[Influence of 4-aminopyridine on human ovarian luteinized granulosa cell proliferation, production, and apoptosis through inhibiting voltage-gated K+ channel].

Objective: To study the influence of 4-aminopyridine (4-AP) on proliferation, production, and apoptosis through inhibiting voltage-gated K(+) channel (Kv) in ovarian luteinized granulosa cells.

Methods: Ovarian luteinized granulosa cells were recovered from 25 women with regular menses who underwent in vitro fertilization programme. The cultured granulosa cells were divided into 4 groups:blank group, 4-AP treated group, human chorionic gonadotropin (hCG)-induced group and hCG + 4-AP co-treated group. The final concentrations of hCG and 4-AP were 1250 U/L and 5 nmol/L respectively. The progesterone production was detected by the chemoluminescence method. The expression of Kv mRNA on human ovarian luteinized granulosa cell was detected by RT-PCR. The influence on the early apoptosis of granulosa cells by 4-AP was observed by flow cytometry. Cellular caspase-3 activities were observed with colorimetric method and the inhibition of the cell proliferation was studied using methyl thiazolyl tetrazolium (MTT) method.

Results: (1) Kv mRNA was expressed in granulosa cell. (2) The progesterone production of the blank group, 4-AP treated group, hCG-induced group and hCG + 4-AP co-treated group were (547 +/- 64), (206 +/- 32), (1991 +/- 172) and (763 +/- 79) nmol/L, respectively after 24 hours culture. Exposure of the granulosa cells to 4-AP reduced the production of progesterone in blank and hCG-induced granulosa cells. (3) The flow cytometry analysis and the cellular caspase-3 A(405) showed that 4-AP increased the percentage of early phase apoptosis (P < 0.01): 4-AP treated group vs blank group [(40 +/- 5)% and 0.049 +/- 0.009] vs [(17 +/- 4)% and 0.029 +/- 0.008], hCG + 4-AP co-treated group vs hCG-induced group [(25 +/- 4)% and 0.039 +/- 0.008] vs [(15 +/- 3)% and 0.022 +/- 0.007]. (4) 24 hours after treated with 4-AP and hCG, the inhibitory rate of cultured granulosa cells of 4-AP treated group was higher than the blank group (19.7% vs 0), and that of hCG + 4-AP co-treated group was obviously higher than hCG-induced group (34.6% vs 0, P < 0.01).

Conclusions: The voltage-gated K(+) channels expressed by ovarian luteinized granulosa cell play an important role in cell proliferation, production, and apoptosis. 4-AP may inhibit differentiation of progesterone in granulosa cells through the inhibition of proliferation and induction of apoptosis.