OBJECTIVE To explore the antidepressant effect and potential mechanism of icariside Ⅱ （ICSⅡ） based on the GABAergic nervous system. METHODS The male Kunming mice were randomly divided into a control group （group C， 10 mice） and a modeling group （50 mice）. The depression model was induced by chronic unpredictable mild stress （CUMS） method in the modeling group. After 21 days of stimulation， the rats of modeling group were randomly divided into depression model group （NS group）， positive control group [ECS group， oxalate escitalopram 15 mg/（kg·d）] and ICSⅡ low-dose， medium-dose and high-dose groups [ICSⅡ-L group， ICSⅡ-M group， ICSⅡ-H group； ICSⅡ 10， 20， 30 mg/（kg·d）]， with 10 mice in each group. Administration groups were given relevant medicine intragastrically， once a day， for 14 consecutive days. The sugar water preference rate， total exercise distance， immobility time in tail suspension and forced swimming experiments were detected in each group. The morphology of neurons and Nissl bodies in the hippocampal CA3 region were observed； the contents of γ-aminobutyric acid （GABA） and glutamic acid （Glu）， GABA/Glu ratio， and the expressions of GABAergic nervous system-related proteins （GABA A receptor α1， GABA B receptor 1， vesicular GABA transporter， glutamate decarboxylase 67， GABA membranal transporter 3） were detected in hippocampus. RESULTS Compared with group C， the sugar water preference rate and the total exercise distance significantly reduced in NS group， while the values of immobility time in the tail suspension test and forced swimming test were significantly prolonged （P＜0.05）. The morphology of neurons in the CA3 area of the hippocampus was irregular and the Nissl bodies were reduced， with a significant decrease in the number of structurally intact neurons （P＜0.05）； the content of Glu was significantly increased， while the content of GABA， GABA/Glu ratio， and the expressions of GABAergic nervous system-related proteins were significantly decreased （P＜0.05）. Compared with NS group， depression behavior in each administration group was improved， and the above indexes were mostly reversed （P＜0.05）. CONCLUSIONS ICSⅡ can improve depression behavior of depression model mice. The mechanisms may be associated with regulating the balance of GABA and Glu， increasing the synthesis， transport and release of GABA， and regulating the expressions of GABA-related receptors， so as to improve GABAergic nervous system.

Objective:To understand the epidemiological characteristics of imported COVID-19 cases in Guangzhou and provide scientific basis for the prevention and control of the disease.Methods:The data of imported COVID-19 in Guangzhou reported as of April 1, 2020 were collected from National Notifiable Disease Report System of China. The software Excel 2010 and SPSS 19.0 were applied for data cleaning and statistical analysis.Results:As of April 1, 2020, a total of 103 imported COVID-19 cases had been reported in Guangzhou, in which 92 were confirmed cases and 11 were asymptomatic infection cases. The number of the confirmed imported cases accounted for 11.4 % (92/806) in of the total in China at the same time. The male to female ratio of the cases was 1.58∶1 (63∶40). The median age of the cases was 31 years ( P 25- P 75:22-40 years), range of age was 11-63 years. The main occupational distributions of the cases were business services (41/103, 39.8 %) and students (36/103, 35.0 %). The imported cases whose destinations were 19 provinces and municipalities rather than Guangdong after entering the country accounted for 43.7 %. The main source countries of infections were the United Kingdom (27/103, 26.2 %), the Philippines (13/103, 12.6 %), the United States (13/103, 12.6 %) and Nigeria (7/103, 6.8 %). There were 34 inbound flights from which the imported COVID-19 cases were detected, in which 10 flights (10/34, 29.4 %) were found to carry more than 3 cases, with an average voyage time of (11.14±0.53) hours. A total of 29 imported cases(28.2 %) showed symptoms before entering the country, and 65 cases (63.1 %) had been isolated before the onset of the disease. The mean free activity time of the isolated cases after the onset was (6.76±0.79) days. The average number of the imported cases’ close contacts was 53. There were 13 clusters of COVID-19 caused by the imported cases, involving 36 cases (including 1 imported associated case). Conclusions:The sources of the imported COVID-19 cases in Guangzhou were widely distributed, and no cases had been found to be infected on the flights. In the early stage of the imported epidemic, there was high risk for the spread of the epidemic. Strengthened prevention and control of imported COVID-19 effectively reduced the of transmission risk of COVID-19 in communities.