Seasonal adiposity and delayed ovulation in a vespertilionid bat, Scotophilus heathi: role of tumor necrosis factor-alpha.
The aim of this article was to evaluate the physiological significance of tumor necrosis factor-alpha (TNF-alpha) in seasonal accumulation of adipose tissue, hyperinsulinemia, and anovulation in Scotophilus heathi. The result showed seasonal variations in the circulating TNF-alpha level. A higher level of circulating TNF-alpha was observed during quiescence and recrudescence, whereas a lower level of TNF-alpha was observed during winter dormancy and the preovulatory period. An increased circulating TNF-alpha level coincided closely with accumulation of adipose tissue and hyperinsulinemia. Immunocytochemical localization of TNF-alpha in the ovary showed immunoreactivity mainly in the oocytes and theca-interstitial cells. The oocytes of small and medium-sized follicles showed strong TNF-alpha immunostaining, whereas weak immunoreactivity was observed in the large antral follicles. The atretic follicles showed mild TNF-alpha immunostaining. TNF-alpha immunoreactivity in the ovary was slightly higher during the quiescence and preovulatory periods compared with the periods of recrudescence and winter dormancy. TNF-alpha alone significantly increased androstenedione and estradiol production by the ovary in vitro but did not augment the luteinizing hormone (LH)-induced androstenedione production. However, TNF-alpha did augment LH-induced estradiol production. The results of this study suggest the involvement of TNF-alpha in the interaction among adipose tissue accumulation, insulin resistance, and ovarian activity in S. heathi.
Chanda
Diptiman
D
Reproductive Physiology Unit, Department of Zoology, Banaras Hindu University, Varanasi-221 005, India.
Abhilasha
Krishna
Amitabh
A
D000273:Adipose Tissue / Q000378:metabolism*; D000735:Androstenedione / Q000378:metabolism; D000818:Animals; D000858:Anovulation / Q000378:metabolism / Q000662:veterinary*; D001823:Body Composition / Q000502:physiology*; D002685:Chiroptera / Q000033:anatomy & histology / Q000502:physiology*; D004958:Estradiol / Q000378:metabolism; D030762:Estrous Cycle / Q000097:blood; D005260:Female; D006946:Hyperinsulinism / Q000503:physiopathology / Q000662:veterinary*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007986:Luteinizing Hormone / Q000502:physiology; D010053:Ovary / Q000033:anatomy & histology / Q000378:metabolism; D034445:Ovulation Inhibition / Q000502:physiology*; D012621:Seasons; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
D014409:Tumor Necrosis Factor-alpha; D000735:Androstenedione; D004958:Estradiol; D007986:Luteinizing Hormone