The role of neurotransmitters in stress-induced antinociception (SIA).
The role of the neurotransmitters, norepinephrine, dopamine and serotonin in stress-induced antinociception (SIA) was examined by altering neurochemical tone with appropriate pharmacological tools. Quipazine (15.0 mg/kg, IP) a serotonin agonist, increased the peak and duration of antinociception following stress and BC-105 (3.0 mg/kg, IP), a serotonin antagonist, blocked the increase of tail-flick latency following stress. Clonidine (0.1 mg/kg, SC) an alpha 2 agonist, markedly decreased SIA whereas phenoxybenzamine (2.5 mg/kg, IP), an alpha 1 antagonist, increased the peak and duration of SIA. When dopaminergic tone was increased with apomorphine (0.05 mg/kg, SC) the increase of tail-flick latency after stress was markedly attenuated whereas blockage of dopamine receptors with haloperidol (2.5 mg/kg, IP) increased the peak and duration of SIA. Alterations of serotonergic, but not noradrenergic or dopaminergic, tone had similar effects on increased latency in tail-flick test produced by brain stimulation produced analgesia (SPA), morphine and SIA. These data support the hypothesis that alterations in tail-flick latency involves a serotonergic system.
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology; D004298:Dopamine / Q000502:physiology*; D006220:Haloperidol / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D018377:Neurotransmitter Agents / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology*; D010146:Pain / Q000503:physiopathology*; D010643:Phenoxybenzamine / Q000494:pharmacology; D010918:Pizotyline / Q000494:pharmacology; D011814:Quipazine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012684:Sensory Thresholds / Q000187:drug effects; D012701:Serotonin / Q000502:physiology*; D013312:Stress, Physiological / Q000503:physiopathology*
D018377:Neurotransmitter Agents; D010918:Pizotyline; D010643:Phenoxybenzamine; D012701:Serotonin; D011814:Quipazine; D006220:Haloperidol; D003000:Clonidine; D001058:Apomorphine; D004298:Dopamine; D009638:Norepinephrine