Effects of supraspinal and spinal GABA receptors on immobilization stress-induced antinociception in the mouse

The involvement of supraspinal or spinal GABA receptors in the modulation o f immobilizaton stress-induced antinociception were determined using the ta il-flick test. The intracerebroventricular pretreatment with muscimol (12.5 to 100 ng) or baclofen (1 to 10 ng) dose dependently attenuated the immobi lization-induced antinociception. In addition, the intrathecal pretreatment with SR 95531(0.1 to 0.6 ng) or 5-aminovaleric acid (1 to 20 mu g) attenua ted dose-dependently the immobilization stress-induced antinociception. Our results suggest that, at the supraspinal and spinal cord level, both GABA( A) and GABA(B) receptors may be involved in modulating the immobilization s tress-induced antinociception.