Hippocampal 8-[3H]hydroxy-2-(di-n-propylamino) tetralin binding site densities, serotonin receptor (5-HT1A) messenger ribonucleic acid abundance, and serotonin levels parallel the activity of the hypothalamopituitary-adrenal axis in rat.
We have previously demonstrated that susceptibility of the Lewis rat to inflammatory disease, compared with the relatively resistant Fischer F344/N rat, is related to a hyporesponsive hypothalamopituitary-adrenal axis to inflammatory and other stress mediators. Because serotonin (5-HT) and the 5-HT1A receptor are important stimulators of this axis, we have investigated the levels of 8-[3H]-hydroxy-2,3-(di-n-propylamino)tetralin binding sites, 5-HT1A mRNA, 5-HT, and 5-hydroxyindoleacetic acid in various brain regions of Lewis, outbred Harlan Sprague Dawley, and Fischer F344/N rats. Lewis rats expressed significantly fewer hippocampal and frontal cortical 8-[3H]-hydroxy-2,3-(di-n-propylamino)tetralin binding sites and less 5-HT1A mRNA than Harlan Sprague Dawley and Fischer F344/N rats. Adrenalectomy increased the number of 8-[3H]hydroxy-2,3-(di-n-propylamino)tetralin binding sites and 5-HT1A mRNA expression in the hippocampus of all three strains. Levels of hippocampal 5-HT in Fischer F344/N rats were significantly greater than levels detected in the same regions from Lewis and Harlan Sprague Dawley rats. Hypothalamic 5-HT and 5-hydroxyindoleacetic acid levels in Harlan Sprague Dawley rats were higher than the same area from the other two strains. Adrenalectomy increased the levels of 5-hydroxyindoleacetic acid in the hypothalamus of all three strains. We conclude that hippocampal 5-HT1A receptor densities and 5-HT levels in the rat parallel the activity and responsiveness of the hypothalamopituitary-adrenal axis.
Burnet
P W
PW
Unit on Neuroendocrine Immunology and Behavior, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892.
Mefford
I N
IN
Smith
C C
CC
Gold
P W
PW
Sternberg
E M
EM
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000315:Adrenalectomy; D000818:Animals; D001665:Binding Sites; D005260:Female; D006624:Hippocampus / Q000378:metabolism*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D010913:Pituitary-Adrenal System / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000235:genetics*; D012701:Serotonin / Q000378:metabolism*; D013764:Tetrahydronaphthalenes / Q000378:metabolism*
D012333:RNA, Messenger; D011985:Receptors, Serotonin; D013764:Tetrahydronaphthalenes; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin