Simple microradiometric technique for the rapid measurement of monoamine oxidase activity in rat testicular minced and teased-tubular preparations

The reproductive cycle of male uinta ground squirrels: some anatomical and biochemical correlates

1. Maximum testicular development and plasma testosterone levels occurred at spring emergence from aestivation-hibernation (A-H), followed by a regression to basal state in June. 2. A slight testicular recrudescense occurred just prior to immergence into A-H, but this development was not accompanied by a definitive increase in plasma testosterone levels or seminal vesicle weights. 3. Four lines of evidence were consistent with the hypothesis that FSH stimulates testicular MAO activity. 4. Changes in pituitary and hypothalamic MAO activity suggested a functional role for this enzyme in controlling releasing factor and gonadotropin production by these organs.

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.

Monoamine oxidase activity of the hypothalamus and pituitary: alterations after pinealectomy, changes in photoperiod, or additions of melatonin in vitro

Rat pituitary MAO activity was reduced by constant darkness and by additions of melatonin in vitro and was increased by constant light and by pinealectomy. Hypothalamic MAO activity followed the same pattern but was less dramatically affected. The data suggest that MAO may be a target enzyme for melatonin.

Inhibition of rat spermatogenesis and seminiferous tubule growth after short-term and long-term administration of a monoamine oxidase inhibitor

Seminiferous tubules from rats killed 24 hours after injection of pargyline, a monoamine oxidase inhibitor, did not grow well in tissue culture when compared to control tubules. Treated tubules showed severe tubular degeneration and loss of cellular detail after nine days in culture. Animals injected with pargyline for ten days had varying degrees of semi-niferous tubule degeneration with depletion of the spermatogenic elements. It is suggested that pargyline has a detrimental effect on spermatogenesis. Pargyline possibly acts by decreasing MAO levels which, in turn, may increase potentially damaging amines which may be responsible for the testicular damage.