bluuebunny/crossref_metadata_2025_split huggingface dataset:
DIFFERENTIAL CONTROL OF LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE BY LUTEINIZING HORMONE RELEASING HORMONE IN THE RAM
Authors: LINCOLN G. A. 
Published: December 2008

Adult Soay rams with low concentrations of gonadotrophins in the circulation as a result of 12 weeks of exposure to long daylengths (16 h light: 8 h darkness) were given small doses (100 ng) of synthetic luteinizing hormone releasing hormone (LH-RH) into the jugular vein two, four or seven times/day for 10 days.
Each injection of LH-RH induced a transitory increase in the concentration of LH and testosterone in the plasma, whereas the concentration of FSH showed little immediate change, After repeated treatment with pulses of LH-RH, the responses of LH and testosterone became slightly enhanced and the plasma concentration of FSH became permanently raised; these changes were most conspicuous in the animals receiving the most frequent injections.
At the end of the study when the injections of LH-RH were stopped, the concentrations of LH and testosterone remained low but the concentrations of FSH continued to be maintained at a high level for at least 24 h.
FURTHER EVIDENCE THAT MELATONIN REPRESENTS THE RELEASING HORMONE FOR PINEAL VASOTOCIN
Authors: PAVEL S. , GOLDSTEIN R. 
Published: December 2008

SUMMARY
As deduced from the antidiuretic and hydro-osmotic activities, intracarotid injection of 10 μg melatonin into urethane-anaesthetized cats significantly decreased the pineal argininevasotocin (AVT) content and increased its level in cerebrospinal fluid (CSF) between 5 and 60 min after the injection. No AVT was detectable in the plasma of cats between 5 and 60 min after the intracarotid injection of melatonin. However, between 60 and 90 min, when AVT disappeared from the CSF, a significant amount of AVT was detectable in plasma. The intracarotid injection of 10 μg serotonin was unable to induce the release of AVT into CSF or plasma, or to affect the pineal AVT content. Although intracarotid injection of 10 ng melatonin was unable to induce the release of AVT during the daylight hours, the same amount of melatonin was highly potent in inducing the release of AVT into the CSF during the night in the dark. The sensitivity of AVT to melatonin appears to be induced by darkness because the same amount (10 ng) of melatonin was ineffective when injected into animals maintained with the light on during the night. Since it was necessary to administer 5 μg melatonin during the hours of daylight to match the effects of 10 ng melatonin given at night, it appears that melatonin is about 500 times more potent in inducing AVT release during the night in the dark. The present results further consolidate the concept that melatonin represents the releasing hormone for pineal AVT and at the same time strongly suggest that AVT is first released into the CSF and reaches the blood only secondarily after its absorption from the CSF.
PLASMA OXYTOCIN AND STEROID CONCENTRATIONS DURING LATE PREGNANCY, PARTURITION AND LACTATION IN THE MINIATURE PIG
Authors: FORSLING M. L. , TAVERNE M. A. M. , PARVIZI N. , ELSAESSER F. , SMIDT D. , ELLENDORFF F. 
Published: December 2008

SUMMARY
Plasma oxytocin concentrations were measured during late pregnancy, parturition and lactation in the miniature pig. Measurements were made of plasma oestradiol, oestrone and progesterone to determine whether there was any relationship between the concentrations of oxytocin and these steroids in the circulation.
Plasma oxytocin concentrations were low or undetectable in late pregnancy. Rises of up to 68·8 μu./ml were seen at the time of delivery of the foetuses and at the expulsion of the placenta. The only steroid that seemed to relate to oxytocin release was progesterone. Oxytocin release was consistently seen when progesterone concentrations had fallen to below 10 ng/ml but no increase in concentration was observed while oestrone and oestradiol increased to their maximum concentrations of 3·86–11·6 and 0·43–0·70 ng/ml respectively.
During lactation, when both oestrogen and progesterone concentrations were low, suckling caused the levels of oxytocin to increase to 7·4 μu./ml. These increases were greater during the first 2 weeks of lactation than later.
EFFECTS OF GLUCOSE AND AMINO ACIDS ON INSULIN, GLUCAGON AND ZYMOGEN GRANULE SIZE OF FOETAL RAT PANCREAS GROWN IN ORGAN CULTURE
Authors: MILNER G. R. , DE GASPARO M. , KAY R. , MILNER R. D. G. 
Published: December 2008

