A Network Pharmacology-Based Method to Explore the Therapeutic Effect of Honokiol on Diabetes with Comorbid Depression in Mice

The effective treatment of diabetes with comorbid depression is a big challenge so far. Honokiol, a bioactive compound from the dietary supplement Magnolia officinalis extract, possesses multiple health benefits. The present study aims to propose a network pharmacology-based method to elucidate potential targets of honokiol in treating diabetes with comorbid depression and related mechanisms. The antidepressant-like efficacy of honokiol was evaluated in high-fat diet (HFD) induced diabetic mice using animal behavior testing, immuno-staining and western blotting assay. Through network pharmacology analysis, retinoid X receptor alpha (RXRα) and vitamin D receptor (VDR) were identified as potential targets related to diabetes and depression. The stable binding conformation between honokiol and RXR/VDR was determined by molecular docking simulation. Moreover, hononkiol effectively alleviated depression-like behaviors in HFD diabetic mice, presented anti-diabetic and anti-neuroinflammatory functions, and protected the hippocampal neuroplasticity. Importantly, honokiol could activate RXR/VDR heterodimer in vivo. The beneficial effects of honokiol on HFD mice were significantly suppressed by UVI3003 (a RXR antagonist), while enhanced by calcitriol (a VDR agonist). Additionally, the disruption of autophagy in the hippocampus of HFD mice was ameliorated by honokiol, which was attenuated by UVI3003 but strengthened by calcitriol. Taken together, the data provide new evidence that honokiol exerts the antidepressant-like effect in HFD diabetic mice via activating RXR/VDR heterodimer to restore the balance of autophagy. Our findings indicate that the RXR/VDR-mediated signaling might be a potential target for treating diabetes with comorbid depression.