bluuebunny/crossref_metadata_2025_split huggingface dataset:
DEVELOPMENT AND APPLICATION OF HOMOLOGOUS RADIOIMMUNOASSAYS FOR PORCINE GONADOTROPHINS
Authors: VANDALEM J. L. , BODART CH. , PIRENS G. , CLOSSET J. , HENNEN G. 
Published: December 2008

Antisera were raised against highly purified preparations of porcine luteinizing hormone (pLH) and follicle-stimulating hormone (pFSH). Highly specific and sensitive radioimmunoassay systems were developed.
The antisera to LH and FSH were used at working dilutions of 1: 500 000 and 1: 200 000 respectively and the sensitivities of the assays were 0·1 ng LH/ml serum (3 × 10−12 mol/l) and 0·5 ng FSH/ml serum (1·5 × 10−11 mol/l). The LH and FSH preparations used as standards were 1·2 and 81 times as potent as NIH-LH-S15 and NIH-FSH-P1 respectively. Both assays were validated and adapted for the measurement of the gonadotrophin content of porcine serum.
The concentrations of LH and FSH in blood were measured simultaneously in prepubertal sows throughout a 24 h period, in adult sows during the oestrous cycle and in both prepubertal and adult animals after treatment with LH releasing hormone.
EFFECT OF CARBENOXOLONE ON THE CONCENTRATIONS OF ALDOSTERONE IN RAT PLASMA AND KIDNEY
Authors: HUMPHREY M. J. , LINDUP W. E. , CHAKRABORTY J. , PARKE D. V. 
Published: December 2008

The renal subcellular distribution of various subcutaneous doses (10−10–10−8 mol) of [3H]aldosterone has been investigated in adrenalectomized rats pretreated with carbenoxolone.
Carbenoxolone increased the concentration of plasma [3H]aldosterone, but the uptake of [3H]aldosterone into the kidney nuclear and cytosol fractions was decreased. Pretreatment of rats with carbenoxolone at low doses of aldosterone (0·4 × 10−10 and 1·5 × 10−10 mol) decreased both the amount of [3H]aldosterone bound to the 50% (NH4)2SO4 precipitate, and that present in the supernatant fraction, of a Tris–CaCl2 extract of the kidney nuclear fraction. Carbenoxolone also decreased the rate of biliary excretion of metabolites of aldosterone.
When [3H]aldosterone and carbenoxolone were incubated with Tris–CaCl2 extracts of a kidney nuclear fraction in vitro, the carbenoxolone did not decrease the [3H]aldosterone bound to the 50% (NH4)2SO4 precipitate, although the [3H]aldosterone bound to the 50% (NH4)2SO4 supernatant was significantly decreased by carbenoxolone at concentrations known to occur in the kidney in vivo.
These results indicate that displacement of aldosterone from binding sites, with a concomitant potential increase in the amount of hormone available to specific receptors may be part of the mechanism by which carbenoxolone potentiates aldosterone action in toad skin in vitro. However, in rat kidney, such a mechanism is unlikely to play a significant role in the manifestation by carbenoxolone of aldosterone-like effects. Data are presented to indicate that carbenoxolone may affect the normal distribution and metabolism of aldosterone, and it is possible that potentiation of aldosterone action may involve receptors in other tissues, such as the gastrointestinal tract which is the major site of action of carbenoxolone.
POSSIBLE PRIMING EFFECT OF LUTEINIZING HORMONE RELEASING HORMONE ON THE ANTERIOR PITUITARY GLAND IN THE JAPANESE QUAIL AND THE STIMULATION OF SECRETION OF FOLLICLE-STIMULATING HORMONE
Authors: DAVIES D. T. , COLLINS J. 
Published: December 2008

