Changes in body mass,serum leptin,and mRNA levels of leptin receptor isoforms during the premigratory period in <Emphasis Type="Italic">Myotis lucifugus</Emphasis> |
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Authors: | Kristy L Townsend Thomas H Kunz Eric P Widmaier |
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Institution: | (1) Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA |
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Abstract: | Migration and hibernation in mammals may be preceded by a period of leptin resistance, which may in part account for the increasing
adiposity and body mass that occurs during these periods. We hypothesized that hypothalamic expression of leptin receptor
mRNA would decrease during the premigration (PM) period in the little brown myotis, Myotis lucifugus. Body mass of M. lucifugus increased during the PM period, but serum leptin levels did not change during that time. Hypothalamic mRNA levels for both
the short (ObRa) and fully active long (ObRb) forms of the leptin receptor increased during PM, but the relative increase
in ObRa was larger and occurred sooner than ObRb. mRNA levels of an inhibitor of leptin signaling (protein inhibitor of activated
STAT3: PIAS3) increased in hypothalami during the PM period in bats. Adiponectin is an adipokine that has been linked to obesity
in rodents; normally, serum levels of adiponectin decrease in obesity. In M. lucifugus, adiponectin mRNA levels decreased in adipose tissue during the period of mass gain, but circulating adiponectin levels did
not change. We conclude that the relative changes in leptin receptor isoform expression during the PM fattening period may
favor binding of leptin to the less active short isoform. Coupled with increased expression of PIAS3 and the dissociation
of serum leptin levels from body mass and adiposity, these changes could account in part for the adaptive fattening during
the PM period. In addition, the adipokine profiles of M. lucifugus during the PM period and that of obesity in non-hibernating mammals are strikingly dissimilar. |
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Keywords: | Little brown myotis Hypothalamus Adiponectin ObRa ObRb |
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