Absence of desensitization by hexarelin to subsequent GH releasing hormone-mediated GH secretion in patients with anorexia nervosa
DESIGNThe GH stimuli used were hexarelin (1 μg/kg i.v.), a GH stimulus whose main action is hypothalamic, followed 120 minutes later by GHRH (1 μg/kg i.v.) as a pituitary stimulus. Each woman was tested once.
PATIENTSThirty-two women matched for age participated in the study: six normal-weight women as controls, 14 women with anorexia nervosa, seven women with secondary amenorrhoea due to voluntary weight loss for aesthetic reasons, and five normal-weight women after 72 hours of a controlled hypocaloric diet (800 cal/day).
MEASUREMENTSPlasma GH levels were measured by time-resolved fluoroimmunosasay, each value shown is the mean±SE in mU/l.
RESULTSThe administration of hexarelin to the normal-weight women induced a clear-cut GH secretion (expressed as mean±SE of GH peak in mU/l of 77.5±21.8, but blocked the GH-releasing capability of GHRH administered 120 minutes later (6.6±2.8, P<0.05). In contrast, the women with anorexia nervosa showed a normal GH response after the two stimuli: hexarelin 64.8±9.2. GHRH 71.1±14.2. The absence of heterologous desensitization was specific to anorexia nervosa, because the women with amenorrhoea due to voluntary weight loss but with a normal energy intake showed a pattern similar to the controls (GH after hexarelin 60.3±9.5 and to GHRH 120 minutes later 6.2±1.0 (P<0.05)). Similarly, the women after the short-term hypocaloric diet showed a hexarelin-mediated GH secretion of 99.6±17.8, which blunted the subsequent administration of GHRH (GH mean peak of 9.9±2.9, P<0.05 vs hexarelin).
CONCLUSIONSIn the normal subjects, the administration of hexarelin induced clear-cut GH secretion, but inhibited the action of GHRH when administered 120 min later, while this heterologous desensitization was not observed in the patients with anorexia nervosa. This sequentially delayed test may be of some value in the clinical setting for assessing the status of patients with anorexia nervosa.
Document Type: Research Article
Affiliations: 1: Institute of Endocrinology, University Clinical Centre, Belgrade, Yugoslavia, the Department of 2: Medicine, Faculty of Medicine and Complejo Hospitalario de Santiago, Santiago de Compostela University, Santiago de Compostela, Spain 3: Physiology and
Publication date: May 1, 1997