Changes in circulating insulin and corticosterone concentrations during different reproductive phases and their relationships to body weight and androstenedione concentration of maleScotophilus heathi

Abstract

The aim of the present study was to determine the serum levels of insulin and corticosterone during different reproductive stages in a natural population of the male bat, Scotophilus heathi and their relationship to body weight and androstenedione level. Changes in body weight were marked by weight gain before winter dormancy and weight loss during winter dormancy. Circulating insulin level varied significantly over the season and correlated positively with changes in body weight and androstenedione level. Circulating corticosterone level also varied significantly over the season but correlated negatively with changes in body weight and androstenedione level. High corticosterone level during August coincided with a period of increased feeding activity in this species. The results suggest that insulin may act as an anabolic agent to promote fat deposition and corticosterone exerts a predominantly fat‐mobilizing influence. A high insulin level prior to winter dormancy may be an important factor responsible for inducing high androstenedione concentration shown in Scotophilus heathi. J. Exp. Zool. 281:201–206, 1998. © 1998 Wiley‐Liss, Inc.

Seasonal variation of energy reserves and reproduction in neotropical free-tailed bats Molossus molossus (Chiroptera: Molossidae)

“…Although glycogen has an important role in energy homeostasis, several bat species rely mainly on lipid reserves to support reproductive activities (Kunz et al, 1998;Krishna et al, 1998;Srivastava and Krishna, 2007;2008). The data obtained here seem to indicate that lipid reserves of male M. molossus remained unaltered in all seasons, except for the adiposity index.…”

“…It has been reported that insect-eating bats are able of fly while foraging powered by exogenous (dietary nutrients) rather than endogenous sources (glycogen or lipids) (Voigt et al, 2010). Reproductive activity in insect-eating bats also seems to require great energy expenditure, but this is based mainly on body lipid reserves stored during the previous seasons (Kunz et al, 1998;Krishna et al, 1998;Srivastava and Krishna, 2007;2008).…”

Seasonal glucocorticoid responses to capture in wild free-living mammals

“…Although glucocorticoid concentrations from these studies are clearly not baseline, because of the potentially large variation in the time individual animals have been in traps, it is difficult to interpret stress-induced concentrations. Nevertheless, most studies report seasonal differences in stress-induced glucocorticoid concentrations, but, as with baseline concentrations, some species, including male yellow-pine chipmunks (54), show a seasonal nadir during breeding (3,29,31,38,41,48), some, including golden-mantled ground squirrels (12), show a seasonal peak during breeding (1,11,30,48), and some, including female yellow-pine chipmunks (37), show no seasonal differences (2,10,28,69). In addition, most (7,16,52), but not all (49), captive studies with nontraditional laboratory animals show seasonal glucocorticoid variation.…”

Physiological biomarkers of Hendra virus infection in Australian Flying-foxes (Pteropus spp.)

“…Plasma glucocorticoid measurement has been employed in numerous chiropteran studies (Krishna et al 1998, Srivastava and Krishna, 2008, Allen et al 2010, Lewanzik et al 2012. Studies of Pteropus species have found that cortisol is the primary glucocorticoid occurring in plasma (Widmaier and Kunz 1993, Widmaier et al 1994, b Reeder et al 2004, and that animals exhibit significant elevations in plasma glucocorticoid levels in response to restraint stress.…”

“…Plasma glucocorticoid measurement has been employed in numerous chiropteran studies (Krishna et al 1998, Srivastava and Krishna, 2008, Lewanzik et al 2012, and cortisol is recognised to be the primary plasma glucocorticoid in Pteropus species Kunz 1993, Reeder et al 2006). …”