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At least 19 recordsLinked to original sources
PubMed1977

Effects of starvation in rats on serum levels of follicle stimulating hormone, luteinizing hormone, thyrotropin, growth hormone and prolactin; response to LH-releasing hormone and thyrotropin-releasing hormone.

Adult male Sprague-Dawley rats averaging 300 g each were subjected to complete food removal for 7 days (acutely starved), 7 days complete food removal followed by 2 weeks of 1/4 ad libitum food intake (chronically strved), 7 days complete food removal and 2 weeks of 1/4 ad libitum intake followed by ad libitum feeding for 7 days (refed), or fed ad libitum throughout (controls). Serum LH, FSH, TSH, PRL, and GH levels were measured by radioimmunoassays for each group of rats. The in vivo response to the combination of synthetic LHRH and TRH also was tested in each group of rats. Circulating LH, TSH, GH, and PRL were significantly depressed in acutely and chronically starved rats, and FSH was lowered only in acutely starved rats. After 7 days of refeeding, serum levels of LH and FSH were significantly greater than in ad libitum fed controls, PRL returned to control levels, and TSH and GH increased but were still below control levels. After LHRH + TRH injection serum LH and TSH were increased significantly in all groups of rats, FSH and PRL rose in acutely but not in chronically starved rats, and GH was not elevated in any group. The increases in serum LH, FSH, TSH and prolactin in response to LHRH + TRH injection in acutely or chronically starved rats were equal to or greater than in the ad libitum fed controls. These data indicate that severe reductions in food intake result in decreased release of at least 5 anterior pituitary hormones, and this is due primarily to reduced hypothalamic stimulation rather than to inability of the pituitary to secrete hormones.

Adrenal Glands↗
PubMed1977

Hormonal response to exogenous luteinizing hormone-releasing hormone and thyrotropin-releasing hormone in pregnancy and puerperium.

Luteinizing hormone-releasing hormone (LH-RH) and thyrotropin-releasing hormone (TRH) were injected into five women in the last month of pregnancy and three women in the postpartum period. In seven of the women, follicle-stimualating hormone (FSH) levels were at the limit of sensitivity of the assay and there was no response to LH-RH. One postpartum subject tested three weeks after delivery did show an FSH response to LH-RH. The thyrotropin response to TRH was within normal limits. When compared with control subjects, the pregnant and puerperal women had elevated basal levels of prolactin and an exaggerated response to TRH. Growth hormone levels were low and there was an inconsistent response to the administration of the releasing hormones. These results indicate that in pregnancy the thyrotroph and lactotroph are responsive to stimulation, whereas the gonadotroph is suppressed.

Adult↗
PubMed1976

Stimulation of growth hormone release by luteinizing hormone-releasing hormone and melanocyte-stimulating hormone-release inhibiting hormone in the hypophysectomized rat bearing an ectopic pituitary.

Intrajugular administration of LHRH (0-6 and 1-2 mug) in hypophysectomized rats which received renal grafts of anterior pituitary induced a small but significant rise in plasma GH 5 and 10 min post-treatment. LHRH, at the same dose levels, was ineffective in weight-matched intact controls. MIF, at the dose of 1-2 mug, induced a slight GH rise 5 min after treatment in hypophysectomized trasnplanted rats, while it was ineffective in intact controls. Unlike the two hypothalamic peptides, alpha-MSH (0-6 and 1-2 mug) was ineffective as a GH-releaser in both transplanted and intact rats.

Animals↗
PubMed1977

Luteinizing hormone responses to luteinizing hormone releasing hormone, and growth hormone and cortisol responses to insulin induced hypoglycaemia in functional secondary amenorrhoea.

