Seasonal adiposity, correlative changes in metabolic factors and unique reproductive activity in a vespertilionid bat, Scotophilus heathi.

ABSTRACT

The aim of this study was to determine the effect of changes in body mass, fat reserves and feeding activity on circulating levels of lipids, glucose, protein and metabolic hormones in a vespertilionid bat, Scotophilus heathi. Furthermore, the relationship between changes in metabolic factors and hormones with the unique reproductive features of female S. heathi was also examined. The results of this study showed annual variation in body mass, fat reserve and feeding activity, which correlated significantly with circulating levels of lipids, protein and metabolic hormones. Increased corticosterone level during September-October in S. heathi promotes increased feeding activity, which in turn induces hyperinsulinemia in S. heathi during November. Hyperinsulinemia together with low body temperature in November facilitates fat accumulation in bat. Coinciding with the period of fat accumulation raises serum leptin level, which has been demonstrated to suppress ovarian activities thus causing delayed ovulation in S. heathi. Circulating levels of lipids were high during winter dormancy, which may provide energy to stored sperms. The study thus suggests that the unique reproductive features of female vespertilionid bat are strongly linked to fat deposition.