bluuebunny/crossref_metadata_2025_split huggingface dataset:
INFLUENCE OF REPRODUCTIVE STATE ON INTESTINAL FLUID AND ION TRANSPORT BY THE RAT JEJUNUM, IN RELATION TO THE POSSIBLE CONTRIBUTION OF PROLACTIN
Authors: MAINOYA J. R. 
Published: December 2008

SUMMARY
Mucosal fluid, sodium and chloride transfer by the rat jejunum was higher at pro-oestrus and oestrus than at dioestrus. Prolactin enhanced intestinal absorption in dioestrous but not in oestrous rats. Ovariectomy had no significant effect on fluid and sodium absorption but resulted in increased chloride absorption. Oestrogen treatment, however, stimulated fluid and sodium transport without affecting chloride absorption in ovariectomized rats. In contrast, progesterone had no influence on fluid and sodium transport but inhibited chloride absorption.
Intestinal absorption of fluid, sodium, chloride, potassium, calcium and magnesium was significantly increased during pregnancy and lactation. The limited effect of 2-Br-αergocryptine in depressing intestinal absorption of fluid and NaCl in both pregnant and lactating rats suggests that hormones other than prolactin are also involved. Lactating rats not suckled for 24 h, or subjected to reduction in the number of pups from eight to three, did not show major changes in intestinal absorption of fluid and NaCl.
The present data suggest that increases in intestinal transport during oestrus, pregnancy and lactation are attributable to hormonal changes to which prolactin may make an important contribution.
DEVELOPMENT OF A RADIOIMMUNOASSAY FOR α-MELANOCYTE-STIMULATING HORMONE IN THE RAT
Authors: THODY A. J. , PENNY R. J. , CLARK DEL , TAYLOR CHRISTINE 
Published: December 2008

SUMMARY
A sensitive and specific radioimmunoassay for α-melanocyte-stimulating hormone (α-MSH) was developed.
Extracts of the neurointermediate lobe of the rat produced displacement curves which were parallel to those obtained with synthetic α-MSH. The mean immunoreactive a-MSH concentration in neurointermediate lobes from normal adult rats was 2768 ± 200 (s.e.m.) ng/lobe. This accounted for approximately 78% of the MSH activity of the neurointermediate lobe as measured by bioassay. Much lower levels of immunoreactive α-MSH were found in the anterior lobe of the rat. Extracts of rat serum and plasma also contained immunoreactive α-MSH and the mean level was found to be 237 ± 20 pg/ml. This was slightly lower than the level measured in rat plasma by bioassay.
Increased levels of α-MSH were found in plasma of rats 1 and 3 h after a single injection of trifluoperazine and after 1·5 min of ether anaesthesia. These changes were reflected by decreases in the α-MSH content of the neurointermediate lobe.
PLASMA LUTEINIZING HORMONE AND TESTOSTERONE IN THE ADULT MALE PIG: 24 HOUR FLUCTUATIONS AND THE EFFECT OF COPULATION
Authors: ELLENDORFF F. , PARVIZI N. , POMERANTZ D. K. , HARTJEN A , KÖNIG A. , SMIDT D. , ELSAESSER F. 
Published: December 2008

SUMMARY
Secretory patterns of LH and testosterone were characterized in the intact male miniature pig. All blood samples were taken from indwelling catheters. Hourly sampling was carried out over 24 h and during a morning period blood was collected for 2 h at 10 min intervals. No significant difference was detected in the plasma LH concentration on the basis of hourly sampling. Plasma testosterone was significantly (P < 0·05) lower during the evening and night when compared with morning values.
The second experiment was concerned with the pattern of plasma LH and testosterone concentrations before and after copulation. Blood sampling was performed at 10 min intervals. Plasma LH was significantly (P < 0·001) raised for 30 min after copulation when compared with any 30 min period (0–120 min) before copulation. Plasma testosterone was not significantly altered for any 30 min period of the experiment (0–270 min). The data are interpreted as a possible mechanism for endocrine control of testicular function.
EFFECTS OF OESTRADIOL-17β, OESTRADIOL BENZOATE AND THE SYNTHETIC OESTROGEN RU 2858 ON SEXUAL DIFFERENTIATION IN THE NEONATAL FEMALE RAT
Authors: DOUGHTY CYNTHIA , BOOTH JANET E. , McDONALD P. G. , PARROTT R. F. 
Published: December 2008

