FIGURE 1.

α7 nicotinic acetylcholine receptor mediates ACh, ZP, or PNU282987 but not calcium Ca²⁺-ionophore-induced acrosome reaction. Sperm from WT or α7-null mice (MUT) (D) were incubated in capacitation medium for 1.5 h. A, α-BgT (20–100 nm) or MLA (20–100 nm) was added for the last 30 min of incubation in capacitation medium, and then ZP (∼7.5 egg ZP/μl) or PNU (5 μm) was added for an additional 30 min. B, α-BgT (100 nm) or MLA (100 nm) was added for the last 30 min of incubation in capacitation medium, and then ACh (250 μm), calcium ionophore (ion) (A23187, 10 μm), ZP (∼7.5 ZP/μl), or PNU (5 μm) was added for an additional 30 min. C, after 1.5 h of incubation in capacitation medium, ZP (∼1.5/7.5 ZP/μl), PNU (1/5 μm), or ACh (125/250 μm) was added, as shown on the graph, for an additional 30 min. D, after 1.5 h of incubation in capacitation medium, ZP (∼1.5 or 7.5 ZP/μl), PNU (1/5 μm), ACh (125/250 μm), phorbol 12-myristate 13-acetate (PMA, 100 ng/ml), 8-Br-cAMP (1 mm), or calcium ionophore (A23187, 10 μm) was added for an additional 30 min. Sperm samples were smeared on slides for acrosome reaction determination as described under “Experimental Procedures.” The data represent the mean ± S.D. of duplicates from at least three experiments. *, significant difference from the corresponding control (cont), p < 0.05. **, significant difference from the corresponding inducers (ZP or PNU) p < 0.05.