Selective lesions of the bulbospinal serotonergic pathways reduce the analgesia induced by p-chloroamphetamine in the hot-plate test.
The antinociceptive effect of the serotonin releasing compound p-chloroamphetamine (PCA) was investigated in rats by means of the hot-plate method. Selective neurotoxic lesions of the descending serotonergic pathways induced by intrathecal injections of 5,6-dihydroxytryptamine (20 micrograms, 7 days before testing), produced hyperalgesia and significantly attenuated the analgesic effect of acutely administered PCA (2.5 mg/kg). The lesions reduced the spinal serotonin content by about 90% without significantly altering noradrenaline levels. It is concluded that the descending serotonergic pathways contribute to the expression of PCA-induced hot-plate analgesia.
D015115:5,6-Dihydroxytryptamine / Q000494:pharmacology; D000662:Amphetamines / Q000494:pharmacology*; D000818:Animals; D008297:Male; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D012701:Serotonin / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*; D010133:p-Chloroamphetamine / Q000494:pharmacology*
D000662:Amphetamines; D012701:Serotonin; D010133:p-Chloroamphetamine; D015115:5,6-Dihydroxytryptamine