In Vivo Evaluation of a Polyethylene Glycol-Based Cryoprotectant during Cold Stress in a Rat Model

Cold stress is an environmental factor that impacts the viability of animals and humans. This study aimed to determine the effectiveness of a cryoprotectant based on polyethylene glycol in reducing cold stress in laboratory rats. For the experiment, 30 outbred Wistar rats (5 weeks) with an average body weight of 55.1 ± 5.3 g were used. Three groups of animals were formed (10 rats per group). The first group served as a positive control, kept at a room temperature of +18 – +20 °С and received 0.1 ml of 0.9% NaCl solution. The second group, the negative control, was kept in critically low temperatures (+2–+4°С) and administered 0.1 ml of 0.9% NaCl solution per experimental animal. Rats of the third group were subjected to cold stress and received 0.1 ml of the experimental preparation. Cold stress in laboratory rats was created using a cooling thermostat. Observation for 14 days included monitoring the dynamics of changes in the live weight of animals (before the start of the experiment, and on days 7 and 14 of the observation) as well as biochemical and haematological blood indicators. Fecal samples were collected from the rectum to determine the qualitative and quantitative state of the intestinal microbiota. The survival level of animals that received the experimental drug within fourteen days was 80.0%, compared to only 40% in the untreated group. When using the experimental drug in laboratory animals, an increase in body weight was noted. The number of full-fledged Escherichia coli in rats that received the drug was 3.4 times higher than the indicator of the group of animals that was kept at a critically low temperature without the drug. The prolonged low temperature in control rats had a negative effect on the animal's body as evidenced by increased leukocyte counts and ALT levels, as well as decreased ALT/AST ratio, and total bilirubin. The use of an experimental polyethylene glycol-based preparation had a positive effect on the weight of rats, blood parameters, and intestinal microbiota of rats under cold stress.