SUMMARY
Groups of neonatal female rats were treated for the first 5 days of life with oestradiol-17β, oestradiol benzoate or a synthetic oestrogen, 11β-methoxy-17-ethynyl-1,3,5(10)-oestratriene-3,17β-diol (RU 2858), in daily doses ranging from 0·5 to 1000 ng. Oestradiol-17β had no effect on adult ovarian cyclicity or sexual receptivity after ovariectomy and oestrogen + progesterone treatment. Ovarian cyclicity was prevented by 100 ng or more oestradiol benzoate/day, and by all doses of RU 2858. Only rats receiving 50 ng oestradiol benzoate/ day or 0·5 ng RU 2858/day showed normal receptivity. The defeminizing action of RU 2858 was at least 100 times greater than that of oestradiol benzoate; it is suggested that this greater potency is due to the low affinity of RU 2858 for the oestradiol-binding protein in the plasma of neonatal rats. These results indicate that defeminization of the neonatal rat brain can be induced by physiological amounts of oestrogen, and are discussed with reference to the action of testosterone.
SUPPRESSION OF THE DEVELOPMENT OF FEMALE HAMSTER BEHAVIOUR BY IMPLANTS OF TESTOSTERONE AND NON-AROMATIZABLE ANDROGENS ADMINISTERED NEONATALLY
Authors: GERALL A. A. , McMURRAY MARCIA M. , FARRELL ALICE 
Published: December 2008

SUMMARY
Testosterone in its free form, and dihydrotestosterone (DHT) and androsterone, both androgens which are not aromatizable to oestrogen, injected in oil during the neonatal period have been reported not to modify the development of female sexual behaviour. This failure might be due to the short period of activity of these substances when injected in liquid vehicles. In the current study, a Silastic pellet containing 9% of its weight of testosterone, androsterone, or DHT was implanted subcutaneously in 42 female and 38 neonatally castrated male hamsters on day 2 of life and removed on day 10. Pellets of pure Silastic were implanted in 36 control animals. Males were gonadectomized on day 5 and females on day 45. Female sexual behaviour induced by oestradiol benzoate and progesterone was measured in a series of 10-min mating tests with vigorous males, starting at 55 days of age. The duration of lordosis was consistently reduced below control levels in females implanted with testosterone, DHT, and androsterone, and in males, with testosterone and DHT. Thus the free form of testosterone, and some non-aromatizable androgens, when present for a sufficiently long period after birth, can permanently suppress development of female reproductive behaviour.
BEHAVIOURAL RESPONSES TO SEX STEROIDS OF GONADECTOMIZED AND SEXUALLY REGRESSED QUAIL
Authors: ADKINS E. K. , NOCK B. 
Published: December 2008

