Alterations with Age in Rat Seminiferous Tubule Monoamine Oxidase Activity when Compared with Whole Testicular Tissue

Abstract

Monoamine oxidase, a deaminating enzyme, (MAO, monoamine: O₂ oxidore-ductase [deaminating] EC. 1.4.3.4.) is normally present in the rat testes (1-3). Testicular MAO activity has been studied in rats during the late embryonic and the early postnatal periods (4). Seminiferous tubules had more MAO activity during the early postnatal period than did tubules from slightly older animals. The most intense MAO activity was observed in the testes of the neonate and foetuses during the late embryonic period (4). Recently MAO activity was found to be high in testicular preparations from neonatal animals, was reduced in preparations from slightly older animals, was elevated during sexual development, and decreased again with advanced age (after 365 days) (5). Testicular MAO activity was also found to be positively correlated with changes in andro-gen synthesis and testicular development with respect to aging (5). There have been no attempts to separate the seminiferous tubules from the interstitial elements of the testes and to follow MAO activity simultaneously in these two tissues with age. We therefore desired to determine the relative amounts of MAO activity in these miniferous tubules and whole testicular tissue in animals of various ages. We also wanted to determine the localization of testicular MAO activity.

Materials and Methods. Male rats (Sprague-Dawley strain) were maintained under controlled conditions in an animal laboratory. The temperature was maintained at 72°F and the approximate relative humidity was 32 %. Artificial lights were used 12 hr each day followed by 12 hr of darkness. Rats used for the following studies were sacrificed by decapitation and their testes quickly removed, decapsulated, and prepared for later assay as described below.