Environment is not the most important variable in determining oral morphine consumption in Wistar rats
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Updated: Nov 2, 2026

Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities
Published on: July 29, 2014
1Department of Psychology, New Mexico Tech, Socorro 87801, USA.
Abstract:
The role of differential housing on sucrose-morphine consumption in outbred Wistar rats was investigated in two studies. The results of earlier research, indicating rats housed in a quasinatural colony drank significantly less sucrose-morphine than rats isolated in standard laboratory cages, could not be replicated, as the consumption of sucrose-morphine by the isolated animals in the present two studies was reduced. It is possible that during a colony conversion the supplier inadvertently introduced strain differences making the present rats more resistant to xenobiotic consumption. Discussion documents the role of genetics in morphine consumption.
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