Journal of Endocrinology
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20 YEARS OF LEPTIN: Role of leptin in energy homeostasis in humans The hyperphagia, low sympathetic nervous system tone, and decreased circulating concentrations of bioactive thyroid hormones that are common to states of congenital leptin deficiency and hypoleptinemia following and during weight loss suggest that the major physiological function of leptin is to signal states of negative energy balance and decreased energy stores. In weight-reduced humans, these phenotypes together with pronounced hypometabolism and increased parasympathetic nervous system tone create the optimal circumstance for weight regain. Based on the weight loss induced by leptin administration in states of leptin deficiency (obese) and observed similarity of phenotypes in states of congenital and dietary-induced states of hypoleptinemia (reduced obese), it has been suggested that exogenous leptin could potentially be useful in initiating, promoting, and sustaining weight reduction. However, the responses of human beings to exogenous leptin administration are dependent not only on extant energy stores but also on energy balance. Leptin administration to humans at usual weight has little, if any, effect on body weight while leptin administration during weight loss mitigates hunger, especially if given in supraphysiological doses during severe caloric restriction. Leptin repletion is most effective following weight loss by dietary restriction. In this state of weight stability but reduced energy stores, leptin at least partially reverses many of the metabolic, autonomic, neuroendocrine, and behavioral adaptations that favor weight regain. The major physiological function of leptin is to signal states of negative energy balance and decreased energy stores. Leptin, and pharmacotherapies affecting leptin signaling pathways, is likely to be most useful in sustaining weight loss.
Journal of Endocrinology - Tập 223 Số 1 - Trang T83-T96 - 2014
THE INFLUENCE OF GONADAL HORMONES ON SERUM RIBOFLAVIN AND CERTAIN OTHER PROPERTIES OF BLOOD AND TISSUES IN THE DOMESTIC FOWL
Journal of Endocrinology - Tập 5 Số 1 - Trang 121-130 - 1946
THE INFLUENCE OF GONADAL HORMONES ON THE COMPOSITION OF THE BLOOD AND LIVER OF THE DOMESTIC FOWL
Journal of Endocrinology - Tập 5 Số 1 - Trang 263-273 - 1946
Pro-opiomelanocortin processing in the hypothalamus: impact on melanocortin signalling and obesity Bioactive peptides derived from the prohormone, pro-opiomelanocortin (POMC), are generated in neurons of the hypothalamus and act as endogenous ligands for the melanocortin-4 receptor (MC4R), a key molecule underlying appetite control and energy homeostasis. It is therefore important to understand many aspects of POMC gene regulation in the brain, as pharmacological manipulation of POMC expression/processing could be a potential strategy to combat obesity. Most studies that have analysed POMC gene expression in the hypothalamus have focused on gene transcription experiments. Ultimately, however, factors that regulate post-translational processing and secretion of peptides will have most bearing on melanocortin signalling. This article focuses on (a) current evidence that POMC is involved in obesity, (b) how POMC transcription is regulated in the hypothalamus, (c) the mechanism by which proteolytic processing of POMC is controlled in the hypothalamus and what peptides are produced and (d) which POMC-derived peptides are the most potent ligands at the melanocortin receptor in vitro and in vivo. It seems that post-translational cleavage of POMC in the hypothalamus may be regulated with respect to energy requirement. We predict that further research into hypothalamic POMC processing, and the proteolytic enzymes involved, may yield important new clues on how flux through the MC4R pathway is regulated.
Journal of Endocrinology - Tập 172 Số 3 - Trang 411-421 - 2002
ENDOCRINE CONTROL OVER PRODUCTION AND ACTIVITY OF THE ANTI-AGGRESSION PHEROMONE FROM FEMALE MICE SUMMARY
In an attempt to clarify the role of gonadal function in the release of anti-aggression pheromone into the urine of female mice, two experiments were carried out. Each involved recording the aggressiveness of 'fighter' male mice when presented with castrated male 'opponents' which had been treated either with urine from one of four categories of female donor mice, or with water.
In the first series of experiments it was shown that the urine from oestrous and dioestrous mice contained similar amounts of anti-aggression activity. Both spaying and testosterone propionate (TP) injection of the female urine-donors abolished this activity.
