AJP - Regulatory, Integrative and Comparative Physiology, Vol 264, Issue 6 1133-R1138, Copyright © 1993 by American Physiological Society
Vasopressin release within the ventral septal area of the rat brain during drug-induced antipyresis
M. F. Wilkinson and N. W. Kasting
Department of Physiology, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
The techniques of push-pull perfusion and radioimmunoassay were used to
determine concentrations of arginine vasopressin (AVP) in extracellular
fluid derived from the ventral septal area (VSA) of the rat brain following
antipyresis elicited by acetaminophen or indomethacin in conscious and
unrestrained rats. Reduction of bacterial lipopolysaccharide (LPS)-induced
fever by intraperitoneal indomethacin resulted in significant increases in
AVP levels in VSA perfusion fluid (P < 0.05). In contrast, antipyresis
after acetaminophen treatment was without significant effect on AVP output
from VSA nerve terminals. In control animals (non-pyrogen treated), body
temperature rose in apparent response to the perfusion procedure. Despite
this elevation in core temperature, subsequent treatment with acetaminophen
or indomethacin did not result in significant changes in AVP release from
VSA perfusates. We conclude that AVP release into VSA extracellular fluids
following intraperitoneal indomethacin is dependent upon the neuronal
sequelae inherent to pyrogen-evoked fever and not nonspecific rises in body
temperature. These results support the hypothesis that endogenous AVP,
acting within the VSA, participates in the neuronal mechanisms mediating
indomethacin-induced antipyresis.
