EFFECT OF INSULIN-LIKE GROWTH-FACTORS (IGFS) AND IGF-BINDING PROTEINSON IN-VITRO SPERM MOTILITY

OBJECTIVE Previous studies have shown that exogenous growth hormone (G H) produces increases in sperm motility when given to subfertile men. Previous studies have also demonstrated the presence of IGFs and IGFBP s in seminal plasma. We have therefore investigated the effects of ins ulin-like growth factor-I (IGF-I), IGF-II, IGF-binding protein 2 (IGFB P-2) and intact IGFBP-3 on in vitro sperm motility, DESIGN AND METHODS Using computer-aided sperm analysis, we investigated the effects of I GFs and IGFBPs on the in vitro sperm motility parameters: curvilinear velocity (CV), progressive velocity (PV), linearity (Ln), straightness (St), amplitude of lateral head movement (ALH), and beat frequency (B F), Washed motile sperm selected by the 'swim-up' method, from normozo ospermic samples, were incubated at 37 degrees C in 5% CO2 in air with IGF-I, IGF-II, IGFBP-2, IGFBP-3, or control Earle's media, and were e xamined at time 0 and after 60 min incubation. Changes in motility par ameters after 60 min incubation were compared with controls by analysi s of variance (ANOVA). RESULTS Compared to controls, statistically sig nificant changes occurred at time 60 min after incubation: IGF-I decre ased CV and ALH significantly (P<0.05), but IGFBP-3 increased Ln, St, BF, and decreased ALH significantly (P<0.05). In contrast, IGF-II, IGF BP-2, and a combination of IGF-I/IGFBP-3, had no significant effects. CONCLUSIONS IGF-I and IGFBP-3 have differing and opposing effects on i n vitro sperm motility parameters and thus may have a role in modulati ng in vivo sperm motility.