Protection of spinal cord ischemia-reperfusion injury mediated by N-methyl-D-aspartate receptors / 中国胸心血管外科临床杂志

@#Objective    To analyze the protective mechanism of spinal cord ischemia-reperfusion injury mediated by N-methyl-D-aspartate (NMDA) receptor. Methods    A total of 42 SD rats were randomly assigned to 4 groups: a non-blocking group (n=6), a saline group (n=12), a NMDA receptor blocker K-1024 (25 mg/kg) group (n=12) and a voltage-gated Ca2+ channel blocker nimodipine (0.5 mg/kg) group (n=12). The medications were injected intraperitoneally 30 min before ischemia. The neural function was evaluated. The neuronal histologic change of spinal cord lumbar region, the release of neurotransmitter amino acids and expression of spinal cord neuronal nitric oxide synthase (nNOS) were compared. Results    At 8 h after reperfusion, the behavioral score of the K-1024 group was 2.00±0.00 points, which was statistically different from those of the saline group (5.83±0.41 points) and the nimodipine group (5.00±1.00 points, P<0.05). Compared with the saline group and nimodipine group, K-1024 group had more normal motor neurons (P<0.05). There was no significant difference in glutamic acid concentration in each group at 10 min after ischemia (P=0.731). The nNOS protein expression in the K-1024 group was significantly down-regulated compared with the saline group (P<0.01). After 8 h of reperfusion, the expression of nNOS protein in the K-1024 group was significantly up-regulated compared with the saline group (P<0.05). Conclusion    K-1024 plays a protective role in spinal cord ischemia by inhibiting NMDA receptor and down-regulating nNOS protein expression; during the reperfusion, K-1024 has a satisfactory protective effect on spinal cord function, structure and biological activity of nerve cells.

Immunohistochemical study on the expression of calcium binding proteins (calbindin-D28k, calretinin, and parvalbumin) in the cerebral cortex and in the hippocampal region of nNOS knock-out(-/-) mice / 대한해부학회지

Nitric oxide (NO) modulates the activities of various channels and receptors to participate in the regulation of neuronal intracellular Ca2+ levels. Ca2+ binding protein (CaBP) expression may also be altered by NO. Accordingly, we examined expression changes in calbindin-D28k, calretinin, and parvalbumin in the cerebral cortex and hippocampal region of neuronal NO synthase knockout(-/-) (nNOS-/-) mice using immunohistochemistry. For the first time, we demonstrate that the expression of CaBPs is specifically altered in the cerebral cortex and hippocampal region of nNOS-/- mice and that their expression changed according to neuronal type. As changes in CaBP expression can influence temporal and spatial intracellular Ca2+ levels, it appears that NO may be involved in various functions, such as modulating neuronal Ca2+ homeostasis, regulating synaptic transmission, and neuroprotection, by influencing the expression of CaBPs. Therefore, these results suggest another mechanism by which NO participates in the regulation of neuronal Ca2+ homeostasis. However, the exact mechanisms of this regulation and its functional significance require further investigation.

Role of nitric oxide in the periaqueductal gray in defensive behavior in mice: influence of prior local N-methyl-D-aspartate receptor activation and aversive condition

Glutamate N-methyl-D-aspartate (NMDA) receptor activation within the dorsal column of the periaqueductal gray (dPAG) leads to antinociceptive, autonomic, and behavioral responses characterized as the fear reaction. Activation of NMDA receptors in the brain increases nitric oxide (NO) synthesis, and NO has been proposed to be a mediator of the aversive action of glutamate. This paper reviews a series of studies investigating the effects of neuronal NO synthase (nNOS) inhibition in the dPAG of mice in different aversive conditions. nNOS inhibition by infusion of Nω-propyl-L-arginine (NPLA) prevents fear-like reactions (e.g., jumping, running, freezing) induced by NMDA receptor stimulation within the dPAG and produces anti-aversive effects when injected into the same midbrain site in mice confronted with a predator. Interestingly, nNOS inhibition within the dPAG does not change anxiety-like behavior in mice exposed to the elevated plus maze (EPM), but it reverses the effect of an anxiogenic dose of NMDA injected into the same site in animals subjected to the EPM. Altogether, the results support a role for glutamate NMDA receptors and NO in the dPAG in the regulation of defensive behaviors in mice. However, dPAG nitrergic modulation of anxiety-like behavior appears to depend on the magnitude of the aversive stimulus.

