Acclimation and testing periods
Vendor Original parental stocks of C57BL/6J, 129S1/SvImJ, A/J, BALB/cByJ, C3H/HeJ, DBA/2J, FVB/NJ, and SJL/J inbred strains were purchased from The Jackson Laboratory (JAX®, Bar Harbor, ME USA). Experimental male mice weaned at 3 weeks of age were generated in the Comparative Biology Unit animal facilities at the Institute of Psychiatry. Ages Male mice 9–13 wks of age Feed Food was available ad libitum (Rat and Mouse No.1 Maintenance Diet, Special Diet Services, Essex, UK), except during behavioral testing. Water Available ad libitum Housing Mice were mostly single housed in standard cages (30.5L × 13W × 11H cm) transferred at approximately 8 wks of age to a separate housing facility. Behavioral tests were performed during the dark cycle between 09:30 and 19:00 h. Bedding Sawdust and nesting materials in each cage were changed once week, but never on the day before or the day of testing to minimize the disruptive effect of cage cleaning on behavior. Photoperiod Mice were maintained on a reversed 12:12 light cycle with white lights on from 20:00 to 8:00 h and red light on during the dark cycle. Light intensity in the housing room was 400 lx (lux) during the lights-ON period and less than 2 lx during the dark period. Four red cluster lights (LED cluster red light No. 310-6757; RS Components Northants, UK) of approximate wavelength 705 nm provided minimal red light during the dark phase, allowing experimenters to work with the mice during their dark phase. Relative humidity ~45% Temperature 21±2°C Regulatory compliance All housing and experimental procedures were performed in compliance with the UK Home Office Animals Scientific Procedures Act 1986.