Interaction of galanin receptors with glutamate receptors in the neostriatum: a neuropharmacological analysis

Bilateral administration of kainic acid (KA) in doses of 100 ng into the rat neostriatum resulted in an increase in the latency of movement initiation, a decrease in the open field motor activity, an increase in muscle tonus, and the appearance of ptosis. Administration of 20 ng KA at each side appeared ineffective. Intrastriatal bilateral administration of galanin (10 and 50 ng) resulted in a decrease in the number of crossed squares and frequency of rearings in the open field, without affecting the movement initiation and muscle tonus, and did not caused ptosis. Combined injections of galanin (2, 10, and 50 ng) and KA (20 ng) into the striatum elicited long-term disturbances resembling those observed when KA (100 ng) was injected into the caudate nucleus. The disturbances caused by KA or galanin intrastriatal administrations, or by their combined administrations, could be partially blocked by naloxon, an opioid antagonist, by ketamine, a glutamate and aspartate antagonist, and by atropine, a cholinergic antagonist. A conclusion is made that galanin potentiates specific behavioral and motor effects of KA injected into the striatum, and this interaction is due to the modulatory influence of the peptide on the receptors to endogenous opioids, excitatory amino acids, or acetylcholine.Neirofiziologiya/Neurophysiology, Vol. 26, No. 4, pp. 276–282, July–August, 1994.