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Monday, December 27, 2010

Differences in voluntary ethanol consumption in Wistar rats from five different suppliers

Understanding the mechanism of action of ethanol and the neurobiological substrates for alcohol use disorders is challenging. 

In search of this knowledge, it is imperative to use valid animal experimental models. The Wistar rat is one example of a commonly used strain that also exert foundation stock for several rat lines selectively bred for high and low voluntary ethanol intake. 

Different studies report varying ethanol intake in Wistar rats posing the question of whether this is because of the methodological differences or the rat strain. 

The purpose of this study was therefore to compare voluntary ethanol intake in Wistar rats from five different suppliers. 

Rats from B&K Universal, UK (BK); Charles River, Germany; Harlan Laboratories, IN (Hsd); Harlan Laboratories, The Netherlands (RccHan™); and Taconic, Denmark were exposed to a three-bottle free-choice paradigm with intermittent 24h access to 5 and 20% ethanol and water three times per week for 6 weeks. 

A general finding was that the RccHan™ rats differed significantly from the other groups. 

At the end of the experiment, the RccHan™ group had the highest median ethanol intake of 3.85g/kg/24h, whereas the BK rats had the lowest intake of 1.84g/kg/24h. 

The preference for ethanol was also different throughout the experiment. 

At the end of the experiment, the RccHan™ rats had the highest preference of approximately 80%, whereas the BK rats had the lowest preference around 25%. 

During the 6-week drinking period, only the Hsd rats increased their ethanol intake, as evidenced by a significant increase of 5% ethanol intake. 

Although all rats are of Wistar origin, they display profound differences in voluntary ethanol consumption depending on the supplier. 

The choice of Wistar can therefore have implications for the outcome and make comparisons between studies difficult. 

The present findings highlight the supplier as an important parameter to consider when planning and performing preclinical animal studies in the field of alcohol research.

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