Vasoactive intestinal peptide is involved in the inhibitory effect of interleukin-1 beta on the jejunal contractile response induced by acetylcholine.
Although previous studies have shown that interleukin-1 beta (IL-1 beta) decreases acetylcholine (ACh)-induced intestinal contraction by an action on the enteric nervous system, the neuromediator(s) involved are still unknown.


OBJECTIVE
To determine the role of nitric oxide (NO), vasoactive intestinal peptide (VIP) and/or adenosine triphosphate (ATP) in mediating this inhibitory effect.


METHODS
The effects of NO synthase inhibitors, VIP and ATP antagonists on motor response to the ACh were investigated before and after 90-min exposure of a rat preparation of jejunal longitudinal muscle-myenteric plexus to IL-1 beta. NG-nitro-L-arginine methyl ester, NG-nitro-L-arginine and NG-monomethyl-L-arginine were used to inhibit NO synthase, VIP (10-28) and [D-p-Cl-Phe6, Leu17] VIP to block VIP receptors, and suramin to block ATP receptors.


RESULTS
NO synthase inhibitors failed to block the inhibitory effect of IL-1 beta on ACh-contracted jejunum smooth muscle. Suramin also failed to affect IL-1 beta-induced inhibition, whereas VIP antagonists abolished it. Moreover, the action of IL-1 beta was partly reproduced by VIP.


CONCLUSIONS
While neither NO nor ATP accounts for the inhibitory effect of IL-1 beta on ACh-contracted jejunum, VIP seems to be a key-mediator of this effect.
Aubé
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INSERM U 539, Hôtel-Dieu, BP 1005, 44035 Nantes. anne-catherine.aube@sante.univ-nantes.fr
Cherbut
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Rozé
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Galmiche
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D000109:Acetylcholine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors / Q000502:physiology; D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005769:Gastrointestinal Motility / Q000187:drug effects* / Q000502:physiology; D007375:Interleukin-1 / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D007583:Jejunum / Q000187:drug effects* / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009569:Nitric Oxide / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D051381:Rats; D017208:Rats, Wistar; D014660:Vasoactive Intestinal Peptide / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D007375:Interleukin-1; D014665:Vasodilator Agents; D009569:Nitric Oxide; D014660:Vasoactive Intestinal Peptide; D000255:Adenosine Triphosphate; D019001:Nitric Oxide Synthase; D000109:Acetylcholine