Evidence for the participation of nigrotectal γ-aminobutyrate-containing neurones in striatal and nigral-derived circling in the rat

摘要: Abstract The γ-aminobutyrate-containing nature of nigrotectal neurones and the possible involvement tectum in circling behaviour were investigated rat. Electrolytic or kainic acid lesions substantia nigra reduced γ-aminobutyrate levels on average by 19–29% intermediate deep, but not superficial superior colliculus. Placement injection muscimol (40 ng) into these γ-aminobutyrate-innervated layers colliculus gave only weak ipsilateral posturing that was intensified apomorphine, which strongly antagonized contraversive apomorphine-induced 6-hydroxydopamine pretreated rats (lateral > medial sites). Contraversive to unilateral intranigral significantly attenuated injections placed ipsi- contralateral Picrotoxin tetanus toxin (30 mouse LD 50 doses) evoked explosive motor from vigorous when injected lateral latter offset ipsiversive asymmetries kainate (0.8 μg) corresponding nigra. Bilateral intratectal picrotoxin produced hyperactivity reversed haloperidol catalepsy. Similar bilateral administration did produce catalepsy a state frozen immobility. Kainic introduced mixed excitatory-inhibitory responses initially followed loss tectal perikarya. None drug effects occurred overlying cerebral cortex subjacent tegmentum. We propose separate ‘non-postural’ ‘postural’ locomotor regions may exist are situated within striato-nigrotectal outflow system capable influencing animal's activity posture.