Animals

Adult male Sprague-Dawley rats (280 to 300 g) were purchased from Beijing Vital River Laboratory Animal Technology Co. Ltd. The rats were housed in groups of four per cage after arrival and individually housed after surgery with appropriate temperature (22 ± 2°C) and humidity (50 ± 5%), as well as freely accessible water and food. The lighting time was controlled under a 12-hour light/dark cycle. All behavioral experiments were performed during the animal’s dark period. Animal care and experimentation were performed in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals and were approved by the Biomedical Ethics Committee for Animal Use and Protection of Peking University.