SUMMARY
The purpose of these experiments was to compare the behavioural and morphological effects of exogenous sex hormones in gonadectomized quail (Coturnix coturnix japonica) with those in quail having regressed gonads as a result of exposure to short days. In Expt 1, male quail were assigned to one of three treatment groups: (1) intact, exposed to 16 h light:8 h darkness and injected with oil (group 16L); (2) gonadectomized, exposed to 16 h light:8 h darkness and injected with 2·5 mg testosterone propionate (TP)/day (group 16Lcastrated); and (3) intact, exposed to 8 h light:16 h darkness, and injected with 2·5 mg TP/day (group 8L). Groups 16L-castrated and 8L responded similarly to testosterone, copulating with equal frequency and rapidity after the same number of days of treatment, and also developing proctodeal (foam) glands of a similar size. Only on day 7 of testosterone treatment did the results for these two groups differ. By day 14, the behaviour of both groups resembled that of the 16L birds.
In Expt 2 female quail were assigned to the same three treatment groups, except that the hormone treatment was 25 μg oestradiol benzoate/day. Group 8L became sexually receptive sooner than the 16L-ovariectomized quail, but by day 13 both groups had oviducts of similar size, were equally receptive, and were as receptive as the 16L females.
The results suggest that the effects of photoperiod on sexual behaviour in this species are mediated largely, if not wholly, by the gonads. They also suggest that exposure to short days and surgical gonadectomy are rather similar experimental procedures in the quail.
ABSENCE OF AN IMMUNOLOGICALLY DISTINCT FOLLICLE-STIMULATING HORMONE RELEASING FACTOR IN RAT STALK MEDIAN EMINENCE EXTRACTS
Authors: SHAHMANESH M. , JEFFCOATE S. L. 
Published: December 2008

SUMMARY
Rat stalk median eminence (SME) extract was incubated with various quantities of an antiserum raised against synthetic luteinizing hormone releasing hormone (LH-RH) and the resulting material was used at two or more dose levels to stimulate release of LH and FSH from anterior pituitary tissue, obtained from male rats, incubated in vitro. The resulting dose–response lines were used to obtain the LH- and FSH-releasing potency of the material, expressed as a percentage of SME extract pre-incubated with normal rabbit serum. Treatment with various doses of antiserum reduced LH-releasing and FSH-releasing potencies to a similar extent.
Stalk median eminence extract and synthetic LH-RH were incubated with antiserum and directly compared in the same experiment in vitro. The changes in LH and FSH release caused by pre-treatment with antibody were similar for SME extract and synthetic LH-RH.
In a final experiment, SME extract was passed through a column of Sepharose 2B particles to which was coupled anti-LH-RH antibody. The resulting material, when mixed with synthetic LH-RH and used to stimulate rat pituitary tissue in vitro caused a similar increase in the LH- and FSH-releasing potencies of the synthetic decapeptide.
It is concluded that rat SME extract contains a single releasing factor for LH and FSH immunologically indistinguishable from synthetic LH-RH.
INCORPORATION OF RADIOACTIVE PRECURSORS INTO THE MEMBRANE AND CONTENTS OF THE NEUROSECRETORY GRANULES OF THE RAT NEUROHYPOPHYSIS AS A METHOD OF STUDYING THEIR FATE
Authors: SWANN R. W. , PICKERING B. T. 
Published: December 2008

SUMMARY
Rat neural lobes have been separated into subcellular fractions by differential centrifugation at various times after an intracisternal injection of [35S]cysteine or [3H]choline. Both isotopes led to a rise and fall in the radioactivity of neurosecretory granules (NSG) which paralleled that found previously for the neurohypophysial hormones and the neurophysins. While the radioactivity of the NSGs resulting from [35S]cysteine injection was predominantly associated with granular contents, [3H]choline injections led to a preferential labelling of the granular membrane. There was no indication of a sequential movement of radioactivity from the NSG-membrane fraction into the microsomal fraction (containing the so-called small vesicles) which might be expected if granular membrane were recaptured as small vesicles after release of secretory product by exocytosis. When release was stimulated in injected animals by giving them 2% NaCl solution to drink, 35S disappeared from the gland as expected, but 3H was retained and, moreover, appeared in the NSG-membrane fraction; results compatible with membrane conservation occurring by recapture of large vesicles. There was an indication that some of the neurophysin in the NSG was membrane-bound and that this too was retained after release of the granular contents.
STUDIES ON ANDROGEN TRANSPORT INTO CANINE PROSTATE IN VITRO
Authors: GIORGI ELEONORA P. 
Published: December 2008