SUMMARY
After the i.m. injection of 10 μg synthetic LH releasing hormone (LH-RH) into Japanese quail the levels of LH and FSH in plasma rose significantly within 2 min. The increased level of LH declined rapidly but that of FSH was maintained for the duration of the experiment. To determine whether the anterior pituitary gland is primed by LH-RH a double injection schedule was adopted. It would appear that, while endogenous LH-RH may prime the avian pituitary gland slightly, synthetic LH-RH is ineffective.
ADRENOCORTICAL FUNCTION IN A FIELD POPULATION OF A MACROPODID MARSUPIAL (SETONIX BRACHYURUS, QUOY AND GAIMARD)
Authors: MILLER T. , BRADSHAW S. D. 
Published: December 2008

SUMMARY
Concentrations of corticosteroids and aldosterone have been measured in the plasma and related to the maximum cortisol binding capacity, to the concentration of sodium and potassium of the plasma and to the condition of the animals, in a natural population of the quokka (Setonix brachyurus, Quoy & Gaimard) on Rottnest Island, Western Australia. A marked population in one area has been repetitively sampled at approximately 6 week intervals over a period of 2 years. Animals were found to be in significantly better condition during the hot–dry season. Their plasma concentrations of corticosteroids, 1·09 ± 0·11 (s.e.m.) and 1·47 ± 0·14 μg/100 ml and their plasma sodium concentrations, 147 ± 0·87 and 142 ± 1·17 mequiv./l, for the hot–dry and cold–wet seasons respectively, were both significantly different (P < 0·05). Plasma concentrations of aldosterone were 8·40 ± 0·57 and 7·06 ± 0·53 ng/100 ml for the hot–dry and cold–wet seasons. The level of aldosterone fell to levels comparable to those found in salt-replete laboratory animals only during the month of July.
In the laboratory, salt deprivation resulted in a significant rise in the concentration of plasma aldosterone, 2·33 ± 0·57 (s.e.m.) ng/100 ml when salt-replete and 16·95 ± 2·74 ng/ 100 ml when salt-deprived (P< 0·001). Total plasma corticosteroid levels were unaffected by changes in the sodium content of the diet.
Injections of ACTH at a rate of 2 i.u./kg caused a significant rise in the levels of plasma corticosteroids which were essentially identical in both high- and low-condition animals. Body temperature fell to a significantly lower level in low-condition animals held in cages after injection of ACTH. These results indicate that the seasonal mortality of the quokka on Rottnest Island does not result from any breakdown in adrenal function, despite a substantial decline in the condition of the animals.
PROLONGED INTRAVENOUS INFUSION OF LABELLED IODOCOMPOUNDS IN THE RAT: [125I]IODIDE METABOLISM AND EFFECTS OF MODERATE DIETARY IODINE DEFICIENCY
Authors: BOONNAMSIRI VIPA , KERMODE J. C. , THOMPSON B. D. 
Published: December 2008

SUMMARY
Radio-iodide was administered by prolonged continuous intravenous infusion to rats maintained under iodine-replete conditions and in moderate iodine deficiency. A close approximation to equilibrium labelling was thereby achieved. Labelled iodocompounds extracted from various tissues were analysed by thin-layer chromatography.
Moderate iodine deficiency resulted in a slight increase in the ratio of mono-iodotyrosine to di-iodotyrosine in the thyroid. No change in the ratio of tri-iodothyronine (T3) to thyroxine (T4) was found in thyroid, plasma or skeletal muscle. Faecal excretion of T3 declined appreciably relative to that of T4.
Under iodine-replete conditions the ratio of thyroidal secretion rates of T3 and T4 was estimated to be more than three times higher than the ratio of these iodocompounds within the thyroid. Heterogeneity of thyroglobulin structure and function may explain these observations.
INFLUENCE OF THE PINEAL GLAND, OLFACTORY BULBS AND PHOTOPERIOD ON SURGES OF PLASMA PROLACTIN IN THE FEMALE RAT
Authors: PIEPER D. R. , GALA R. R. 
Published: December 2008

