Nociceptive inhibition of migrating myoelectric complex by nitric oxide and monoaminergic pathways in the rat.
This study investigated the role of nitric oxide (NO) and adrenergic and dopaminergic mechanisms in reflex inhibition of the migrating myoelectric complex (MMC) after intraperitoneal administration of acid in rats. Acid instilled immediately after an activity front inhibited the migrating complex and prolonged the cycle length from 13.0 +/- 0.7 to 98.5 +/- 17.2 min (P < 0.001). Administration of N omega-nitro-L-arginine, reserpine, or guanetidine before acid decreased the prolonged cycle length to 18.1 +/- 2.8 (P < 0.001), 19.0 +/- 2.0 (P < 0.001), and 27.5 +/- 9.3 min (P < 0.001), respectively. Similarly, haloperidol given before acid shortened the prolonged cycle length to 46.7 +/- 5.2 min (P < 0.05). There was no effect of phentolamine in combination with propranolol or hexamethonium given alone. After intraperitoneal instillation of acid there was an increase in the plasma levels of somatostatin and a decrease of calcitonin gene-related peptide, but there was no change of neuropeptide Y, vasoactive intestinal peptide, substance P, neurokinin A, or neurotensin. The results indicate that NO and adrenergic, dopaminergic, and somatostatinergic mechanisms cooperate in inhibiting the MMC after nociceptive stimulation of the peritoneum.
Hellström
P M
PM
Department of Medicine, Karolinska Hospital, Stockholm, Sweden.
Thollander
M
M
Theodorsson
E
E
D000818:Animals; D015306:Biogenic Monoamines / Q000502:physiology*; D015740:Calcitonin Gene-Related Peptide / Q000097:blood; D004576:Electromyography; D007274:Injections, Intraperitoneal; D008297:Male; D016065:Myoelectric Complex, Migrating / Q000187:drug effects*; D015288:Neurokinin A / Q000097:blood; D009478:Neuropeptide Y / Q000097:blood; D009479:Neuropeptides / Q000097:blood*; D009496:Neurotensin / Q000097:blood; D009569:Nitric Oxide / Q000008:administration & dosage / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013004:Somatostatin / Q000097:blood; D013373:Substance P / Q000097:blood; D014660:Vasoactive Intestinal Peptide / Q000097:blood
D015306:Biogenic Monoamines; D009478:Neuropeptide Y; D009479:Neuropeptides; D009569:Nitric Oxide; D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D009496:Neurotensin; D013004:Somatostatin; D015288:Neurokinin A; D015740:Calcitonin Gene-Related Peptide