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Naunyn Schmiedebergs Arch Pharmacol. 2003 Jan;367(1):51-5. Epub 2002 Nov 12.

Endotoxin stimulates fecal pellet output in rats through a neural mechanism.

Author information

1
Unidad Mixta de Investigación, Facultad de Medicina/Hospital Clínico Universitario, Avda. Blasco Ibáñez 17, 46010 Valencia, Spain.

Abstract

The effects of endotoxin on fecal pellet output and the neural mechanisms involved in this response were investigated in conscious rats. E. coli endotoxin (40 micro g/kg i.p.) significantly increased fecal excretion for 3 h after the injection. Water content in feces was not modified by endotoxin. Ablation of primary afferent neurons by systemic administration of high doses of capsaicin (20+30+50 mg/kg s.c.) to adult rats prevented the stimulatory effect of endotoxin and so did abdominal vagotomy. Adrenoceptor blockade with phentolamine (5 mg/kg i.p.) + propranolol (3 mg/kg i.p.) did not modify pellet output in endotoxin-treated rats while muscarinic receptor blockade with atropine (1 mg/kg i.p.) abolished the stimulatory effect of endotoxin. Finally, the increase in pellet output induced by endotoxin was prevented in animals receiving the substance P receptor antagonist D-Pro2, D-Trp7,9-substance P (2 mg/kg i.p.) or the NO-synthase inhibitor L-NAME (10 mg/kg i.p.). None of the above treatments modified pellet output in saline-treated rats. These observations indicate that endotoxin increases fecal pellet output through a nervous reflex in which capsaicin-sensitive afferent neurons and the release of excitatory (acetylcholine and substance P) and inhibitory (NO) neurotransmitters in the colonic wall are involved.

PMID:
12616341
DOI:
10.1007/s00210-002-0646-7
[Indexed for MEDLINE]

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