SUMMARY
The role of the pineal gland, olfactory bulbs and photoperiod in the regulation of the two daily surges of plasma prolactin in the pseudopregnant rat has been investigated. Pinealectomy had no effect on the surges of prolactin in pseudopregnant rats maintained on either a long (14 h light: 10 h darkness; 14L: 10D) or a short (2L: 22D) photoperiod, but olfactory bulbectomy decreased the nocturnal surge in animals maintained on 14L: 10D. This effect of bulbectomy was eliminated if the rats maintained on 14L: 10D were also pinealectomized. After cervical stimulation, bulbectomized rats maintained on a 2L: 22D photoperiod had nocturnal-type prolactin surges similar to those of intact rats maintained on the same photoperiod. These results indicate that the pineal gland and length of photoperiod are not involved in the regulation of the surges of plasma prolactin in pseudopregnant rats but that the olfactory bulbs may enhance the nocturnal surge.
CYCLICAL CHANGES IN CONCENTRATIONS OF α-MELANOTROPHIN IN THE PLASMA OF MALE AND FEMALE RATS
Authors: WILSON J. F. , MORGAN MERRILL A. 
Published: December 2008

Radioimmunoassay measurements of α-melanotrophin in plasma have identified a diurnal rhythm in male rats. Animals maintained on a 12 h light: 12 h darkness photoperiod had raised levels of plasma α-melanotrophin during the dark phase. Time-series analysis gave a fitted mean level of α-melanotrophin of 52·4 pmol/l, an amplitude of 12·1 pmol/l and peak levels 2·2 h before dawn.
Measurements throughout the oestrous cycle in female rats showed that similar variations between the dark and light phases occurred on the 2 days of dioestrus. The raised levels during the dark period were, however, absent on the nights of pro-oestrus and oestrus. During this pro-oestrous/oestrous period, plasma α-melanotrophin levels were below average but higher than the normal minimum levels found during the light period.
REDUCTION OF ANDROSTENEDIONE BY SKIN IN VITRO AND SERUM LEVELS OF GONADOTROPHINS AND ANDROGENS IN MEN WITH HYPOSPADIAS
Authors: SVENSSON JAN , ENEROTH PETER , GUSTAFSSON JAN-ÅKE , RITZÉN MARTIN , STENBERG ÅKE 
Published: December 2008

The reduction of 4-[1,2-3H]androstene-3,17-dione (androstenedione) in vitro by scrotal skin was measured in samples from nine men (16–34 years old) with hypospadias and from ten male control subjects. The reduction of androstenedione was also studied in axillary and upper arm skin of seven control subjects. Androstenedione was reduced to material with chromatographic characteristics of 5α-androstane-3,17-dione and to 3α- and 3β-hydroxy-5α-androstan-17-one.
No difference in 5α-reductase activity (defined as the sum of these three metabolites formed) was found in scrotal skin from hypospadic and control men.
The mean concentration of 5α-dihydrotestosterone in serum from men with hypospadias was lower than that in serum from control subjects (P< 0·01). The mean ratio of the serum concentrations of testosterone and 5α-dihydrotestosterone was higher in hypospadic men than in control subjects (P< 0·05). No differences between the two groups were found in the mean serum concentrations of LH, FSH, prolactin, dehydroepiandrosterone, androstenedione, testosterone or testosterone-binding globulin.
EFFECTS OF LESIONS OF THE SUPRACHIASMATIC NUCLEI AND OF p-CHLOROPHENYLALANINE ON THE CIRCADIAN RHYTHMS OF ADRENOCORTICOTROPHIC HORMONE AND CORTICOSTERONE IN THE PLASMA, AND ON LOCOMOTOR ACTIVITY OF RATS
Authors: SZAFARCZYK A. , IXART G. , MALAVAL F. , NOUGUIER-SOULÉ J. , ASSENMACHER I. 
Published: December 2008