Luteinizing hormone (LH) responses to luteinizing hormone releasing hormone (LHRH), and growth hormone (GH) and cortisol responses to insulin induced hypoglycaemia were studied in 56 women classified into 4 distinct groups of functional secondary amenorrhoea. The groups were: I, self-induced weight reduction (20 patients); II, post pill amenorrhoea (14 patients); III, anorexia nervosa (10 patients); and IV, idiopathic secondary amenorrhoea (12 patients). Only patients with no overlapping anamnestic factors were included. Group I patients had the most heavily impaired LHRH-LH responses, and the GH response to hypoglycaemia was smaller than in other groups. Cortisol responses were normal. Group II patients showed blunted LH responses and normal GH and cortisol responses. Group III patients showed normal or exaggerated LH responses in the recovery phase of anorexia nervosa, while those two patients who were in the static phase of the illness had impaired responses. GH responses varied greatly. Group IV patients had normal basal levels of LH and normal LH, GH and cortisol responses. The restoration of LH response is not solely correlated to body mass, since patients recovering from anorexia nervosa showed greater LHRH-LH responses with nutritional rehabilitation at 76% of ideal body weight than patients with self-induced weight reduction at 87% of ideal body weight. In idiopathic amenorrhoea the hypothalamic pituitary axis seems to be practically intact. The function of hypothalamic-pituitary axis may be impaired selectively in functional amenorrhoea. Corticotrophin releasing hormone function remains intact, and GH-response may be impaired or normal independently of the LH-response to LHRH. In self-induced weight reduction both functions were impaired. These tests are easily carried out with out-patients, and they give more information about the functional state of hypothalamic-pituitary axis than basal analyses of hypothalamic-pituitary axis than basal analyses of gonadotrophins and oestrogens. However, a single pathologic reading in the LH response is not specific enough to indicate to which group of amenorrhoea the patients belong, but these tests together elucidate the severity of lesion in hypothalamic pituitary axis.

Adolescent↗
PubMed1977

Gonadotrophin release by a highly active analogue of luteinizing hormone releasing hormone in rats immunized against luteinizing hormone releasing hormone.

Immunization against luteinizing hormone releasing hormone (LH-RH) in adult male rats produced a progressive decline in LH and FSH in the circulation to low or non-detectable levels. D-Serine-tertiary-butyl6,des-glycine-NH210 LH-RH ethylamide is an analogue of LH-RH having highly active LH-RH properties in the normal rat. Because it is also immunologically different from LH-RH it can stimulate gonadotrophin release from the anterior pituitary gland of rats immunized against LH-RH without interference from the antibody. The analogue stimulated LH and FSH release in rats 15 weeks after immunization against LH-RH when antibody titre was highest, and after long-term (35 weeks) immunization against LH-RH. D-Serine-tertiary-butyl6,des-glycine-NH210 LH-RH ethylamide and related analogues are therefore potentially useful for reversing the effects of immunization against LH-RH.

Animals↗
PubMed1979

Differential control of luteinizing hormone and follicle-stimulating hormone by luteinizing hormone releasing hormone in the ram.

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.

Animals↗
PubMed1979

Sleep-wake patterns and integrated values of luteinizing hormone, follicle stimulating hormone, prolactin, growth hormone and thyroid stimulating hormone in normal and cryptorchid pubertal patients.

The sleep-wake behaviour of LH, FSH, PRI, GH and TSH was studied in seven cryptorchid patients (four unilateral and three bilateral cryptorchids) average age 12 years and in nine normal pubertal boys of 13 years (mean age). Blood samples were collected by a continuous withdrawal pump, every hour, for 24 h. The hormonal concentration for every fraction of time was measured and related to the sleep (Sc-), wake (Wc-) and total 24 h period (Dc-). The integrated concentrations of the corresponding periods (IS, IW, ID) were calculated as well as their ratios (IS/IW; IS/ID%). For GH and TSH, the data obtained demonstrated no differences between cryptorchid and pubertal subjects. The PRL secretion in cryptorchid patients was moderately increased during the hours of nocturnal sleep. A normal pubertal sleep-wake rhythm was found for gonadotrophins in both groups of subjects. More marked levels of LH secretion were observed in cryptorchid boys compared to normal pubertals. The presence of a sleep-wake rhythm was also found in the cryptorchid patients and normal pubertal subjects in the P 1 stage. These data suggest that the CNS "programme" which controls the onset of puberty may be normal in cryptorchid patients.

