GROWTH-HORMONE (GH) THERAPY MARKEDLY INCREASES THE MOTILITY OF SPERMATOZOA AND THE CONCENTRATION OF INSULIN-LIKE GROWTH-FACTOR-I IN SEMINAL-VESICLE FLUID IN THE MALE GH-DEFICIENT DWARF RAT

There is increasing evidence for an important role of the somatotropic axis in male reproductive function. We investigated the effect of rec ombinant bovine GH (rbGH) treatment for 21 days on semen characteristi cs in post-pubertal GH-deficient dwarf (dw/dw) rats. Male dw/dw rats a t an age of 75-80 days were divided into two groups (n=10 per group) a nd injected twice per day with either rbGH (2 mu/g/day) or saline. Whi le the concentration (96.4+/-51.3 x10(6) per mi) and morphology of spe rmatozoa (spermatozoa with normal morphology 73.5+/-6.3 %) in the dw/d w rat were within the normal range, the motility of spermatozoa was ve ry low (27.5+/-11.7 %), establishing a state of sub-fertility. The rbG H treatment markedly increased (p<0.01) motility of spermatozoa (44.5/-10.7 %) but did not change the concentration (144+/-80.3 x10(6) per mi) and morphology (spermatozoa with normal morphology 79.5+/-6.0 %). The rbGH treatment also significantly increased the concentration of i nsulin-like growth factor-I (IGF-I) in blood plasma (control 389.1+/-6 5 ng/ml, rbGH 813.9 ng/ml, p<0.001) and in seminal vesicle fluid (cont rol 11.3+/-3.0 ng/ml, rbGH 16.1+/-5.4 ng/ml, p<0.05). We conclude that rbGH therapy markedly increases motility of spermatozoa in sub-fertil e male GH-deficient dw/dw rats. Thus, GH therapy may offer considerabl e potential for the treatment of impaired male reproductive performanc e.