CIRCADIAN-RHYTHM IN LEU-BETA-NAPHTHYLAMIDE HYDROLYZING ACTIVITY IN SELECTED PHOTONEUROENDOCRINE AREAS OF ADULT MALE-RATS

Soluble Leu-beta-naphthylamide hydrolysing activity (arylamidase activ ity) was assayed in retina, superior cervical ganglia, several brain a reas and serum of adult male rats, at different time points of a 12:12 h light:dark cycle (from 7h to 19h light). The results demonstrated a left or right biased asymmetrical distribution of this activity depend ing on the time point studied: While the levels of activity were signi ficantly higher in the left retina than in the right one at 10h of the light period, these were predominant in the right side, at 01h of the dark period. In addition, this activity was higher in the left hypoth alamus at 13h of the light period. No asymmetries were disclosed in th e rest of time points and structures studied. On the other hand, this activity demonstrated a diurnal variation in the left anterior hypotha lamus and total posterior hypothalamus but no periodic variation was e videnced in right anterior hypothalamus or the rest of zones studied. These results may reflect the role of this activity regulating the fun ctional status of its susceptible endogenous substrates.