Are AH-type neurons DRG-like sensory afferents?
Evidence that AH neurons might be mechanoreceptors like DRG neurons came from Kunze et al. [38], who reported that stretching in the circumferential direction evoked repetitive action potential discharge in AH neurons. Nevertheless, the interpretation by Kunze et al. [38] of this as evidence that AH neurons are mechanosensory neurons is equivocal. An alternative explanation for the observation is that DRG mechanoreceptors in the myenteric ganglia were stimulated to release substance P or calcitonin gene-related peptide, which in turn evoked slow excitatory postsynaptic potentials (EPSPs) in the AH neurons. The behavior of the AH neurons during stretching of the preparation mimicked the slow EPSPs that are mediated by synaptic release of the DRG neurotransmitters, substance P and calcitonin gene-related peptide [39–43]. Electrical stimulation of DRG afferents, which enter the intestine in perivascular nerves, evokes slow EPSPs in AH-type myenteric neurons [43–45]. Slow EPSP characterist
