Establishment of scald-induced pain model in rats: a constant-temperature electrical scald instrument

Abstract

Objective To establish a scald-induced pain model using a constant-temperature electrical scald instrument in rats. Methods Thirty-six pathogen-free male Sprague-Dawley rats, weighing 200-250 g, were randomly divided into 4 groups (n=9 each) using a random number table: control group (group C), scald for 5 s group (group S5), scald for 10 s group (group S10), and scald for 15 s group (group S15). The rats were anesthetized with intraperitoneal chloral hydrate.In S5, S10 and S15 groups, the plantar surface of the left hindpaw of rats were exposed to a constant-temperature electrical scald instrument (85 ℃) for 5, 10 and 15 s, respectively.The plantar surface of the left hindpaw of rats was exposed to an electrical scald instrument (room temperature) for 10 s in group C. At 1 day before treatment (T0), and 1, 3, 5, 7 and 14 days after treatment (T1-5), the mechanical and thermal pain thresholds were measured.Immediately after treatment, and at 24 h after treatment, the total body condition, wound color, and shape of the margin of the wound were observed and recorded.At 24 h after treatment, 3 rats were randomly sacrificed, and the skin from the plantar surface of the left hindpaw was removed for microscopic examination. Results Compared with group C, the thermal pain threshold at T1-2, and the mechanical pain threshold at T1-3 were significantly decreased in group S5, and the thermal pain threshold, and mechanical pain threshold were significantly decreased at T1-4 in group S10 (P 25 s, and the mechanical pain threshold >30 g at T1-5 in group S15.The swelling in foot was bovious, burn blister appeared, and the degree of damage was aggravated in group S10 compared with S5 and S15 groups. Conclusion The scald-induced pain model is successfully established using a constant-temperature electrical scald instrument in rats. Key words: Burns; Pain