resiniferatoxin and Gastrointestinal-Hemorrhage

Neurochemical and functional studies were performed to investigate and to compare the effects of resiniferatoxin and capsaicin in the rat stomach. Neonatal administration of resiniferatoxin (0.6-1.6 mumol/kg subcutaneously (s.c.)) produced a marked decrease in gastric calcitonin gene-related peptide-like immunoreactivity in both secretory and non-secretory region of the stomach. Almost complete depletion of the peptide was determined by neonatal administration of capsaicin (164 mumol/kg s.c.). Vasoactive intestinal polypeptide-like immunoreactivity was concomitantly unaffected by resiniferatoxin or capsaicin, thus showing the selectivity of action of the neurotoxins on gastric afferent fibers. Oral administration of an equimolar dose (0.3 nmol/kg) of resiniferatoxin or capsaicin together with 50% ethanol reduced at a similar extent gastric haemorrhagic lesions produced by the mucosal barrier-breaker agent. These findings provide evidence that resiniferatoxin and capsaicin may act on a common neuronal target in the rat stomach and that the acute exciting (protective) effect is of the same magnitude.

Topics: Administration, Oral; Animals; Animals, Newborn; Calcitonin Gene-Related Peptide; Capsaicin; Diterpenes; Dose-Response Relationship, Drug; Ethanol; Gastric Mucosa; Gastrointestinal Hemorrhage; Injections, Subcutaneous; Male; Neurons, Afferent; Neurotoxins; Rats; Stomach Ulcer; Vasoactive Intestinal Peptide