Further characterisation of particulate neuronal nitric oxide synthase in rat small intestine

The purpose of this study was to analyze the nicotinamide adenine dinucleotide phosphate - diaphorase (NADPH-d) activity in the rat jejunum after a mesenteric ischemia/reperfusion injury. Nitric oxide, synthetised from L-arginine by the enzyme nitric oxide synthase, is a nonadrenergic noncholinergic relaxant neurotransmitter of the intestinal smooth muscle. It plays an important role in the process of plasticity after the ischemia/reperfusion injury. Experimental animals were divided in two groups: the control group and the ischemic/reperfusion group, with different period of the reperfusion. The NADPH-d histochemical method has been used as a marker for the nitric oxide synthase. NADPH-d activity has been rapidly decreased in the neurons of both enteric nervous systems in plexuses of the jejunum after 1 h mesenteric ischemia and 1 h reperfusion. Differences were predominantly detected in the myenteric plexus; they were seen in change of the neuronal shape, in the arrangement of neurons and in intensity of their staining. The NADPH-d positivity was absent in the intestinal crypts. After 1 h ischemia and 24 h reperfusion, the NADPH-d activity was gradually increased, but it was lower in comparison with the control group. On the 30th day following the ischemia/reperfusion there were no changes in NADPH-d positivity compared with the control animals. These results indicated that the jejunal ischemia/reperfusion has affected the neurons of the enteric nervous system of adult rats and resulted in the early decrease of NADPH-d positivity 1 h of the reperfusion insult. The gradual increasing of NADPH-d activity in 24 h following the reperfusion could be considered as a result of the plasticity process. On the 30th day after the ischemia/reperfusion all histochemical changes were returned to the control levels.

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“…It also could be involved in neuronal communication within the enteric nerve plexuses and may influence on different digestive functions. 43,44 …”

Section: Discussionmentioning

confidence: 99%

NADPH-diaphorase expression in the rat jejunum after intestinal ischemia/reperfusion

et al. 2011

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“…Microsomal components or pelleted mitochondrial fragments were not used in the analytical materials. These preparatory methods are based on standardized methods of synaptosomal preparations using gut tissues (30,37). Furthermore, these samples were examined for PGP9.5 and synaptophysin for their nerve terminal identity.…”

Section: Preparation Of Enteric Varicositiesmentioning

confidence: 99%

Myosin Va plays a key role in nitrergic neurotransmission by transporting nNOSα to enteric varicosity membrane

Chaudhury

Goyal

2011

American Journal of Physiology-Gastrointestinal and Liver Physi

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Nitrergic neurotransmission at the smooth muscle neuromuscular junctions requires nitric oxide (NO) release that is dependent on the transport and docking of neuronal NO synthase (nNOS) α to the membrane of nerve terminals. However, the mechanism of translocation of nNOSα in actin-rich varicosities is unknown. We report here that the processive motor protein myosin Va is necessary for nitrergic neurotransmission. In wild-type mice, nNOSα-stained enteric varicosities colocalized with myosin Va and its tail constituent light chain 8 (LC8). In situ proximity ligation assay showed close association among nNOSα, myosin Va, and LC8. nNOSα was associated with varicosity membrane. Varicosities showed nitric oxide production upon stimulation with KCl. Intracellular microelectrode studies showed nitrergic IJP and smooth muscle hyperpolarizing responses to NO donor diethylenetriamine-NO (DNO). In contrast, enteric varicosities from myosin Va-deficient DBA (for dilute, brown, non-agouti) mice showed near absence of myosin Va but normal nNOSα and LC8. Membrane-bound nNOSα was not detectable, and the varicosities showed reduced NO production. Intracellular recordings in DBA mice showed reduced nitrergic IJPs but normal hyperpolarizing response to DNO. The nitrergic slow IJP was 9.1 ± 0.7 mV in the wild-type controls and 3.4 ± 0.3 mV in the DBA mice (P < 0.0001). Deficiency of myosin Va resulted in loss of nitrergic neuromuscular neurotransmission despite normal presence of nNOSα in the varicosities. These studies reveal the critical importance of myosin Va in nitrergic neurotransmission by facilitating transport of nNOSα to the varicosity membrane.

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“…Diverse organ systems reveal that nNOS remains membrane-bound during enzymatic synthesis, suggesting that membrane localization of nNOS may be critical for enzyme action in a physiological context ( 5 , 24 – 33 ). Evidence has suggested the role of motor proteins like myosin Va in transposition of nNOS within the nerve terminals to the membranes to facilitate nitrergic neurotransmission ( 11 , 12 ).…”

Section: Mere Localization Of Nnos In Prejunctional Nerve Terminals Imentioning

confidence: 99%

Molecular Handoffs in Nitrergic Neurotransmission

Chaudhury

2014

Front. Med.

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Postsynaptic density (PSD) proteins in excitatory synapses are relatively immobile components, while there is a structured organization of mobile scaffolding proteins lying beneath the PSDs. For example, shank proteins are located further away from the membrane in the cytosolic faces of the PSDs, facing the actin cytoskeleton. The rationale of this organization may be related to important roles of these proteins as “exchange hubs” for the signaling proteins for their migration from the subcortical cytosol to the membrane. Notably, PSD95 have also been demonstrated in prejunctional nerve terminals of nitrergic neuronal varicosities traversing the gastrointestinal smooth muscles. It has been recently reported that motor proteins like myosin Va play important role in transcytosis of nNOS. In this review, the hypothesis is forwarded that nNOS delivered to subcortical cytoskeleton requires interactions with scaffolding proteins prior to docking at the membrane. This may involve significant role of “shank,” named for SRC-homology (SH3) and multiple ankyrin repeat domains, in nitric oxide synthesis. Dynein light chain LC8–nNOS from acto-myosin Va is possibly exchanged with shank, which thereafter facilitates transposition of nNOS for binding with palmitoyl-PSD95 at the nerve terminal membrane. Shank knockout mice, which present with features of autism spectrum disorders, may help delineate the role of shank in enteric nitrergic neuromuscular transmission. Deletion of shank3 in humans is a monogenic cause of autism called Phelan–McDermid syndrome. One fourth of these patients present with cyclical vomiting, which may be explained by junctionopathy resulting from shank deficit in enteric nitrergic nerve terminals.

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Further characterisation of particulate neuronal nitric oxide synthase in rat small intestine

Cited by 11 publications

References 52 publications

NADPH-diaphorase expression in the rat jejunum after intestinal ischemia/reperfusion

NADPH-diaphorase expression in the rat jejunum after intestinal ischemia/reperfusion

Myosin Va plays a key role in nitrergic neurotransmission by transporting nNOSα to enteric varicosity membrane

Molecular Handoffs in Nitrergic Neurotransmission

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