Abstract: Objective To observe the effect of light emitting diode (LED) red light irradiation on serum lipid in experimental hyperlipidemia rats. Methods 36 healthy male Sprague-Dawley rats were randomly divided into normal control group (n=12) and hyperlipidemic model group (n=24). The normal group was fed with normal diet while the hyperlipidemic model group with fat-rich forage for 6 weeks. The hyperlipidemic model group rats were randomly divided into the hyperlipidemic control group (n=12) and LED treatment group (n=12), and the latter accepted LED red light irradiation for 28 d. The levels of serum lipid including total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL-C), high-density lipoprotein (HDL-C), and the activities of lipoproteinesterase (LPL) and hepatic lipase (HL) were detected with biochemical assay. The expression of 3-hydroxy-3-methylglutaryl coenzyme A reducase (HMG-CR) of hepatic tissue were measured with immunohistochemical staining. Results Compared with the hyperlipidemic control group, the levels of serum TC, TG and LDL-C decreased while the serum HDL-C increased significantly in the LED treatment group (P<0.01) after treated with LED. The levels of LPL and HL in serum increased (P<0.01) while the activity of HMG-CR decreased (P<0.05). Conclusion LED red light irradiation might play a regulating effect on serum lipid by enhancing the activities of LPL and HL and inhibiting the expression of HMG-CR to interfere the metabolism of TC, TG, LDL-C and HDL-C.

Key words: red light irradiation, hyperlipidemia, lipoproteinesterase, hepatic lipase, 3-hydroxy -3-methylglutaryl coenzyme A reducase, rats