Aminopeptidase activities after water deprivation in male and female rats

Aminopeptidases (APs) play a major role in the metabolism of circulating an d local peptides, such as angiotensins and vasopressin, substances involved in the control of blood pressure and water balance. In the present work. w e studied the influence of dehydration on angiotensinases and vasopressin-d egrading activity. Since sex differences may exist in the regulation of wat er balance by angiotensin II and differential sexual steroid modulation of vasopressin secretion, in response to osmotic stimulation have been reporte d. gonadotropin releasing hormone (GnRH)-degrading activity was also analys ed in serum, neurohypophysis and adrenal glands of male and female rats. Ou r results did not suggest sex differences in the response to changes in osm olality. GnRH-degrading activity decreased in serum of dehydrated males and females, which suggests a longer action of the peptide under these conditi ons. In neurohypophysis, there was an increase in the activity of aminopept idase A (APA), the enzyme responsible for the metabolism of angiotensin If to angiotensin III. This occurs with a decrease in alanyl aminopeptidase ac tivity, which would lead to a prolonged action of angiotensin III by reduct ion of its metabolism. In adrenals of dehydrated animals. the results would imply a high degree of metabolism of angiotensin III and vasopressin. (C) 2001 Elsevier Science B.V. All rights reserved.