INHIBIN BIOACTIVITY IN HUMAN TESTICULAR EXTRACTS

: Inhibin bioactivity was measured in human testicular extracts by a sensitive sheep pituitary cell bioassay. The relationship between testicular inhibin bioactivity, daily sperm production (DSP) and plasma concentrations of FSH, LH, testosterone and oestradiol were examined. The mean level of testicular inhibin bioactivity was 4.4 +/- 1.3 U/g (mean +/- SD) with a significantly lower value in those who received radiotherapy (3.2 +/- 1.4 U/g) than in the untreated group (4.8 +/- 1.1 U/g). In contrast to the rat, human testicular inhibin bioactivity was not significantly correlated to FSH or DSP. These findings suggest that inhibin may have a complex role in normal and/or pathological testicular function.