Behavioral video coding analysis of chronic morphine administration in rats

The present study assessed the behavior of morphine-addicted rats using behavioral video coding technology, to evaluate effective methods for identifying morphine addiction. Rats were divided into a control group (n=15) and a morphine addiction group (n=15). The morphine addiction model was established with a 14-day increasing dose scheme, confirmed using a conditional place preference (CPP) experiment. After successful modeling, the rats' behavior was recorded for 12 h, then coded and analyzed using Observer XT behavior analysis software. Compared with the control group, morphine-addicted rats showed increased heat pain tolerance time (P=0.039) and spent more time in the white box during the CPP experiment (P<0.001). Video coding analysis revealed significant behavioral changes in morphine-addicted rats compared to controls. In addition to being lighter, morphine-addicted rats showed decreased water intake, reduced licking of forelimbs and hind limbs, and altered sleeping posture (sleeping curled up) during the day (all P<0.05). In conclusion, chronic morphine administration in rats leads to distinctive behavioral changes, including decreased licking frequency, reduced water intake and altered sleep posture. Video coding analysis, as a safe and non-invasive method, may provide a convenient and efficient approach for studying morphine addiction in rats.