SUMMARY
Adrenocorticotrophin (ACTH) and corticosterone in the plasma of adult female rats were measured sequentially at 4 h intervals for 24 h before and after lesions of the suprachiasmatic nuclei or treatment with p-chlorophenylalanine (to inhibit serotonin synthesis). After lesions or p-chlorophenylalanine treatment, the concentrations of ACTH were diminished relative to those in control animals and rhythmic changes could not be detected. However, injection of animals, pretreated with p-chlorophenylalanine, with 5-hydroxytryptophan (60 mg/kg) 8 h before the time when plasma ACTH is maximal in intact animals, stimulated ACTH secretion up to control values. Mean corticosterone concentrations in plasma remained unchanged (after lesions) or increased (after p-chlorophenylalanine). This increase was associated with an increased minimal concentration of corticosterone. After both treatments there was evidence of continued circadian or ultradian rhythms of corticosterone concentration.
Locomotor activity of female rats given identical treatment, but without blood sampling, indicated that nocturnal activity was diminished after lesions whereas diurnal activity was enhanced after p-chlorophenylalanine treatment. Periodicity analysis detected the persistence of free-running circadian, and sometimes ultradian activity, rhythms. Adrenalectomy did not alter further the activity pattern observed in rats with lesions.
These results therefore support the proposition that both the suprachiasmatic nuclei and the serotoninergic system play an irreplaceable role in the mechanism of ACTH secretory rhythms. The suprachiasmatic nuclei are also important for synchronization of locomotor activity and corticosterone rhythms, which may both persist after the suppression of ACTH rhythms.
ACTION OF OESTROGENS AND ANTIOESTROGENS ON OESTROGEN-INDUCIBLE CYTOPLASMIC AND ANDROGEN-INDUCIBLE MICROSOMAL ACTIVITY OF 3α-HYDROXYSTEROID DEHYDROGENASE IN MALE RAT KIDNEY
Authors: GHRAF R. , LAX E. R. , SCHRIEFERS H. 
Published: December 2008

The influence of steroidal and non-steroidal antioestrogenic compounds on the effect of systemically administered oestradiol (OE2) and diethylstilboestrol (DES) was investigated in adult male rats with intact gonads. In this animal model, oestrogens induced the NADP-dependent cytoplasmic activity and prevented the inductive action of androgens on NADP-dependent microsomal activity of renal 3α-hydroxysteroid dehydrogenase (3α-HSDH). Simultaneous administration of tamoxifen (0·5 mg/day) with OE2 (5 μg/day) or DES (10 μg/day) for 10 days completely blocked the inductive effect of OE2 on cytoplasmic 3α-HSDH, whereas, in the case of the microsomal enzyme, the repressive effects of OE2 and DES were antagonized only to 28 and 16% respectively. Simultaneous administration of 5α-dihydrotestosterone (DHT; 0·5 mg/day) for 10 days antagonized the inductive effect of OE2 on the cytoplasmic enzyme activity to 86% and completely by-passed the repressive effects of OE2 and DES on the microsomal enzyme activity.
It is concluded that oestrogenic induction of renal cytoplasmic 3α-HSDH involves an oestrogen receptor mechanism which, in this animal model, can be antagonized by tamoxifen. In contrast, oestrogenic repression of renal microsomal 3α-HSDH is obviously the consequence of the strong antigonadotrophic activity of oestrogens leading to subsequent repression of testicular androgen secretion by mechanisms which can be only weakly antagonized by tamoxifen. Exogenous DHT, even in the presence of OE2 or DES, completely compensates for this centrally mediated deficit of peripheral androgen.
EXAMINATION OF THE ROLE OF 'NON-FUNCTIONAL' CORPORA LUTEA IN THE FEMALE RAT
Authors: DE GREEF W. J. , VAN DER SCHOOT P. 
Published: December 2008

