Effects of adenosine receptor agents on the expression of morphine withdrawal in mice

Effects of different doses of adenosine receptor agonists and antagonists on naloxone-induced jumping and diarrhea in morphine-dependent mice were studied. The adenosine A(1) receptor agonists, N(6)-cyclohexyladenosine (CHA: 0.1, 0.25 and 0.5 mg kg(-1)) and R-isomer of N(6)-phenylisopropyladenosine (R-PIA: 0.1, 0.3 and 1 mg kg-L), decreased jumping and diarrhea induced by naloxone in morphine-dependent mice. The adenosine A(1) receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX: 0.3-9 mg kg(-1)), increased jumping but decreased diarrhea. The adenosine A, receptor agonist, 5'-(N-cyclopropyl)-carboxamidoadenosine (CPCA), decreased jumping and diarrhea. However, the adenosine A(2) receptor antagonist, 3,7-dimethyl-1-propargylxanthine (DMPX: 0.5 and 1 mg kg(-1)), did not elicit any response in this respect. DPCPX (0.3 and 3 mg kg(-1)), decreased the inhibition of jumping and diarrhea induced by CHA (0.5 mg kg(-1)), while DMPX (0.5 and 1 mg kg(-1)), decreased the inhibition of diarrhea induced by CPCA (0.1 mg kg(-1)). It is concluded that jumping induced by naloxone in morphine-dependent mice may be modified by the adenosine A(1) receptor mechanism(s) and diarrhea induced by the opioid receptor antagonist could be mediated by the adenosine A(1) and A(2) receptors. (C) 1999 Elsevier Science B.V. All rights reserved.