alternate days. There was no diurnal variation in plasma gonadotrophin concentrations in male animals implanted with an oestradiol capsule, or in animals of either sex bearing empty capsules.
BINDING OF HUMAN CHORIONIC GONADOTROPHIN TO RAT OVARY DURING DEVELOPMENT
Authors: SIEBERS J. W. , PETERS F. , ZENZES MARIA TERESA , SCHMIDTKE J. , ENGEL W.
Published: December 2008

Ovarian tissue of prenatal, newborn, and 5-day-old rats does not specifically bind 125Ilabelled HCG. Specific binding of HCG was first observed in ovaries of 10-day-old animals and binding increased with age. These results indicate that, contrary to rat testis, the HCG receptor in the rat ovary is not present during foetal and early postnatal development. Thus, the insensitivity of the ovary to endogenous and exogenous LH or HCG during this developmental period is due to the lack of specific receptors.
IMPAIRMENT OF THE CONTROL OF GONADOTROPHIN SECRETION AFTER OESTROGEN ADMINISTRATION TO ADULT FEMALE RATS
Authors: BROWN-GRANT K. , TER HAAR M. B.
Published: December 2008

The possible occurrence of long-term changes in gonadotrophin control mechanisms following the administration of oestrogen to adult female rats has been studied. Administration of 2·5 mg oestradiol benzoate (OB) to normal female rats at 60 days of age did not result in failure of ovulation at 120 days of age but significant impairment of the LH and FSH responses to progesterone after ovariectomy and oestrogen priming was observed at 160–180 days of age. Treatment with the same dose of OB at 60 days of rats injected with 10 μg testosterone propionate on Day 4 of postnatal life resulted in an increased incidence of failure of ovulation at 120 though not at 150 days of age but did not further impair the already reduced gonadotrophin response to progesterone at 160–180 days of age. Removal of the ovaries at 60 days of age did not modify the effects of oestrogen given at 60 days of age in either group nor did ovariectomy at 60 days improve the response of neonatally androgen-treated rats to progesterone at 160–180 days of age. The increases in plasma prolactin and TSH levels in response to oestrogen priming after ovariectomy were not affected in any of the experimental groups.

The administration of a long-acting oestrogen preparation (oestradiol cyclopentyl propionate, 2·5 mg at 60 days of age) to normal female rats suppressed ovulation and depressed plasma LH and FSH concentrations for at least 90 days; anterior pituitary weights were greatly increased and plasma prolactin concentrations were very high.
PROGESTAGEN EFFECTS ON ELICITATION OF AGGRESSIVE BEHAVIOUR IN MALE MICE
Authors: SOARES M. J. , KALBERER W. D. , ERPINO M. J.
Published: December 2008

Effects of progesterone on production of androgen-dependent aggression-eliciting pheromones were investigated. Two groups of anosmic (non-fighting) castrated mice treated with testosterone or with testosterone and progesterone, respectively, were attacked to the same degree by intact, isolated (fighting) mice while control mice (castrated only) were attacked less. The findings support the idea that progesterone may inhibit androgen-induced aggression via a neural and not via a somatic mechanism.
ANALYSIS OF ANDROGEN-BINDING PROTEIN IN MEDIA FROM SERTOLI CELL INCUBATIONS AND CYTOSOLS FROM RAT TESTES
Authors: ROMMERTS F. F. G. , KRÜGER-SEWNARAIN B. Ch. , GROOTEGOED J. A. , VAN DER MOLEN H. J.
Published: December 2008

Binding ability of androgen-binding protein (ABP) in concentrated media from Sertoli cell cultures and in various preparations of cytosols from rat testicular tissue have been estimated using dialysis and polyacrylamide gel electrophoresis (PAGE). Equilibrium dialysis in the presence of 1 nm-17β-hydroxy-5α-androstan-3-one appears to be the most convenient and reliable method for estimation of ABP if no other binding proteins are present. PAGE can be applied for estimation of ABP in samples which also contain other steroid-binding proteins. Estimated binding activities in culture media measured by PAGE and dialysis were essentially similar. Binding of androgens to ABP estimated with PAGE in cytosols prepared after sonication of testicular tissue was much lower than in cytosols obtained after homogenization using a Potter–Elvehjem homogenizer. When ABP was added to cytosols prepared after sonication or homogenization, approximately 50 and 90% respectively of the original binding of androgens to ABP was recovered.
IN-VITRO STUDIES OF THE EFFECTS OF OESTROGEN PRETREATMENT ON THE SENSITIVITY OF THE IMMATURE FEMALE RAT PITUITARY GLAND TO STIMULATION WITH GONADOTROPHIN RELEASING HORMONE
Authors: WILKINSON M. , DE ZIEGLER D. , CASSARD DANIELLE , RUF K. B.
Published: December 2008

