Declines in levels of hyperpolarization-activated cation (HCN) channels in the rat ovary after cisplatin exposure.

The distribution of the 4 hyperpolarization-activated cation (hyperpolarization-activated, cyclic nucleotide-gated [HCN]) channels (HCN1-4), channels associated with rhythmic electrical bursting, varies in the different cells of the ovary. Cisplatin is a broadly used chemotherapeutic agent that results in ovarian damage. The objective of this study was to test the hypothesis that cisplatin treatment will affect expression of the ovarian HCN channels. Adult female Sprague-Dawley rats were dosed with saline, 4.5 mg/kg cisplatin, or 6.0 mg/kg cisplatin as 2 weekly injections and then were killed 5 days after the second cisplatin dose. The ovaries were studied for HCN1-4 using semiquantitative H score immunohistochemical analysis and using Western blot analysis. By immunohistochemistry, for HCN4, the oocyte-specific staining declined after cisplatin treatment (P < .001). There was a decline in HCN2 intensity after cisplatin in the antral granulosa cells (P < .05) and thecal cells (P < .05). There were no differences found for the immunohistochemical HCN1 and HCN3 H scores after cisplatin. The Western blot analysis revealed that there was a decline in HCN3 levels after cisplatin exposure (P < .05). For HCN1 and HCN2, there was no change in the total ovarian protein levels after cisplatin. Treatment in vivo with cisplatin resulted in decline in the levels of the HCN channels in the rat ovary, with oocytes, antral cells, and thecal cells being specifically affected.