Correlation between grooming and scratching behavior in BALB/c mice related to itch sensation caused by house dust mite allergen

Objective Self-grooming can be induced by stressful situations. External stimuli such as house dust mites (HDM) allergen can cause acute itch sensations that lead to scratching behavior. This pilot study compared grooming and scratching behavior between mice that exposed to allergen and placebo as well as the correlation between the two behaviors. Methods This experimental pilot study involved six to eight weeks old male BALB/c mice, divided randomly into 2 groups, 8 mice each. The first group underwent the treatment of patch and spray with Dermatophagoides pteronyssinus allergen extract, while the second group was given placebo. The assessment for grooming and scratching was done on day 8. Grooming behavior assessed in this study consisted of total grooming chain with cephalocaudal pattern, grooming with non-cephalocaudal pattern, interrupted grooming bouts, body grooming, and total grooming duration. Results The amount of grooming activity (number of bouts and time spent grooming) and number of non-chain (non-cephalocaudal pattern) grooming as well as the scratching bouts were higher in HDM allergen group compared to placebo group. The agreement between two researchers for grooming and scratching evaluation was assessed and showed substantial to almost perfect agreement with ĸ ranged between 0.535-0.911 and p <0.001. The difference between two groups was significant for the scratching bouts (p=0.017), non-chain patterned grooming (p=0.022), body grooming (p=0.014) and grooming duration (p=0.008). The correlation between scratching bouts and total grooming duration, scratching bouts and non-chain patterned grooming, as well as scratching bouts and body grooming had high positive correlation. . Conclusion House dust mite allergen increased grooming and scratching behavior in mice compared to placebo. There were positive correlations between scratching behavior and non-chain patterned grooming, body grooming and duration of grooming, which could indicate the anxiety or stressful situation caused by itchiness from HDM allergen.