Neuropharmacology of purinergic receptors in human submucous plexus: Involvement of P2X(1), P2X(2), P2X(3) channels, P2Y and A(3) metabotropic receptors in neurotransmission

作者：Lifian Rico A; Wunderlich J E; Enneking J T; Tso D R; Grants I; Williams K C; Otey A; Michel K; Schemann M; Needleman B; Harzman A; Christofi F L^*

来源：Neuropharmacology, 2015, 95: 83-99.

DOI：10.1016/j.neuropharm.2015.02.014

• ATP
• Endogenous adenosine
• Human enteric nervous system
• Submucous plexus
• Purinergic synaptic transmission
• P2X channels
• Inhibitory P2Y receptors
• A(3) inhibitory receptors

Rationale: The role of purinergic signaling in human ENS is not well understood. We sought to further characterize the neuropharmacology of purinergic receptors in human ENS and test the hypothesis that endogenous purines are critical regulators of neurotransmission.
Experimental approach: LSCM-Fluo-4/(Ca2+)-imaging of postsynaptic Ca2+ transients (PSCaTs) was used as a reporter of synaptic transmission evoked by fiber tract electrical stimulation in human SMP surgical preparations. Pharmacological analysis of purinergic signaling was done in 1,556 neurons (identified by HuC/D-immunoreactivity) in 235 ganglia from 107 patients; P2XR-immunoreactivity was evaluated in 19 patients. Real-time MSORT (Di-8-ANEPPS) imaging tested effects of adenosine on fast excitatory synaptic potentials (fEPSPs).
Results: Synaptic transmission is sensitive to pharmacological manipulations that alter accumulation of extracellular purines: Apyrase blocks PSCaTs in a majority of neurons. An ecto-NTPDase-inhibitor 6-N,N-diethyl-D-beta,gamma-dibromomethyleneATP or adenosine deaminase augments PSCaTs. Blockade of reuptake/deamination of eADO inhibits PSCaTs. Adenosine inhibits fEPSPs and PSCaTs (IC50 = 25 mu M), sensitive to MRS1220-antagonism (A(3)AR). A P2Y agonist ADP beta S inhibits PSCaTs (IC50 = 111 nM) in neurons without stimulatory ADPbS responses (EC50 = 960 nM). ATP or a P2X(1,2,2/3) (alpha,beta-MeATP) agonist evokes fast, slow, biphasic Ca2+ transients or Ca2+ oscillations (ATP,EC50 = 400 mM). PSCaTs are sensitive to P2X(1) antagonist NF279. Low (20 nM) or high (5 mu M) concentrations of P2X antagonist TNP-ATP block PSCaTs in different neurons; proportions of neurons with P2XR-immunoreactivity follow the order P2X(2) > P2X(1) >> P2X(3); P2X(1) + P2X(2) and P2X(3) + P2X(2) are co-localized. RT-PCR identified mRNA-transcripts for P2X(1-7), P2Y(1,2,12-14)R.
Conclusions: Purines are critical regulators of neurotransmission in human ENS. Purinergic signaling involves P2X(1), P2X(2), P2X(3) channels, P2X(1) + P2X(2) co-localization and inhibitory P2Y or A(3) receptors. These are potential novel therapeutic targets for neurogastroenterology. Published by Elsevier Ltd.

• 出版日期2015-8