THE ROLE OF MONOAMINEOXIDASE ISOZYMES ON RESERPINE INDUCED ADRENAL-HORMONE RELEASE IN THE PIGEON (COLUMBA-LIVIA)

The present investigation was performed to study the participation of the specific isozyme of mono-amineoxidase (MAO) during reserpine-modul ated release of medullary catecholamines (CAM). This was carried out b y pretreatments of pargyline and clorgyline followed by reserpine admi nistration. The findings revealed that the pigeon adrenal contained pr edominantly MAO-A. Blockade of type B activity by pargyline caused a s ignificant rise in adrenomedullary CAM content in reserpinized pigeons . However, clorgyline (an MAO-A inhibitor) administration followed by reserpine treatment showed no appreciable change in the medullary CAM level, suggesting that type B activity is mainly responsible for reser pine action on the adrenal medulla in the pigeon. In addition, reserpi ne was also able to decrease the glandular corticosterone content, whi le pargyline and clorgyline failed to alter this trend in reserpinized pigeons.