Effect of recombinant human growth hormone on intestinal mucosal cellular apoptosis in severely scalded rats.

Objective To investigate whether recombinant human growth hormone(rhGH) can improve the intestinal mucosal barrier in severely scalded rats and by which possible mechanisms these changes occur.Methods 42 adult male Wistar rats were randomly divided into 3 groups: the control(n=6),scald(n=18) and GH groups(n=18).Rats in the scald and GH groups were inflicted with 25% total body surface area full-thickness skin scald on the back and immediately followed by intraperitoneal injection of dexamethasone(80 mg/kg).The scalded rats in the two groups were subcutaneously injected with normal saline and rhGH [1.33 U/(kg·d)] respectively from 2 hours to 3 days after scald.At 12,24 and 72 h after scald, the intestinal mucosal histomorphology in distal ileum tissues,morphological changes of apoptotic cells and apoptotic rate and changes of activity of Caspase3 of intestinal mucosal cells were observed by HE stain,TUNEL and fluorescence method,respectively.Results Intestinal mucosal histomorphology and intestinal epithelia in the scald group was severely injured but significantly meliorated by rhGH to near that in the control group.The intestinal mucosal cellular apoptotic rate in both scald and GH groups was significantly higher than that in the control group(P0.01) while that in the GH group was evidently lower than that in the scald group(P0.01),and reached a peak(15.40%±3.21% vs 38.80%±6.98%) at 24 h after burn.Also,activity of Caspase-3 was more significantly increased in the scald and GH groups than in the control group(P0.05) while it was lower in the GH group than in the scald group(P0.05),and reached a peak(156.13±4.66 U/mg vs 214.60±9.29 U/mg) at 24 h.Conclusion rhGH administered in early severe burn could inhibit intestinal mucosal cellular apoptosis,which might be induced by down-regulation of activity of Caspase-3.As a result,intestinal mucosal integrity and function was maintained.