Changes in the expression of HSL and OCTN2 in the female reproductive tract of the bat, Scotophilus heathii in relation to sperm storage.

The aim of this study was to compare the changes in the expression of hormone sensitive lipase (HSL) and organic cation transporter 2 (OCTN2) in different regions of the female reproductive tract of bats (Scotophilus heathii) during the period of sperm storage. Western blot analysis revealed that both HSL and OCTN2 showed elevated expression in the utero-tubal junction, the site of sperm storage, compared to the vagina, cervix and uterus. An immunohistochemical study showed localization of HSL and OCTN2 in the cytoplasm of luminal epithelial cells in the utero-tubal junction of S. heathii, which suggests a role of fatty acids metabolism at the site of sperm storage. Furthermore, this study showed the presence OCTN2 immunostaining in the tail of stored sperm, which suggests a direct role of carnitine in sperm physiology. However, the role of carnitine in sperm storage needs further investigation. It is hypothesized that the utero-tubal junction may be finely tuned with fat depletion to support sperm storage in the female genital tract of S. heathii.