In rats with 5 day reproductive cycles, 'anovulatory' cycles were induced by blockade of ovulation with sodium pentobarbitone injected at pro-oestrus. Such anovulatory cycles were characterized in the ovaries by gradual atresia of the large follicles present at the time of the injection and the growth of a new cohort destined for the next ovulation. In the vaginal smears, anovulatory cycles were indistinguishable from normal ovulatory cycles.
The serum concentrations of progesterone remained at baseline levels during dioestrus of anovulatory cycles whereas increased concentrations of progesterone were observed during dioestrus of ovulatory cycles. It is concluded that the 'non-functional' corpora lutea of the cycle are the source of dioestrous progesterone.
The length of anovulatory cycles after a single injection of pentobarbitone was 5 days despite the absence of any increase in progesterone concentrations during dioestrus. It is concluded that progesterone production during dioestrus plays no major role in the control of the duration of 5 day reproductive cycles.
OESTROGEN RECEPTORS IN CELL NUCLEI OF THE HYPOTHALAMUS-PREOPTIC AREA-AMYGDALA FOLLOWING AN INJECTION OF OESTRADIOL OR THE ANTIOESTROGEN CI-628
Authors: ROY E. J. , McEWEN B. S. 
Published: December 2008

Oestrogen receptors were measured by an exchange assay in cell nuclei of the hypothalamus–preoptic area-amygdala (HPA) of ovariectomized-adrenalectomized (OVX-ADX) rats following an intravenous injection of oestradiol or an antioestrogen, CI-628. Receptors were translocated to the nucleus by both compounds. Receptors translocated by the antioestrogen were specific for oestrogens; testosterone, corticosterone and progesterone were not bound by these receptors. Several properties of antioestrogen– and oestradiol–receptor complexes were compared.
The time-course in cell nuclei in vivo showed that receptors were still present in HPA nuclei 24 h after administration of CI-628 but not 24 h after oestradiol. This prolonged increase of nuclear receptors after the antioestrogen treatment was attributed to the continued presence of CI-628 and its metabolites in plasma.
The maximum level of receptors produced in the HPA cell nuclei following CI-628 treatment was lower than the peak level of nuclear receptors following oestradiol. The dissociation rate in vitro of nuclear antioestrogen–receptor complexes formed in vivo was more rapid at 0 °C than that of nuclear oestradiol–receptor complexes. This property may be related to the lower peak level of binding after CI-628 treatment and to the inhibitory actions of antioestrogens.
EFFECTS OF TREATMENT WITH PROGESTERONE AND OESTRADIOL-17β ON THE ENDOCRINE PANCREAS IN OVARIECTOMIZED RATS: ULTRASTRUCTURAL VARIATIONS IN THE B CELLS
Authors: AERTS L. , VAN ASSCHE F. A. , FAURE A. , SUTTER-DUB M. TH. 
Published: December 2008

The effects of progesterone and/or oestradiol treatment on the ultrastructural appearance of the pancreatic B cells has been studied in ovariectomized Wistar rats. A morphometric examination of the numerical density of dark and light granules in the B cells was therefore performed in each group of experimental rats as well as in control (olive oil-injected) rats.
In the oestradiol-treated rats, and especially in the rats with combined oestradiol/progesterone treatment, the proportions of light and dark granules in the pancreatic B cells changed, compared with control values, in favour of the light granules. This increase in light granule content was comparable to changes in B cells during pregnancy and it is suggested that the secretory activity of the B cells increases during pregnancy in a manner similar to that seen during oestradiol treatment.
TISSUE ANDROGEN CONCENTRATIONS IN GOLDEN HAMSTERS WITH BENIGN PROSTATIC TUMOURS
Authors: FINNEY R. W. , HARPER M. E. , GASKELL S. J. , GRIFFITHS K. 
Published: December 2008

