S-nitrosoglutathione modulates HDAC2 and BDNF levels in the brain and improves cognitive deficits in experimental model of Alzheimer's disease in rats.

AIM: Alzheimer's disease (AD) is a neurodegenerative disorder which is characterized by cognitive deficits and abnormal memory formation. Histone acetylation is essential for hippocampal memory formation and improving the cognitive deficits, and histone deacetylase 2 (HDAC2) is increased in the hippocampus of AD patients. The present study evaluated the effects of the nitric oxide (NO) mimetics, L-arginine and the nitrosothiol NO donor, s-nitrosoglutathione (GSNO), on memory and brain HDAC2 levels in experimental animal model of sporadic Alzheimer's disease (sAD). METHODS: AD was induced experimentally in rats by intracerebroventricular injection of streptozotocin (STZ, 3 mg/kg). The effects of NO mimetics, GSNO and L-arginine, were assessed on STZ induced cognitive deficits in the Morris water maze (MWM) test, and, following this, the hippocampal homogenates were assayed for amyloid-ß, brain derived neurotropic factor (BDNF) and HDAC2 levels. The neurobehavioral and biochemical data of the drug treated groups were compared with those of experimental control group. RESULTS: The results showed that icv-STZ induced cognitive deficits were differentially attenuated by GSNO (50 µg/kg) and, to a lesser extent, L-arginine (100 mg/kg) with improvement in the spatial learning tasks in MWM test. These behavioral changes were associated with decreased levels of biochemical markers viz. amyloid ß, BDNF and HDAC2 levels in hippocampus. CONCLUSIONS: It is inferred that NO donors like GSNO could influence AD pathophysiology via epigenetic modification of HDAC2 inhibition.