Immunohistochemical study on the expression of calcium binding proteins (calbindin-D28k, calretinin, and parvalbumin) in the cerebellum of the nNOS knock-out(-/-) mice / 대한해부학회지

Nitric Oxide (NO) actively participates in the regulation of neuronal intracellular Ca2+ levels by modulating the activity of various channels and receptors. To test the possibility that modulation of Ca2+ buffer protein expression level by NO participates in this regulatory effect, we examined expression of calbindin-D28k, calretinin, and parvalbumin in the cerebellum of neuronal NO synthase knock-out (nNOS(-/-)) mice using immunohistochemistry. We observed that in the cerebellar cortex of the nNOS(-/-) mice, expression of calbindin-D28k and parvalbumin were significantly increased while expression of calretinin was significantly decreased. These results suggest another mechanism by which NO can participate in the regulation of Ca2+ homeostasis.

Temporal Changes of Post Synaptic Signaling Molecules, Post Synaptic Density-95 and Neuronal Nitric Oxide Synthase, in the Inner Molecular Layer of the Mouse Dentate Gyrus during Voluntary Running / 대한해부학회지

Here, we investigated the temporal change of post synapse signaling molecules, post synaptic density-95 (PSD-95) and neuronal nitric oxide synthase (nNOS) using immunohistochemistry during voluntary running with upregulated neurogenesis. Rate of running was stabilized after two weeks of the six week trial. By using immunohistochemsitry for phosphorylated cAMP response element binding protein (pCREB) and polysialylatedneural cell adhesion molecules (PSA-NCAM), we observed that the differentiation in dentate granule cells of adult mouse hippocampus increased at 1 and 2 weeks of voluntary running. We found that, at 6 weeks of voluntary running, the differentiation in dentate granule cells of adult mouse hippocampus returned to sedentary control levels. On the other hand, PSD-95 and nNOS immunoreactivity decreased in the inner molecular layer in the dentate gyrus of hippocampus after 1 and 2 weeks of voluntary running. At 6 weeks of voluntary running, the density of the PSD-95 and nNOS in the inner molecular layer was returned to the sedentary control level. The reactivity of nicotinamide dinucleotide phosphate diaphorase (NADPH-diaphorase), the marker of nitric oxide synthase activity, confirmed the change of nNOS in the inner molecular layer during voluntary running. These results demonstrate that the differentiation and the synaptic activity of granule cells during voluntary running are changed reciprocally once the rate of running has stabilized. These granule cell changes during voluntary running suggest an adaptation response to the new environment.

Effect of Intermittent Electrical Stimulation of Sciatic Nerve on Expression of Neuronal Nitric Oxide Synthase (nNOS) Protein in the Soleus and Medial Gastrocnemius Muscles following Hindlimb Suspension in Rats / 대한정형외과학회잡지

PURPOSE: The present study was designed to evaluate the effect of intermittent electrical stimulation (ES) of the sciatic nerve on the expression of neuronal nitric oxide synthase (nNOS) protein in the soleus and in the medial gastrocnemius muscles 2 weeks following hindlimb suspension (HS). MATERIALS AND METHODS: In the HS+ES group, a pair of stainless steel electrodes were placed at the midportion of the unilateral sciatic nerve during hindlimb unloading. Square wave pluses with a 5 seconds ON-OFF pattern were applied to the sciatic nerve 4 hours a day for 14 days. The electrical stimulation parameters were 20 Hz, 0.3 ms, 1-5 voltage. 14 days later the sciatic nerve stimulation maximal twitch response was measured in the soleus and medial gastrocnemius muscles using an isometric tension transducer and polygraph. Western blot was used to analyze the expression of nitric oxide synthase (nNOS) protein in hindlimb muscles. RESULTS: The soleus muscle consisted of slow-twitch muscle fiber and showed a prominent decrease in maximum twitch tension and muscle weight than the medial gastrocnemius muscle 2 weeks after hindlimbs suspension. Hindlimbs suspension caused a reduction in the relative quantity of nNOS protein by 89% and 55% in the soleus and the medial gastrocnemius muscles, respectively, after 2 weeks of unloading compared with the ambulatory controls. However, intermittent electrical stimulation of the sciatic nerve delayed reduction significantly with respect to the expression of nNOS protein and twitch tension during hindlimb unloading. CONCLUSION: The results suggest that application of electrical stimulation to the sciatic nerve has a significant effect on NO signal transduction by regulating nNOS expression in atrophied hindlimb extensor muscles.