Opposite turning effects of dainic and ibotenic acid injected in the rat substantia nigra.

Unilateral intranigral administration of kainic and ibotenic acid, two putative stimulants of glutamatergic mechanisms, elicited turning behaviour starting from doses of 10 ng. While the turning produced by kainic acid was ipsilateral, that produced by ibotenic acid was contralateral to the injected side. Previous destruction of dopaminergic neurons on the side of the intranigral injection failed to reduce the turning behaviour. Peripheral treatment with picrotoxin did not reduce the turning in response to ibotenic acid. The results might suggest the existence of excitatory and inhibitory glutamate receptors which control nigral non-dopaminergic neurons mediating turning-behaviour.