SUMMARY
Foetal rat pancreatic rudiments explanted on day 14 of gestation were grown for 6 days in organ culture in medium containing glucose (5·5 (1G) or 16·5 (3G) mmol/l) and amino acids at the 'physiological' (1AA) or seven times the 'physiological' (7AA) concentration. Cultures were also performed in medium to which zinc sulphate had been added at 10−7 to 10−5 mol/l concentration. At the end of the period of culture the diameters of insulin, glucagon and zymogen granule profiles in the rudiments were compared with those in normal 20-day foetal pancreas by quantitative morphology. The β cell volume, the number of granules per β cell, the insulin granular volume fraction and the area of insulin granule core and halo were also measured under selected experimental conditions.
Zymogen granule profiles were largest in vivo, intermediate in diameter when grown in 1G × 7AA medium and smallest in 1G × 1AA medium. The mean diameter of glucagon granule profiles remained constant for growth in vivo, in 1G × 1AA medium or in 1G × 7AA medium. Insulin granule profiles were largest in 1G ×7AA medium, smallest in 3G × 1AA medium and of intermediate diameter in vivo. Amino-acid enrichment increased the diameter of insulin granules and glucose enrichment decreased it. The addition of zinc to the culture medium had no effect on insulin granule diameter. In 1G × 7AA cultures the β cells were of similar size to those in vivo, but there were 29% fewer insulin granules per cell. The increased size of the insulin granules in 1G × 7AA cultures resulted in the insulin granule volume fraction in 1G × 7AA being 17·6 compared with 10·8% in vivo. Insulin granule cores were made larger by amino-acid enrichment of the culture medium but they were unaffected by glucose. The haloes were larger in 7AA medium and smaller in 3G medium. Glucose and amino-acid enrichment had a significant interaction on halo area, the mean area in 3G × 7AA medium being less than would have been expected from the summation of the effects of the two conditions.
EFFECT OF CHICKEN HYPOTHALAMUS ON PROLACTIN AND GROWTH HORMONE SECRETION IN MALE CHICKENS
Authors: HARVEY S. , SCANES C. G. , CHADWICK A. , BORDER G. , BOLTON N. J. 
Published: December 2008

SUMMARY
The effects of a chicken hypothalamic extract (HE) on the secretion of prolactin and growth hormone (GH) in vivo have been investigated by radioimmunoassay in the domestic fowl. Different i.v. doses of HE (0·25–25 HE equivalents/kg body weight) had no effect on GH secretion in conscious or anaesthetized cockerels. In both groups of birds the concentration of plasma prolactin was significantly increased within 10 min of administration of the extract. Extracts of other brain tissues (cerebral cortex, cerebellum and medulla oblongata) had no stimulatory effect on prolactin or GH secretion. Release of both prolactin and GH by dispersed pituitary cells and by hemipituitary glands in vitro was enhanced following incubation with HE (5 hypothalami equivalents/ml) or with single whole hypothalami respectively. Other brain tissues (cerebellum, optic lobes and medulla oblongata) had no effect on the concentration of prolactin or GH released by incubated hemipituitary glands.
INFLUENCE OF IODINE ON THE FORMATION OF 27S AND LARGER IODOPROTEINS IN RAT THYROID FOLLICLES
Authors: SMEDS S. , EKHOLM R. , STUDER H. 
Published: December 2008

SUMMARY
The importance of the presence of iodine for the formation of iodoproteins larger than 19S thyroglobulin, i.e. 27S and larger iodoproteins (large-TG), was studied. Samples of colloid were collected in vivo by micropuncture of single rat thyroid follicles after treatment with a low iodine diet or potassium perchlorate. The protein composition of the colloid was analysed by microgel electrophoresis on polyacrylamide gels.
It was observed that the large-TG fractions were reduced by approximately 50% after treatment with a low iodine diet for 3 months. The large-TG fractions were almost absent after treatment with perchlorate for 3 weeks.
Administration of 5 or 10 μg potassium iodide to the animals on a low iodine diet resulted in a significant increase of the relative amount of the large-TG fractions in the colloid within approximately 2 h, the higher dose of KI producing a more pronounced accumulation of the large-TG fractions. Inhibition of protein synthesis by cycloheximide did not prevent the increase of large-TG proteins in animals on a low iodine diet after the administration of 5 μg KI. The administration of iodide to rats treated with potassium perchlorate did not result in the appearance of large-TG fractions.
It is concluded that the aggregation of thyroglobulin molecules occurs in the follicle lumen as a consequence of iodine administration. This formation of large-TG fractions does not require exocytosis of newly synthesized protein.
PROLONGED INTRAVENOUS INFUSION OF LABELLED IODOCOMPOUNDS IN THE RAT: [125I]THYROXINE AND [125I]TRI-IODOTHYRONINE METABOLISM AND EXTRATHYROIDAL CONVERSION OF THYROXINE TO TRI-IODOTHYRONINE
Authors: BOONNAMSIRI VIPA , KERMODE J. C. , THOMPSON B. D. 
Published: December 2008

