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Fear overgeneralization is widely accepted as a pathogenic marker of post‐traumatic stress disorder (PTSD). Recently, GABAergic interneurons have been regarded as key players in the regulation of fear memory. The role of hippocampal GABAergic interneurons in contextual fear generalization of PTSD remains incompletely understood. In the present study, we established a rat model of PTSD with inescapable foot shocks (IFS) and observed the loss of GABAergic interneuron phenotype in the hippocampal cornu ammonis‐1 (CA1) subfield. To determine whether the loss of GABAergic interneuron phenotype was associated with fear generalization in PTSD rats, we used adeno‐associated virus (AAV) to reduce the expression of GAD67 in CA1 and observed its effect on fear generalization. The results showed that the reduction of GAD67 in CA1 enhanced contextual fear generalization in rats. We investigated whether the PERK pathway was involved in the GABAergic interneuron injury. Increased expression of p‐PERK, CHOP, and Caspase12 in GABAergic interneurons of PTSD rats was observed. Then, we used salubrinal, an endoplasmic reticulum stress inhibitor, to modulate the PERK pathway. The salubrinal treatment significantly protected the GABAergic interneurons and relieved fear generalization in PTSD rats. In addition, the results showed that salubrinal down‐regulated the expression of CHOP and Caspase12 in GABAergic interneurons of PTSD rats. In conclusion, this study provided evidence that the loss of GABAergic interneuron phenotype in CA1 may contribute to contextual fear generalization in PTSD. The PERK pathway is involved in the GABAergic interneuron injury of PTSD rats and modulating it can protect GABAergic interneurons and constrain contextual fear generalization. [ABSTRACT FROM AUTHOR]

The excitatory‐inhibitory imbalance has been considered an important mechanism underlying stress‐related psychiatric disorders. In the present study, rats were exposed to 6 days of inescapable foot shock (IFS) to induce stress. The open field test and elevated plus maze test showed that IFS‐exposed rats exhibited increased anxiety‐like behavior. Immunofluorescence showed that IFS rats had a decreased density of GAD67‐immunoreactive interneurons in the dorsal hippocampal CA1 region, while no significant change in the density of CaMKIIα‐immunoreactive glutamatergic neurons was seen. We investigated the expression of different interneuron subtype markers, including parvalbumin (PV), somatostatin (SST), and calretinin (CR), and noted a marked decline in the density of PV‐immunoreactive interneurons in the dorsal CA1 region of IFS rats. The perineuronal net (PNN) is a specialized extracellular matrix structure primarily around PV interneurons. We used Wisteria floribunda agglutinin lectin to label the PNNs and observed that IFS rats had an increased proportion of PNN‐coated PV‐positive interneurons in CA1. The number of PSD95‐positive excitatory synaptic puncta on the soma of PNN‐free PV‐positive interneurons was significantly higher than that of PNN‐coated PV‐positive interneurons. Our findings suggest that the effect of IFS on the hippocampal GABAergic interneurons could be cell‐type‐specific. Loss of PV phenotype in the dorsal hippocampal CA1 region may contribute to anxiety in rats. The dysregulated PV‐PNN relationship in CA1 after traumatic stress exposure might represent one of the neurobiological correlates of the observed anxiety‐like behavior. [ABSTRACT FROM AUTHOR]

Exploring highly efficient heterostructured photocatalysts for converting CO2 to value-added chemicals has long been pursued, which is mainly limited by inefficient visible/near-infrared (NIR) photon capture, undesirable electron–hole recombination, and insufficient accessible active sites. Herein, we report a robust heterojunction photocatalyst, consisting of mesh-like Bi2S3 nanoarrays epitaxially grown on BiOBr nanoplates via a facet-selective topotactic transformation process, for synchronically overcoming the aforementioned obstacles and markedly advancing the CO2 conversion efficiency: (i) vertically aligned Bi2S3 nanowalls harness solar photons from the visible to NIR region beyond 1000 nm and minimize the light shielding effect on BiOBr substrates, while multiple light reflection in the mesh pores enclosed by Bi2S3 walls and BiOBr supports accounts for improved light utilization efficiency; (ii) intimate coupling of BiOBr and Bi2S3 endows the heterojunction with enhanced charge separation efficiency through the interfacial Bi–S/Br–Bi bonds between them; (iii) etched pores and oxygen vacancies on the surface of BiOBr strengthen the adsorption and activation of CO2, and decrease the barrier of the rate-determining step in CO2-to-CO reduction. By virtue of these distinguished features, the optimized BiOBr/Bi2S3 heterojunction delivers an outstanding CO evolution rate of 103.5 μmol gcat−1 h−1 and selectivity of 90.1% under broadband light irradiation. This work sets up a significant milestone in simultaneously manipulating the three critical steps in photocatalysis during the construction of novel hybrid architectures for solar energy conversion applications. [ABSTRACT FROM AUTHOR]