Ovarian cholesterol dynamics in teleost Channa punctatus (Bloch): relationship with reproductive cycle and response to gonadotropins

Abstract

Thin-layer chromatography was employed to separate free and esterified cholesterol from total ovarian cholesterol in the teleost Channa punctatus. Results clearly showed that free cholesterol was almost double the concentration (5.37 ± 0.32 nmol/mg) of esterified cholesterol (2.67 ± 0.26 nmol/mg). An annual profile of free and esterified cholesterol determined per ovary showed that both altered in different months of the year although fluctuation was more prominent with free cholesterol. In contrast, the study in terms of per milligramovarian tissue, showed fluctuation of free cholesterol only. Among the pituitaries collected in different reproductive stages, prespawning pituitary extract had maximum depletive effect on ovarian total and free cholesterol in comparison to others. Ovine LH (1 μg/100 g body wt) could effectively induce the depletion of ovarian free cholesterol; the most remark-able effect was obtained with a similar dose of SG-G100 but there was insignificant alteration of esterified cholesterol. In hypophysectomized fish, SG-G100 in increasing doses (1 to 10 μg/100 g body wt) evoked a linear response in regard to the ovarian free cholesterol depletion. These findings contrast strikingly with reports on the mammalian ovary.