Inhibition of astroglial hemichannels ameliorates infrasonic noise induced short-term learning and memory impairment.

As a kind of environmental noise, infrasonic noise has negative effects on various human organs. To date, research has shown that infrasound impairs cognitive function, especially the ability for learning and memory. Previously, we demonstrated that impaired learning and memory induced by infrasound was closely related with glia activation; however, the underlying mechanisms remain unclear. Connexin 43 hemichannels (Cx43 HCs), which are mainly expressed in hippocampal astrocytes, are activated under pathological conditions, lending support to the hypothesis that Cx43 HCs might function in the impaired learning and memory induced by infrasound. This study revealed that that blocking hippocampal Cx43 HCs or downregulating hippocampal Cx43 expression significantly alleviated impaired learning and memory induced by infrasound. We also observed that infrasound exposure led to the abundant release of glutamate and ATP through Cx43 HCs. In addition, the abundant release of glutamate and ATP depended on proinflammatory cytokines. Our finds suggested that the enhanced release of ATP and glutamate by astroglial Cx43 HCs may be involved in the learning and memory deficits caused by infrasound exposure.

Environmental Enrichment Protects Against Cognition Deficits Caused by Sepsis-Associated Encephalopathy.

BACKGROUND: One of the most serious complications of sepsis is sepsis-associated encephalopathy (SAE), which impairs the cognition ability of survivors. Environmental enrichment (EE) has been demonstrated to alleviate cognition deficits under many kinds of brain injury conditions. However, EE's effects on SAE remain unknown. Therefore, this study aimed to determine EE's effect on cognition disorders under SAE conditions and the underlying mechanism. MATERIALS AND METHODS: Adult male rats, subject to SAE or not, were housed under a standard environment (SE) or EE for 30 days. Subsequently, the rats were subjected to cognitive tests, such as the novel object recognition (NOR) test, the Morris water maze (MWM) test, an Open Field (OF) test, the elevated plus maze (EPM) test, and a sensory neglect (SN) test. Neuroinflammation, apoptosis, and oxidative stress changes in the brain were also detected. RESULTS: The results revealed that SAE impaired somatesthesia, recognition memory, spatial learning and memory, and exploratory activity, which were significantly improved by EE housing. EE also prevented SAE-induced anxiety-like behavior. In addition, EE housing capable induced a decrease in pro-inflammatory cytokines, and an increase in anti-inflammatory cytokines and antioxidant properties in the brain. Moreover, EE housing exerted an anti-apoptosis function by upregulating the level of B-cell lymphoma/leukemia-2 (Bcl-2) level and downregulating the level of p53 level in the hippocampus. CONCLUSIONS: The results of the present study indicated that EE exerts a neuroprotective function on cognitive ability in SAE rats. The effect is achieved by increasing antioxidants, and anti-inflammatory and antiapoptotic capacities. EE can effectively rescue SAE-induced cognitive deficits.