INTRATHECAL AND SYSTEMIC R-PHENYLISOPROPYLADENOSINE REDUCES SCRATCHING BEHAVIOR IN A RAT MONONEUROPATHY MODEL

THE aim of the present study was to investigate the effect of intraven ous or intrathecal (i.t.) administration of R-phenylisopropyladenosine (R-PIA), a selective A, adenosine receptor agonist, on spontaneous sc ratching behaviour, a phenomenon presumably related to pain in a monon europathy model (sciatic nerve ligation) in rats. The acute effect of daily i.t. R-PIA injections was studied up to 21 days following nerve ligation. The results demonstrate that both i.v. (30 nmol) and i.t. (3 nmol) R-PIA, in doses not producing any motor impairment, significant ly reduces scratching behaviour in this animal model. The mechanism of action for this presumed antinociceptive effect is suggested to occur at the spinal cord level.