1. ¹Laboratory of Pharmacology, Instituto Butantan, São Paulo, Brazil
2. ²Department of Neurosciences and Behavior, Universidade de São Paulo, São Paulo, Brazil

Correspondence: Paulo F. Silveira (pefesil@butantan.gov.br)

Received 13 February 2009; Accepted 27 September 2009; Published online 29 October 2009.

Abstract

Biometric parameters, glycemia and activity levels of plasma neutral aminopeptidase (APN) and dipeptidyl peptidase IV (DPPIV) were measured in monosodium glutamate obese and food-deprived rats (MSG-FD), to analyze the involvement of these enzymes in such situations. Plasma APN was distinguished as sensitive (PSA) (K_m = 7.8 10^-5 mol/l) and predominantly insensitive (APM) (K_m = 21.6 10^-5 mol/l) to puromycin, whereas DPPIV was sensitive (DPPIV-DS) (K_m = 0.24 10^-5 mol/l) and predominantly insensitive (DPPIV-DI) (K_m = 7.04 10^-5 mol/l) to diprotin A. Although unchanged in the MSG and food-deprived animals, APM activity levels were closely correlated with body mass, Lee index, and mass of retroperitoneal fat pad in the food deprived, but not in the MSG animals. DPPIV-DI activity levels decreased by 33% and were correlated with body mass, Lee index, and mass of periepididymal fat pad in the food-deprived MSG rats. These data suggest that APM and DPPIV-DI are respectively related to the downregulation of somatostatin in food-deprived rats, and to the recovery of energy balance in MSG obese rats during food deprivation.