ObjectiveTo observe the effect of Liuwei Dihuangwan on behavioral impairments in the rat model of autism spectrum disorder （ASD） and explore the mechanism of action. MethodsTwelve SD pregnant rats were intraperitoneally injected with valproic acid （VPA） （10 rats） or normal saline （2 rats）， and male offspring were selected to establish the model of ASD and the control rats. Rats were randomly assigned into model， low-dose （0.75 g·kg^-1） and high-dose （1.5 g·kg^-1） Liuwei Dihuangwan， vitamin D （positive drug， 3.7×10^-5 g·kg^-1）， and blank groups. Each group was administrated with the corresponding concentration of drugs or the same volume of normal saline by gavage for 2 weeks. After the intervention， the three-chamber social test was conducted to evaluate social interaction and social preference. The open field test was carried out to observe spontaneous behavior and anxiety state. Hematoxylin-eosin staining （HE） was used to observe the pathological changes of the prefrontal tissue. Transmission electron microscopy was employed to observe the ultrastructure of mitochondria in prefrontal neurons. Immunofluorescence was used to detect the expression of ionized calcium-binding adapter molecule-1 （Iba-1） in the prefrontal tissue. Enzyme-linked immunosorbent assay （ELISA） was adopted to measure the levels of tumor necrosis factor-α （TNF-α） and interleukin-6 （IL-6）. Western blot was employed to assess the expression differences of phosphorylated adenosine monophosphate-activated protein kinase （p-AMPK）， adenosine monophosphate-activated protein kinase （AMPK）， phosphorylated Unc-51-like autophagy-activating kinase 1 （p-ULK1）， Unc-51-like autophagy-activating kinase 1 （ULK1）， and FUN14 domain-containing protein 1 （FUNDC1）. ResultsCompared with the blank group， the model group spent less time sniffing stranger 1 and stranger 2 in the three-chamber social test （P<0.01） and showed reductions in the total distance traveled， average speed， distance traveled in the central area， and time spent in the central area in the open field test （P<0.01）. In addition， the model group showed extensive apoptosis of neurons， with shrunken nuclei and red-stained cytoplasm， and extensive necrosis of neurons in the prefrontal tissue， mitochondrial swelling， decreased matrix density， disrupted cristae， and autophagic lysosomes in neurons， increases in the rate of Iba-1 positive cells in the prefrontal area （P<0.01） and the levels of TNF-α and IL-6 （P<0.01）， and down-regulation in the expression of p-AMPK/AMPK， p-ULK1/ULK1， and FUNDC1 （P<0.01）. Compared with the model group， low-dose and high-dose Liuwei Dihuangwan and the vitamin D prolonged the time spent sniffing stranger 1 and stranger 2 in the three-chamber social test （P<0.05， P<0.01）， increased the total distance traveled， average speed， distance traveled in the central area， and time spent in the central area in the open field test （P<0.05， P<0.01）， restored the morphology of neurons in the prefrontal tissue， decreased the number of apoptotic cells， alleviated the swelling of mitochondria in neurons， increased the matrix density， mitigated the fragmentation and disorder of cristae， and increased the number of autophagosomes. Moreover， the drugs decreased the rate of Iba-1 positive cells in the prefrontal area （P<0.01）， lowered the levels of TNF-α and IL-6 （P<0.01）， and up-regulated the expression of p-AMPK/AMPK， p-ULK1/ULK1， and FUNDC1 （P<0.01）. ConclusionLiuwei Dihuangwan ameliorate autism-like behaviors and reduce neuronal apoptosis and neuroinflammatory damage in the rat model of ASD by promoting mitophagy mediated by the AMPK/ULK1/FUNDC1 pathway.

ObjectiveTo investigate the effects of Liuwei Dihuangwan on mammalian target of rapamycin （mTOR）-mediated synaptic plasticity in the prefrontal cortex-hippocampus circuit in the rat model of valproic acid （VPA）-induced autism spectrum disorder （ASD） and to explore its potential mechanism for reducing behavioral abnormalities in ASD rats. MethodsThirteen SD pregnant rats were randomized into the VPA group （10 rats） and the control group （3 rats）. On gestational day 13， the VPA group was intraperitoneally injected with VPA solution （600 mg·kg^-1）， while the control group was injected with an equal volume of normal saline. Male pups of 21 days old from both groups underwent behavioral tests to screen the ASD model rats （32 rats）. These rats were then randomly assigned to the model （distilled water）， vitamin D （1 480 U·kg^-1）， low-dose （0.75 g·kg^-1） Liuwei Dihuangwan， and high-dose （1.5 g·kg^-1） Liuwei Dihuangwan groups， and normal male pups were selected as the blank group （distilled water）， with 8 rats in each group. Each group was treated with the corresponding drug or an equal volume of distilled water via gavage daily. After drug administration， behavioral tests were conducted again， followed by anesthesia and tissue collection. Nissl staining was carried out to observe the morphological changes of neurons in the prefrontal cortex and hippocampus. Transmission electron microscopy was used to observe changes in hippocampal synaptic structure. Immunohistochemistry and Western blot were employed to determine the expression of mTOR， phosphatidylinositol 3-kinase （PI3K）， and protein kinase B （Akt） in the prefrontal cortex， as well as synaptophysin-1 （SYP-1）， postsynaptic density 95 （PSD95）， and N-methyl-D-aspartate receptors （NMDARs） in the hippocampus. ResultsCompared with the control group， the model group exhibited severe growth retardation and developmental deformities， with abnormal behavioral performance and pathological damage to neurons and synapses in the prefrontal cortex and hippocampus. Compared with the model group， all treatment groups showed reduced behavioral abnormalities and pathological damage to neurons and synapses in the prefrontal cortex and hippocampus， with the most significant effects in the high-dose Liuwei Dihuangwan group. Immunohistochemistry and Western blotting results showed that compared with the control group， the model group exhibited significantly increased protein levels and phosphorylation ratios of p-mTOR， p-Akt， and p-PI3K in the prefrontal cortex （P<0.05， P<0.01）， and decreased protein levels of SYP-1 and PSD95 and increased protein level of NMDARs in the hippocampus （P<0.01）. Compared with those in the model group， the protein levels of p-mTOR， p-Akt， and p-PI3K in the prefrontal cortex decreased in the vitamin D and high-dose Liuwei Dihuangwan groups （P<0.05）， and the p-mTOR/mTOR， p-Akt/Akt， and p-PI3K/PI3K ratios in the prefrontal cortex declined in the vitamin D group （P<0.05）. The high-dose Liuwei Dihuangwan group showed a reduction in p-PI3K/PI3K ratio （P<0.05）. The protein level of SYP-1 and PSD95 in the hippocampus increased in the vitamin D， low-dose Liuwei Dihuangwan， and high-dose Liuwei Dihuangwan groups （P<0.05， P<0.01）， while the protein level of NMDARs decreased in the vitamin D and high-dose Liuwei Dihuangwan groups （P<0.01）. ConclusionLiuwei Dihuangwan significantly reduces VPA-induced ASD-like behaviors and enhances the regeneration and repair of neurons in the prefrontal cortex and synaptic structures in the hippocampus by downregulating of PI3K/Akt/mTOR expression in the prefrontal cortex， upregulating SYP-1 and PSD95 expression in the hippocampus， and inhibiting NMDARs expression.