Fluoxetine Combination with Metformin Enhances Neuroprotection in PC12 Cell Injury Model

Abstract

Background: Depression is a multifactorial mood disorder with a high prevalence worldwide. To date, advances in drug discovery have widened therapeutic options with the synthesis of so-called selective serotonin reuptake inhibitors. Fluoxetine is the first selective serotonin reuptake inhibitor with a proven clinical efficacy and safety profile. Metformin, a first-line antiglycemic drug, has been shown to have antidepressant effects in patients with type 2 diabetes. However, the effectiveness of the combination of metformin and fluoxetine in the treatment of depression has not been investigated. Methods: PC12 (rat adrenal pheochromocytoma) cells were subjected to high-level corticosterone (200 μM) and drug administration. Then the cell apoptosis was measured by a flow cytometry assay. The potential mechanism of the combined application of metformin and fluoxetine on PC12 cells was discussed using reactive oxygen species, intracellular Ca²⁺ analysis, immunofluorescence, and Western blotting. Results: Our results showed that a combination of metformin and fluoxetine decreased apoptosis, the level of reactive oxygen species, and intracellular Ca²⁺ accumulation. Furthermore, the combined administration lowered the P62 protein expression and the autophagosome ratio, while promoting the expression of LC3B (microtubule-associated protein B-light chain 3) proteins. Conclusions: The combined use of metformin and fluoxetine in PC12 was found to have a protective effect against corticosterone. Mitochondrial apoptosis inhibition, autophagy flux unblocking, and activation of the AMPK (AMP-activated protein kinase)/BDNF (brain-derived neurotrophic factor) pathway may represent new approaches to enhance neuroprotection.