[Effects of met-enkephalin on the testis. III. Histoenzymatic study]

We studied the testis of Wistar rats weighing 280-300 gms. following the administration of a single, acute intracardiac dose of methionine-enkephalin (100 microliters of 50% met-enkephalin solution), or a chronic intramuscular dose (50 microliters of 40% met-enkephalin solution). Rats were sacrificed at 15, 30 and 60 minutes following acute injection. Those on chronic treatment were injected once daily for 10 or 20 days. For the study, we utilized 105 male Wistar rats; 30 comprised the control group, and 75 comprised the study group. The following staining methods were used: 1) succinate dehydrogenase, 2) lactate dehydrogenase, 3) ATPase, 4) acid phosphatase, 5) alkaline phosphatase. We observed marked histoenzymological changes in the rat testis. Particularly noteworthy was a marked change in the energy pathways consisting of a decreased activity of aerobic pathways (decreased SDH activity), increased anaerobic activity (increased LDH activity), and consequently, decreased cellular energy stores (decreased ATPase activity). Similarly, changes were observed in other nonspecific enzymes that led to a fall in acid phosphatase activity and a rise in alkaline phosphatase activity.