Inhibition of testicular testosterone biosynthesis following experimental varicocele in rats.

: In an attempt to determine whether defective testicular testosterone (T) biosynthesis may be associated with a varicocele, an experimental study was performed in adult rats whereby a unilateral left varicocele was surgically created. At 2, 4, 8, and 12 wk following the creation of the varicocele, intratesticular T as well as the activities of three (17 alpha-hydroxylase, 17,20-desmolase, and 17 beta-hydroxysteroid dehydrogenase) of the five enzymes in the delta 4 pathway of testicular T biosynthesis were measured. Intratesticular T (ng/g testis +/- SEM) in the left testis decreased significantly from 121 +/- 21 in the control group to 59 +/- 8 in the two-wk varicocele group (p less than 0.01), and remained significantly suppressed throughout the experimental period. The T concentrations in the right testis paralleled those in the left in both the control and varicocele animals. At 2 wk following the creation of the varicocele, the activity (nmol/min/testis +/- SEM) of the 17,20-desmolase enzyme decreased significantly, from 115 +/- 8 in the left testis of control rats to 87 +/- 6 in the left testis of the varicocele animals (p less than 0.025), and remained low throughout the 12 weeks of the study. The activity of the 17 alpha-hydroxylase enzyme was significantly decreased at the 8th and 12th weeks of the study, while the 17 beta-hydroxysteroid dehydrogenase activity did not show any significant change during the study period. The enzyme activities in the right testis paralleled those in the left testis.(ABSTRACT TRUNCATED AT 250 WORDS)