SUMMARY
Slices from canine prostate were superfused with [17α-3H]testosterone and 5α-dihydro[1,2-3H]testosterone at 'physiological' concentrations; to some superfusions, either [3H]cyproterone or [3H]cyproterone acetate was also added. The following parameters were measured: 'uptake' of anti-androgen by the tissue, rate of entry of testosterone and 5αdihydrotestosterone into the tissue, rate of efflux from the tissue of 5α-dihydrotestosterone and concentration of 'diffusible' 5α-dihydrotestosterone in the slices. The adsorption of steroids on to the surface of the slices and the bulk flow of tritiated water into the slices were also investigated. It was concluded that these two factors did not interfere with the measurement of entry and efflux of the androgens. Cyproterone and cyproterone acetate were not metabolized, but were concentrated in the slices to many times the level in the medium. With rate of supply of anti-androgens up to 43 pmol/min, their uptake increased together with the rate of entry of the two androgens and the rate of efflux of 5α-dihydrotestosterone. At a higher rate of supply of anti-androgens, their uptake and the rates of entry and efflux of the androgens decreased sharply. In most cases, the inward movement of 5α-dihydrotestosterone into the slices took place against a negative concentration gradient, while that of testosterone always occurred down a positive concentration gradient. These results confirmed the hypothesis already put forward that 'carriers' involved in the transport of androgens are present in the membrane of prostatic cells (Giorgi, Moses, Grant, Scott & Sinclair, 1974).
Non-specific and specific intracellular binding, exhibiting greater affinity for 5α-dihydrotestosterone than for testosterone, was demonstrated in canine prostate by means of 'washing-out' experiments. On the basis of its affinity for androgens and the presence of inhibition by low concentrations of anti-androgen, intracellular binding seemed to be due to components distinct from the postulated membrane 'carriers'.
INTERACTION BETWEEN OESTROGEN AND GONADOTROPHIN-RELEASING HORMONE ON THE RELEASE AND SYNTHESIS OF LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE FROM INCUBATED PITUITARIES
Authors: APFELBAUM MARTA E. , TALEISNIK S. 
Published: December 2008

SUMMARY
The release and synthesis of LH and FSH were studied in adenohypophyses from ovariectomized rats incubated for a period of 4 h in flasks containing 1 ml Eagle's medium. One hemipituitary was used as the experimental gland and the other half served as a control. Glands from ovariectomized untreated animals showed a spontaneous release of LH and FSH and the amount of hormones released (per mg gland) by both the hemipituitaries was not significantly different. Also the content of the hormones at the end of the incubation period was similar in both halves.
Gonadotrophin-releasing hormone (Gn-RH) added to the incubation medium stimulated the release of LH and FSH. A dose–response relationship was obtained between doses of 0·51 and 8·00 ng/ml medium. Although lower doses were required to increase the release of LH, the amount of FSH released was higher when expressed as a percentage of gland content. Pituitary glands from ovariectomized rats treated with 5 μg oestradiol benzoate 24 h before being killed showed an increase in sensitivity to Gn-RH, but the response decreased when oestrogen was injected 2 h before death. Also the addition of oestradiol-17β to the incubation medium inhibited LH and FSH release induced by Gn-RH.
Gonadotrophin-releasing hormone increased the spontaneous synthesis of LH and FSH observed in the incubated pituitaries. This effect of Gn-RH was stimulated by the injection of oestrogen into the donor animals whereas administration of oestrogen into the medium enhanced the synthesis of LH and partially inhibited that of FSH.
These results provide evidence for a dual effect of oestrogen on the release of LH and FSH induced by Gn-RH. They also show that synthesis of gonadotrophic hormones was favoured by oestrogen or by increased gonadotrophin release.
APPLICATION OF AN IN-VITRO PERIFUSION TECHNIQUE TO STUDIES OF LUTEINIZING HORMONE RELEASE BY RAT ANTERIOR HEMI-PITUITARIES: SELF-POTENTIATION BY LUTEINIZING HORMONE RELEASING HORMONE
Authors: EDWARDSON J. A. , GILBERT D. 
Published: December 2008

