UNIT-ACTIVITY IN MEDIAL THALAMUS - COMPARATIVE EFFECTS OF CAFFEINE AND AMPHETAMINE

  • 1 January 1980
    • journal article
    • research article
    • Vol. 213  (3) , 580-585
Abstract
The effects of caffeine and d-amphetamine sulfate were evaluated on single unit activity of medial thalamus in chloral hydrate anesthetized rats. Single unit activity was recorded extracellulary with PI microelectrodes. Caffeine, 0.1-0.5 mg/kg i.v., suppressed and amphetamine, 0.1-1 mg/kg i.v., augmented the spontaneous firing rates of medial thalamic neurons. Amphetamine was capable of activating the medial thalamic neuronal activity while it was suppressed by caffeine. While the firing rate was increased by a previous amphetamine injection, administration of caffeine suppressed the amphetamine-induced augmentation of neuronal activity. The 2 CNS stimulants, caffeine and amphetamine, may have different mechanisms of action at least at the medial thalamic site. Its medial thalamus participates in the recruitment phenomenon and exerts a stabilizing action on the cerebral cortex, that caffeine suppressed this brain area suggest that the medial thalamus may be an important site of action for the arousal induced by caffeine. The inhibitory effects of caffeine on the medial thalamus and excitatory effects on brain stem reticular formation from previous studies indicate that caffeine has differential actions on different brain areas. Caffeine may excite at all levels of the CNS including inhibition of inhibitory influences in at least 1 functional system of the brain.