Baclofen and 2-hydroxysaclofen modify acute hypolocomotive and antinociceptive effects of nicotine

The aim of the present study was to evaluate the possible involvement of GABAB receptors in nicotine-induced hypolocomotion and antinociceptive effects in mice. Animals were exposed to nicotine only once. Acute nicotine hydrogen tartrate salt (3 mg/kg; subcutaneous, s.c.) administration induced hypolocomotion and antinociceptive responses in the tail-immersion and the hot-plate tests. The effects of pretreatment with either the GABAB receptor agonist baclofen (1, 2 and 3 mg/kg; intraperitoneal, i.p.) or GABAB receptor antagonist 2-hydroxysaclofen (0.25, 0.5 and 1 mg/kg; i.p.) were evaluated on these behavioral nicotine responses. The GABAB receptor agonist, baclofen (3 mg/kg, i.p.) abolished nicotine-induced antinociceptive effects in the tail-immersion and the hot-plate tests, but did not modify nicotine-induced hypolocomotion. In addition, the GABAB receptor antagonist, 2-hydroxysaclofen (1 mg/kg, i.p.) increased nicotine-induced antinociceptive effects in the tail-immersion and the hot-plate tests, and abolished nicotine-induced hypolocomotion. The present results shed light that the GABAB receptor has an important role in mediating specific acute nicotine responses such as hypolocomotion and antinociception in mice.Fil: Varani, Andrés P.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas (i); ArgentinaFil: Aso, Ester. Universitat Pompeu Fabra; EspañaFil: Maldonado, Rafael. Universitat Pompeu Fabra; EspañaFil: Balerio, Graciela Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas (i); Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Cátedra de Farmacología; Argentin