Growth Hormone Response to Thyrotropin-Releasing Hormone in Diabetes*

Abstract

The effect of TRH on GH secretion was assessed in 13 insulin-dependent diabetics. PRL and TSH responses to TRH were also determined. Glycosylated hemoglobin levels and serial fasting glucose concentrations indicated that all but 1 of the patients had a period of poor diabetic control for several months before the study. Peak PRL and TSH levels after TRH injection in these diabetic patients did not differ significantly from values observed in nondiabetic individuals. Six of the patients responded to TRH with a significant rise in GH levels; basal GH concentrations were also elevated in these patients. Five of the 6 responders and none of the nonresponders had proliferative diabetic retinopathy. The results suggest that diabetics with elevated basal GH levels hyperrespond to TRH, and that nonspecific secretion of GH in response to TRH occurs in some patients with proliferative diabetic retinopathy. Chronic hyperglycemia does not appear to be the critical factor in determining this response.

Preoperative growth hormone response to thyrotropin-releasing hormone and oral glucose tolerance test in acromegaly: A retrospective evaluation of 50 patients

“…20,21 However, the GH response to TRH can be also observed in normal subjects after pharmacological manipulation of the complex interactions between the hypothalamus and pituitary or in various pathological situations, other than acromegaly, in which an alteration of these relationships could be present. [2][3][4][5][6][7][8][9] The mechanism of this response in acromegaly remains unknown. A direct pituitary-stimulating action 22 and an indirect effect mediated via a decrease in the hypothalamic release of somatostatin or an increase in GHreleasing hormone (GHRH) secretion 12,23 have been proposed as possibilities.…”

“…Some investigators ascribed this paradoxical response to the presence of adenomatous tissue, with de-differentation and the appearance of specific receptors for TRH. 1 On the other hand, a GH response to TRH has been illustrated in other pathological conditions, 2 including renal failure, 3 depression, 4 anorexia nervosa, 5 primary hypothyroidism, 6 insulin-dependent diabetes mellitus, 7 schizophrenia, 8 and aging. 9 This GH response to TRH, absent in normal subjects, 10 is of diagnostic importance in acromegaly: as suggested in our previous study, 11 an increased "somatostatinergic" tone is conceivable in diseases with increased GH levels.…”

Suppression of Growth Hormone and Somatomedin C by Long-Acting Somatostatin Analog SMS 201–995 in Type I Diabetes mellitus

“…In addition, a dampening effect on GH oscillations may also favorably influence the course of diabetes. Thus, GH levels in type I diabetics are significantly increased when measured basally [26,27] or after exercise [28] , and show an abnormal stimulatory re sponse to thyrotropin-releasing hormone [29] , In controlled clinical trials diabetic ret inopathy could be brought to a halt by hypophysectomy and deprivation of GH [30], It is of interest to mention that raised SM-C levels have been brought in connection with the development of retinopathy in diabetics [10,31], although such relationship has been contested in a recent study [32]. However, excessive GH or SM-C production cannot be considered to be its sole cause since retinop athy does not occur with particular fre quency in acromegalic patients.…”

TSH and PRL Responses to Domperidone and TRH in Men with Insulin-Dependent Diabetes Mellitus of Different Duration

“…TSH and PRL responses to metoclopramide, an antidopaminergic agent, have been tested to prove this hypothesis [ 18], However, because of its interactions with other ncurotransmitters such as serotonin [20,21,26,34] or acetyl choline [3,12,19,25,26,43], mctoclopramide does not seem to be just an antagonist of dopamine. Furthermore, data in the litera ture describing TSH and PRL alterations in IDDM are scant and often contradictory, since decreased [9,18], increased [1,22] or unchanged [6,10,13,15,24,30,32,33,38,40,42] circulating levels of these hormones have been reported. These discrepancies might be due to inappropriate selection of subjects: in some studies subjects have been chosen without regard to their sex and, in others, regardless of the duration of their dis ease.…”