Effects of seasonal adiposity on ovarian activity of Vespertilionid bat, Scotophilus heathi: Proteomics analysis

• Increased expression of metabolic enzymes in the ovary during hibernation phase (period of adiposity).
• Increased energy produced may be required for synthesis of excess androgen (A4) in the ovary of the bat during winter dormancy.
• 14-3-3 protein expression was found to be high in the ovary during winter dormancy.
• 14-3-3 protein expression was found to be positively correlated with survival marker and negatively with apoptotic markers.
• Adiposity associated rise in adipokines are responsible for increased expression of 14-3-3 protein in the ovary.

In present study comparative proteomics was utilized to identify ovarian protein profiles and correlate the expression of these proteins with adiposity induced changes in ovarian activity leading to suppression of ovulation (delayed ovulation) in the bat, S. heathi. To achieve this, two-dimension gel electrophoresis combined with protein identification by tandem mass spectrometry (LC–MS/MS) was applied. Protein profiles were obtained from intact ovaries of bats collected during recrudescence (basal body weight) and delayed ovulation (increased body weight) phases of reproductive cycle. Out of 42 differentially expressed protein spots, 15 protein spots were identified by LC–MS/MS. A majority of the 15 protein spots identified belonged to a group of enzymes within the glycolytic and citrate cycles. Greater concentrations of these enzymes were found during the period of delayed ovulation, which may be responsible for an increase in the production of ATP within the ovary. The increased metabolic activity and energy production observed within the ovary during winter dormancy may be required for increased steroidogenic activity during this period. The protein 14-3-3 identified by LC–MS/MS was verified by immunoblotting, which confirmed its increased expression during the period of delayed ovulation and may be associated with development of insulin resistance. Treatment with adipokines (adiponectin, resistin) is responsible for increased expression of 14-3-3 protein in the ovary of S. heathi. Adiposity-associated rise in adipokines are thus responsible for increased expression of 14-3-3 protein in the ovary of S. heathi, which may be responsible for prolonged survival of antral follicles and suppression of ovulation. The 14-3-3 protein may represent a new marker for adiposity associated ovarian anovulation (disorders).