Cm. Fraser et al., THE INVOLVEMENT OF ADENOSINE RECEPTORS IN THE EFFECT OF DIZOCILPINE ON MICE IN THE ELEVATED PLUS-MAZE, European neuropsychopharmacology, 7(4), 1997, pp. 267-273
It has been claimed that blockade of receptors for N-methyl-D-aspartat
e (NMDA) can enhance adenosine receptor function on single neurones. P
revious work has also indicated that the NMDA channel blocker dizocilp
ine, and the A(1) selective agonist N6-cyclopentyladenosine (CPA) both
had anxiolytic profiles in the elevated plus-maze. The anxiolytic eff
ect of dizocilpine was accompanied by an increase in locomotor activit
y. In the present study, the elevated plus-maze has been used to deter
mine whether dizocilpine's effects on behaviour are mediated through a
ctivation of adenosine receptors. When co-administered with dizocilpin
e (0.05 mg/kg), CPA (0.05 mg/kg) reduced the anxiolytic and locomotor
effects of dizocilpine. The A(1) selective antagonist 1,3-dipropyl-8-c
yclopentylxanthine (CPX, 0.05 mg/kg) had no effect when administered a
lone. When co-administered with dizocilpine, CPX reversed the anxiolyt
ic and increased locomotor effects induced by dizocilpine. The A(2) re
ceptor selective agonist -dimethoxyphenyl)-2(2-methylphenyl)-ethyladen
osine (DPMA) (1 mg/kg) reversed both the anxiolytic effect and the inc
reased locomotion induced by dizocilpine, while the A(2) selective ant
agonist 3,7-dimethyl-1-propargylxanthine (DMPX) (1 mg/kg) did not. It
is concluded that at least part of the anxiolytic and locomotor stimul
ant properties of dizocilpine may be explained by the release of endog
enous adenosine acting at A1, but not A2 receptors. (C) 1997 Elsevier
Science B.V.