TY - JOUR
T1 - Dual purinergic synaptic transmission in the human enteric nervous system
AU - Wunderlich, J. E.
AU - Needleman, B. J.
AU - Chen, Z.
AU - Yu, J. G.
AU - Wang, Y.
AU - Grants, I.
AU - Mikami, D. J.
AU - Melvin, W. S.
AU - Cooke, H. J.
AU - Christofi, F. L.
PY - 2008/2
Y1 - 2008/2
N2 - Based on findings in rodents, we sought to test the hypothesis that purinergic modulation of synaptic transmission occurs in the human intestine. Time series analysis of intraneuronal free Ca2+ levels in submucosal plexus (SMP) from Roux-en-Y specimens was done using Zeiss LSM laser-scanning confocal fluo-4 AM Ca2+ imaging. A 3-s fiber tract stimulation (FTS) was used to elicit a synaptic Ca2+ response. Short-circuit current (Isc = chloride secretion) was recorded in mucosa-SMP in flux chambers. A distension reflex or electrical field stimulation was used to study Isc responses. Ca2+ imaging was done in 1,222 neurons responding to high-K+ depolarization from 61 surgical cases. FTS evoked synaptic Ca2+ responses in 62% of recorded neurons. FTS caused frequency-dependent Ca2+ responses (0.1-100 Hz). FTS Ca2+ responses were inhibited by Ω-conotoxin (70%), hexamethonium (50%), TTX, high Mg2+/low Ca2+ (≤100%), or capsaicin (25%). A P2Y1 receptor (P2Y1R) antagonist, MRS-2179 or PLC inhibitor U-73122, blocked FTS responses (75-90%). P2Y1R- immunoreactivity occurred in 39% of vasoactive intestinal peptide-positive neurons. The selective adenosine A3 receptor (AdoA3R) agonist 2-chloro-N6-(3-iodobenzyl)adenosine-5′-N- methylcarboxamide (2-Cl-IBMECA) caused concentration- and frequency-dependent inhibition of FTS Ca2+ responses (IC50 = 8.5 × 10-8 M). The AdoA3R antagonist MRS-1220 augmented such Ca2+ responses; 2-Cl-IBMECA competed with MRS-1220. Knockdown of AdoA1R with 8-cyclopentyl-3-N-(3-{[3-(4-fluorosulphonyl)benzoyl]-oxy} -propyl)-1-N-propyl-xanthine did not prevent 2-Cl-IBMECA effects. MRS-1220 caused 31% augmentation of TTX-sensitive distension Isc responses. The SMP from Roux-en-Y patients is a suitable model to study synaptic transmission in human enteric nervous system (huENS). The P2Y 1/Gαq/PLC/inositol 1,3,5-trisphosphate/Ca2+ signaling pathway, N-type Ca2+ channels, nicotinic receptors, and extrinsic nerves contribute to neurotransmission in huENS. Inhibitory AdoA 3R inhibit nucleotide or cholinergic transmission in the huENS.
AB - Based on findings in rodents, we sought to test the hypothesis that purinergic modulation of synaptic transmission occurs in the human intestine. Time series analysis of intraneuronal free Ca2+ levels in submucosal plexus (SMP) from Roux-en-Y specimens was done using Zeiss LSM laser-scanning confocal fluo-4 AM Ca2+ imaging. A 3-s fiber tract stimulation (FTS) was used to elicit a synaptic Ca2+ response. Short-circuit current (Isc = chloride secretion) was recorded in mucosa-SMP in flux chambers. A distension reflex or electrical field stimulation was used to study Isc responses. Ca2+ imaging was done in 1,222 neurons responding to high-K+ depolarization from 61 surgical cases. FTS evoked synaptic Ca2+ responses in 62% of recorded neurons. FTS caused frequency-dependent Ca2+ responses (0.1-100 Hz). FTS Ca2+ responses were inhibited by Ω-conotoxin (70%), hexamethonium (50%), TTX, high Mg2+/low Ca2+ (≤100%), or capsaicin (25%). A P2Y1 receptor (P2Y1R) antagonist, MRS-2179 or PLC inhibitor U-73122, blocked FTS responses (75-90%). P2Y1R- immunoreactivity occurred in 39% of vasoactive intestinal peptide-positive neurons. The selective adenosine A3 receptor (AdoA3R) agonist 2-chloro-N6-(3-iodobenzyl)adenosine-5′-N- methylcarboxamide (2-Cl-IBMECA) caused concentration- and frequency-dependent inhibition of FTS Ca2+ responses (IC50 = 8.5 × 10-8 M). The AdoA3R antagonist MRS-1220 augmented such Ca2+ responses; 2-Cl-IBMECA competed with MRS-1220. Knockdown of AdoA1R with 8-cyclopentyl-3-N-(3-{[3-(4-fluorosulphonyl)benzoyl]-oxy} -propyl)-1-N-propyl-xanthine did not prevent 2-Cl-IBMECA effects. MRS-1220 caused 31% augmentation of TTX-sensitive distension Isc responses. The SMP from Roux-en-Y patients is a suitable model to study synaptic transmission in human enteric nervous system (huENS). The P2Y 1/Gαq/PLC/inositol 1,3,5-trisphosphate/Ca2+ signaling pathway, N-type Ca2+ channels, nicotinic receptors, and extrinsic nerves contribute to neurotransmission in huENS. Inhibitory AdoA 3R inhibit nucleotide or cholinergic transmission in the huENS.
KW - Adenosine A receptors
KW - Calcium signaling
KW - P2Y receptors
KW - Purinergic transmission
KW - Submucous nerve plexus
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U2 - 10.1152/ajpgi.00500.2007
DO - 10.1152/ajpgi.00500.2007
M3 - Article
C2 - 18079280
AN - SCOPUS:39149091374
SN - 0193-1857
VL - 294
SP - G554-G566
JO - American Journal of Physiology - Gastrointestinal and Liver Physiology
JF - American Journal of Physiology - Gastrointestinal and Liver Physiology
IS - 2
ER -