؉/؊ mice, but not Nrf2 ؊/؊ , confirming the Nrf2-specific action of the inducer in vivo. Increased Nrf2 activity alone was sufficient to protect animals from 3-NP toxicity because intrastriatal adenovirus-mediated Nrf2 overexpression significantly reduced lesion size compared with green fluorescent protein overexpressing controls. In cultured astrocytes, 3-NP was found to increase Nrf2 activity leading to antioxidant response element-dependent gene expression providing a potential mechanism for the increased sensitivity of Nrf2

The balance between detrimental, pro-aging, often stochastic processes and counteracting homeostatic mechanisms largely determines the progression of aging. There is substantial evidence suggesting that the endocannabinoid system (ECS) is part of the latter system because it modulates the physiological processes underlying aging. The activity of the ECS declines during aging, as CB1 receptor expression and coupling to G proteins are reduced in the brain tissues of older animals and the levels of the major endocannabinoid 2-arachidonoylglycerol (2-AG) are lower. However, a direct link between endocannabinoid tone and aging symptoms has not been demonstrated. Here we show that a low dose of Δ-tetrahydrocannabinol (THC) reversed the age-related decline in cognitive performance of mice aged 12 and 18 months. This behavioral effect was accompanied by enhanced expression of synaptic marker proteins and increased hippocampal spine density. THC treatment restored hippocampal gene transcription patterns such that the expression profiles of THC-treated mice aged 12 months closely resembled those of THC-free animals aged 2 months. The transcriptional effects of THC were critically dependent on glutamatergic CB1 receptors and histone acetylation, as their inhibition blocked the beneficial effects of THC. Thus, restoration of CB1 signaling in old individuals could be an effective strategy to treat age-related cognitive impairments.

No abstract

BACKGROUND Kynurenine 3-monooxygenase (KMO) converts kynurenine to 3-hydroxykynurenine, and its inhibition shunts the kynurenine pathway - which is implicated as dysfunctional in various psychiatric disorders - towards enhanced synthesis of kynurenic acid (KYNA), an antagonist of both α7 nicotinic acetylcholine and NMDA receptors. Possibly as a result of reduced KMO activity, elevated central nervous system levels of KYNA have been found in patients with psychotic disorders, including schizophrenia (SZ). METHODS In the present study, we investigated adaptive – and possibly regulatory – changes in mice with a targeted deletion of Kmo (Kmo−/−) and characterized the KMO-deficient mice using six behavioral assays relevant for the study of SZ. RESULTS Genome-wide differential gene expression analyses in the cerebral cortex and cerebellum of these mice identified a network of SZ- and psychosis-related genes, with more pronounced alterations in cerebellar tissue. KYNA levels were also increased in these brain regions in Kmo−/− mice, with significantly higher levels in the cerebellum than in the cerebrum. Kmo−/− mice exhibited impairments in contextual memory and spent less time than controls interacting with an unfamiliar mouse in a social interaction paradigm. The mutant animals displayed increased anxiety-like behavior in the elevated plus maze and in a light-dark box. After a D-amphetamine challenge (5 mg/kg, i.p.), Kmo−/− mice showed potentiated horizontal activity in the open field paradigm. CONCLUSIONS Taken together, these results demonstrate that the elimination of Kmo in mice is associated with multiple gene and functional alterations that appear to duplicate aspects of the psychopathology of several neuropsychiatric disorders.