| Abstrakt: |
The effects of methamphetamine on tritiated and endogenous norepinephrine metabolism was examined in various regions of brain. In acute experiments, 30 minutes or 5 hours after methamphetamine i.p., 3H-norepinephrine was injected into the cisterna magna. In chronic experiments, rats were administered increasing doses of methamphetamine twice a day for 17 days, then 18 hours after the last dose of methamphetamine, 3H-norepinephrine was injected intracisternally. All rats were killed 5 minutes after the intracisternal injection and their brains removed, dissected into five parts and assayed for endogenous norepinephrine, 3H-norepinephrine and its metabolites. In rats treated acutely, methamphetamine caused a significant block in uptake of 3H-norepinephrine and a marked increase in the content of 3H-normetanephrine in all regions except the cortex. Five hours after methamphetamine administration, increased levels of 3H-norepinephrine occurred in the pons-medulla, whereas endogenous norepinephrine content tended to decrease in most regions. In rats treated chronically, enhanced accumulation of 3H-norepinephrine was also confined to the pons-medulla region, whereas endogenous levels of norepinephrine were high in the pons-medulla and low in the hypothalamus and cortex. These data suggest that chronic administration of methamphetamine affects either catecholaminergic nerve cell bodies or nerve terminals in the pons-medulla differentially, as compared to other regions studied. |