SUMMARY
Extrathyroidal tissues of the rat were labelled to steady state by prolonged continuous intravenous infusion of 125I-labelled thyroxine (T4) or tri-iodothyronine (T3). Labelled iodocompounds extracted from various tissues were analysed by thin-layer chromatography.
Significant amounts of labelled T3 were found in all tissues examined after infusion of [125I]T4, confirming that conversion of T4 to T3 occurs in extrathyroidal tissues of the rat. Faecal excretion of labelled T3 after [125I]T4 infusion provided an assessment of the extent of extrathyroidal conversion: about a third of the T4 was metabolized by this pathway. Extrathyroidal conversion was independently estimated to account for about a third of the total production of T3.
The site of extrathyroidal conversion was established by comparing the distributions of labelled T3 after the two types of infusion: kidney and liver were both prominent sites of conversion of T4 to T3.
EVALUATION OF THE BOVINE TESTICULAR RADIORECEPTOR ASSAY FOR PITUITARY FOLLICLE-STIMULATING HORMONE
Authors: SAIRAM M. R. 
Published: December 2008

SUMMARY
A modified bovine testicular receptor was used to evaluate highly purified follicle-stimulating hormone (FSH) from a number of species. The particulate receptor obtained from adult bovine testes could be stored frozen or lyophilized for long periods without appreciable decrease in the binding of the ligand facility or in loss of specificity. The bovine testis receptor binds twice as much 125I-labelled ovine FSH as 125I-labelled human hormone. When FSH from different species was compared against NIH-FSH-S10, using various FSH ligands, the ovine hormone was clearly the most active, although many had comparable in-vivo biological potencies. The results suggest that there is probably some species specificity in the hormone–receptor interactions. As the ovine hormone is structurally closer to the bovine, from which the receptor was derived, it appears to have the highest activity in vitro. Marked differences in the biological activities of the different preparations between the human chorionic gonadotrophin-augmentation test and the in-vitro assays have been observed. In the in-vitro assays, all preparations, with the exception of the porcine hormone preparation, were less active and the ratio of bioassay/radioreceptor assay varied widely. In the radioreceptor assays, all FSH preparations except pregnant mare serum gonadotrophin (PMSG) showed parallel inhibition curves. The three different PMSG preparations examined gave inhibition lines that were parallel to each other.
INFLUENCE OF TESTICULAR SECRETIONS ON TISSUE WEIGHT AND ON METABOLIC AND ENZYME ACTIVITIES IN THE EPIDIDYMIS OF THE RAT
Authors: BROOKS D. E. 
Published: December 2008

SUMMARY
Preventing the entry of testicular secretions into the epididymis by ligating the efferent ducts resulted in reduced epididymal weight and an alteration in the distribution of carnitine throughout the segments. The metabolic activity of the distal regions of the duct was unaffected by ligation but some changes were apparent in more proximal regions, particularly in the initial segment. Inhibition of spermatogenesis by the administration of busulphan resulted in a loss of weight of the caput epididymidis similar to that caused by ligation of the efferent ducts, even though testicular fluid was not prevented from entering the epididymis. Treatment with busulphan also led to a reduction in androgen-binding protein (ABP) and to a lower activity of pyruvate carboxylase in the caput. Ligation of the efferent ducts in busulphan-treated animals prevented the entry of testicular fluid into the epididymis as judged by the absence of ABP. Despite the absence of ABP, and hence any androgens normally associated with it, there was no appreciable change in the activity of androgenregulated enzymes, indicating that sufficient androgen was reaching the epididymis by way of the peripheral circulation. However, the results suggest that, in addition to androgens, the testis normally produces some other component(s), possibly associated with spermatozoa, which are required for full maintenance of the weight of the epididymal duct and of metabolic activity in the more proximal regions.
EFFECTS OF THE METHOD OF EXSANGUINATION ON MEASUREMENTS OF DEVELOPMENTAL CHANGES IN SERUM CONCENTRATIONS OF FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE IN PREPUBERTAL AND ADULT MALE HOUSE MICE
Authors: BERKOWITZ A. S. , LLOYD J. A. , CHOWDHURY MRIDULA 
Published: December 2008

