Meeting Abstract

P2.9  Tuesday, Jan. 5  Response of Carp Leptin to Acute Cold Shock COPELAND, Donald*; SHAH, Shilp; LONDRAVILLE, Richard/L; University of Akron; University of Akron; University of Akron londraville@uakron.edu

The cytokine hormone, leptin, is involved in several energetically costly processes including thermogenesis, reproduction, immune function, and bone remodeling. The pleiotropic nature of this peptide hormone has also led researchers to examine its role in cold acclimation. In mammals, cold exposure has been shown to negatively affect leptin mRNA and serum protein concentrations, though the physiological significance of this response is still unknown. Recently, the mammalian homologue of leptin has been discovered in the common carp (Cyprinus carpio). Although little is known about leptin signaling in fishes, cold shock is an established stressor in carp and it is expected to decrease leptin production similarly to mammalian cold exposure responses. We tested the effect of cold shock on leptin-I gene expression by exposing koi(an ornamented variety of carp) to 10°C cold shock for 30 and 360 minutes. Cold shock significantly reduced hepatic leptin expression at 30 minutes and 360 minutes compared to controls. However, at 360 minutes, leptin expression increased significantly compared to the 30 minute group. These results suggest that, similar to the mammalian response, cold shock antagonizes leptin expression by curtailing leptin mRNA expression. The consequent rise in expression at 360 minutes suggests that koi acclimate to cold shock relatively quickly. It is not known whether plasma leptin concentrations reflect the changes seen in gene expression however, we are currently developing an ELISA for leptin-I using recombinant carp leptin produced in BL21 cells.