Two independent lines of High Drinking in the Dark (HDID-1, HDID-2) mice have been bred to reach high blood alcohol levels after a short period of binge-like ethanol drinking. Male mice of both lines were shown to have reduced sensitivity to develop a taste aversion to a novel flavor conditioned by ethanol injections as compared with their unselected HS/NPT founder stock. We have subsequently developed inbred variants of each line. The current experiments established that reduced ethanol-conditioned taste aversion is also seen in the inbred variants, in both males and females. In other experiments, we asked whether HDID mice would ingest sufficient doses of ethanol to lead to a conditioned taste aversion upon retest. Different manipulations were used to elevate consumption of ethanol on initial exposure. Access to increased ethanol concentrations, to multiple tubes of ethanol, and fluid restriction to increase thirst motivation all enhanced initial drinking of ethanol. Each condition led to reduced intake the next day, consistent with a mild conditioned taste aversion. These experiments support the conclusion that one reason contributing to the willingness of HDID mice to drink to the point of intoxication is a genetic insensitivity to the aversive effects of ethanol.

Background/Objectives: Extracts of the plant Centella asiatica can enhance mitochondrial function, promote antioxidant activity and improve cognitive deficits. Asiatic acid (AA) is one of the constituent triterpene compounds present in the plant. In this study, we explore the effects of AA on brain mitochondrial function, antioxidant response and cognition in a beta-amyloid (Aβ)-overexpressing 5xFAD mouse line. Methods: Six- to seven-month-old 5xFAD mice were treated with 1% AA for 4 weeks. In the last week of treatment, associative memory was assessed along with mitochondrial bioenergetics and the expression of mitochondrial and antioxidant response genes from isolated cortical synaptosomes. The Aβ plaque burden was also evaluated. Results: AA treatment resulted in improvements in associative memory in female 5xFAD mice without altering the Aβ plaque burden. Cortical mitochondrial function and mitochondrial gene expression were increased in the AA-treated female 5xFAD mice, as was the expression of antioxidant genes. More modest effects of AA on cortical mitochondrial function and mitochondrial and antioxidant gene expression were observed in male 5xFAD mice. Conclusions: Oral AA treatment improved cognitive and mitochondrial function and activated antioxidant in Aβ-overexpressing mice. These changes occurred independent of alterations in Aβ plaque burden, suggesting that AA could have translational therapeutic relevance in later-stage AD when plaques are well established.

Alterations in epigenetic modifications, like DNA methylation, in peripheral blood could serve as a useful, minimally invasive biomarker of the effects of anti-aging interventions. This study explores this potential with a water extract of the botanical Centella asiatica (CAW). Eighteen-month-old mice were treated with CAW in their drinking water for 5 weeks alongside vehicle-treated eighteen-month-old C57BL6 mice. Reduced representation bisulfite sequencing (RRBS) was used to identify genome-wide differential methylation in the blood of CAW-treated aged mice compared to vehicle-treated aged mice. Our results showed a distinct enrichment of differentially methylated regions (DMRs) nearby genes involved in biological processes relevant to aging (i.e., antioxidant response, metabolic regulation, cellular metabolism). A distinct difference was observed between males and females in both the number of methylation sites and the state of methylation. Moreover, genes nearby or overlapping DMRs were found to be enriched for biological processes related to previously described cellular effects of CAW in the mouse brain (i.e., antioxidant response, metabolic regulation, calcium regulation, and circadian rhythm). Together, our data suggest that the peripheral blood methylation signature of CAW in the blood could be a useful, and readily accessible, biomarker of CAW’s effects in aging.

