INVOLVEMENT OF THE NUCLEUS-ACCUMBENS IN THE MYORELAXANT EFFECT OF BACLOFEN IN RATS

The study was designed to search for brain structures responsible for the myorelaxant action of baclofen. Rats were chronically implanted wi th cannulae in the medial nucleus accumbens (NAS). The muscle tone was increased by reserpine (10 mg/kg i.p.) and measured as a resistance o f the hind foot, developed in response to successive passive bendings and straightenings in the ankle joint. (+/-)Baclofen (1 or 2.5 mg/0.5 mu l), injected bilaterally into the NAS 1.5 h after pretreatment with reserpine, decreased the muscle tone of flexors and extensors enhance d by that compound. It is suggested that GABA(3) receptors of the NAS are involved in the myorelaxant action of baclofen.