Age-related Changes in Male Rat Reproductive Organ Weights and Plasma Testosterone Concentrations After Administration of a Monoamine Oxidase Inhibitor

Experiments were conducted to determine the effects of pargyline, a monoamine oxidase inhibitor, onmale rat reproductive organ weights, testicular histology, and plasma testosterone levels. Pargyline was administered to various groups of rats by implanting it, either dissolved or in a powder form, in Silastic tubing capsules. Additional rats were injected with pargyline solutions. The effects of pargyline.appeared to be age-related with younger animals, weighing under 400 gm (less than 100 days of age), showing a decrease in testicular and accessory organ weights and plasma testosterone. Older animals did not show a decrease in organ weights. Testicular histology in the pargyline-treated groups showed sloughage of cellular material into the tubular lumina, decreases in the number of cell layers, and a reduction of the number of mature spermatocytes. Other areas in the same testis were normal, however, and resembled control histology. The results suggest that pargyline can have detrimental effects on testicular function and that the effects may be age-related.