چكيده لاتين :
The term opioid was coined to refer in a generic sense to all drugs, natural and synthetic, with morphin - like actions. Three distinct families of peptides have been identified so far in gastrointestinal (GI) nervous system in mammalian.
These peptides include : dynorphin, Met - enkephalin and leu - enkephalin .
Results from studies about opioid which have been started 15 years ago , depend on species , dosages, route of administration and laboratory techniques. Nerve fibers are observed in different parts of GI tract by antiopioid antibody , radioimmunoassay and immunocytochemistry.
The myentric plexus, mucosa , submucosa, circular and longitudinal smooth muscle and perivertebral ganglion of sympathics are innervated by dymorphin and enkephalinergic fibers .
Effect of endogenous opioid are accomplished by special receptors that 8 types of them are known so far. Mu - 1 µ_1) and delta (δ) receptors are preferentially responsible for the effects of opioid in human GI tract. physiological and pharmacological properties of endogenous opioid in different parts of GI tract such as motility and secretion are
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