Fig. 5.

Melatonin activated the AMPK/SERCA2a pathway to suppress Ca²⁺-XO-ROS-Drp1 damage signals. a, b The change of SERCA2a. LPS suppressed the expression of SERCA2a. c, d Inhibition of SERCA2a could alleviate the protective effect of melatonin on calcium overload. e, f Melatonin had the ability to activate the AMPK pathway. g Inhibition of AMPK pathway abated the promotive effect of melatonin on SERCA2a expression. However, activation of AMPK under LPS treatment could partly reverse the SERCA2a content. h The AMPK pathway was involved in ATP production. i Apart from SERCA2a expression, AMPK was also activated by melatonin and contributed to the SERCA2a activity. j Inhibition of AMPK augmented the cellular apoptosis despite melatonin treatment. Compound c: cc, AICAR:AI. *P < 0.05 vs Ctrl group, ^# P < 0.05 vs LPS group, ^@ P < 0.05 vs LPS + melatonin group