CALL FOR PAPERS Physiology and Pharmacology of Temperature Regulation Hypothermia-enhanced splenic cytokine gene expression is independent of the sympathetic nervous system

Ganta, Chanran K., Bryan G. Helwig, Frank Blecha, Roman R. Ganta, Richard Cober, Sujatha Parimi, Timothy I. Musch, Richard J. Fels, and Michael J. Kenney. Hypothermia-enhanced splenic cytokine gene expression is independent of the sympathetic nervous system. Am J Physiol Regul Integr Comp Physiol 291: R558–R565, 2006. First published February 9, 2006; doi:10.1152/ajpregu.00846.2005.— Splenic nerve denervation abrogates enhanced splenic cytokine gene expression responses to acute heating, demonstrating that hyperthermia-induced activation of splenic sympathetic nerve discharge (SND) increases splenic cytokine gene expression. Hypothermia alters SND responses; however, the role of the sympathetic nervous system in mediating splenic cytokine gene expression responses to hypothermia is not known. The purpose of the present study was to determine the effect of hypothermia on the relationship between the sympathetic nervous system and splenic cytokine gene expression in anesthetized F344 rats. Gene expression analysis was performed using a microarray containing 112 genes, representing inflammatory cytokines, chemokines, cytokine/chemokine receptors and housekeeping genes. A subset of differentially expressed genes was verified by real-time RT-PCR analysis. Splenic SND was decreased significantly during cooling (core temperature decreased from 38 to 30°C) in splenicintact rats but remained unchanged in sham-cooled splenic-intact rats (core temperature maintained at 38°C). Hypothermia upregulated the transcripts of several genes, including, chemokine ligands CCL2, CXCL2, CXCL10, and CCL20, and interleukins IL-1 , IL-1 , and IL-6. Gene expression responses to hypothermia were similar for the majority of cytokine genes in splenic-intact and splenic-denervated rats. These results suggest that hypothermia-enhanced splenic cytokine gene expression is independent of splenic SND.