SUMMARY
A technique is described for the continuous perifusion of rat adenohypophyses. Exposure of the perifused glands to repeated equal 5 min stimuli with hypothalamic extract resulted in a series of equal peaks of corticotrophin secretion, the response was proportional to log dose over the range 0·25–2·0 rat hypothalamic equivalents/ml. Repeated equal stimuli with hypothalamic extract, or with luteinizing hormone releasing hormone (LH-RH) at concentrations of 2 or 10 ng/ml, resulted in a progressively increasing series of peaks of LH secretion, i.e. a self-potentiating or priming effect. The effect took between 30 min and 1 h to develop. A delayed increase in the responsiveness of the glands was also seen with continuous incubation of anterior pituitaries with LH-RH. The relevance of these observations to the physiological control of LH secretion is discussed.
ABILITY OF VARIOUS FACTORS TO OPPOSE THE STIMULATORY EFFECT OF DIBUTYRYL CYCLIC AMP ON THE RELEASE OF MELANOCYTE-STIMULATING HORMONE BY THE RAT PITUITARY IN VITRO
Authors: BAKER BRIDGET I. 
Published: December 2008

SUMMARY
Various agents were tested for their ability to oppose the stimulatory effect of dibutyryl cyclic AMP on the release of the melanocyte-stimulating hormone from the rat neuro-intermediate lobe in vitro. Only dopamine exhibited an inhibitory effect; serotonin, γ-aminobutyric acid, tocinoic acid, tocinamide, the tripeptide Pro-Leu-Gly-NH2 and dibutyryl cyclic GMP were all ineffective.
TAMOXIFEN AS AN ANTI-TUMOUR AGENT: EFFECT ON OESTROGEN BINDING
Authors: JORDAN V. C. , DOWSE LYNNE J. 
Published: December 2008

SUMMARY
Tamoxifen (ICI 46,474) has been shown to possess anti-tumour properties in the dimethylbenz(a)anthracene (DMBA)-induced rat mammary carcinoma model. During tamoxifen therapy the binding of [3H]oestradiol in vivo to uterine (P < 0·001), vaginal (P < 0·01) and tumour (P < 0·001) tissues was significantly reduced. Tamoxifen therapy was without effect on the binding of [3H]oestradiol in heart tissue. The determination of specific oestrogen-binding components in vitro was significantly reduced (P < 0·01) in tumours from tamoxifen-treated rats and tamoxifen inhibited the binding of [3H]oestradiol to 8S oestrogen-binding components, derived from rat uteri and DMBA-induced tumours, in vitro.
TAMOXIFEN AS AN ANTI-TUMOUR AGENT: ROLE OF OESTRADIOL AND PROLACTIN
Authors: JORDAN V. C. , KOERNER S. 
Published: December 2008

SUMMARY
Four-day cyclic rats fed 7,12-dimethylbenz(a)anthracene (DMBA) (20 mg) at 50 days of age had peak prolactin, oestradiol and uterine wet weights at pro-oestrus. Tamoxifen (50, 200 and 800 μg daily), administered to ovariectomized rats, produced significant (P < 0·05) decreases in oestrogen-stimulated prolactin levels but was unable to reduce prolactin to control values. Tamoxifen (12·5, 50 and 200 μg daily) produced decreases in size in DMBAinduced rat mammary carcinomata in intact rats although some tumours did not respond to therapy. The ability of the pituitary to produce prolactin was not impaired. Decreases in uterine wet weights and peripheral oestradiol levels occurred during tamoxifen treatment.
CONTROL OF OESTROGEN PRODUCTION IN HUMAN PREGNANCY: EFFECT OF TROPHIC HORMONES ON STEROID BIOSYNTHESIS BY THE FOETAL ADRENAL GLAND IN VITRO
Authors: ISHERWOOD D. M. , OAKEY R. E. 
Published: December 2008

