Topiramate effects lipolysis in 3T3-L1 adipocytes

Abstract

Studies have shown that topiramate (TPM)-induced weight loss can be dependent on the central nervous system (CNS). However, the direct action of TPM on adipose tissue has not been tested previously. Thus, the present study aimed to examine whether TPM modulates lipolysis in 3T3-L1. The 3T3-L1 cells were incubated in 50 µM TPM for 30 min. The β-adrenergic stimulator, isoproterenol, was used as a positive control. The release of lactate dehydrogenase, non-esterified fatty acid, glycerol and incorporation of ¹⁴C-palmitate to lipid were analyzed. The phosphorylation of protein kinase A (PKA), hormone-sensitive lipase (HSL), adipocyte triglyceride lipase (ATGL) and perilipin A, as well as the protein levels of comparative genetic identification 58 (CGI-58) were assessed. The levels of glycerol and non-esterified fatty acid increased markedly when the cells were treated with TPM. The TPM effects were similar to the isoproterenol positive control. Additionally, TPM reduced lipogenesis. These results were observed without any change in cell viability. Finally, the phosphorylation of PKA, HSL, ATGL and perilipin A, as well as the protein levels of CGI-58 were increased compared to the control cells. These results were similar to those observed in the cells treated with isoproterenol. The present results show that TPM increased the phosphorylation of pivotal lipolytic enzymes, which induced lipolysis in 3T3-L1 adipocytes, suggesting that this drug may act directly in the adipose tissue independent from its effect on the CNS.

Keywords: 3T3-L1 adipocytes; lipolysis; obesity; topiramate; weight loss.

Figure 1.

Effects of topiramate on the lipolysis and lipogenesis in 3T3-L1 adipocytes. Adipocytes were incubated for 30 min at 37°C in the presence or absence of topiramate or isoproterenol. (A) Release of glycerol and (B) non-esterified fatty acid (NEFA) into culture medium was measured and expressed as mg/dl/µg of protein and nM/µl/µg of protein, respectively. Isoproterenol was the positive control. (C) The incorporation of [¹⁴C]-palmitate into lipids in the presence or absence of insulin (10 nmol/l) and presence or absence of topiramate (50 µM) was evaluated. The results are expressed as percentage of basal control. Cellular viability was evaluated by (D) monitoring lactate dehydrogenase (LDH) and expressed as mmol/l/dl/µg of protein. Phosphorylation of (E) protein kinase A (PKA), (F) hormone-sensitive lipase^Ser660 (HSL^Ser660), (G) HSL^Ser563, (H) perilipin, (I) ATGL^Ser406 and (J) cofactor comparative genetic identification 58 (CGI-58) protein levels, respectively. The lower panel shows bands representative of PKA, HSL, perilipin, adipocyte triglyceride lipase (ATGL) and protein levels β-actin. Bars represent the mean ± standard error of the mean of 6 different experiments. *P<0.05, vs. control group. In Fig. 1C, *P<0.05 vs. control group without insulin (-) and ^#P<0.05 for topiramate vs. control group with insulin (+). CON, control; ISO, isoproterenol; TOP, topiramate.