The expression of angiotensin II receptors during wound healing in rat model of partial thickness cutaneous thermal injury

Objective To detect the spatial-temporal expression characteristic of both angiotensin Ⅱ type 1 receptor (AT1) and angiotensin Ⅱ type 2 receptor (AT2) receptors,and explore the possible link between the expression of angiotensin Ⅱ ( Ang Ⅱ ) receptor and activity of cell proliferation and apoptosis in rat model of partial thickness thermal injury.Methods The samples were obtained from deep partial thickness thermal injury skin in Wistar rats,and unjuried skin in normal Wisrar rats,respectively.Thirty-six male Wistar rats were divided randomly into two groups as follows:( 1 ) normal control group (n =6) ; (2) injured group:that was further subdivided into subgroups of immediate,3rd day,7th day,14th day and 21st day after injury,respectively (n =30).Immunofluorescence staining was used to examine the expression of AT1 and AT2 receptors in topical skin.Proliferating cell nuclear antigen (PCNA) labeling index and TdT-mediated dUTP nick end labeling (TUNEL) staining were used to evaluate the cellular proliferation and apoptosis in burned skin.Results In the normal skin,the expression of both AT1 and AT2 receptors was mainly located in epidermal keratinocytes and dermal vessel walls.The expression of AT1 and AT2 receptors was increased after thermal injury,peaking at the 7th day postburn.Thereafter the expression of AT1 and AT2 receptors was reduced,and the reduction of AT1 receptor expression seemed to be more significant than AT2 receptor.Cell proliferation was increased in burned sites,peaking at the 7th day after burn,and then decreased.Apoptosis was also increased after burn,reaching a peak at the 7th day postburn.Apoptosis was decreased at the 21st day after burn.Conclusion These results indicate that Ang Ⅱ via AT1 and AT2 receptors might be involved in the regulation of cellular proliferation and apoptosis during wound healing. Key words: Angiotensin Ⅱ ;  Wound healing;  Proliferation;  Apoptosis