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

Effects of different doses of adenosine receptor agonists and antagonists o n naloxone-induced jumping and diarrhea in morphine-dependent mice were stu died. 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 na loxone in morphine-dependent mice. The adenosine A(1) receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX: 0.3-9 mg kg(-1)), increased jump ing but decreased diarrhea. The adenosine A, receptor agonist, 5'-(N-cyclop ropyl)-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. D PCPX (0.3 and 3 mg kg(-1)), decreased the inhibition of jumping and diarrhe a induced by CHA (0.5 mg kg(-1)), while DMPX (0.5 and 1 mg kg(-1)), decreas ed the inhibition of diarrhea induced by CPCA (0.1 mg kg(-1)). It is conclu ded that jumping induced by naloxone in morphine-dependent mice may be modi fied by the adenosine A(1) receptor mechanism(s) and diarrhea induced by th e opioid receptor antagonist could be mediated by the adenosine A(1) and A( 2) receptors. (C) 1999 Elsevier Science B.V. All rights reserved.