Isoginkgetin treatment attenuated lipopolysaccharide-induced monoamine neurotransmitter deficiency and depression-like behaviors through downregulating p38/NF-κB signaling pathway and suppressing microglia-induced apoptosis.

Background: Microglia activation-induced neuroinflammation may contribute to the etiology of depression. containing high concentration of isoginkgetin could effectively treat mental diseases in ancient times. However, the therapeutic role, peculiarly in the brain-immune modulation in depression is still unclear. This study aimed to determine effects of isoginkgetin on lipopolysaccharide (LPS)-induced depression-like changes. Furthermore, its modulation on the p38/nuclear factor-kappa B (NF-κB) pathway in LPS-activated microglia was evaluated.

Methods: Adult Kunming mice were intraperitoneally injected vehicle or isoginkgetin (4 mg/kg) daily for 14 days before saline or LPS (0.83 mg/kg) administration. Depression-like behavior, neurotransmitter levels, and markers of neuroinflammation were determined. Isoginkgetin effect on LPS-induced microglial activation was then assessed in BV2 cells. Finally, conditioned medium (CM) derived from isoginkgetin-treated BV2 cells was co-cultured with SH-SY5Y cells for 24 h. Cell viability and apoptosis were evaluated.

Results: LPS significantly induced helplessness and anxiety, which were associated with decreased 5-HT, noradrenaline, and dopamine concentrations. Meanwhile, LPS increased microglia M1 hallmark Iba1 expression and serum interleukin (IL)-1β concentration. These changes were attenuated by isoginkgetin treatment. In vitro, isoginkgetin markedly suppressed the production of IL-1β, IL-6, tumor necrosis factor-alpha, cyclooxygenase-2, inducible nitric oxide, and reactive oxygen species, which are released from LPS-stimulated BV2 cells. More interestingly, CM from isoginkgetin-treated BV2 cells significantly alleviated SH-SY5Y cell apoptosis and restored cell viability compared to LPS-treated group through the inhibition of p38/NF-κB signaling pathway.

Conclusion: These data demonstrate that isoginkgetin is an effective therapeutic agent for depression-like behaviors and neuropathological changes via potent anti-inflammatory property.