237 POTASSIUM CONCENTRATION AND mRNA LEVELS OF POTASSIUM CHANNELS DECREASED IN CYSTIC OVARIAN FOLLICLE FLUID

Abstract

Cystic ovarian follicle (COF) is one of the most frequently diagnosed ovarian diseases and a major cause of reproductive failure in cattle. Despite an abundance of reports on this subject, the exact pathogenesis of COF still remains unclear. It is generally accepted that disruption of the hypothalmo-pituitary-gonadal axis, by endogenous and/or exogenous factors, causes cystic formation. We here examined whether ion concentration and expression of ion channels are altered in the follicle fluid derived from a Korean native cow with COF. In an ovary with a cystic follicle, granulosa cell layers were exfoliated; the theca interna was thinner than that in an ovary without cystic follicle, based on histological examination. Concentrations of K⁺, Na⁺, and Cl^- in COF fluid (COFF) were 10.4 ± 3.5 mM, 138 ± 12 mM, and 104.9 ± 7.0 mM, respectively. In COFF, K⁺ concentration showed a significant difference from the value observed in normal follicle fluid (NFF) (P < 0.05; NFF: 10.4 ± 3.5 mM vs. COFF: 6.2 ± 0.8 mM). The total numbers of follicles observed (normal, 3–5 mm in diameter vs. COF, 20–30 mm in diameter) were 200 and 20 in normal and COF, respectively. To compare mRNA expression of K⁺ channels, we performed semiquantitative RT-PCR using follicle fluid and ovaries with or without cystic follicles. RT-PCR showed that mRNA levels of TASK channels (TASK-1, TASK-3, and TASK-5) decreased by 50% in COFF and an ovary with cystic follicles compared to NFF and a normal ovary. TASK channels are involved in apoptosis of mammalian cells. Our results suggest that potassium may play an important role in the pathogenesis of COF.