Alterations in brain dopamine and serotonin metabolism during the development of tolerance to human beta-endorphin in rats.
Repeated intracisternal injections of human beta-endorphin lead to development of tolerance with respect to the catalepsy, analgesia, and hypothermia which are seen following a single injection. The initial injection of beta-endorphin results in increases in the dopamine metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), in neostriatum, as well as increases in the serotonin metabolite, 5-hydroxyindoleacetic acid (5-HIAA), in hypothalamus and brainstem and a decrease in 5-HIAA in hippocampus. In the present study, we report changes in metabolism of dopamine and serotonin in specific brain areas during the development of tolerance to beta-endorphin. Thus, the development of tolerance to beta-endorphin with respect to catalepsy, analgesia, and hypothermia may be mediated by development of tolerance to the effects of beta-endorphin on brain dopamine and serotonin release.
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000700:Analgesics; D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002375:Catalepsy / Q000139:chemically induced; D004298:Dopamine / Q000378:metabolism*; D004361:Drug Tolerance; D004723:Endorphins / Q000494:pharmacology*; D006719:Homovanillic Acid / Q000378:metabolism; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D051381:Rats; D012701:Serotonin / Q000378:metabolism*; D013997:Time Factors
D000700:Analgesics; D004723:Endorphins; D015102:3,4-Dihydroxyphenylacetic Acid; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D004298:Dopamine; D006719:Homovanillic Acid