Adenosine mediates spinal norepinephrine-produced antinociception as revealed by nociceptive discharges in parafascicular neurons in rats.
The effects of intrathecal pretreatment with aminophylline on intrathecal norepinephrine-produced or serotonin-produced suppression of noxiously evoked discharges in thalamic parafascicular neurons were investigated in 35 urethane-anesthetized rats. The results showed that: (1) both intrathecal norepinephrine (15 nmol) or serotonin (20 nmol) produced significant suppression of noxiously evoked discharges in parafascicular neurons; (2) intrathecal aminophylline (120 nmol) blocked the norepinephrine-produced suppression of noxiously evoked discharges, while the same dose of aminophylline exhibited no significant effect on the serotonin-produced suppression of these discharges in parafascicular neurons. The results suggest that spinal norepinephrine-produced, but not serotonin-produced, antinociceptive effects may be mediated by adenosine as one of successive chemical links in the spinal dorsal horn circuitry.
Department of Neurobiology, Shanxi Medical College, Taiyuan, Shanxi 030001, China.
S
S
Yang
R
R
Liu
J
J
Qiao
L E
LE
Laufman
N
N
Dafny
D000241:Adenosine / Q000494:pharmacology*; D000628:Aminophylline / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D004594:Electrophysiology; D005260:Female; D007278:Injections, Spinal; D008297:Male; D009474:Neurons / Q000502:physiology*; D009619:Nociceptors / Q000187:drug effects*; D009638:Norepinephrine / Q000008:administration & dosage* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology; D013788:Thalamus / Q000166:cytology / Q000502:physiology*
D000628:Aminophylline; D012701:Serotonin; D000241:Adenosine; D009638:Norepinephrine