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Although learning and memory decline are associated with aging, some older individuals show high cognitive function. The mechanism underlying successful aging is not clear, although augmented N-methyl-D-aspartate receptor-independent long-term depression (LTD) has been found in successfully aged rats. We hypothesized that metabotropic glutamate receptor dependent LTD (mGluR-LTD) is associated with successful aging in mice and explored its molecular mechanisms. We divided aged mice into impaired and unimpaired groups and examined mGluR-LTD in the hippocampus. We examined the role of hydrogen sulfide (H2S) in mGluR-LTD establishment in aged mice and investigated the requirement of protein synthesis and intracellular calcium levels. We assessed learning and memory of mice treated with sodium hydrogen sulfide (NaHS) using behavior tests. We found that unimpaired mice elicited larger mGluR-LTD that correlated with H2S production which was blocked by inhibiting cystathionine synthase. Enhanced H2S production of NaHS treatment augmented mGluR-LTD in impaired group. mGluR-LTD establishment required protein synthesis, as well as intracellular calcium, although NaHS treatment leads to reduced sensitivity to calcium chelator 1,2-bis(o-amino phenoxy)ethane-N,N,N',N'-tetraacetic acid treatment. Finally, we found that NaHS treatment enhanced learning and memory of aged mice as indicated by behavioral assessments. Our results indicate that successful aging mice are associated with the function of H2S. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by dopaminergic neurons degeneration and oxidative damage may underlie this process. However, there are still no efficient drugs to cure the disease. Pycnogenol (PYC) isolated from the procyanidin-rich French maritime pine (Pinus maritime) bark has shown various antioxidant activities in previous studies. In this study, we explored its effect against rotenone (Rot)-induced neurotoxicity and the underlying mechanisms in PC12 cells. Using Rot-induced cell model of PD, we found that PYC treatment significantly increased cell viability and decreased cell apoptosis in Rot-treated PC12 cells in a dose-dependent manner. Furthermore, data showed that PYC markedly reduced inducible nitric oxide synthase (iNOS)-nitric oxide (NO) signaling in Rot-treated PC12 cells. Pretreatment with the iNOS-specific inhibitor significantly attenuated Rot-induced neurotoxicity. Moreover, PYC was found to be capable of reducing Rot-induced NF-κB activation. Blocking NF-κB signaling with its inhibitor mimicked the biological effect of PYC on Rot-induced iNOS and NO expression levels, as well as neurotoxicity in PC12 cells, suggesting that the NF-κB-iNOS signaling pathway was likely to participate in the PYC-mediated protective progress. Our results suggest that PYC protects against Rot-induced neurotoxicity in PC12 cells, and the mechanism may be associated with the downregulation of NF-κB-iNOS signaling pathway. [ABSTRACT FROM AUTHOR]