Clozapine-induced reduction of l-carnitine reabsorption via inhibition/down-regulation of renal carnitine/organic cation transporter 2 contributes to liver lipid metabolic disorder in mice.

ABSTRACT

Clozapine, an atypical antipsychotic drug, is widely utilized for the treatment of schizophrenia; however, clozapine-induced metabolic disorders, such as fatty liver and weight gain, warrant increased attention. Considering the crucial role of l-carnitine (L-Car) in fatty acid oxidation and carnitine/organic cation transporter (OCTN) 2 in renal reabsorption of L-Car, we aimed to study whether clozapine-induced liver lipid metabolic disorder is associated with L-Car dysregulation via inhibition/down-regulation of renal OCTN2. Our results reveal that clozapine inhibits L-Car uptake in MDCK-hOCTN2 cells with an IC50 value of 1.78 µM. Additionally, clozapine significantly reduces the uptake of L-Car in HK-2 cells, mouse primary cultured proximal tubular (mPCPT) cells and HepG2 cells. Acute (intraperitoneal injection) and 21-day successive oral administration of clozapine at 12.5, 25, and 50 mg/kg to mice resulted in 2-3-fold greater renal excretion of L-Car than in the vehicle group, and the concentration of L-Car in plasma and liver was significantly decreased. Concomitantly, mRNA and protein levels of mOctn2 in the kidney were markedly down regulated. Additionally, 28-day oral administration of clozapine induced increased triglyceride (TG) and total cholesterol (TCHO) levels in mouse livers, while L-Car (40 mg/kg - 1 g/kg) attenuated clozapine-induced liver TG and TCHO increase in a dose-dependent manner. These results indicate that clozapine-induced reduction of L-Car reabsorption via inhibition/down-regulation of renal OCTN2 contributes to liver lipid metabolic disorder. L-Car supplementation is probably an effective strategy to attenuate clozapine-induced abnormal lipid metabolism.