Biphasic nature of the effects of delta9-tetrahydrocannabinol on body temperature and brain amines of the rat.
The effects of i.v. injected delta9-tetrahydrocannabinol (delta9-THC) on behaviour, body temperature and levels of brain monoamines, measured spectrophotofluorimetrically, of the rat were determined. Doses of delta9-THC in the range of 0.05--5.0 mg/kg produced biphasic changes in behaviour, body temperature and levels of 5-hydroxyindoleacetic acid (5-HIAA). The whole brain levels of dopamine (DA), noradrenaline (NA) and 5-hydroxytryptamine (5-HT) were not altered by delta9-THC. The subjective behavioural biphasic responses did not appear to be dose related, whereas the biphasic changes in body temperature and brain levels of 5-HIAA were dose-related. Low doses of delta9-THC (0.05 and 0.1 mg/kg) caused hyperthermia, while doses of 1.0, 2.0 and 5.0 mg/kg induced hypothermia. On the other hand, 0.05 mg/kg delta9-THC significantly reduced, whereas doses of 1.0, 2.0 and 5.0 mg/kg significantly increased the 5-HIAA levels in a dose-related manner. It is concluded that an inverse relationship exists between delta9-THC-induced changes in body temperature and alterations in brain 5-HIAA levels.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001679:Biogenic Amines / Q000378:metabolism*; D001831:Body Temperature / Q000187:drug effects*; D001923:Brain Chemistry / Q000187:drug effects*; D013759:Dronabinol / Q000008:administration & dosage / Q000494:pharmacology*; D006897:Hydroxyindoleacetic Acid / Q000032:analysis; D008297:Male; D051381:Rats; D013997:Time Factors
D001679:Biogenic Amines; D006897:Hydroxyindoleacetic Acid; D013759:Dronabinol