PURINE MODULATION OF DIZOCILPINE EFFECTS ON SPONTANEOUS-ALTERNATION

The Y-maze was used to assess spontaneous alternation behaviour in mic e to examine possible interactions between the N-methyl-D-aspartate re ceptor channel blocker dizocilpine and purine receptor agonists and an tagonists. Scopolamine reduced spontaneous alternation. Dizocilpine al so produced a dose-dependent reduction in alternation scores, which wa s accompanied by an increase in locomotion. The selective A(1) adenosi ne receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (CPX) had no effect when administered alone, or in combination with scopolamine. H owever, when co-administered with dizocilpine, CPX reversed both the d eficit in alternation behaviour and also the increase in locomotion in duced by dizocilpine. The A(1) selective agonist N-6-cyclopentyladenos ine (CPA) had no effect on either locomotion or alternation scores whe n administered alone, but in combination with scopolamine, CPA attenua ted the scopolamine-induced deficit. CPA had no significant effect on the dizocilpine-induced deficit. The A(2) selective agonist N-6-[2-(3, dimethoxyphenyl)-2(2-methylphenyl)-ethyl]adenosine (DPMA), had no eff ect on spontaneous alternation when administered alone, but did cause a depression of locomotion. DPMA had no significant effect when co-adm inistered with scopolamine, but reversed the deficit in spontaneous al ternation, and the increase in locomotion induced by dizocilpine. The A(2) selective antagonist 3,7-dimethyl-1-propargylxanthine (DMPX) had no effect when given alone or in combination with scopolamine, but whe n co-administered with dizocilpine, DMPX reversed the reduction in spo ntaneous alternation caused by dizocilpine. It is concluded that dizoc ilpine has a detrimental effect on spontaneous alternation which is me diated partly by A(1) and A(2) adenosine receptors.