Download 454 Efavirenz Produces a Differential Bioenergetic Response in

454 Efavirenz Produces a Differential Bioenergetic Response in Neurons and Glial Cells
Haryes A. Funes1, Nadezda Apostolova1, Fernando Alegre2, Miriam Polo3, Ana Blas-Garcia3, Juan V. Esplugues1
Departamento de Farmacologia, Facultad de Medicina, Universitat de Valencia, Valencia, Spain, 2Univeristy Hospital Dr. Peset, Valencia, Spain, 3University Hospital Dr. Peset,
Valencia, Spain
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Background: CNS side effects are the main adverse events of Efavirez (EFV), but the mechanisms responsible are unknown although recent evidence
shows that this drug undermines mitochondrial function. Neurological pathogenesis is often associated with mitochondrial dysfunction and it is known that
glia cells overcome the damaging effects of mitochondrial inhibition by rapidly up-regulating AMP-kinase (AMPK)-mediated glycolysis and maintaining
ATP levels, which is crucial for cell homeostasis and viability. In contrast, neurons lack this defence mechanism, which makes them more vulnerable
to bioenergetic challenge. We have analysed if EFV interferes with the mitochondria of neurons and glia cells and assessed its influence on cellular
bioenergetics. Since there is a substrate of CNS inflammation during HIV-related cognitive disorders, we have also evaluated if EFV effects are exacerbated
by nitric oxide (NO), a mediator of inflammation and inhibitor of mitochondrial respiration.
Methodology: Human cell lines (glioma and neuroblastoma) and rat primary cultures of astrocytes and neurons were treated with clinically relevant
concentrations of EFV. Exogenous NO was applied by addition of its donor DETA-NO. Parameters of mitochondrial function and bioenergetics were studied
using standard cell biology techniques. Data (mean±S.E.M, n=3-5) were expressed as % (of untreated cells, considered 100%) and analysed by Student’s
t-test, significance vs. vehicle.
Results: EFV (10 and 25 µM) inhibited mitochondrial respiration, enhanced ROS generation, undermined Δψm and reduced ATP levels in a significant
and concentration-dependent fashion in both neurons and glia. However, AMPK was activated only in glia, leading to an up-regulation of glycolysis
(enhanced lactate production and increased intracellular ATP), whereas in neurons there was a decrease in ATP concentration. The combination of
EFV+NO potentiated the effects of either one on mitochondrial parameters in both neurons and glia, but ATP generation and lactate production were
again enhanced only in the latter. EFV+NO did not deplete the number of glia (Veh=103.1±1.831; EFV10=103.3±2.078; DETA-NO=74.43±1.645***;
DETA-NO+EFV10=69.86±2.703***), but substantially aggravated the effect of EFV (10µM) on neurons (Veh=103.2±1.372; EFV10=96.38±2.761*;
DETA-NO=65.00±4.359***; DETA-NO+EFV10=27.80±3.666***) (% of untreated cells).
Conclusions: Our results suggest that EFV exerts a direct and specific effect on the energetic balance and viability of neurons and glia through a
mechanism involving acute mitochondrial inhibition, an action that could be exacerbated in neuroinflammatory conditions like those often present in HIVpatients, or when the brain-blood-barrier is disrupted.