Abstract: MA Li-juan, ZHAO Guang, GU Wei-jie, NIU Jian-rong, SHAO Li-fang, MENG Ru-song, YAN Wen-ting, CHENG Yu. Air Force General Hospital of PLA，Beijing 100142, China Corresponding author: ZHAO Guang, Email: guangfen@ yahoo.com 【Abstract】 Objective To evaluate the in vitro effect of heat treatment on the secretion of α-melanocyte-stimulating hormone （α-MSH） by human melanocytes and HaCaT keratinocytes. Methods Cultured normal human melanocytes from forskin tissue and HaCaT cells were treated with hyperthermia at 42 ℃ for 1 hour per day for 3 days. Subsequently, real time fluorescence-based quantitative PCR and enzyme-linked immunosorbent assay （ELISA） were performed to detect the mRNA and protein expressions of α-MSH, respectively. Results The mRNA expression level of α-MSH was significantly higher in heat-treated melanocytes and HaCaT cells than in those untreated （1.5862 ± 0.3262 vs. 1.0000 ± 0.2715, P < 0.05; 1.8013 ± 0.1216 vs. 1.0000 ± 0.2532, P < 0.05）. Moreover, ELISA showed a statistical increase in the supernatant level of α-MSH protein in heat-treated melanocytes and HaCaT cells compared with those untreated （0.3142 ± 0.0469 vs. 0.2557 ± 0.0330, P < 0.05; 0.4632 ± 0.0345 vs. 0.4389 ± 0.0399, P < 0.05）. Conclusion Heat treatment can promote the secretion of α-MSH by melanocytes and HaCaT cells. 【Key words】 Heat; Melanocytes; HaCaT cells; α-MSH