Assessing Neurobiological and Behavioral Responses in Rats: Modified UCMS Protocol with Psychological Stress Device

Abstract

The antidepressant effect of drugs can be tested using various methods, including unpredictable chronic mild stress (UCMS). Although the initial UCMS protocol involved administering stressors for 21 days, many modifications have been made, one of which is shortening the duration of the stressors to 10-15 days. This study aims to modify the UCMS model to increase the stress response in male Wistar rats. UCMS protocol in this study did not use predator odor (2,5-dihydro-2,4,5-trimethylthiazoline) as in the previous protocol, but a psychological stress device (PSD) was used instead. Forty male Wistar rats (150-200 grams) were given UCMS treatment for 10 and 15 days. Sucrose consumption, coat score, body weight, and serum corticosterone levels were measured. Immunohistochemical examination of 5-HT1A receptors, TNF-α, NOX2, and NF-ĸB were performed in the hippocampus part of the brain. All data were analyzed using the Mann-Whitney test. UCMS treatment for 10 and 15 days reduced sucrose consumption and body weight and increased the coat score. UCMS treatment increased corticosterone levels, decreased 5-HT1A receptor expression, and increased TNF-α, NOX2, and NF-ĸB expression. The primary behavioral response during PSD was head dip as a preparatory behavior for jumping. Modifying the UCMS model using a PSD can increase the stress response. Keywords: animal model, depression, unpredictable chronic mild stress, psychological stress devic