Low-level Laser Therapy Rescues Depression-like Behaviors In Mice

Objective: To investigate whether Low-level laser therapy(LLLT) rescues the depression-like behaviors in mice and explore the mechanisms of LLLT treatment.Method: Ahi1 knockout(KO) mice were used in this study; Behavioral tests including tail suspension test and forced swimming test were used to examine the depressive phenotype. Western blot was used to determine the expression of BDNF. High performance liquid chromatography(HPLC) was used to measure the contents of neurotransmitters(including DA and 5-HT). Ahi1 KO mice were randomly divided into the control group and treatment group; ICR mice were randomly divided into two groups, control group and the Stress group. Chronic restraint stress was used to induce acute depression-like behaviors in mice. Stress mice were randomly divided into two groups, Treatment group and no treatment group; When Stress group mice showed depression phenotype, we treated them with Low-level laser. Furthermore, the stress group continued to space constraints. We measured the content of mitochondria complex IV and ATP by an enzyme linked immunosorbent assay.Results : Tail suspension test and forced swimming test showed that the immobility time of KO group were significantly increased than the HET group(P<0.05). The expression of BDNF and neurotransmitters including DA and 5-HT in the brain tissue of Ahi1 knockout mice significantly decreased(P<0.05). After 4 weeks of Low-level laser therapy, Low-level laser rescued depression-like behaviors in Ahi1 KO mice(P<0.05); Tail suspension test and forced swimming test shown that the immobility time of Con group obviously increased compared with the immobility time in the Stress group(P<0.05).The content of BDNF and neurotransmitters(including DA and 5-HT) also decreased in Stress group(P<0.05). After 4 weeks of Low-level laser therapy, no treatment group mice gradually increased the immobility time, but the treatment group reduced immobility time(P<0.05).We found that the content of ATP and mitochondrial complex IV in the prefrontal cortex(PFC) after low-level laser treatment had obvious changes(P<0.05). While in other brain regions, the level of mitochondrial complex I ~ IV and ATP had no significant changes(P>0.05).Conclusion:1. Low-level laser therapy rescues depression-like behaviors in mice.2. Low-level laser therapy increases mitochondrial complex IV and ATP.3. Low-level laser therapy may improve depression-like behaviors by increasing mitochondrial complex IV and ATP production.