In a second series of experiments urine from spayed donors injected with TP greatly increased the aggression response to a level which exceeded that obtained with the urine of TP-treated intact mice. High doses of oestrogen resulted, in the spayed urine-donors, in an actual increase in aggression response. Both treatments increased clitoral gland weight, and it is concluded that androgen or high levels of oestrogen can stimulate the clitoral gland of the female, a possible consequence being a release of aggression-promoting pheromone.
The aggression-inhibiting pheromone, which depends on the ovary for its release, is probably the product of some other tissue, as yet unidentified.
Journal of Endocrinology - Tập 49 Số 2 - Trang 225-232 - 1971
CONCENTRATIONS OF OXYTOCIN IN THE PLASMA AND AMNIOTIC FLUID OF RHESUS MONKEYS (MACACA MULATTA) DURING THE LATTER HALF OF PREGNANCY A specific radioimmunoassay for oxytocin has been established with a sensitivity of 0·8 pg/tube. This assay has been applied to the measurement of oxytocin in serial samples of peripheral plasma and amniotic fluid from pregnant rhesus monkeys, collected at weekly intervals by venepuncture and amniocentesis. Concentrations of oxytocin in both fluids were generally low and showed no trends throughout the latter half of gestation.
Journal of Endocrinology - Tập 84 Số 3 - Trang 473-478 - 1980
SIMULTANEOUS RELEASE OF OXYTOCIN AND NEUROPHYSIN DURING PARTURITION IN THE GOAT
Journal of Endocrinology - Tập 52 Số 1 - Trang 213-214 - 1972
Prolactin and the control of gonadotrophin secretion
Journal of Endocrinology - Tập 115 Số 1 - Trang 1-5 - 1987
THE HYPOTHALAMIC CENTRES INVOLVED IN THE CONTROL OF PRODUCTION AND RELEASE OF PROLACTIN IN SHEEP SUMMARY
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.
Journal of Endocrinology - Tập 73 Số 1 - Trang 21-29 - 1977
RELATIVE ACTIVITY, PLASMA ELIMINATION AND TISSUE DEGRADATION OF SYNTHETIC LUTEINIZING HORMONE RELEASING HORMONE AND CERTAIN OF ITS ANALOGUES The abilities of three nonapeptide analogues of synthetic luteinizing hormone releasing hormone (LH-RH) to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in anoestrous and cyclic ewes were examined, as were their elimination from the plasma in vivo and degradation by extracts of the hypothalamus, anterior pituitary gland, lung, kidney, liver and plasma in vitro . In all cases, comparisons were made with synthetic LH-RH.
When injected i.v. into mature ewes as a single dose, the potencies of the analogues were graded and Des Gly-NH2 10 LH-RH ethylamide was found to be the least potent. It was not possible to demonstrate any significant increase in the potency of this analogue over LH-RH, although a trend was apparent with each parameter examined. [d -Ser(But )6 ] Des Gly-NH2 10 LH-RH ethylamide had the greatest potency. There were no differences between the responses of anoestrous ewes and those of ewes treated on day 10 of the oestrous cycle. None of the analogues had a rate of elimination from the plasma different from that of LH-RH during either the first or the second components of the biphasic disappearance curve.
The incubation of LH-RH with tissue extracts showed that extracts of the hypothalamus and anterior pituitary gland degraded LH-RH to a similar extent. Both the hypothalamic and anterior pituitary gland extracts degraded more LH-RH than did lung extract, which in turn destroyed more LH-RH than did extracts of kidney or liver tissue. The degradative abilities of kidney and liver extracts did not differ from each other. Plasma failed to degrade LH-RH or the analogues. Although LH-RH was rapidly destroyed by hypothalamic extract in vitro , of the analogues, only Des Gly-NH2 10 LH-RH ethylamide was degraded. The anterior pituitary gland and kidney extracts failed to degrade [d -Ser6 ] Des Gly-NH2 10 LH-RH ethylamide and [d -Ser(But )6 ] Des Gly-NH2 10 LH-RH ethylamide as rapidly as LH-RH. Extracts of liver and lung were incapable of catabolizing any of the analogues.
There was an inverse correlation between the LH- and FSH-releasing potency of an analogue and its rate of degradation by anterior pituitary gland extract. The slower rates of catabolism of certain analogues of LH-RH by the anterior pituitary gland may explain their increased LH- and FSH-releasing potency.
Journal of Endocrinology - Tập 80 Số 1 - Trang 141-152 - 1979
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