Differential influence of recombinant non-glycosylated and glycosylated glycodelin on human sperm function: comparative studies with hamster spermatozoa

Glycodelin, also known as placental protein 14, has been implicated in endometriosis-related infertility. To determine the role of glycodelin and its glycosylated state, the influence of recombinant nonglycosylated-glycodelin (nongly-glycodelin) and glycosylated-glycodelin (gly-glycodelin) on human sperm function was evaluated. Whereas there was a significant (P<0.001) increase in the capacitation of nongly-glycodelin-treated spermatozoa compared with untreated controls (28.8 +/- 1.0% v. 21 +/- 1.5% respectively), treatment of spermatozoa with gly-glycodelin markedly (P<0.001) inhibited capacitation (10.7 +/- 0.3%); acrosome reaction (AR) remained unaltered in all treatments. In a zona-free hamster egg penetration assay, the egg penetration index was higher (P<0.001) with nongly-glycodelin-treated spermatozoa (3.4 +/- 0.3) than with gly-glycodelin-treated spermatozoa (0.4 +/- 0.1) and untreated spermatozoa (1.6 +/- 0.2). A similar influence of glycodelin on capacitation was observed with hamster spermatozoa. However, the AR rate was higher (P<0.01) in nongly-glycodelin-treated spermatozoa (39.4 +/- 1.6%) than in either gly-glycodelin-treated spermatozoa (19.3 +/- 2.0%) or untreated controls (30.0 +/- 1.2%). Moreover, the in vitro fertilization rate was significantly (P<0.01) higher with nongly-glycodelin treated-spermatozoa compared with untreated spermatozoa (77.5 +/- 2.3% v. 52.9 +/- 4.3%) and gly-glycodelin-treated spermatozoa (38.3 +/- 6.5%; P<0.05). These results indicate that whereas nongly-glycodelin improves, gly-glycodelin inhibits, capacitation and fertilization potential of human and hamster spermatozoa, and that the glycosylation status of glycodelin determines its influence on sperm function.