A large body of evidence suggests that nitric oxide (NO) gas play a key role in nonadrenergic noncholinergic (NANC) inhibitory neuro-smooth muscle transmission throughout the body including the gut. Clinically, deficiency of nitrergic transmission has been shown to be responsible for many major gastrointestinal motility disorders. However, several important questions regarding nitrergic neurotransmission remain unanswered. For example, the precise site(s) of production of NO at the neuro-smooth muscle junctions, including the prejunctional nerve varicosities, the postjunctional smooth muscle cells or the intramuscular type of interstitial cells of Coal (ICC-IM) remain undefined. Some investigators believe that NO produced in the postjunctional structures is essential in the neuromuscular transmission. It is also unclear how this highly diffusible gas can fulfill the function of a neurotransmitter that requires highly controlled release. The release of a classical neurotransmitter is regulated by exocytosis of a small fraction of the secretory granules that are docked onto the plasma membrane. However, NO is not stored in the secretory granules and is thought to be produced on demand during the neurotransmission. The nerve varicosities that contain nNOS also contain peptide VIP, however, the role VIP in nitrergic neuro smooth muscle neurotransmission is controversial. We propose models of regulation of nNOS and an intermediary role of VIP in nitrergic neurotransmission. To test these models we plan to utilize: (1) a novel technique using fluorescent dye markers and multi-photon microscopy to visualize NO and calcium signals in real-time in live nerve varicosities and other structures at the neuromuscular junctions;(2) immunocytological studies using multi-photon microscopy to localize the proteins that may be involved in cycling of nNOS from catalytically inactive to catalytically active forms;(3) intracellular recordings of the nitrergic inhibitory junction potentials. Using the above techniques, we plan to study the effects of pharmacological manipulations to test the proposed models. These studies will help define:(1) whether during the neurotransmission NO is produced in the nerve varicosities and also in the postjunctional smooth muscle cells or ICC-IM;(2) the regulation of nNOS that permits NO gas to function as a neurotransmitter;(3) the intermediary role of VIP and its unique receptor subtype in nitrergic neurotransmission. This information may help in understanding physiology, and the pathogenesis and rational treatment of clinical disorders due to deficiency of nitrergic neuro-smooth muscle transmission.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
3R01DK062867-05S1
Application #
7929153
Study Section
Special Emphasis Panel (ZRG1-GMA-3 (01))
Program Officer
Hamilton, Frank A
Project Start
2009-09-30
Project End
2010-08-31
Budget Start
2009-09-30
Budget End
2010-08-31
Support Year
5
Fiscal Year
2009
Total Cost
$100,000
Indirect Cost
Name
Harvard University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
047006379
City
Boston
State
MA
Country
United States
Zip Code
02115
Chaudhury, Arun; Cristofaro, Vivian; Carew, Josephine A et al. (2014) Myosin Va plays a role in nitrergic smooth muscle relaxation in gastric fundus and corpora cavernosa of penis. PLoS One 9:e86778
Goyal, R K; Sullivan, M P; Chaudhury, A (2013) Progress in understanding of inhibitory purinergic neuromuscular transmission in the gut. Neurogastroenterol Motil 25:203-7
Goyal, Raj K; Chaudhury, Arun (2013) Structure activity relationship of synaptic and junctional neurotransmission. Auton Neurosci 176:11-31
He, Xue-Dao; Goyal, Raj K (2012) CaMKII inhibition hyperpolarizes membrane and blocks nitrergic IJP by closing a Cl(-) conductance in intestinal smooth muscle. Am J Physiol Gastrointest Liver Physiol 303:G240-6
Chaudhury, Arun; He, Xue-Dao; Goyal, Raj K (2012) Role of myosin Va in purinergic vesicular neurotransmission in the gut. Am J Physiol Gastrointest Liver Physiol 302:G598-607
Chaudhury, Arun; He, Xue-Dao; Goyal, Raj K (2011) Myosin Va plays a key role in nitrergic neurotransmission by transporting nNOSýý to enteric varicosity membrane. Am J Physiol Gastrointest Liver Physiol 301:G498-507
Goyal, Raj K (2011) Evidence for ?-nicotinamide adenine dinucleotide as a purinergic, inhibitory neurotransmitter in doubt. Gastroenterology 141:e27; author reply e27-8
Goyal, Raj K; Chaudhury, Arun (2010) Mounting evidence against the role of ICC in neurotransmission to smooth muscle in the gut. Am J Physiol Gastrointest Liver Physiol 298:G10-3
Goyal, Raj K; Chaudhury, Arun (2010) Pathogenesis of achalasia: lessons from mutant mice. Gastroenterology 139:1086-90
Thatte, Hemant S; He, Xue D; Goyal, Raj K (2009) Imaging of nitric oxide in nitrergic neuromuscular neurotransmission in the gut. PLoS One 4:e4990

Showing the most recent 10 out of 19 publications