Adolescent↗
PubMed1978

Effect of luteinizing hormone-releasing hormone on the secretion of luteinizing hormone, follicle-stimulating hormone, and testosterone in adult male rhesus monkeys.

Plasma levels of radioimmunoreactive LH, FSH, and testosterone (T) were assayed before and after administration of synthetic gonadotropin-releasing hormone (GnRH) to five chair-restrained rhesus monkeys with chronic indwelling venous catheters. Intravenous injection of 1, 5, and 25 microgram or infusion of 1 microgram/min for 25 min of GnRH resulted in a significant increase in plasma levels of LH. However, no significant increases in plasma FSH levels were detected. Plasma levels of T were also elevated after administration of 25 microgram GnRH, but peak concentration of T lagged behind peak levels of LH by approximately 30 min. These studies indicate that the male rhesus responds to GnRH administration by increased secretion of LH, followed by an increase in T levels. A concomitant increase in plasma FSH was not observed after treatment with GnRH in the doses used.

Animals↗
PubMed1977

Serum growth hormone concentrations after growth hormone or thyrotropin releasing hormone in cows.

A single subcutaneous injection of 10, 50, or 100 mg bovine growth hormone into lactating Holstein cows increased concentrations of growth hormone, insulin, and glucose in serum above preinjection baselines for at least 16 h. Growth hormone concentrations in serum after injection of growth hormone or thyrotropin-releasing hormone were greater in cows during early (2 to 4 mo) as compared with cows during late (8 to 12 mo) lactation. Stage of lactation did not affect rate of metabolic clearance of growth hormone in eight cows, but larger cows cleared growth hormone more rapidly than smaller cows. Data of these experiments may help to explain how injections of growth hormone every 3 days stimulate milk yields.

Animals↗
PubMed1978

Changes in plasma luteinizing hormone-releasing hormone and gonadotropin concentrations during constant rate intravenous infusion of luteinizing hormone-releasing hormone in cyclic rats.

Further analysis has been made of the response of the rat pituitary gland to LHRH during the 4-day estrous cycle. LHRH was infused iv at a constant rate (50 ng/h) into phenobarbital-treated rats at different times during the estrous cycle. Infusion at this rate in proestrous rats simulates the rising and plateau phases of the spontaneous proestrous surges of LH and FSH in plasma. Plasma LH rose to similar heights during the "initial phase" of LH release (during the first 40 min of infusion) on the afternoons of estrus, diestrous day one, and proestrus and during the morning of proestrus. The increase during the afternoon of diestrous day two was significantly less than that in all the other groups. A similar response was seen in the case of FSH release. A "rapid rising" or "augmented" phase of LH release (during 40-120 min of infusion) was present in all groups and the magnitude of the response was greatest during the afternoon of proestrus. In the case of FSH, an augmented phase of release started 60 min after the start of infusion, and the response during the afternoon of proestrus was slightly greater than the responses measured at the other times tested. The responses on diestrous day one were not altered when phenobarbital was omitted or when rats were ovariectomized shortly before LHRH infusion. Other differences in the LH and FSH responses during both initial and augmented phases of release were seen in rats tested at different times during the estrous cycle with an LHRH infusion rate which caused a supraphysiological response on proestrus. The results suggest that 1) the initial rising phases in plasma LH and FSH during the spontaneous surges during proestrus are not the result of an increase in pituitary responsiveness to LHRH during the estrous cycle, 2) augmented phases of LH and FSH release can be elicited on all days of the estrous cycle, and 3) the increases in magnitude of the augmented phases of LH and FSH release on proestrus, as compared to those on other days of the cycle, are the result of an increase in pituitary responsiveness to LHRH during the estrous cycle.

Animals↗