Pre-Exposure to Environmental Enrichment Protects against Learning and Memory Deficits Caused by Infrasound Exposure

Abstract

With the development of industrialization in recent years, infrasound has become an important component of public noise. To date, diverse studies have revealed the negative effects of infrasound on the central nervous system (CNS), especially the learning and memory ability. It is widely reported that environmental enrichment (EE) ameliorates the learning and memory deficits in different models of brain injury. Therefore, the present study was designed to determine the possible benefits of pre-exposure to EE in preventing functional deficits following infrasound exposure and their related mechanism. Adult male rats were given enriched or standard housing for 30 days. Following enrichment, the rats were exposed to 16 Hz, 130 dB infrasound for 14 days, and then their learning and memory ability was assessed. Changes to neuroinflammation, apoptosis, and oxidative stress in the hippocampus were also detected. Our results showed that the infrasound-induced deficit in learning and memory was attenuated significantly in EE pre-exposed rats. Pre-exposure to EE could induce a decrease in proinflammatory cytokines and increased anti-inflammatory cytokines and antioxidant properties in the hippocampus. Moreover, pre-exposure to EE also exerted antiapoptosis functions by upregulating the B-cell lymphoma/leukemia-2 (Bcl-2) level and downregulating the P53 level in the hippocampus. In conclusion, the results of the present study suggested that EE is neuroprotective when applied before infrasound exposure, resulting in an improved learning and memory ability by enhancing antioxidant, anti-inflammatory, and antiapoptosis capacities.

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

“…As described in our previous study [ 25 , 26 ], the infrasound system comprised an infrasound generator, a power amplifier, an infrasonic cabin, an infrasonic sensor, and a data collection system. The infrasound generator generates infrasonic waves at a sound pressure of 90–140 dB, with a frequency range of 2–20 Hz.…”

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

“…Inflammatory mediators and apoptosis-related molecules in the brain or blood were measured using ELISAs. The brain tissues were obtained according to our past study [35]. Briefly, the isolated brain was homogenized in normal saline, followed by centrifugation for 10 min at 4 °C and 2000 rpm.…”

“…The extent of lipid peroxidation was measured by determining the level of thiobarbituric acidreactive substances (TBARS), as previously described [35,36]. Isolated brain tissue was sonicated in 10% (w/v) radioimmunoprecipitation assay (RIPA) buffer added with a protease inhibitor cocktail (Sigma, St. Louis, MO, USA).…”

“…Tissue was subjected sonication for homogenization by sonication in cold 50 mM NaH 2 PO 4 and 1 mM EDTA buffer at pH 7.5. The, homogenates were then subjected to centrifugation for 10 min at 4 °C and 10,000 × g. According to Barsotti's method [35,37], a spectrophotometer was used to determine AOPP levels at 340 nm.…”

“…In vivo, NO's final and stable end products are nitrates and nitrites, whose sum (NOx) represents total NO production. A colorimetric assay (Cayman Chemical Company, Ann Arbor, MI, USA) was used to determine NOx [35,38]. In sample homogenates, nitrates were converted to nitrites using nitrate reductase and NADPH.…”