The effects of oestrogen priming on the sensitivity of the anterior pituitary gland to stimulation with gonadotrophin releasing hormone (GnRH) was investigated in immature female rats using a new organ culture technique. Hemipituitary glands obtained from animals primed with a single dose of oestradiol benzoate (OB; 20 μg/100 g body weight) released significantly more LH when pulsed with GnRH (4 nmol/l) than did control hemipituitary glands. This potentiating effect was detectable as early as 5 days after birth. After a second stimulation, LH secretion remained high. These results were compared with those obtained from animals treated to induce increased levels of endogenous oestrogen on day 26 of life. Thus, hemipituitary glands were obtained from animals given two injections of OB, an injection of pregnant mare serum gonadotrophin (PMSG) or a unilateral brain lesion placed in the basal hypothalamus. Pituitary tissue was stimulated as before with a pulse of GnRH. Two injections of OB enhanced the sensitivity to stimulation. Conversely, both PMSG and lesion treatment severely reduced the sensitivity to GnRH, although PMSG-treated and lesioned animals have been used as models for the study of ovulation.
EFFECT OF NEONATAL ANDROGENIZATION ON LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE, PROLACTIN AND TESTOSTERONE LEVELS IN MALE RATS
Authors: MOGUILEVSKY J. A. , SCACCHI P. , RUBINSTEIN L.
Published: December 2008

Department of Neuroendocrinology, Centro de Investigaciones Médicas Albert Einstein (CIMAE), Luis Viale 2831, Buenos Aires, Argentina and *Department of Obstetrics and Gynecology, UCLA School of Medicine, Los Angeles, California, U.S.A.

(Received 18 January 1977)

It is generally accepted that the administration of androgens to female rats in the neonatal period suppresses cyclic gonadotrophin release and a tonic gonadotrophin release occurs (Barraclough, 1966; Gorski, 1971). The tonic or male gonadotrophin pattern characteristically shows higher levels of plasma and pituitary follicle-stimulating hormone (FSH) and serum prolactin compared with female rats (Johnson, 1967, 1971; Kragt & Ganong, 1968; Neill, 1972).

In spite of the fact that the neonatal administration of androgens also induces changes in the reproductive physiology of adult male rats (Johnson & Witscht, 1963; Johnson, Yasuda & Sridharan, 1964; Morrison & Johnson, 1966), the effect of androgenization on gonadotrophin secretion in this sex is not clear.

The purpose of the present study
EFFECT OF THE HOST HORMONAL STATUS ON DEVELOPMENT OF SUCRASE AND ACID β-GALACTOSIDASE IN ISOGRAFTS OF RAT SMALL INTESTINE
Authors: KENDALL KEVIN , JUMAWAN JOCELYN , KOLDOVSKY OTAKAR , KRULICH LADISLAV
Published: December 2008

Division of Biochemical Development and Molecular Diseases, Joseph Stokes, Jr Research Institute, Children's Hospital of Philadelphia and the Department of Pediatrics, Medical School of the University of Pennsylvania, Philadelphia, Pennsylvania 19104, U.S.A. and *Department of Physiology, University of Texas Southwestern Medical School, Dallas, Texas 75275, U.S.A.

(Received 6 January 1977)

It has been shown that diet and endocrine regulation are two factors influencing perinatal development of various intestinal enzymes (e.g. Koldovsky, 1972; Koldovsky, Jumawan & Palmieri, 1975; Yeh & Moog, 1975). So far, most studies have been performed in vivo; studies using organ cultures are hampered by the short viability of the preparations (Trier, 1976). Ferguson, Gerskowitch & Russell (1973) introduced an ingenious method of implanting under the kidney capsula of adult mice isografts of foetal small intestine, and these developed in a similar manner to normal intestine in situ. Since the isografts were never exposed to external stimuli (food, etc.),
SPECIFIC BINDING OF PROLACTIN TO SEMINAL VESICLE, PROSTATE AND TESTICULAR HOMOGENATES OF IMMATURE, MATURE AND AGED RATS
Authors: BARKEY R. J. , SHANI J. , AMIT T. , BARZILAI D.
Published: December 2008

Ovine prolactin was iodinated by the lactoperoxidase method and purified by gel filtration on Sephadex G-100. The binding ability of the labelled hormone was determined, by incubation with liver homogenate from rabbits in late pregnancy, to be 8·8% total binding/ mg protein, of which 86% was specific. The fraction of 125I-labelled ovine prolactin which bound most strongly was subsequently used to study its binding to rat seminal vesicle, prostate and testicular homogenates. The total binding to the seminal vesicle homogenate taken from mature (80-day-old) rats was the highest (11·69%/mg protein), but the greatest degree of binding specificity (82·6%) was to immature (30-day-old) rat prostate. Both total and specific binding to rat testicular homogenate were consistently very low. The binding specificity was demonstrated by displacement studies: while ovine prolactin caused displacement of specific binding, human chorionic gonadotrophin, rat thyrotrophin and human follicle-stimulating hormone did not cause any significant displacement of bound 125I-labelled ovine prolactin. Affinity constants (Ka) and binding capacities for the seminal vesicle and prostate homogenates were determined by Scatchard analysis and the effect of age on these parameters was studied. There was no difference in Ka between the aged (220-day-old), immature and mature rat tissue homogenates; however, a significant fall in binding capacity was observed in the mature rat prostate, and a further fall in the aged rat prostate. No such change was observed in the binding capacity of the seminal vesicle, as estimated by Scatchard analysis, although total and specific binding to the mature homogenates was higher than that of the other age groups.
CAPILLARY BLOOD FLOW IN THE GENITAL TRACTS OF CONSCIOUS EWES: CYCLIC CHANGES AND THE EFFECT OF OVARIAN HORMONES
Authors: BROWN B. W. , MATTNER P. E.
Published: December 2008

