Neuronal responses of the globus pallidus to systemic administration of d-amphetamine: investigation of the involvement of dopamine, norepinephrine, and serotonin.
Systemic administration of d-amphetamine (d-AMP) caused significant increases in the unit activity of spontaneously firing neurons in the rat globus pallidus. Intravenous injection of 0.2 mg/kg of d-AMP produced an average increase of 32% while a cumulative dose of 6.4 mg/kg of d-AMP increased cell firing 81% above base line control. The excitatory effects of d-AMP on pallidal cells were effectively blocked and reversed by haloperidol. Increasing intravenous doses of l-amphetamine (l-AMP), totaling 12.8 mg/kg, caused a slight excitation of pallidal neurons. The average maximum increase was 18.3%. Minor rate-elevating effects were also observed after systemic administration of desmethylimipramine and clonidine. The serotonin uptake inhibitor, fluoxetine, produced varied changes in firing frequencies. Pretreatment with reserpine and alpha-methyl-p-tyrosine significantly attenuated the d-AMP-induced increase in pallidal activity. These results suggest that dopamine plays a prominent role in mediating the stimulatory effects of d-AMP on the firing rates of a population of globus pallidus cells in gallamine-paralyzed rats.
D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D003891:Desipramine / Q000494:pharmacology; D003913:Dextroamphetamine / Q000494:pharmacology*; D004298:Dopamine / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004336:Drug Antagonism; D005917:Globus Pallidus / Q000187:drug effects / Q000502:physiology*; D006220:Haloperidol / Q000494:pharmacology; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology*; D051381:Rats; D012701:Serotonin / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000037:antagonists & inhibitors; D019805:alpha-Methyltyrosine
D008781:Methyltyrosines; D012701:Serotonin; D019805:alpha-Methyltyrosine; D014446:Tyrosine 3-Monooxygenase; D006220:Haloperidol; D003000:Clonidine; D003891:Desipramine; D003913:Dextroamphetamine; D004298:Dopamine; D009638:Norepinephrine