Sealsafe plus gr900

Sprague-Dawley rats (48 males and 24 females) aged 8-9 weeks (Janvier Labs, France) were used in this study because rats' behavioral repertoire makes them a species of choice for the investigation of addiction-related processes (Parker et al., 2014) (link). The experiments were performed in 3 separate cohorts of animals: 1) 24 males to establish the procedure; 2) 24 males to replicate and assess reliability of the procedure and 3) 24 females to assess whether the results depend on sex. It should be noted that the female cohort and the 2 cohorts of males were all run separately. Results from the two male groups were basically superimposed qualitatively and quantitatively suggesting that the conducting the experiments in separate cohorts had minimal effects on the results. Data from the two cohorts of males were combined for analysis and presentation here. Rats were housed in pairs with two wooden sticks for enrichment, in IVC cages (Techniplast, Sealsafe Plus GR900), in a temperature-and humidity-controlled room kept under reversed light-dark cycle conditions (12 hours light-dark cycle, lights off at 7 AM). All experiments were conducted during the dark phase and in accordance with European Union directives (2010/63/EU) for the care of laboratory animals and approved by the local ethics committees (COMETHEA).