Highlights d Striatal MSNs release GABA to activate astrocyte Gi-coupled GABA B receptors d Astrocyte Gi pathway activation results in hyperactivity with disrupted attention d Astrocyte Gi pathway activation increases fast synaptic excitation and MSN firing d Behavioral and synaptic effects are due to reactivation of TSP1 in astrocytes
Astrocytes are implicated in neurodegenerative disorders and may contribute to striatal neuron loss or dysfunction in Huntington’s disease (HD). Here, we assessed striatal astrocyte gene and protein signatures in two HD mouse models at three stages and compared our results to human HD data at four clinical grades and to mice exhibiting polyglutamine length–dependent pathology. We found disease-model and stage-specific alterations and discovered a core disease-associated astrocyte molecular signature comprising 62 genes that were conserved between mice and humans. Our results show little evidence of neurotoxic A1 astrocytes that have been proposed to be causal for neuronal death in neurodegenerative disorders such as HD. Furthermore, 61 of the 62-core gene expression changes within astrocytes were reversed in a HD mouse model by lowering astrocyte mutant huntingtin protein (mHTT) expression using zinc finger protein (ZFP) transcriptional repressors. Our findings indicate that HD astrocytes progressively lose essential normal functions, some of which can be remedied by lowering mHTT. The data have implications for neurodegenerative disease rescue and repair strategies as well as specific therapeutic relevance for mHTT reduction and contribute to a better understanding of fundamental astrocyte biology and its contributions to disease.
Despite the advent of highly active antiretroviral therapy (HAART), HIV-associated neurological disorders (HAND) remain a major challenge in human immunodeficiency virus (HIV) treatment. The early implementation of HAART in the infected individuals helps suppress the viral replication in the plasma and other compartments. Several studies also report the beneficial effect of drugs that successfully penetrate central nervous system (CNS). However, recent data in both clinical setup and in in vitro studies indicate CNS toxicity of the antiretrovirals (ARVs). Although the evidence is limited, correlation between prolonged use of ARVs and neurotoxicity strongly suggests that it is essential to study the underlying mechanisms responsible for such toxicity. Furthermore, closer attention toward clinical outcomes is required to screen various ARV regimens for their association with HAND and other comorbidities. A growing body of literature also indicates a possible role of accelerated aging in the antiretroviral therapy-associated neurotoxicity. Lastly, owing to high pill burden, multiple drugs in the HIV treatment also invite a possible role of drug–drug interaction via various cytochrome P450 enzymes. The particular emphasis of this review is to highlight the need to identify alternative approaches in reducing the CNS toxicity of the ARV drugs in HIV-infected individuals.
Highlights d Multiple approaches reveal transient K + elevations during ChR2 excitation d ChR2-mediated K + elevations increase neuronal excitability and cFos expression d Neuronal effects of K + are recapitulated with a model and in vivo d Increased K + may contribute to astrocyte experiments employing ChR2 in vivo
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