The effects of cortical ablation on multiple unit activity in the striatum following dexamphetamine.
Bilateral removal of the fronto-parietal cortex of the rat resulted in decreased spontaneous multiple-unit activity recorded in the striatum of freely-moving rats. Cortical ablations changed the neuronal response in the striatum to systemic administration of dexamphetamine (2.5 mg/kg i.p.) from excitation in control animals (88%) to inhibition in ablated animals (61%). Furthermore, catalepsy, induced by haloperidol, but not by morphine, was markedly attenuated after cortical ablation. These changes were accompanied by a 23% decrease in the specific binding of [3H]spiperone in the striatum. The binding of [3H]met-enkephalin was unaffected by the cortical lesions. Levels of glutamate in the striatum decreased from 8.88 +/- 0.5 mumols/g in control animals to 6.93 +/- 0.37 mumols/g after bilateral cortical ablation. On the other hand, cortical ablations did not alter the content of either the gamma-aminobutyric acid or glutamine of the striatum. It is concluded that the excitatory response, observed in striatal neurons in freely-moving animals, is dependent upon an intact cerebral cortex and requires intact cortico-striatal afferents. The results further suggest that neurons in the striatum are under the tonic influence of glutamate, released from cortico-striatal afferents. Lastly, some dopamine D2 binding sites in the striatum are located on cortico-striatal afferent terminals and blockade of these striatal D2 sites may be involved in the induction of catalepsy by neuroleptic drugs.
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D003342:Corpus Striatum / Q000187:drug effects / Q000502:physiology*; D003913:Dextroamphetamine / Q000494:pharmacology*; D004594:Electrophysiology; D004744:Enkephalin, Methionine / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D006220:Haloperidol / Q000494:pharmacology; D008297:Male; D009410:Nerve Degeneration; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D051381:Rats
D005971:Glutamates; D018698:Glutamic Acid; D004744:Enkephalin, Methionine; D006220:Haloperidol; D003913:Dextroamphetamine