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The Journal of Experimental Biology 205, 3513-3518 (2002)
Copyright © 2002 The Company of Biologists Limited

Discrete electrolytic lesion of the preoptic area prevents LPS-induced behavioral fever in toads

Kenia C. Bicego and Luiz G. S. Branco*

Department of Physiology, Dental School of Ribeirao Preto and Department of Physiology, Faculty of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Sao Paulo, Brazil

* Author for correspondence (e-mail: branco{at}forp.usp.br)

Accepted 5 August 2002

The preoptic area (POA) plays an important role in fever in mammals, but the role of this region in fever in ectothermic vertebrates has never been assessed. Toads, like all ectotherms, regulate their body temperature (Tb) primarily by behavior and develop behavioral fever when injected with lipopolysaccharide (LPS). Therefore, we tested the hypothesis that the POA plays a role in the behavioral fever induced by LPS in the toad Bufo paracnemis. We made electrolytic lesions in the POA of toads (0.3 mA, 8 s) and measured preferred Tb using a thermal gradient. After a period of 24h inside the gradient chamber, control, sham-operated and lesioned toads were systemically injected with LPS (200 µg kg-1) or pyrogen-free saline. There was no significant effect of POA lesion in animals at their normal preferred Tb. LPS caused a significant increase in preferred Tb of control and sham-operated toads, but lesions in the POA abolished this response. These results indicate that the POA is an important site in the central nervous system of toads, and perhaps of all vertebrates, involved in the development of fever.

Key words: behavioral thermoregulation, amphibian, Bufo paracnemis, thermoregulatory set point






© The Company of Biologists Ltd 2002