Premium
Opioid agonists modulate excitatory and inhibitory neurotransmission in human colon
Author(s) -
ANGEL F.,
CHAMOUARD P.,
KLEIN A.,
MARTIN E.
Publication year - 1993
Publication title -
neurogastroenterology and motility
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.489
H-Index - 105
eISSN - 1365-2982
pISSN - 1350-1925
DOI - 10.1111/j.1365-2982.1993.tb00133.x
Subject(s) - excitatory postsynaptic potential , cholinergic , inhibitory postsynaptic potential , endocrinology , medicine , enkephalin , neurotransmission , chemistry , agonist , muscle contraction , contraction (grammar) , opioid , dynorphin , stimulation , acetylcholine , isometric exercise , opioid peptide , receptor
The effects of different opioid agonists on spontaneous mechanical activity and response to electrical transmural nerve stimulation of both longitudinal and circular muscle strips from the human colon were studied by using a superfusion apparatus to record isometric contractions. Exogenously added opioid agonists did not modify the spontaneous contractile activities of both types of strips. Nerve stimulation induced a triphasic response composed of a first contraction C 1 followed by a relaxation C 2 and an off‐contraction C 3 ; this response was mediated by cholinergic excitatory nerves and non‐adrenergic, non‐cholinergic (NANC) excitatory and inhibitory nerves. The delta‐agonists methionine enkephalin, [D‐Pen 2 , D‐Pen 5 ] enkephalin (DPDPE) and the kappa‐agonists dynorphin, trans‐3,4 dichloro‐N‐methyl‐N‐(2‐[1 pyrolidinyl]‐cyclohexyl) (U‐50488H) decreased the amplitudes of the contractions C 1 and C 3 of both strips in a dose‐dependent manner. The selective mu‐agonist D‐alaglymepheglyol (DAGO) decreased the contraction C 1 of longitudinal and circular muscle at high dose (1 μM) and often reduced the relaxation C 2 of both types of strips at low dose (0.05 μM), finally, naloxone, but only at higher concentrations (1 μM) decreased the C 1 amplitude significantly in circular muscle. In conclusion, these data suggest that mu, delta and kappa opioid receptors are involved in the neuro‐regulation of smooth muscle of human colon and that opioid agonists modulate both excitatory and inhibitory neurotransmission through an action on cholinergic and non‐adrenergic, non‐cholinergic neurons.