Plasma cortisol response to thyrotrophin releasing hormone and luteinizing hormone releasing hormone in healthy kennel dogs and in dogs with pituitary-dependent hyperadrenocorticism

1982 ◽  
Vol 93 (3) ◽  
pp. 365-369 ◽  
Author(s):  
R. Stolp ◽  
R. J. M. Croughs ◽  
J. C. Meijer ◽  
A. Rijnberk

The change in the plasma concentration of cortisol after the administration of thyrotrophin releasing hormone (TRH) and LH releasing hormone (LH-RH) was studied in normal dogs and in dogs with pituitary-dependent hyperadrenocorticism (PDH). The normal dogs showed a small but significant increase in the plasma concentration of cortisol 15 min after intravenous injection of TRH and LH-RH. In ten of the dogs with PDH the response to TRH was not significantly different from that in the normal dogs, but in 13 the response was significantly greater. In 15 of the dogs with PDH the response to LH-RH administration was within or below the range of responses in the normal dogs and in only one dog was the response to LH-RH greater than that in the normal dogs. These findings are discussed in relation to the pathogenesis of PDH.

1982 ◽  
Vol 92 (1) ◽  
pp. 141-146 ◽  
Author(s):  
R. L. MATTERI ◽  
G. P. MOBERG

During treatment with cortisol or ACTH, dairy heifers were given two doses of LH releasing hormone (LH-RH) spaced 1·5 h apart. Serum concentrations of cortisol and LH were monitored during each treatment. Treatment with both ACTH and cortisol raised plasma cortisol levels above the respective saline controls (P<0·001). Neither treatment affected basal LH concentrations. A slight depression in LH response was seen in the cortisol-treated animals after the first LH-RH injection, as shown by a statistically significant depression at three of the sample times. There was no significant difference between treated and control LH values after the second LH-RH administration. Treatment with ACTH resulted in significantly reduced LH values at all sample times after both injections of LH-RH.


1977 ◽  
Vol 73 (1) ◽  
pp. 37-52 ◽  
Author(s):  
B. T. DONOVAN ◽  
M. B. TER HAAR

SUMMARY Heterologous radioimmunoassays for FSH and LH were employed to examine the effect of synthetic LH-RH upon gonadotrophin secretion in the ferret. Intravenous injection of 4 μg LH-RH induced a surge of FSH and of LH secretion in male and in female animals. In intact and in castrated males, the rise of LH was much more marked than that of FSH. The gonadotrophin response to LH-RH was greater in anoestrous than in oestrous females; FSH secretion was not enhanced during oestrus. Ovariectomized females behaved as anoestrous females with respect to LH secretion, while FSH secretion remained unchanged. Treatment of ovariectomized females with progesterone did not alter the pattern of response to LH-RH, but oestradiol treatment depressed the reaction to match that seen in oestrous females. Repetitive injections of LH-RH induced repetitive surges of FSH and LH in anoestrous females, but only of LH during oestrus: slow i.v. infusion of LH-RH induced a sustained elevation of plasma LH levels both in oestrous and in anoestrous females; again FSH levels rose only in anoestrous females. Injection of synthetic TRH did not alter gonadotrophin secretion in corresponding groups of male or female ferrets.


1982 ◽  
Vol 94 (2) ◽  
pp. 283-287 ◽  
Author(s):  
G. Fink ◽  
W. J. Sheward ◽  
H. M. Charlton

We have investigated the LH response to LH releasing hormone (LH-RH) in female hypogonadal (hpg) mice in which the hypothalamus contains no LH-RH and the pituitary gland contains significantly less LH than in normal mice. Both the releasing action and the priming effect of LH-RH were not significantly different in hpg compared with normal mice. Raised plasma concentrations of oestradiol-17β reduced pituitary responsiveness to LH-RH in normal but not in hpg mice. These results show that in the mouse neither longterm exposure to normal levels of LH-RH nor a normal pituitary content of LH are necessary for either the releasing or the priming action of LH-RH.


1977 ◽  
Vol 75 (1) ◽  
pp. 175-176 ◽  
Author(s):  
R. GOLDSTEIN ◽  
S. PAVEL

Institute of Endocrinology, Bucharest, Rumania (Received 29 March 1977) The mammalian pineal gland contains (Pavel, 1965) and synthesizes (Pavel, Goldstein, Ghinea & Calb, 1977) the nonapeptide arginine-vasotocin (AVT). Since luteinizing hormone releasing hormone (LH–RH), thyrotrophin releasing hormone (TRH) and growth hormone release-inhibiting hormone (somatostatin, SRIF) have now been localized not only in the brain, but also in the pineal gland (White, Hedlund, Weber, Rippel, Johnston & Wilber, 1974; Pelletier, Le Clerc, Dube, Labrie, Puviani, Arimura & Schally, 1975), we investigated the effects of these peptides on the release of AVT into the cerebrospinal fluid (CSF) of cats. Intracarotid injections of 0·1 μg LH-RH, TRH (Hoechst, Frankfurt), SRIF (Serono, Rome) or oxytocin (Syntocinon, Sandoz Ltd, Basel) in 0·5 ml saline were given to urethane-anaesthetized male cats weighing 3–4 kg. Controls received an equal volume of saline only. The pineal glands were removed 60 min after the injections, quickly homogenized, and extracted