Using gas chromatography–high resolution mass spectrometry with selected ion detection, the concentrations of testosterone, 5α-dihydrotestosterone, androsterone, 5α-androstane-3α,17β-diol, 5α-androstane-3β,17α-diol and 5α-androstane-3β,17β-diol were measured in the dorsal and ventral prostates of two strains of golden hamster (Mesocricetus auratus) at various ages from 60 to 250 days. The tissue concentrations from a control strain were compared with those of the BIO 87·2 strain of hamster, the latter developing benign hyperplasia of the prostate between 90 and 120 days of age.
Marked increases in the concentration of total 5α-androstanediols in both prostatic lobes of the BIO 87·2 strain were detected, with the highest level of over 345 nmol/g protein being found at 200 days of age. In comparison, the control strain showed a less pronounced increase in concentration at 150 days. Increases in total 5α-androstanediols were mainly associated with increases in the concentration of 5α-androstane-3α,17β-diol. Concentrations of testosterone in prostatic tissue were also found to increase in the BIO 87·2 animals with peak values being seen at 200 days. Increases in concentration of androsterone were observed by 150 days and these levels were maintained up to 250 days of age. Control animals showed no comparable increases in testosterone and androsterone during the time-course studied.
Surprisingly, no significant variation in 5α-dihydrotestosterone concentration was detected in either strain from 60 to 250 days although levels were slightly but consistently higher in the BIO 87·2 strain.
There were no significant fluctuations in any of the androgens assayed either before or during tumour development. The increases in 5α-androstane-3α,17β-diol, testosterone and androsterone were detected only after tumours had become established.
EFFECTS OF DIHYDROTESTOSTERONE AND OESTRADIOL ON SEXUAL DIFFERENTIATION IN MALE RATS
Authors: VAN DER SCHOOT P. 
Published: December 2008

Adult male rats which had been castrated at birth and treated with the non-aromatizable androgen dihydrotestosterone propionate (DHTP) showed incomplete copulatory behaviour. When tested with oestrous female rats during treatment with testosterone propionate (TP) they readily mounted these females and showed frequent penile intromissions but rarely ejaculated. In a long series of observations the proportion of ejaculating rats in tests of 30 min did not exceed 50%. Neonatally castrated rats treated with DHTP during infancy thus seemed to be capable of ejaculation in adulthood during treatment with TP, but the threshold for the occurrence of the ejaculatory reflex seemed to be higher than in normal male rats.
By replacing treatment in adulthood with TP by a combined treatment with DHTP and oestradiol benzoate (OB), the frequency of ejaculation was not increased. It was concluded that the incomplete copulatory behaviour was not due to reduced efficiency of aromatization of androgen within the brain of these rats.
The addition of OB to DHTP during the neonatal period of treatment enhanced the frequency of ejaculation in adulthood. The combined treatment of 0·1 mg DHTP on days 1, 3 and 5 with 0·01 mg OB on day 1 made adult copulatory behaviour during treatment with TP indistinguishable from that of rats castrated on day 10 or rats castrated at birth and treated with TP during infancy.
It was concluded that the masculine organization of systems and structures involved in the display of male copulatory behaviour occurs under the influence of both non-aromatizable androgen and oestrogen, oestrogen being most likely the substance required to 'organize' the central nervous aspects of the regulation of this behaviour. The absence neonatally of nonaromatizable androgen and/or oestrogen results in specific deficiencies in adult copulatory behaviour as compared with the behaviour of normal male rats.
RENIN, ALDOSTERONE AND CORTISOL IN THE THOROUGHBRED HORSE
Authors: GUTHRIE G. P. , CECIL S. G. , KOTCHEN T. A. 
Published: December 2008

SUMMARY
To assess the renin–aldosterone system in a large mammal, simultaneous morning activities of plasma renin and concentrations of aldosterone and cortisol were measured in 25 thoroughbred horses. Renin was relatively low in all horses (0·16±0·02 (s.e.m.) ng angiotensin I/ml per h), levels of aldosterone in plasma were 527±130 pmol/l and levels of cortisol in plasma were 141±11 nmol/l. Levels of aldosterone were significantly correlated with levels of renin in all horses (r = 0·62, P < 0·001) but not with those of cortisol, and renin was negatively correlated with age in male horses (r = −0·54. P < 0·05). Horse plasma renin had a pH optimum of 6·0.
These data suggest that the thoroughbred horse has a functioning renin–aldosterone system characterized by levels of plasma renin activity that are much lower relative to those of other mammalian species.