SUMMARY
The relationship between the method of exsanguination and the serum concentration of gonadotrophins was investigated in male house mice. Mice were killed 21–99 days post partum by ether anaesthesia and cardiac puncture, or by decapitation. Results of gonadotrophin radioimmunoassays indicated that titres of serum FSH were not affected by the method of exsanguination, while concentrations of serum LH were significantly raised when blood was collected by ether anaesthesia and cardiac puncture. Serum FSH in an inbred strain of mice peaked at 21 days post partum and declined steadily to a relatively constant pubertal and postpubertal level. Concentrations of serum LH were variable during the prepubertal period with a peak occurring 31–35 days post partum. Extremely high titres of FSH on days 21–35 post partum indicated that mice in this study might be relatively insensitive to FSH in the prepubertal period.
MEASUREMENT OF THE INTEGRATED CONCENTRATION OF PROLACTIN IN NORMAL SUBJECTS AND PATIENTS WITH HYPERPROLACTINAEMIA
Authors: DAGGETT P. R. , NABARRO J. D. N. 
Published: December 2008

SUMMARY
To determine whether the fluctuations in the concentration of prolactin in plasma of man affect diagnostic procedures, the integrated concentration of prolactin has been compared with a basal concentration. A continuous sampling apparatus was used to study nine normal subjects and 12 subjects with features of the hyperprolactinaemia syndrome. Small differences were demonstrated, which were, however, neither statistically significant nor likely to influence clinical decisions. It is concluded that single estimations of the concentration of prolactin in blood, taken under resting conditions, are adequate for routine diagnostic use.
THYMUS AND THE ENDOCRINE SYSTEM: OVARIAN DYSGENESIS IN NEONATALLY THYMECTOMIZED RATS
Authors: HATTORI M. , BRANDON M. R. 
Published: December 2008

SUMMARY
By 10 days after neonatal thymectomy, the areas of lymphocytic depletion were being repopulated by plasma or reticular cells. Subsequently, ovarian dysgenesis was observed in 50-day-old thymectomized female rats as hyperplasia of ovarian interstitial cells and an enhanced degeneration of follicles. Thymectomized rats at 130 and 170 days of age showed complete ovarian dysgenesis, testicular atrophy, hypertrophy of pituitary β-cells with pronounced cytoplasmic haloes, and lymphocytic infiltration in the pituitary, thyroid and prostate glands. These results suggest that neonatal thymectomy may initially influence the lymphoid organs (i.e. the immune system) and that changes in the immune system may result in the autoimmune-like damage in the endocrine organs and the prostate gland.
Associated with these changes, the concentrations of plasma progesterone and 17α-hydroxyprogesterone were significantly reduced in 130-day-old thymectomized female rats with respect to the sham-thymectomized controls. The concentration of plasma oestradiol-17β in thymectomized female rats was the same as in sham-thymectomized female rats. These results suggest that gestagens may normally suppress immune responses but that, in the case of thymectomized female rats, the reduced levels of gestagens may lead to enhanced immune responses.
SERUM LEVELS OF GONADOTROPHINS IN HAMSTERS EXPOSED TO SHORT PHOTOPERIODS: EFFECTS OF ADRENALECTOMY AND OVARIECTOMY
Authors: BITTMAN E. L. , GOLDMAN B. D. 
Published: December 2008

SUMMARY
Female hamsters rendered acyclic by exposure to short photoperiods (10 h light: 14 h darkness) showed diurnal surges of both LH and FSH which persisted after removal of the ovaries and adrenal glands. The reduced increase in gonadotrophin secretion after ovariectomy, typical of hamsters exposed to short days, was also not contingent upon the presence of the adrenal glands. The results demonstrate that 'supersensitivity' of the neuroendocrine axis to feedback of ovarian or adrenal steroids cannot fully account for either the daily surges of gonadotrophins or the diminished response of LH and FSH to ovariectomy in hamsters maintained on short days. It is suggested that these changes result instead from other pineal-mediated actions of short photoperiods upon the brain.
SOMATOMEDIN-LIKE ACTIVITY IN PLASMA AFTER FOETAL HYPOPHYSECTOMY OR NEPHRECTOMY AND IN EXPERIMENTAL INTRA-UTERINE GROWTH RETARDATION IN SHEEP
Authors: FALCONER J. , FORBES J. M. , HART I. C. , ROBINSON J. S. , THORBURN G. D. 
Published: December 2008

