Evidence against transmitter function of met-enkephalin and chemosynaptic impulse generation in "Merkel cell" mechanoreceptors.
Using the mechanoreceptors in the cat's sinus hair follicles as a model system the recent hypothesis (Hartschuh and Weihe 1980) was tested that Merkel cells are mechanoreceptive sensory cells releasing met-enkephalin as a neurotransmitter to initiate action potentials in the terminals of type I afferent fibres. Since the met-enkephalin antagonist naloxone, even in high doses, did not affect responses in any type I mechanosensitive afferent it is unlikely that a synaptic mechanism with the release of met-enkephalin underlies impulse generation in Merkel cell-axon complexes, nor did naloxone influence the responses from other types of mechanoreceptors.
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001369:Axons / Q000502:physiology; D002415:Cats; D004723:Endorphins / Q000502:physiology*; D004744:Enkephalin, Methionine; D004745:Enkephalins / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects; D008465:Mechanoreceptors / Q000502:physiology*; D009270:Naloxone / Q000494:pharmacology; D009412:Nerve Fibers / Q000502:physiology; D012867:Skin / Q000294:innervation; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects
D004723:Endorphins; D004745:Enkephalins; D009270:Naloxone; D004744:Enkephalin, Methionine