1974 ◽  
Vol 62 (3) ◽  
pp. 639-643 ◽  
Author(s):  
G. G. MURTHY ◽  
R. R. MODESTO

SUMMARY The effects of luteinizing hormone releasing hormone (LH-RH) and thyrotrophin releasing hormone (TRH) on rabbit adipose tissue were studied. LH-RH increased [14C]glucose oxidation and incorporation into fatty acids and had lipolytic activity, at the same time decreasing [14C]glucose incorporation in glyceride—glycerol fractions. TRH had no significant effect on glucose oxidation or lipolysis but decreased [14C]fatty acid synthesis and [14C]glucose incorporation into glyceride—glycerol fractions.


1976 ◽  
Vol 81 (1) ◽  
pp. 1-8 ◽  
Author(s):  
K. Maeda ◽  
Y. Kato ◽  
N. Yamaguchi ◽  
K. Chihara ◽  
S. Ohgo ◽  
...  

ABSTRACT The effect of thyrotrophin-releasing hormone (TRH) or luteinizing hormone-releasing hormone (LH-RH) on plasma levels of growth hormone (GH), prolactin (PRL), thyrotrophin (TSH), and luteinizing hormone (LH), were studied in patients with anorexia nervosa. The basal plasma GH levels were elevated in 6 of 11 patients studied. Intravenous injection of synthetic TRH (500 μg) significantly raised the plasma GH levels in 9 of 11 patients. The peak values of plasma GH after TRH ranged from 6.0 to 31.5 ng/ml. Plasma GH concentrations also increased following the administration of synthetic LH-RH (100μg) in 1 of 7 patients. The intravenous injection of saline solution caused no significant change in plasma GH in these patients. The plasma LH responses to LH-RH were significantly blunted in all patients, whereas the plasma PRL and TSH responses to TRH were almost normal in the patients examined. These results suggest that the hypothalamo-pituitary function regulating GH and LH secretion is altered in patients with anorexia nervosa.


1974 ◽  
Vol 75 (4) ◽  
pp. 625-635 ◽  
Author(s):  
S. L. Jeffcoate ◽  
H. M. Fraser ◽  
D. T. Holland ◽  
A. Gunn

ABSTRACT A radioimmunoassay for luteinizing hormone-releasing hormone (LH-RH) has been developed. Antisera were raised against the decapeptide conjugated to albumin in rabbits and against the 3-10 octapeptide conjugated to albumin in rats. LH-RH was iodinated with 125I and purified on Sephadex, the most immunoreactive fractions of the 125I-LH-RH being eluted after 125I. A serum assay was developed using a simple methanol extraction procedure. The rabbit antiserum could detect levels of LH-RH in the jugular vein of the sheep at various times and in the rat on the afternoon of pro-oestrus. The assay using the rat antiserum was 30 times more sensitive and could detect LH-RH in peripheral serum in man. 10-20 pg/ml in peripheral serum of man, but the RIA could be used to measure the disappearance and clearance of LH-RH after intravenous injection of large test doses (Jeffcoate et al. 1974a). In this study we describe the details of a RIA of LH-RH in serum from man, sheep and rat.


1977 ◽  
Vol 86 (3) ◽  
pp. 517-521
Author(s):  
A. D. B. Harrower ◽  
P. L. Yap ◽  
E. H. D. Cameron ◽  
G. P. Lidgard

ABSTRACT The effect of luteinizing hormone - releasing hormone (LH-RH) and insulin-induced hypoglycaemia on the release of thyrotrophin (TSH) was studied in five patients with primary hypothyroidism. All five patients had elevated TSH levels with an exaggerated rise in response to thyrotrophin-releasing hormone (TRH). No rise over control values was found after LH-RH or insulin indicating that despite the augmentation of TSH release in primary hypothyroidism there is no alteration of the specificity of the thyrotroph response.


1982 ◽  
Vol 93 (1) ◽  
pp. 75-81 ◽  
Author(s):  
S. A. Whitehead ◽  
J. M. Pennington ◽  
D. A. Carter

Changes in pituitary responses to pulses of LH releasing hormone (LH-RH) after ovariectomy in the rat have been investigated with an in-vitro perifusion system. On the third day after ovariectomy there was a large increase in the responsiveness of the pituitary gland to LH-RH compared with days 1 and 2 and this preceded the first significant rise in circulating concentrations of LH. Exaggerated responses were observed on all subsequent days tested (days 4, 6, 10, 18 and 28) although the size of the response on day 10 was significantly lower compared with days 6, 18 or 28. It is suggested that the early phase of increased pituitary responsiveness to LH-RH results from a rise in pituitary LH-RH receptors, which increases both the synthesis of LH and the response to exogenous LH-RH. The reduced LH response, measured on day 10, may correlate with an increase in the endogenous secretion of LH-RH and an imbalance between LH synthesis and secretion at this time.


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