Trazodone exerts cytoprotective effects in human activated microglial
cells by modulating inflammatory pathways
Abstract
Microglia are resident brain cells that regulate neuronal development
and innate immunity. Microglia activation is involved in the cellular
response to neuroinflammation, thus representing a possible target for
pharmacological strategies aimed to counteract the onset and progression
of brain disorders, including depression. In this sense, antidepressant
drugs have been reported to reduce neuroinflammation by acting on glial
cells, too. Herein, the potential anti-inflammatory and neuroprotective
effects of trazodone (TRZ) on the microglial HMC3 cell line were
investigated. HMC3 cells were activated by a double inflammatory
stimulus (LPS and TNF-α, 24 h each), and the induction of inflammation
was demonstrated by i) the increased expression levels of Nuclear Factor
kappa-light-chain-enhancer of activated B cells (NF-kB) and Ionized
calcium-Binding Adapter molecule 1 (IBA-1), and ii) the increased
release of interleukin 6 (IL-6) and Transforming Growth Factor-beta
(TGF-β). TRZ effects were evaluated by treating HMC3 cells for 24 h
before (pre-treatment) and after (post-treatment) the double
inflammatory stimulus. Notably, both TRZ treatment approaches restored
microglia, significantly decreasing the expression of NF-kB and IBA-1,
and the release of the cytokines IL-6 and TGF-β. Moreover, TRZ prevented
and reduced the release of quinolinic acid (QUIN), a known neurotoxic
kynurenine metabolite, demonstrating a potential neuroprotective effect.
In this sense, neuronal-like cells were incubated with conditioned media
collected from microglial cells previously treated with LPS-TNF-α in the
absence or in the presence of TRZ to evaluate cell viability. Overall,
for the first time, this study suggests anti-inflammatory and
neuroprotective effects of TRZ on human microglia.