Effect of Clozapine and Olanzapine on the Expression of Selected Genes and Epigenetic Regulators of Insulin Resistance Pathway in Human Preadipocytes – a Preliminary Study

Clozapine and olanzapine, popular second-generation antipsychotics used for various psychiatric disorders, cause significant side effects such as metabolic syndrome, but the exact mechanism remains unclear. The present study aimed to assess clozapine and olanzapine effects on the expression of mRNA insulin pathway genes (IRS-1, PTEN, PIK3CG and PIK3R1), microRNAs (miR-152-3p, miR-214-3p, miR-15b-5p, miR-16-5p, miR-126-3p) and long non-coding RNAs (lncRNAs: XIST, H19, SNHG16, PVT1), in human visceral preadipocytes (HPAd). Expression was examined by real - time PCR. Cell viability was determined by MTT assay. The findings revealed that in HAPd, both clozapine and olanzapine (at doses of 5 µM and 25 µM) decreased IRS-1 gene expression after 24 hours. After 48 hours, IRS-1 expression was reduced by clozapine at both concentrations and olanzapine at 5 µM. In addition, olanzapine (at 25 µM) decreased the expression of PIK3CG, miR-152-3p, miR-214-3p, miR-15b-5p and miR-16-5p after 24 hours, while increasing the expression of miR-126-3p at 5 µM. Clozapine at 25 µM decreased miR-16-5p expression and increased SNHG16 lncRNA expression at 5 µM after 24 hours. After 48 hours, olanzapine (at 25 µM) increased PIK3R1 expression and decreased PIK3CG expression at 5 µM. Both drugs at 5 µM increased the expression of miR-152-3p, miR-214-3p, miR-15b-5p and miR-16-5p after 48 hours, with clozapine further increasing the expression of miR-126-3p at this concentration. The results suggest that clozapine and olanzapine may affect the expression of key genes and epigenetic molecules in the insulin pathway, which is one potential cause leading to insulin resistance in adipose tissue.