Perineuronal Nets Alterations Contribute to Stress-Induced Anxiety-Like Behavior

Lateral periaqueductal gray participate in the regulation of irritable bowel syndrome induced by chronic restraint stress

Irritable bowel syndrome (IBS) is a functional bowel disorder defined by recurrent abdominal pain, coupled with irregular bowel habits and alterations in the frequency as well as the consistency of stool. At present, IBS is considered as a disease of gut-brain interaction, and an increasing number of studies are focusing on the brain-gut axis. However, the brain regions associated with IBS have not been fully studied yet. In this study, we utilized the chronic restraint stress (CRS) model to evoke IBS-like symptoms in mice, which were accompanied by anxiety-like behaviors and hyperalgesia. Through cFOS staining, we observed the activation of the lateral periaqueductal gray (LPAG) in the mice after CRS. By inhibiting the activity of the LPAG through tetanus toxin or chemogenetics, we found that IBS-like symptoms could be relieved, whereas chemogenetic activation of the LPAG induced IBS-like symptoms. Finally, we utilized the classic analgesic drug sufentanil and found that it could alleviate CRS-induced IBS-like symptoms.

Modulation of stress-, pain-, and alcohol-related behaviors by perineuronal nets

Perineuronal nets (PNNs) are a special form of central nervous system extracellular matrix enriched in hyaluronan, chondroitin sulfate proteoglycans, tenascins, and link proteins that regulate synaptic plasticity. Most PNNs in the brain surround parvalbumin-expressing inhibitory interneurons, which tightly regulate excitatory/inhibitory balance and brain activity associated with optimal cognitive functioning. Alterations in PNNs have been observed in neurological diseases and psychiatric disorders, suggesting that they may be key contributors to the neuropathological progression and behavioral changes in these diseases. Alcohol use disorder (AUD), major depressive disorder (MDD), and chronic pain are highly comorbid conditions, and changes in PNNs have been observed in animal models of these disorders, as well as postmortem tissue from individuals diagnosed with AUD and MDD. This review focuses on the literature describing stress-, alcohol-, and pain-induced adaptations in PNNs, potential cellular contributors to altered PNNs, and the role of PNNs in behaviors related to these disorders. Medicines that can restore PNNs to a non-pathological state may be a novel therapeutic approach to treating chronic pain, AUD, and MDD.

The Neurovascular Unit as a Locus of Injury in Low-Level Blast-Induced Neurotrauma

Blast-induced neurotrauma has received much attention over the past decade. Vascular injury occurs early following blast exposure. Indeed, in animal models that approximate human mild traumatic brain injury or subclinical blast exposure, vascular pathology can occur in the presence of a normal neuropil, suggesting that the vasculature is particularly vulnerable. Brain endothelial cells and their supporting glial and neuronal elements constitute a neurovascular unit (NVU). Blast injury disrupts gliovascular and neurovascular connections in addition to damaging endothelial cells, basal laminae, smooth muscle cells, and pericytes as well as causing extracellular matrix reorganization. Perivascular pathology becomes associated with phospho-tau accumulation and chronic perivascular inflammation. Disruption of the NVU should impact activity-dependent regulation of cerebral blood flow, blood-brain barrier permeability, and glymphatic flow. Here, we review work in an animal model of low-level blast injury that we have been studying for over a decade. We review work supporting the NVU as a locus of low-level blast injury. We integrate our findings with those from other laboratories studying similar models that collectively suggest that damage to astrocytes and other perivascular cells as well as chronic immune activation play a role in the persistent neurobehavioral changes that follow blast injury.