ICF-I treatment increases motility and improves morphology of immature spermatozoa in the GH-deficient dwarf (dw/dw) rat

It has recently been shown that short-term growth hormone (GH) treatment ca n increase the motility of spermatozoa in the GH-deficient dw/dw rat. To ex amine whether the effects of GH on motility of immature spermatozoa are med iated by an increase in plasma concentrations of IGF-I, we treated GH-defic ient dw/dw rats with 2 mu g/g/day of IGF-I using osmotic minipumps. Body we ight (saline 227+/-5 g, IGF-I 253+/-4 g) and IGF-I concentrations in blood plasma (saline 472+/-19.9 ng/ml, IGF-I 986+/-43.5 ng/ml) and seminal vesicl e fluid (saline 30.9+/-1.7 ng/ml, IGF-I 47.9+/-2.9 ng/ml) were significantl y increased with IGF-I treatment (P<0.001), similar to the observed respons es to GH therapy in our earlier study. While epididymal fluid IGF-I concent rations were not changed, IGF-I treatment significantly increased the numbe r of immature motile spermatozoa (saline 14.4+/-3.5%, IGF-I 28.3+/-4.1%, P< 0.05) and the number of spermatozoa with normal morphology (control 65.7+/- 3.3%, IGF-I 75+/-1.9%, P<0.05). These data suggest that increasing the circ ulating concentrations of IGF-I in the GH-deficient rat can improve the mot ility and morphology of immature spermatozoa and thus mimic, at least in pa rt, the effects of GH. (C) 1999 Harcourt Publishers Ltd.