The indicator fractionation technique with [86Rb]rubidium chloride as the indicator was used in conscious animals to determine the relative blood flow (RBF) as a measure of capillary blood flow in regions of the genital tract of cyclic ewes and of hormonally treated ovariectomized ewes. The RBF values in the ampulla, isthmus, uterus and cervix of cyclic ewes were markedly raised at pro-oestrus and declined thereafter to low levels during the remainder of the oestrous cycle. On Day 4 a small secondary rise in flow occurred in the ampulla and isthmus.

In ovariectomized ewes, oestradiol induced high levels of RBF in the ampulla, isthmus, uterus and cervix whether the animals had been treated previously with progesterone or given concurrent small doses of progesterone. Though progesterone given alone caused a significant rise in RBF in the uterus, this effect appeared to be one occurring only during active re-growth of regressed tracts.

The findings are discussed in relation to oestradiol inducing a stimulatory effect on RBF in the genital tract of the ewe around oestrus but not at Days 3–4 of the oestrous cycle.
SENSITIVITY OF ANTERIOR HYPOTHALAMIC AREAS TO GONADAL STEROID IMPLANTATION IN ANDROGENIZED FEMALE RATS
Authors: DANGUY A. , PASTEELS J. L. , ECTORS F.
Published: December 2008

A single injection of 1 mg of a complex of testosterone esters on day 5 of life was used to prepare constantly oestrous rats. Such androgenized female rats were then ovariectomized and submitted to stereotaxical implantation of 1 μg oestradiol benzoate, 5 μg testosterone isobutyrate or, as a control, 10 μg cholesterol in the anterior hypothalamic areas. The effects of the steroids on plasma and pituitary FSH and LH were assessed by radioimmunoassay. As reported previously by us in normal female and male rats, the preoptic–suprachiasmatic area (POA) was able to control synthesis and secretion of both gonadotrophins and did not lose its sensitivity to oestradiol and testosterone in androgenized rats. Evidence for enhanced prolactin secretion in androgenized rats was derived from immunofluorescence studies of the pituitary gland and from histology of the mammary glands. In this respect the condition of the androgenized females was opposite to that of the males. The present work demonstrated that stimulation of prolactin secretion in androgenized female rats resulted from oestrogen action due to permanent oestrus rather than from impairment of hypothalamo-hypophysial relationships. Indeed, prolactin stimulation was suppressed when the androgenized rats were ovariectomized and restored when they were subsequently implanted with oestradiol in the POA.
PHOTOPERIODIC CONTROL OF GONADOTROPHIN SECRETION IN THE RAM: A DETAILED STUDY OF THE TEMPORAL CHANGES IN PLASMA LEVELS OF FOLLICLE-STIMULATING HORMONE, LUTEINIZING HORMONE AND TESTOSTERONE FOLLOWING AN ABRUPT SWITCH FROM LONG TO SHORT DAYS
Authors: LINCOLN G. A. , PEET M. J.
Published: December 2008

Six adult Soay rams were housed under artificial lighting conditions of long days (16 h light: 8 h darkness) for 4 months and this caused the animals to lapse into a state of reproductive quiescence with low levels of gonadotrophins in the circulation and regressed testes secreting very low amounts of testosterone. The photoperiod was changed abruptly to short days (8 h light: 16 h darkness) to induce a resurgence of sexual activity, and a detailed study was made of the pituitary and testicular responses over the first 100 days.

Plasma levels of LH and FSH first began to increase between days 6 and 12 of short days, and rose progressively until days 33–54 before declining again. Testicular growth of the rams began on days 19–26 and continued for most of the remaining period of study. Plasma testosterone levels rose in parallel with the growth of the testes, and were greatly increased by day 100 when gonadotrophin levels were reduced.

At most stages there were short-term fluctuations in the plasma levels of FSH, LH and testosterone indicative of episodic secretion. Peaks in plasma levels of LH were especially conspicuous and from the changes in frequency and amplitude of these peaks it was possible to predict the way in which photoperiod influenced gonadotrophin secretion by its effect on hypothalamic LH-RH secretion. A slight 24 h rhythm in the plasma levels of all three hormones was observed, and the significance of this in relation to the photoperiodic response is discussed.