Oxidative stress and neuroinflammation are widespread in the Parkinson’s disease (PD) brain and contribute to the synaptic degradation and dopaminergic cell loss that result in cognitive impairment and motor dysfunction. The polymethoxyflavone Gardenin A (GA) has been shown to activate the NRF2-regulated antioxidant pathway and inhibit the NFkB-dependent pro-inflammatory pathway in a Drosophila model of PD. Here, we evaluate the effects of GA on A53T alpha-synuclein overexpressing (A53TSyn) mice. A53TSyn mice were treated orally for 4 weeks with 0, 25, or 100 mg/kg GA. In the fourth week, mice underwent behavioral testing and tissue was harvested for immunohistochemical analysis of tyrosine hydroxylase (TH) and phosphorylated alpha synuclein (pSyn) expression, and quantification of synaptic, antioxidant and inflammatory gene expression. Results were compared to vehicle-treated C57BL6 mice. Treatment with 100 mg/kg GA improved associative memory and decreased abnormalities in mobility and gait in A53TSyn mice. GA treatment also reduced cortical and hippocampal levels of pSyn and attenuated the reduction in TH expression in the striatum. Additionally, GA increased cortical expression of NRF2-regulated antioxidant genes and decreased expression of NFkB-dependent pro-inflammatory genes. GA was readily detectable in the brains of treated mice and modulated the lipid profile in the deep gray brain tissue of those animals. While the beneficial effects of GA on cognitive deficits, motor dysfunction and PD pathology are promising, future studies are needed to further fully elucidate the mechanism of action of GA, optimizing dosing and confirm these effects in other PD models. Significance Statement: The polymethoxyflavone Gardenin A can improve cognitive and motor function and attenuate both increases in phosphorylated alpha synuclein and reductions in tyrosine hydroxylase expression in A53T alpha synuclein overexpressing mice. These effects may be related to activation of the NRF2-regulated antioxidant response and downregulation of NFkB-dependent inflammatory response by Gardenin A in treated animals. The study also showed excellent brain bioavailability of Gardenin A and modifications of the lipid profile, possibly through interactions between Gardenin A with the lipid bilayer, following oral administration. The study confirms neuroprotective activity of Gardenin A previously reported in toxin induced Drosophila model of Parkinson’s disease.

Background/objectives: A water extract of the plant Centella asiatica (CAW) has been shown to improve cognitive deficits in aged mice when administered for 5 weeks in drinking water. However, the contribution of the constituent compounds within CAW to the beneficial effects of the extract remains unelucidated. This study evaluated the effects of triterpene (TT) and caffeoylquinic acids (CQA) found within CAW, on learning, cognitive flexibility, memory, and anxiety-like behaviors in aged C57BL6 mice. Methods: Eighteen-month-old male and female C57BL6 mice were administered either TT, CQA, or the combination (TT+CQA) in their drinking water for a total of 5 weeks, at concentrations corresponding to their presence in CAW. During the final two weeks of treatment learning, executive function, memory, and anxiety were assessed. Results: Aged mice of both sexes showed significant improvement in learning when treated with TT and CQA separately and in combination. Treatment with TT also improved cognitive flexibility in aged mice of both sexes, but CQA and the combination of TT+CQA did not alter cognitive flexibility in aged male mice. There was no effect on recognition memory or anxiety in any of the treatment groups (TT, CQA, TT+CQA) relative to mice treated with the vehicle control although there was a trend towards improved recognition memory with TT treatment. Conclusions: These results suggest that the TT and CQA present in CAW likely contribute to its previously reported amelioration of age-related cognitive changes, especially in learning and cognitive flexibility, while other constituents may be responsible for CAW’s anxiolytic effects.

Parkinson’s Disease (PD) is the second most diagnosed neurological disorder globally, affecting millions of people worldwide. Oxidative stress is implicated in the progression of PD, yet its direct effects on motor function, particularly in the context of synucleinopathy, are not fully understood. Here, we investigated the effects of the loss of the antioxidant regulatory transcription factor NRF2 in the A53TSyn mouse model of synucleinopathy. Motor function was evaluated in separate cohorts of A53TSyn mice without NRF2 (A53TSyn/NRF2KO), as well as A53TSyn mice expressing NRF2 (A53TSyn/NRF2+) and healthy wild-type (WT) mice at four, six, and eight months of age. The overall mobility decreased in A53TSyn/NRF2KO mice relative to WT mice at all ages. Significant alterations in gait were also apparent in A53TSyn/NRF2KO mice compared to A53TSyn mice without NRF2 deletion. Expression of tyrosine hydroxylase (TH) was also quantified in the brains of those mice. While there were no differences in cortical pSyn expression between A53TSyn/NRF2+ and A53TSyn/NRF2KO mice, a reduction in TH abundance in the striatum was evident in A53TSyn/NRF2KO mice at all ages. In summary, our data suggest that NRF2 plays a role in maintaining mobility and gait in the context of synucleinopathy and may represent a therapeutic target to mitigate mobility decline in PD-affected individuals.