The comparative effects of high dose atorvastatin and proprotein convertase subtilisin/kexin type 9 inhibitor on the mitochondria of oxidative muscle fibers in obese-insulin resistant female rats.

The present study aimed to compare the effects of high dose atorvastatin and a proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor on the mitochondrial function in oxidative muscle fibers in obese female rats. Female Wistar rats were fed with either a normal diet (ND: n = 12) or a high-fat diet (HFD: n = 36) for a total of 15 weeks. At week 13, ND-fed rats received a vehicle, and HFD-fed rats were divided to three groups to receive either a vehicle, 40 mg/kg/day of atorvastatin, or 4 mg/kg/day of PCSK9 inhibitor (SBC-115076) for 3 weeks. Soleus muscles were investigated to assess mitochondrial ROS, membrane potential, swelling, mitochondrial-related protein expression, and level of malondialdehyde (MDA). The results showed that HFD-fed rats with vehicle developed obese-insulin resistance and dyslipidemia. Both atorvastatin and PCSK9 inhibitor reduced obesity and dyslipidemia, as well as improved insulin sensitivity in HFD-fed rats. However, the efficacy of PCSK9 inhibitor to increase weight loss and reduce dyslipidemia in HFD-fed rats was greater than those of atorvastatin. An increase in MDA level, ratio of p-Drp1ser616/total Drp1 protein, CPT1 protein, mitochondrial ROS, and membrane depolarization in the soleus muscle were observed in HFD-fed rats with vehicle. PCSK9 inhibitor enabled the restoration of all these parameters to normal levels. However, atorvastatin facilitated restoration of some parameters, including MDA level, p-Drp1ser616/total Drp1 ratio, and CPT1 protein expression. These findings suggest that PCSK9 inhibitor is superior to atorvastatin in instigating weight loss, cholesterol reduction, and attenuation of mitochondrial oxidative stress in oxidative muscle fibers of obese female rats.