SUMMARY
[14C]Acetate was incorporated into dehydroepiandrosterone, pregnenolone and their sulphates and into cholesterol during incubations of adrenal tissue from three human foetuses of 10–18 weeks of gestation. No incorporation of [14C]acetate into cortisol or other 4-en-3-oxo steroids could be demonstrated.
Porcine ACTH stimulated the incorporation of [14C]acetate into both dehydroepiandrosterone sulphate and cholesterol when added to incubations of adrenal tissue from foetuses of 18 weeks gestation. Such an effect was not observed with tissue from a 10-week-old foetus. Stimulation of steroid biosynthesis from [14C]acetate was also achieved by addition of human growth hormone or human chorionic somato-mammotrophin.
These trophic hormones may therefore play some part in regulating the provision of precursors for oestrogen biosynthesis in pregnancy.
PROLACTIN INHIBITION TEST WITH l-DOPA: DECREASE AND RESTORATION OF PLASMA PROLACTIN LEVELS IN THE RAT BY A PERIPHERAL PROCESS
Authors: VAN DER GUGTEN A. A. , SAHULEKA P. C. , VAN GALEN G. H. , KWA H. G. 
Published: December 2008

SUMMARY
l-DOPA, within 30 min after administration, induced a highly significant decrease of plasma prolactin levels (phase 1) in a number of groups of rats, differing in age and/or endocrine status, apparently by direct inhibition of prolactin release from the pituitary. Three hours after administration of l-DOPA these low plasma prolactin concentrations in treated animals had increased (phase 2) and did not differ significantly from levels in control animals, indicating that the effect of l-DOPA on plasma prolactin levels is only of short duration. During this process some interesting phenomena were observed, especially in the animals treated with oestrone. The elimination rate of prolactin from plasma was very high (t½ = 2·8 min), as indicated by decreasing concentrations of the hormone during phase 1. Pituitary prolactin content did not change during phase 1, suggesting that prolactin synthesis was also stopped. Notwithstanding the high elimination rate, plasma prolactin regained initial concentrations in phase 2, suggesting release of a substantial part of the pituitary prolactin content. The latter, however, remained constant during the whole experiment (i.e. before l-DOPA administration and during phase 1 as well as phase 2).
The results suggested another working mechanism of l-DOPA in decreasing plasma prolactin levels, namely by stimulating the uptake of this hormone in the periphery. After the effect of l-DOPA had ceased, most of the prolactin from the periphery returned into the bloodstream, causing a rapid restoration of plasma prolactin levels without substantial release from the pituitary. The nature of the processes responsible for the peripheral uptake of prolactin is discussed.
PARTURITION IN THE GOAT: PLASMA CONCENTRATIONS OF PROSTAGLANDIN F AND STEROID HORMONES AND UTERINE ACTIVITY DURING LATE PREGNANCY AND PARTURITION
Authors: UMO I. , FITZPATRICK R. J. , WARD W. R. 
Published: December 2008

SUMMARY
Changes in plasma concentrations of hormones and uterine activity associated with spontaneous parturition in the goat were examined. No change in oestradiol-17β concentration was detected during the experimental period, but oestradiol-17α consistently increased in concentration 3–4 days before parturition. This was followed by an increase in prostaglandin F two days later, while a pre-partum decline in progesterone concentration occurred 18–20 h after the significant increase in prostaglandin F.
The onset of uterine contractions coincided with a significant decline in progesterone concentration and a period of continually rising prostaglandin F and oestradiol-17α concentrations. Uterine activity expressed in Montevideo units did not change until 10–8 h before foetal expulsion.
These results support the hypothesis that in the goat the elevated prepartum concentration of prostaglandin F brings about luteolysis and a subsequent decline in progesterone concentration.