title: Increased self-administration of d-amphetamine by rats pretreated with metergoline.
abstract: Rats trained to self-administer d-amphetamine were pretreated with metergoline, a long-acting 5-hydroxytryptaminergic antagonist, and immediately placed in self-administration cages for 8 hours. During the first 3 hours after metergoline the normal pattern of d-amphetamine self-administration was unaltered, but thereafter the rate of self-injections was increased. Between 4 and 6 hr the self-injections in metergoline-treated rats were increased in a regular fashion and subsequently (7-8 hr) in a stereotyped manner, i.e., rapid bursts of lever presses with little space between injections. In amphetamine-naive rats the levels of striatal and nucleus accumbens dopamine metabolites, dihydroxyphenylacetic acid and homovanillic acid, rose with time after metergoline injection. Levels of 5-hydroxyindoleacetic acid remained unchanged in these brain areas. The neurochemical results suggest a correlation between the dopaminergic actions of metergoline and d-amphetamine self-administration.
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D003342:Corpus Striatum / Q000378:metabolism; D003913:Dextroamphetamine / Q000008:administration & dosage*; D004873:Ergolines / Q000494:pharmacology*; D006719:Homovanillic Acid / Q000378:metabolism; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D008711:Metergoline / Q000494:pharmacology*; D009714:Nucleus Accumbens / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012653:Self Stimulation / Q000187:drug effects*; D012701:Serotonin / Q000378:metabolism
chemical_list: D004873:Ergolines; D015102:3,4-Dihydroxyphenylacetic Acid; D008711:Metergoline; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D003913:Dextroamphetamine; D006719:Homovanillic Acid