Baicalin and ginsenoside Rb1 regulate the expression of adipocyte GRK2 and browning markers under lipid overload

Abstract

Aim: Baicalin and ginsenoside Rb1 show the ability to promote adipocyte browning, but their effects, especially combined treatment, and the related mechanisms under pathological conditions are less known. The study investigated the regulation of browning markers by baicalin and Rb1 under lipid overload and explored the potential implication of a serine/threonine protein kinase G protein-coupled receptor kinase 2 (GRK2). Methods: The 3T3-L1 cells under palmitic acid (PA) stimulation and male ICR mice on a high-fat diet (HFD) challenge were used to evaluate the effects of drugs. Results: GRK2 silencing and overexpression inversely regulated the protein abundance of PGC-1α and UCP-1 in 3T3-L1 adipocytes. Baicalin, Rb1, and their combination decreased the PA-induced elevation of GRK2 while increasing the thermogenetic markers at the protein and mRNA levels. In vivo, the tested drugs restored the expression of thermogenetic and mitochondrial biogenetic markers in the inguinal white adipose tissue (WAT) of HFD-fed mice. Consistently, the drug-treated mice displayed an improved metabolic profile. The baicalin-Rb1 combination showed a more potent effect in some examinations, and its effect was comparable to that of GRK2 inhibitor paroxetine or AMP-activated protein kinase activator metformin. Conclusions: Baicalin and Rb1, alone or in combination, improved the browning of adipocytes during differentiation and prevented the whitening shift of WAT on an HFD, which was associated with the downregulation of GRK2. The study expands the understanding of the anti-obesity effects of baicalin and Rb1 and the potential of Scutellariae Radix- Ginseng Radix et Rhizoma compatibility for treating obesity-associated metabolic diseases.

Keywords

baicalin / ginsenoside Rb1 / G protein-coupled receptor kinase 2 / adipocyte browning / adipocyte whitening / palmitic acid / high-fat diet

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