AJP - Regulatory, Integrative and Comparative Physiology, Vol 263, Issue 3 596-R601, Copyright © 1992 by American Physiological Society
Effective loci and roles of acetylcholine in temperature regulation of goldfish
L. I. Crawshaw and L. P. Wollmuth
Department of Biology, Portland State University, Oregon 97207.
Microinjections of acetylcholine (ACh) and carbachol were made into
discrete forebrain loci in goldfish (Carassius auratus) to evaluate the
importance of cholinergic mechanisms for behavioral thermoregulation.
Injections of 5, 10, 25, and 50 micrograms ACh into the far anterior
nucleus preopticus periventricularis (NPP) (R. Peter and V. Gill. J. Comp.
Neurol. 159: 69-102, 1975) and immediately adjacent ventral telencephalon
led to consistent dose-dependent decrease in selected temperature. No
effect was observed following injections of 2 micrograms ACh or 0.7% NaCl.
Injections of ACh into a different portion of the ventral telencephalon led
to increases in the selected temperature. Lower doses of carbachol (0.5 and
1.0 micrograms) injected into the NPP produced decreases in selected
temperature similar to the highest doses of ACh. Injections of ACh into
loci other than those mentioned above either had no thermoregulatory effect
or had lesser thermoregulatory effects which, in comparison with injections
into the most effective sites, were inconsistent and required larger doses
to obtain. The site where cholinergic stimulation led to decreases in the
selected temperature exactly overlapped the effective site of ethanol
hypothermia in the goldfish.