SUMMARY
Plasma samples from pregnant ewes and their foetuses during the last quarter of gestation were assayed for somatomedin-like activity (SLA) using the porcine costal cartilage assay. In maternal plasma, the mean potency (compared with pooled serum from six sheep) was 0·84 ± 0·05 (s.e.m.) units/ml (n = 15). Somatomedin-like activity in the plasma of five control foetuses (0·91 ± 0·1 units/ml) was similar to the maternal levels and did not change with gestational age. After foetal hypophysectomy the SLA in foetal plasma (0·37 ± 0·05 units/ ml, n = 4) was significantly less than in control animals. In two nephrectomized foetuses, the mean SLA in plasma (0·08 and 0·51 units/ml respectively) was less than in control animals. Retardation of intra-uterine foetal growth was induced by removal of endometrial caruncles before pregnancy in four sheep. The SLA in plasma from these foetuses was 0·38 ± 0·05 units/ml (P< 0·01 v. control animals). The results suggest that SLA in the foetus may be important in the regulation of foetal growth, but they also indicate that factors other than growth hormone may be important in the control of SLA in foetal plasma.
OESTROGEN CONTENT OF THE UTERINE TISSUES OF MICE AND THEIR RELATIONSHIP TO EPITHELIAL CELL PROLIFERATION AFTER SUBCUTANEOUS AND INTRALUMINAL ADMINISTRATION OF HORMONES
Authors: FAGG BARBARA , MARTIN L. 
Published: December 2008

The oestrogen content of the separated uterine tissues (epithelium, stroma and myometrium) of mice was determined at various times between 1 and 24 h after administration of [3H]oestradiol or [3H]oestriol either subcutaneously or directly into the uterine lumen. After subcutaneous injections, the oestrogen levels of both the stroma and myometrium declined steadily from a maximum at 2–4 h after injection and more oestradiol than oestriol was always present. In contrast, the epithelium contained more oestriol than oestradiol and the levels of both hormones remained fairly constant over the period studied. However, a smaller percentage of the epithelial oestriol than of oestradiol was associated with the nuclear fraction. On the contrary, after intraluminal injections, the oestrogen content of all the separated tissues decreased from a maximum at 1–2 h and more oestradiol than oestriol was retained in all cases. A high proportion of the total epithelial content of both oestrogens was recovered in the nuclear fraction.
The uterine proliferative response after intraluminal injection of oestradiol or oestriol was qualitatively and quantitatively similar to that observed after subcutaneous injection of hormone, indicating that the efficacy of the oestrogens is not markedly dependent on the route of administration. These data support current concepts of oestrogen action in the uterus but indicate that studies of the whole organ may not, in all respects, be extrapolated to the individual target tissue. The importance of nuclear hormone levels as the determinant of the oestrogenic response is also emphasized.
SUPPRESSION OF PITUITARY SECRETION OF FOLLICLE-STIMULATING HORMONE BY PORCINE FOLLICULAR FLUID DURING PRO-OESTRUS AND OESTRUS IN THE RAT: EFFECTS ON GONADOTROPHIN AND STEROID SECRETION, FOLLICULAR DEVELOPMENT AND OVULATION DURING THE FOLLOWING CYCLE
Authors: DEPAOLO L. V. , HIRSHFIELD ANNE N. , ANDERSON L. D. , BARRACLOUGH C. A. , CHANNING CORNELIA P. 
Published: December 2008

In this study, we have examined whether the suppression of raised plasma FSH concentrations at pro-oestrus and/or oestrus by porcine follicular fluid (PFF) affected the development of follicles for ovulation in the next cycle. Adult, 4-day-cyclic rats were injected with PFF or pig serum at various hours of pro-oestrus and oestrus. Plasma FSH levels were suppressed following PFF treatment at any time of pro-oestrus and oestrus. Furthermore, this suppression was always followed by a 'rebound' increase in plasma FSH. In contrast, plasma LH concentrations were unaffected by PFF treatment and neither gonadotrophin was altered by treatment with pig serum.
When rats treated with PFF or pig serum were allowed to complete one additional cycle, plasma LH and FSH concentrations at the pro-oestrus and oestrus after treatment were not significantly different among groups regardless of treatment or time of treatment. All ovaries of rats treated with PFF or pig serum on the next pro-oestrus morning before ovulation were histologically similar. Furthermore, all animals ovulated a normal complement of ova at the next oestrus regardless of whether preovulatory, secondary or both increases of plasma FSH had been blocked by PFF treatment during the previous cycle. However, in animals given PFF during the preceding cycle, plasma oestradiol and progesterone concentrations were significantly altered on the morning and afternoon of pro-oestrus respectively.
These results suggest that increased plasma FSH concentrations at pro-oestrus and oestrus may not be essential for folliculogenesis and ovulation in the subsequent cycle. Alternatively, the 'rebound' of FSH on day 1 of dioestrus after the suppression of both phases of FSH secretion at pro-oestrus and oestrus may be sufficient to provide ovulatory follicles for the next pro-oestrous day.