Commentary: Supplier-dependent differences in intermittent voluntary alcohol intake and response to naltrexone in Wistar rats

Response: Commentary: Supplier-dependent differences in intermittent voluntary alcohol intake and response to naltrexone in Wistar rats

“…The authors appreciate Prof. Kalueffs interest in our work (Momeni et al, 2015 ). The issues highlighted (Kalueff, 2016 ) are indeed of great importance. Many factors associated with animal husbandry can potentially have an impact on behavior (Castelhano-Carlos and Baumans, 2009 ), and a more thorough description of experimental conditions is often warranted for replicability and/or comparison across labs.…”

“…Momeni et al ( 2015 ) attempted to harness of some of the known differences in Wistar rats from different suppliers (Palm et al, 2011a , b , 2012 ; Goepfrich et al, 2013 ) in order to create a more heterogeneous group of animals. Kalueff ( 2016 ) suggests that the differences observed by Momeni et al ( 2015 ) are due to environmental factors and/or in combination with acclimatization. These are important aspects, often poorly described in publications, but in our opinion not the full explanation behind the results (Momeni et al, 2015 ).…”

“…The most striking observation ( Supplementary Table ) is that Wistar rats and CD-1 mice are kept in the same housing room at Charles River GmbH (Personal communication, Charles River distributor, Scanbur employee), a particular concern to users of CD-1 mice from that supplier. A comparison between Supplementary Table and Kalueff ( 2016 ) render discrepancies in information, i.e., number of animals per cage. This may be referred to EU Guidelines, stating that body weight and not age determine the number of animals per cage, applicable to Momeni et al ( 2015 ).…”

“…The impact of transportation procedures ( Supplementary Table ) should not be underestimated. The distance transported per se (Kalueff, 2016 ) is likely of less importance with regard to the animals used in Momeni et al ( 2015 ), considering that negligible effects were demonstrated in mice bred locally vs. shipped (Wahlsten et al, 2003 ). Moreover, the undisturbed acclimatization period of 2 weeks upon arrival is in line with recommendations for male rats (Arts et al, 2012 , 2014a , b ), also when transferred from normal to reversed light/dark cycle (Arts et al, 2016 ).…”

“…In Momeni et al ( 2015 ) the aim was indeed to apply a behavioral phenomics approach (Gerlai, 2002 ; Kalueff, 2016 ) to create a heterogenic group by combining Wistar rats from different suppliers; known to display different characteristics and thus pose as a representative of the heterogeneity in a human population (Stewart and Kalueff, 2015 ) to explore how subgroups with different behavioral characteristics acquire and maintain voluntary alcohol intake. We were hoping to find a pattern similar to that described by Kalueff ( 2016 ).…”