The Perineuronal Net Protein Brevican Acts in Nucleus Accumbens Parvalbumin-Expressing Interneurons of Adult Mice to Regulate Excitatory Synaptic Inputs and Motivated Behaviors

Perineuronal nets: Role in normal brain physiology and aging, and pathology of various diseases

Perineuronal nets (PNNs) are a specialized extracellular matrix in the central nervous system. They are widely distributed in the brain, with distribution patterns varying by brain region. Their unique structure and composition allow them to play an important role in a range of physiological and pathological activities. In this article, we review the composition and structure of PNNs across different life stages, and provide a detailed analysis and comparison of the region-specific distribution patterns of PNNs in different brain areas. We also discuss the specific mechanisms by which PNNs are involved in plasticity, memory, and neuroprotection. Furthermore, we describe the abnormal changes in PNNs in aging and various brain diseases, such as Alzheimer's disease, Parkinson's disease, drug addiction, and schizophrenia. Finally, we review emerging and established therapeutic strategies targeting PNNs to modulate brain function and address neurological disorders from three perspectives: gene therapy, nanotechnology, and biomaterials. This review summarizes the physiological roles of PNNs at different stages of life and the mechanisms by which PNNs abnormalities contribute to various brain diseases, providing insights for potential therapeutic approaches.

The nucleus accumbens in reward and aversion processing: insights and implications

The nucleus accumbens (NAc), a central component of the brain's reward circuitry, has been implicated in a wide range of behaviors and emotional states. Emerging evidence, primarily drawing from recent rodent studies, suggests that the function of the NAc in reward and aversion processing is multifaceted. Prolonged stress or drug use induces maladaptive neuronal function in the NAc circuitry, which results in pathological conditions. This review aims to provide comprehensive and up-to-date insights on the role of the NAc in motivated behavior regulation and highlights areas that demand further in-depth analysis. It synthesizes the latest findings on how distinct NAc neuronal populations and pathways contribute to the processing of opposite valences. The review examines how a range of neuromodulators, especially monoamines, influence the NAc's control over various motivational states. Furthermore, it delves into the complex underlying mechanisms of psychiatric disorders such as addiction and depression and evaluates prospective interventions to restore NAc functionality.

Sex-Specific Regulation of Stress Susceptibility by the Astrocytic Gene Htra1

Major depressive disorder (MDD) is linked to impaired structural and synaptic plasticity in limbic brain regions. Astrocytes, which regulate synapses and are influenced by chronic stress, likely contribute to these changes. We analyzed astrocyte gene profiles in the nucleus accumbens (NAc) of humans with MDD and mice exposed to chronic stress. Htra1 , which encodes an astrocyte-secreted protease targeting the extracellular matrix (ECM), was significantly downregulated in the NAc of males but upregulated in females in both species. Manipulating Htra1 in mouse NAc astrocytes bidirectionally controlled stress susceptibility in a sex-specific manner. Such Htra1 manipulations also altered neuronal signaling and ECM structural integrity in NAc. These findings highlight astroglia and the brain's ECM as key mediators of sex-specific stress vulnerability, offering new approaches for MDD therapies.