Pharmacologic evidence for role of endothelial nitric oxide synthase in neuroprotective mechanism of ischemic postconditioning in mice.
BACKGROUND
The present study was conducted to pharmacologically investigate the isoform-specific role of nitric oxide pathway in neuroprotective mechanism of ischemic postconditioning (iPoCo).


METHODS
Bilateral carotid artery occlusion of 12 min followed by reperfusion for 24 h was used to produce ischemia- and reperfusion-induced cerebral injury in male Swiss mice. Memory was assessed using Morris water maze test. Degree of motor in-coordination was evaluated using inclined beam-walk test, rotarod test, and lateral push test. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Brain acetylcholinestrase activity, thiobarbituric acid-reactive species, nitrite/nitrate, and reduced glutathione levels were also estimated. Western blotting was performed to determine endothelial nitric oxide synthase (eNOS) expression.


RESULTS
Bilateral carotid artery occlusion followed by reperfusion produced significant rise in cerebral infarct size, acetylcholinesterase activity, and thiobarbituric acid-reactive species levels along with fall in nitrite/nitrate, and glutathione and eNOS expression levels. A significant impairment of memory and motor coordination was also noted. iPoCo consisting of three episodes of 10-s carotid artery occlusion and reperfusion significantly attenuated infarct size, memory impairment, motor in-coordination, altered biochemicals, and protein expression levels. iPoCo-induced neuroprotective effects were significantly abolished by L-NAME (a nonselective nitric oxide synthase inhibitor) and L-NIO (a selective eNOS inhibitor). However, aminoguanidine (a selective inducible nitric oxide synthase inhibitor) and 7-nitroindazole (a selective neuronal nitric oxide synthase inhibitor) did not modulate beneficial effects of iPoCo.


CONCLUSIONS
It may be concluded that nitric oxide pathway probably plays a vital role with specific involvement of eNOS in neuroprotective mechanism of iPoCo.
Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, Punjab, India.
Puja
P
Gulati
Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, Punjab, India. Electronic address: nirmal_puru@rediffmail.com.
Nirmal
N
Singh
Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, Punjab, India.
Arunachalam
A
Muthuraman
D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology; D002544:Cerebral Infarction / Q000473:pathology / Q000517:prevention & control*; D002560:Cerebrovascular Circulation; D057775:Ischemic Postconditioning; D008297:Male; D008568:Memory; D051379:Mice; D009048:Motor Skills; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D015427:Reperfusion Injury / Q000517:prevention & control*; D045442:Rotarod Performance Test
D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse
Cerebral ischemia; Ischemic post-conditioning; Memory; Neuroprotection; l-NIO; l-Name