Premium
Effect of environmental temperature on the turnover of 5‐hydroxytryptamine in various areas of rat brain
Author(s) -
Simmonds M. A.
Publication year - 1970
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1970.sp009268
Subject(s) - pargyline , hypothalamus , preoptic area , medicine , endocrinology , serotonin , turnover , monoamine oxidase , striatum , chemistry , endogeny , cerebral cortex , hippocampus , cortex (anatomy) , midbrain , biology , dopamine , central nervous system , neuroscience , biochemistry , enzyme , receptor , management , economics
1. Rats were exposed to environmental temperatures of 9, 24 or 32° C and the turnover of 5‐hydroxytryptamine (5‐HT) was estimated in various areas of brain by two different methods in separate series of experiments. In the first method, small amounts of tritium labelled 5‐HT, [ 3 H]5‐HT, were injected into the c.s.f. in order to label radioactively the endogenous 5‐HT in the brain. The rates of disappearance of [ 3 H]5‐HT from discrete areas of brain were taken as indices of the rates of turnover of endogenous 5‐HT in these areas. In the second method, the rate of accumulation of endogenous 5‐HT after inhibition of monoamine oxidase by pargyline was taken as an estimate of 5‐HT turnover. 2. The results obtained by each method were in agreement. The turnover of 5‐HT increased with increasing environmental temperature from 9 to 32° C in specific brain areas. During the first hour of exposure to 32° C, the turnover of 5‐HT increased in the preoptic area, hypothalamus and cortex + hippocampus, but not in striatum or midbrain. During the subsequent 2 hr at 32° C, however, the turnover of 5‐HT in the preoptic area and hypothalamus fell while that in the striatum showed a delayed rise. 3. It is concluded that 5‐HT is involved in several different cerebral pathways which increase their activity upon exposure of the rat to heat. These pathways are not located exclusively in the preoptic area and hypothalamus.