AJP - Regulatory, Integrative and Comparative Physiology, Vol 269, Issue 1 215-R221, Copyright © 1995 by American Physiological Society
Glossopharyngeal nerve transection does not compromise the specificity of taste-guided sodium appetite in rats
S. Markison, S. J. St John and A. C. Spector
Department of Psychology, University of Florida, Gainesville 32611-2250, USA.
The chorda tympani nerve (CT) has been shown to be critical in the
sodium-specific drinking behavior of sodium-depleted rats, but the role of
other gustatory nerves and the contribution of the major salivary glands
remain to be elucidated. In this study, rats received either bilateral
section of the CT (CTX) or the glossopharyngeal nerve (GLX), extirpation of
the sublingual and submaxillary salivary glands (DSAL), or sham surgery.
After recovery, rats were sodium depleted with furosemide and tested for
their licking responses to 0.05 and 0.3 M NaCl, KCl, CaCl2, and NH4Cl, as
well as distilled water in an automated gustometer. Rats that received GLX
maintained a specific sodium appetite comparable to controls despite
denervation of approximately 64% of the taste buds. In contrast, compared
with control rats, CTX and DSAL rats had altered response profiles, showing
much smaller differences in licking to NaCl relative to the other stimuli.
This was accompanied by a substantially lower lick rate in DSAL rats,
raising the possibility that general licking impairments contributed to the
decreased NaCl responsiveness in these rats. These findings imply that the
CT, but not the glossopharyngeal nerve, is necessary for the maintenance of
normal sodium-specific, taste-guided behavior under sodium deplete
conditions.
