Gastric nNOS reduction accompanied by natriuretic peptides signaling pathway upregulation in diabetic mice.
OBJECTIVE
To investigate the relationship between neuronal nitric oxide synthase (nNOS) expression and the natriuretic peptide signaling pathway in the gastric fundus of streptozotocin (STZ)-induced diabetic mice.


METHODS
Diabetic mice were induced by injection of STZ solution. Immunofluorescence labeling of HuC/D, nNOS and natriuretic peptide receptor-A, B, C (NPRs) in the gastric fundus (GF) was used to observe nNOS expression and whether NPRs exist on enteric neurons. The expression levels of nNOS and NPRs in the diabetic GF were examined by western blotting. An isometric force transducer recorded the electric field stimulation (EFS)-induced relaxation and contraction in the diabetic GF. An intracellular recording method assessed EFS-induced inhibitory junction potentials (IJP) on the GF. GF smooth muscles acquired from normal mice were incubated with different concentrations of the NPRs agonist C-type natriuretic peptide (CNP) for 24 h, after which their nNOS expressions were detected by western blotting.


RESULTS
Eight weeks after injection, 43 diabetic mice were obtained from mouse models injected with STZ. Immunofluorescence indicated that the number of NOS neurons was significantly decreased and that nNOS expression was significantly downregulated in the diabetic GF. The results of physiological and electrophysiological assays showed that the EFS-induced relaxation that mainly caused by NO was significantly reduced, while the contraction was enhanced in the diabetic GF. EFS-induced IJP showed that L-NAME sensitive IJP in the diabetic GF was significantly reduced compared with control mice. However, both NPR-A and NPR-B were detected on enteric neurons, and their expression levels were upregulated in the diabetic GF. The nNOS expression level was downregulated dose-dependently in GF smooth muscle tissues exposed to CNP.


CONCLUSIONS
These findings suggested that upregulation of the NPs signaling pathway may be involved in GF neuropathy caused by diabetes by decreasing nNOS expression.
Hong-Li Lu, Xu Huang, Yi-Song Wu, Chun-Mei Zhang, Xiang-Min Meng, Dong-Hai Liu, Wen-Xie Xu, Department of Physiology, Shanghai Jiaotong University School of Medicine, Shanghai 200240, China.
Hong-Li
HL
Lu
Hong-Li Lu, Xu Huang, Yi-Song Wu, Chun-Mei Zhang, Xiang-Min Meng, Dong-Hai Liu, Wen-Xie Xu, Department of Physiology, Shanghai Jiaotong University School of Medicine, Shanghai 200240, China.
Xu
X
Huang
Hong-Li Lu, Xu Huang, Yi-Song Wu, Chun-Mei Zhang, Xiang-Min Meng, Dong-Hai Liu, Wen-Xie Xu, Department of Physiology, Shanghai Jiaotong University School of Medicine, Shanghai 200240, China.
Yi-Song
YS
Wu
Hong-Li Lu, Xu Huang, Yi-Song Wu, Chun-Mei Zhang, Xiang-Min Meng, Dong-Hai Liu, Wen-Xie Xu, Department of Physiology, Shanghai Jiaotong University School of Medicine, Shanghai 200240, China.
Chun-Mei
CM
Zhang
Hong-Li Lu, Xu Huang, Yi-Song Wu, Chun-Mei Zhang, Xiang-Min Meng, Dong-Hai Liu, Wen-Xie Xu, Department of Physiology, Shanghai Jiaotong University School of Medicine, Shanghai 200240, China.
Xiang-Min
XM
Meng
Hong-Li Lu, Xu Huang, Yi-Song Wu, Chun-Mei Zhang, Xiang-Min Meng, Dong-Hai Liu, Wen-Xie Xu, Department of Physiology, Shanghai Jiaotong University School of Medicine, Shanghai 200240, China.
Dong-Hai
DH
Liu
Hong-Li Lu, Xu Huang, Yi-Song Wu, Chun-Mei Zhang, Xiang-Min Meng, Dong-Hai Liu, Wen-Xie Xu, Department of Physiology, Shanghai Jiaotong University School of Medicine, Shanghai 200240, China.
Young-Chul
YC
Kim
Hong-Li Lu, Xu Huang, Yi-Song Wu, Chun-Mei Zhang, Xiang-Min Meng, Dong-Hai Liu, Wen-Xie Xu, Department of Physiology, Shanghai Jiaotong University School of Medicine, Shanghai 200240, China.
Wen-Xie
WX
Xu
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000201:enzymology* / Q000503:physiopathology; D015536:Down-Regulation; D004558:Electric Stimulation; D017615:Enteric Nervous System / Q000201:enzymology* / Q000503:physiopathology; D005748:Gastric Fundus / Q000294:innervation*; D008297:Male; D008813:Mice, Inbred ICR; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000294:innervation*; D045265:Natriuretic Peptides / Q000378:metabolism*; D026602:Nitrergic Neurons / Q000201:enzymology*; D009569:Nitric Oxide / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism*; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism; D015398:Signal Transduction; D013311:Streptozocin; D046509:Tissue Culture Techniques; D015854:Up-Regulation; D000099242:Atrial Natriuretic Factor Receptor B
D001786:Blood Glucose; D045265:Natriuretic Peptides; D009569:Nitric Oxide; D052248:Nitric Oxide Synthase Type I; D017461:Receptors, Atrial Natriuretic Factor; D013311:Streptozocin; D000099242:Atrial Natriuretic Factor Receptor B; C496321:Nos1 protein, mouse; C091715:atrial natriuretic factor receptor A
Diabetic gastroparesis; Enteric neuron; Natriuretic peptides; Nitric oxide synthase