Biology subjects

Zalachoras, I.

Publications and source records attributed to Zalachoras, I..

3 recordsLinked to original sources

bioRxiv2026

Deletion of TNFR1 in astrocytes restores memory in aged Alzheimer's disease mice

Astrocytes participate in local inflammation and cognitive decline in Alzheimers disease (AD). Aberrant cytokine TNF signaling via astrocyte type-1 receptor (aTNFR1) could causally link the two AD pathology aspects. To verify this hypothesis, we crossed transgenic AD mice with mice enabling astrocyte-specific conditional TNFR1 deletion (aTNFR1KO). Induction of aTNFR1KO at early AD stages, preserved memory and reduced {beta}-amyloid load and astrogliosis in the aged mice. Induction of aTNFR1KO at late AD stages, in mice already memory-impaired, surprisingly produced rapid memory rescue, without affecting {beta}-amyloid load and astrogliosis. Single nucleus-RNA-seq analysis of all hippocampal cell populations revealed that late-stage aTNFR1KO rapidly modifies gene expression mainly in neurons, primarily targeting synaptic pathways, causing combined glutamatergic downregulation and GABAergic up-regulation. Consistently, hippocampal EEGs showed a pro-inhibitory effect of aTNFR1KO, which thus restores memory by "rebalancing" hippocampal circuitry excitability. This pro-memory effect identifies a new mechanism and astrocyte target against cognitive decline in AD.

neuroscience↗

bioRxiv2022

Glutathione in the nucleus accumbens regulates motivation to exert reward-incentivized effort

Emerging evidence is implicating mitochondrial function and metabolism in the nucleus accumbens in motivated performance. However, the brain is vulnerable to excessive oxidative insults resulting from neurometabolic processes and whether antioxidant levels in the nucleus accumbens contribute to motivated performance is not known. Here, we identify a critical role for glutathione (GSH), the most important endogenous antioxidant in the brain, in motivation. Using proton magnetic resonance spectroscopy (1H-MRS) at ultra-high field in both clinical and preclinical populations, we establish that higher accumbal GSH levels are highly predictive of better, and particularly steady performance over time in effort-related tasks. Causality was established in preclinical in vivo experiments that, first, showed that down-regulating GSH levels through micro-injections of the GSH synthesis inhibitor buthionine sulfoximine in the nucleus accumbens impaired effort-based reward-incentivized performance. In addition, systemic treatment with the GSH precursor N-acetyl-cysteine (NAC) increased accumbal GSH levels and led to improved performance, potentially mediated by a cell-type specific shift in glutamatergic inputs to accumbal medium spiny neurons. Our data indicate a close association between accumbal GSH levels and individuals capacity to exert reward-incentivized effort over time. They also suggest that improvement of accumbal antioxidant function may be a feasible approach to boost motivation.

neuroscience↗

bioRxiv2019

The glucocorticoid receptor in the nucleus accumbens plays a crucial role in social rank attainment in rodents

Social hierarchy in social species is usually established through competitive encounters with conspecifics. It determines the access to limited resources and, thus, leads to reduced fights among individuals within a group. Despite the known importance of social rank for health and well-being, the knowledge about the processes underlying rank attainment remains limited. Previous studies have highlighted the nucleus accumbens (NAc) as a key brain region in the attainment of social hierarchies in rodents. In addition, glucocorticoids and the glucocorticoid receptor (GR) have been implicated in the establishment of social hierarchies and social aversion. However, whether GR in the NAc is involved in social dominance is not yet known. To address this question, we first established that expression levels of GR in the NAc of high anxious, submissive-prone rats are lower than that of their low anxious, dominant-prone counterparts. Furthermore, virally-induced downregulation of GR expression in the NAc in rats led to an improvement of social dominance rank. We found a similar result in a cell-specific mouse model lacking GR in dopaminoceptive neurons (i.e., neurons containing dopamine receptors). Indeed, when cohabitating in dyads of mixed genotypes, mice deficient for GR in dopaminoceptive neurons had a higher probability to become dominant than wild-type mice. Overall, our results highlight GR in the NAc and in dopaminoceptive neurons as an important regulator of social rank attainment.

neuroscience↗