PKC-ϵ translocation in enteric neurons and interstitial cells of Cajal in response to muscarinic stimulation

Abstract

Interstitial cells of Cajal in the deep muscular plexus (ICC-DMP) of the small intestine express excitatory neurotransmitter receptors. We tested whether ICC-DMP are functionally innervated by cholinergic neurons in the murine intestine. Muscles were stimulated by intrinsic nerves and ACh and processed for immunohistochemistry to determine these effects on PKC-ϵ activation. Under control conditions, PKC-ϵ-like immunoreactivy (PKC-ϵ-LI) was only observed in myenteric neurons within the tunica muscularis. Electrical field stimulation or ACh caused translocation of neural PKC-ϵ-LI from the cytosol to a peripheral compartment. After stimulation, PKC-ϵ-LI was found in spindle-shaped cells in the DMP. These cells were identified as ICC-DMP by Kit-LI and vimentin-LI. PKC-ϵ-LI in ICC-DMP and translocation of PKCϵ-LI in neurons were blocked by tetrodotoxin or atropine, suggesting that these responses were due to activation of muscarinic receptors. Western blots also confirmed translocation of PKC-ϵ-LI. In conclusion, PKC-ϵ translocation is linked to muscarinic receptor activation in ICC-DMP and a subpopulation of myenteric neurons. These studies demonstrate that ICC-DMP are functionally innervated by excitatory motoneurons.