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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]

The structure of an improved wind turbine gearbox is presented for meeting the operation of the optimized wind turbine power‐wind speed curve (P‐v curve). When the wind speed is lower than the cut‐in wind speed, the operation mode of the wind turbine is changed by the extra power, which is supplied by the motor excited source to keep the wind turbine running. Moreover, the transmission principle of the improved wind turbine gearbox is discussed. Various motor power impacts on the transmission characteristic for the improved transmission structure are investigated and results are compared with the professional software. Results indicate that as the motor power increases, the transverse vibration of sun gears and meshing forces of the low‐speed and medium‐speed planetary stages decreases. The transverse vibration for the pinion gear of the high‐speed stage enhances with the increase of the motor power. Load‐sharing coefficients of the planetary gear stages are augmented with the enlargement of the motor power. It is found that meshing forces of the torque‐implement parallel stage are increased with augmentation of the motor power. [ABSTRACT FROM AUTHOR]