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.