INTRATHECAL ADMINISTRATION OF A NOVEL PYRAZOLYL-THIAZOLE DERIVATIVE INDUCES DELAYED ANTINOCICEPTION IN MICE

In this study we investigated whether the intrathecal administration (i.t.) of the novel pyrazolyl-thiazole derivative 2-[5-trichloromethyl-5-hidroxy-3-phenyl-4,5-dihydro-1H-pyrazol-1-yl]-4-(4-bromophenyl)-5-methylthiazole (B50) caused antinociception in adult male mice, using the hot plate and acetic acid writhing assays. B50 (200 nmol/ 5 ml, i.t.) caused antinociception 90-120 minutes after its administration. Naloxone (8.25 mmol/ kg, s.c.) reverted the antinociceptive action of B50 (200 nmol/ 5 ml, i.t.), in the acetic acid writhing assay, suggesting that opioid mechanisms are involved in the antinociception caused by B50. B50 had no effect on spontaneous locomotion or rotarod performance, indicating that the currently reported antinociceptive effect of B50 is not related to unspecific motor effects