Lys- and Tyr-arylamidase activities in serum and brain during the estrous cycle of the rat.

Peptidase enzymes are involved in neuropeptide processing or degradation. In order to analyse a possible functional participation of these enzymes, arylamidase activity of several rat brain regions and serum was assayed in the soluble fraction during the estrous cycle using L-Lys- and L-Tyr-beta-naphthylamide as substrates. Significant differences were present in the hypothalamus, the pituitary and serum when both substrates were used. However, there were no differences in cortical areas. These results suggest a role for arylamidase activity in the hormonal changes that happen during the estrous cycle of the rat.