Participation of nucleus reticularis gigantocellularis in the antinociceptive effect of angiotensin III in the rat.
We evaluated the participation of nucleus reticularis gigantocellularis (NRGC), a medullary nucleus that plays an important role in the regulation of nociceptive processes, in the antinociceptive effect of angiotensin III (AIII), a biologically active peptide of the renin-angiotensin system. Adult, male Sprague-Dawley rats anesthetized with pentobarbital sodium (40 mg/kg, i.p., with 10 mg/kg/h i.v. infusion supplement) were used. Bilateral, site-specific microinjection of AIII (80 or 160 pmol) into the NRGC produced a dose-related increase in the latency of tail-flick response to noxious thermal stimuli (50 degrees C hot water). Such an antinociceptive action of AIII was blocked by concomitant administration of the AIII receptor antagonist, Ile7-angiotensin III (Ile7-AIII, 10 nmol). At the neuronal level, microiontophoretic application of AIII suppressed, Ile7-AIII reversibly, the responsiveness of nociception-related neurons in the NRGC to tail-clamping. These results demonstrated that central AIII may elicit antinociception via a process that may at least take place at the NRGC.
Yien
H W
HW
Department of Anesthesiology, National Yang-Ming Medical College, Taipei, Taiwan, ROC.
Chan
J Y
JY
Tsai
H F
HF
Lee
T Y
TY
Chan
S H
SH
D000700:Analgesics / Q000494:pharmacology*; D000805:Angiotensin III / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D001479:Basal Ganglia / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects; D007478:Iontophoresis; D008297:Male; D008845:Microinjections; D009474:Neurons / Q000187:drug effects; D009619:Nociceptors / Q000187:drug effects; D010147:Pain Measurement / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013238:Stereotaxic Techniques
D000700:Analgesics; D000805:Angiotensin III; C056764:angiotensin III, Ile(7)-