Effect Of LED Red Light On Blood Lipid And Its Mechanism In Hyperlipidemic Rats

Objective: Cadiovascular disease was one of the leading disease thataffect human health in china.The happening of cadiovascular disease has aintimate connection with dyslipidemia,lipid-lowering treatment can greatlyreduce cadiovascular deaths,so how to safely and effectly reduce the bloodlipid has become the hot spot of clinical research. At present, there are twoways to regulate lipid:non-drug therapy and drug therapy.The former ismainly through change the lifestyle (low fat diet,exercise,lose weight andsmoking cessation)to reduce the blood lipid,this way is more suitable forpatients with mild dyslipidemia.When non-drug therapy can’t regulate lipidwell after3-6months, the drugs need to be added. At present,there are5kinds of drugs to regulate lipid in the market:statins,fibrates,nicotinicacid,resin (bile acid chelating agent),cholesterol absorptioninhibitors,especially statins and fibrates.The major adverse reactions of thesedrugs are increase in liver enzymes,muscle pain and rhabdomyolysis.Physicaltherapy such as red light has been safely and effectively used in clinicalpractice.Meanwhile,the effect of red light therapy to regulate lipid has gotgreat attention in basic and clinical research.Some research showed that red light radiation therapy could lower bloodlipid content and improve hemorheology. LED red light have the samewavelength range with low intensity laser and has a low power consumptionand easy integration characteristics.Small sample clinical trials of ourdepartment suggested that LED red light could regulate blood lipid.Therefore,we successfully established rat hyperlipidemia model.On thisbasis,we irradiated the abdomen of rats by LED red light instrument(wavelength630nm±15nm, brightness≥8000cd/m2);observed the effect ofLED red light on the content of serum TC TG, LDL-C, HDL-C; the activity of plasma LPL, HP;liver changes and liver HMG-CoA reductase express ofrats.Methods:36male Sprague-Dawley rats (218～287g)were randomlydivided into the normal control group(12rats) and hyperlipidemic modelgroup. The normal group was kept on feeding with normal diet while the othergroups fed high-lipid-diet for six weeks. After the rats were forbidden to eatfor12hours, blood was taken from the angular vein plexus and the content ofserum TC,TG were tested.The content of Serum TC, TG of the hyperlipidemicmodel groups were higher than those in the normal control group and itsuggested that the hyperlipidemic model was successful.After thehyperlipidemic model was ready,the hyperlipidemic model group rats wererandomly divided into the hyperlipidemic control group and LED treatmentgroup.The LED treatment group were given LED red light for28days.During the course, the two group rats continue to feed high-lipid-diet. At14thday and28thof the irradiation,the content of serumTC,TG,LDL-C,HDL-Cwere tested. At28thof the irradiation, after the activity of LPL and the HLwere tested, liver wet weight was weighed, the pathological changes of theliver were were examined by using HE stainning and the expression ofHMG-CoA reductase in liver cells were examined usingimmunohistochemistry staining.Results:1. Effect of high-lipid-diet on the content of serum TC,TG,LDL-C,HDL-C: after6weeks’ high-lipid-diet, the content of serum TC,TG,LDL-C ofhyperlipidemic model group were obviously higher those of normal controlgroup, the difference was significant(P<0.01), it suggested that thehyperlipidemic model was successful.2. Effect of LED red light on the content of serum TC,TG,LDL-C,HDL-C: at the beginning of the experiment, the content of serum TC、TG、HDL-C、LDL-C was not significantly difference between hyperlipidemiccontrol group and LED treatment group.After14days of irradiation, thecontent of serum TC、TG、LDL-C of the LED treatment group was lower and serum HDL-C was higher compared with the hyperlipidemic controlgroup,but only the difference of serum LDL-C was significant(P<0.05). After28days of irradiation, the content of serum TC、TG、LDL-C of the LEDtreatment group was lower and the content of serum HDL-C was highercompared with the hyperlipidemic control group, and the differences weresignificant(P<0.01)3. Effect of LED red light on the activity of LPL and HL: the activity ofLPL and HL of the LED treatment group was higher compared with thehyperlipidemic control group after28days’irradiation, the difference wassignificant (P<0.01).4. Effect of LED red light on body weight,liver weight and hepatic indexof rats:by the end of the experiment,liver weight and hepatic index of LEDtreatment group had a significantly lower compared with the hyperlipidemiccontrol group,and the difference was significant(P<0.05); the body weight ofLED treatment group had a certain lower compared with the hyperlipidemiccontrol group,but the difference was not statistically significant (P>0.05).5.The changes of liver pathology: visual observation:the liver of normalcontrol group was reddish brown, quality of a material is medium, capsularsmooth, sharp edge, bright and clean cut.The liver of hyperlipidemic controlgroup was yellowish-white, quality of a material is partial hard, capsularnervous, edge obtuse, cut fat.The liver colour and quality of a material of theLED treatment group had a certain improvement.Microscopic Observation: the liver lobules structure of normal controlgroup was clear, liver cells were arranged in order, the nuclear shape wasnormal and cytoplasm was uniform. Lots of large fatty vacuoles were greatlyfilled with liver cells in the hyperlipidemic control group,the nuclei werepacked to the edge of the cell membrane and liver cells were arranged indisorder.The number of fatty vacuoles of the liver cells in LED treatmentgroup had a significant reduce, the nuclei were almost in the center of thecells.Some cells seemed as the same as the normal hepatic cells.6.The expression of HMG-CoA Reductase：The positive parts of the HMG-CoA reductase showed brown in the cytoplasm of liver cells. In thenormal control group, the positive cells scattered around the central vein andcollect abbacy, the score of immunohistochemistry(ISH) was1.9±0.99.In theHyperlipidemic control group, lots of positive cells around the central veinand collect abbacy, the score of ISH (3.8±1.99) was higher than that in thenormal control group and the difference was significant(P<0.05).In the LEDcontrol group, a few of positive cells around the central vein and collectabbacy,the number of the positive cells was lower than that in theHyperlipidemic control group,the score of ISH(2.1±1.29) was lower than thatin the Hyperlipidemic control, the difference was significant(P<0.05).Conclusion:1.The experiment successfully reproduce the rat hyperlipidemic modelby high-lipid-diet.2.LED red light might lower the content of serum TC,TG,LDL-C andraise the content of serum HDL-C of hyperlipidemic rats.3.LED red light might heighten the activity of serum LPL and HL ofhyperlipidemic rats.4.LED red light might lower the liver weight and liver index ofhyperlipidemic rats.5.LED red light might reduce the liver fatty degeneration ofhyperlipidemic rats.6.LED red light might reduce the expression of HMG-CoA reductase ofhyperlipidemic rats.