Dissociation of leptin secretion and adiposity during prehibernatory fattening in little brown bats

Abstract

Hibernating animals deposit adipose tissue before hibernation to withstand long periods of reduced energy intake. Normally, adiposity is positively correlated with increased secretion from adipose tissue of the satiety hormone, leptin. During the prehibernatory phase of the little brown bat, Myotis lucifugus, body mass and adiposity increased to a maximum within 12 days. Leptin secretion from adipose tissue in vitro and plasma leptin, however, increased before the increase in adiposity, then significantly decreased when adiposity increased. Basal metabolic rate (BMR) decreased when plasma leptin was increasing. This was followed by an increase in nonshivering thermogenic capacity and brown adipose tissue mass. We conclude that in the early prehibernatory phase, BMR decreases despite increasing plasma leptin levels, suggesting a state of relative leptin resistance at that time. At later stages, adiposity increases as BMR continues to decrease, and plasma leptin becomes dissociated from adiposity. Thus, in M. lucifugus, hibernation may be achieved partly by removing the metabolic signal of leptin during the fattening period of prehibernation.

Adiposity associated rise in leptin impairs ovarian activity during winter dormancy in Vespertilionid bat, Scotophilus heathi

“…In other vespertilionid bat, Myotis lucifugus, plasma leptin level decreased during late pre-hibernating period when adiposity was highest (Kronfeld-Schor et al 2000). Dissociation between leptin level and body adiposity, as seen in M. lucifugus, was not observed in the present study in S. heathi.…”

“…In baboons, bats, and humans, the placenta is a major source of circulating leptin level during pregnancy (Hoggard et al 2000, Kronfeld-Schor et al 2001. The conservation of hyperleptinemia during pregnancy across mammalian orders implies a fundamental role of leptin either in the maintenance of pregnancy or preparation for lactation (Kronfeld-Schor et al 2000).…”

Obese super athletes: fat-fueled migration in birds and bats

“…Furthermore, bats may feed before or during nocturnal migratory flight, thus using both endogenous and ingested fuels for flight . Seasonal fat storage for migration could potentially be regulated by the leptin signaling system, which has been shown to be important during fattening of bats prior to hibernation (Kronfeld-Schor et al, 2000). Much basic research with captive and wild bats on the fundamental aspects of lipid storage and metabolism during migration remains to be undertaken.…”

Thermogenesis, food intake and serum leptin in cold-exposed lactating Brandt's volesLasiopodomys brandtii

“…It should be noted that, although serum leptin levels decrease little in lactating voles exposed to cold, food intake was further increased compared with that in the warm, which may suggest that the lactating voles were much sensitive to the levels of leptin. Compared with cold-active mammals, hibernators ignore 'satiety signal' of leptin to allow extreme fat deposition during prehibernatory period (Kronfeld-Schor et al, 2000).…”