RESUMO
ObjectiveTo study whether Chaihu Longgu Mulitang can inhibit hypothalamic inflammation， mitigate anxiety-like behavior， and alleviate anxiety symptoms by regulating the p38 mitogen-activated protein kinase/nuclear factor-κB （p38 MAPK/NF-κB） signaling pathway in the rat model of generalized anxiety disorder （GAD）. MethodTwelve out of 74 Wistar rats were randomly selected as the blank group， and the remaining rats were subjected to chronic restraint stress for the modeling of GAD. The open field test （OFT） and elevated Porteus maze test （PMT） were conducted 14 days after modeling to detect the anxiety-like behaviors. Sixty successfully modeled rats were selected and randomized into model， low-， medium-， and high-dose （6， 12， and 24 g·kg-1， respectively） Chaihu Longgu Mulitang， and diazepam （1 mg·kg-1） groups （n=12） and administrated with corresponding drugs for 14 consecutive days. OFT and PMT were then carried out to examine the anxiety-like behaviors of the rats. The levels of tumor necrosis factor-α （TNF-α）， interleukin-6 （IL-6）， and interleukin-1β （IL-1β） in the hypothalamus and serum of rats were determined by the enzyme-linked immunosorbent assay （ELISA）. Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR）was conducted to determine the mRNA levels of p38 MAPK， NF-κB p65， nuclear factor κB inhibitor α （IκBα）， and ionized calcium binding adaptor molecule 1 （Iba-1）. The protein levels of p38 MAPK， phosphorylated （p）-p38 MAPK， NF-κB p65， p-NF-κB p65， and IκBα in the hypothalamus of rats were determined by Western blot. The expression of Iba-1 in the hypothalamic microglia was detected by immunofluorescence assay. ResultCompared with the blank group， the model group had decreased body weight， scattered dark yellow fur， increased irritability， and preference to hibernation in the corner. In addition， the modeled rats showed increased edge movement distance and time in OFT （P<0.01） and decreased movement distance and time and the number of entries in the open arm in PMT （P<0.01）. The modeling increased the fluorescence intensity of Iba-1 in paraventricular nucleus of hypothalamus （P<0.01）， elevated the levels of IL-1β， IL-6， and TNF-α in the serum and hypothalamus （P<0.01）， up-regulated the protein and mRNA levels of p38 MAPK， NF-κB p65， p-p38 MAPK， p-NF-κB p65， and Iba-1 （P<0.05， P<0.01）， and down-regulated the protein and mRNA levels of IκBα （P<0.01） in the hypothalamus. Compared with the model group， medium- and high-dose Chaihu Longgu Mulitang and diazepam increased the body weight， improved the fur and behaviors， decreased the edge movement distance and time in OFT （P<0.05， P<0.01）， and increased the movement distance and time in the open arm in PMT （P<0.05， P<0.01）. Furthermore， they decreased the fluorescence intensity of Iba-1 in hypothalamic microglia （P<0.05， P<0.01）， lowered the levels of IL-1β， IL-6， and TNF-α in the serum and hypothalamic tissue （P<0.05， P<0.01）， down-regulated the mRNA and protein levels of p38 MAPK， NF-κB p65， p-p38 MAPK， p-NF-κB p65， and Iba-1 （P<0.05， P<0.01）， and up-regulated the mRNA and protein levels of IκBα （P<0.05， P<0.01） in the hypothalamus. ConclusionChaihu Longgu Mulitang can mitigate anxiety-like behaviors and relieve anxiety in GAD rats by inhibiting the p38 MAPK/NF-κB signaling pathway and reducing the activation of microglia and the levels of pro-inflammatory cytokines in the hypothalamus.