Influence of capsaicin-sensitive afferent fibers on acetic acid-induced chronic gastric ulcers in rats.
Accumulating evidence indicates that capsaicin-sensitive afferent fibers play a pivotal role in acute gastroprotection. However, whether they also influence healing of chronic gastric ulcers is still unknown. The effects of ablation of sensory neurons on acetic acid-induced chronic gastric ulcers in rats were investigated at morphologic and biochemical levels by computerized imaging analysis of the ulcerated area, histologic examination, and neuropeptide determination. Afferent nerve ablation, as a result of treating rats with a neurotoxic dose of capsaicin (50 + 50 mg/kg subcutaneously over 2 days), produced a significant increase in the ulcer area at 1 and 2 weeks after acetic acid injection. The delay in ulcer healing was associated with a marked and persistent decrease in tissue calcitonin gene-related peptide-like immunoreactivity, whereas gastric vasoactive intestinal polypeptide was unaffected by capsaicin pretreatment. Histologically, as compared with control rats, capsaicin-desensitized animals only differed in a slight increase in the inflammatory infiltrate during the early phase of ulcer formation. These findings suggest that capsaicin-sensitive afferent fibers may play a role in the healing of chronic experimental gastric ulcers in rats, but the underlying mechanisms remain to be elucidated and deserve further investigation.
Dept. of Pharmacology, Malesci Pharmaceuticals, Florence, Italy.
M
M
Tramontana
D
D
Renzi
A
A
Calabrò
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C
Panerai
S
S
Milani
C
C
Surrenti
S
S
Evangelista
D000085:Acetates; D019342:Acetic Acid; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002211:Capsaicin / Q000494:pharmacology*; D002908:Chronic Disease; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013276:Stomach Ulcer / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism; D014945:Wound Healing
D000085:Acetates; D014660:Vasoactive Intestinal Peptide; D015740:Calcitonin Gene-Related Peptide; D019342:Acetic Acid; D002211:Capsaicin