Tempol improves neuroinflammation and delays motor dysfunction in a mouse model (SOD1G93A) of ALS

Gabriela Bortolança Chiarotto,Alexandre Leite Rodrigues de Oliveira,Natalia Perussi Biscola,Aline Barroso Spejo,Fernanda Gubert,Matheus Perez,Marcondes França Junior,Rosália Mendez-Otero,Luciana Politti Cartarozzi

doi:10.1186/s12974-019-1598-x

Gabriela Bortolança Chiarotto, Alexandre Leite Rodrigues de Oliveira + Show 7 more

Open Access

https://doi.org/10.1186/s12974-019-1598-x

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Abstract

BackgroundThe development of new therapeutic strategies to treat amyotrophic lateral sclerosis (ALS) is of utmost importance. The use of cyclic nitroxides such as tempol may provide neuroprotection and improve lifespan. We investigated whether tempol (50 mg/kg) presents therapeutic potential in SOD1G93A transgenic mice.MethodsTempol treatment began at the asymptomatic phase of the disease (10th week) and was administered every other day until week 14, after which it was administered twice a week until the final stage of the disease. The animals were sacrificed at week 14 (initial stage of symptoms—ISS) and at the end stage (ES) of the disease. The lumbar spinal cord of the animals was dissected and processed for use in the following techniques: Nissl staining to evaluate neuronal survival; immunohistochemistry to evaluate astrogliosis and microgliosis (ISS and ES); qRT-PCR to evaluate the expression of neurotrophic factors and pro-inflammatory cytokines (ISS); and transmission electron microscopy to evaluate the alpha-motoneurons (ES). Behavioral analyses considering the survival of animals, bodyweight loss, and Rotarod motor performance test started on week 10 and were performed every 3 days until the end-stage of the disease.ResultsThe results revealed that treatment with tempol promoted greater neuronal survival (23%) at ISS compared to untreated animals, which was maintained until ES. The intense reactivity of astrocytes and microglia observed in vehicle animals was reduced in the lumbar spinal cords of the animals treated with tempol. In addition, the groups treated with tempol showed reduced expression of proinflammatory cytokines (IL1β and TNFα) and a three-fold decrease in the expression of TGFβ1 at ISS compared with the group treated with vehicle.ConclusionsAltogether, our results indicate that treatment with tempol has beneficial effects, delaying the onset of the disease by enhancing neuronal survival and decreasing glial cell reactivity during ALS progression in SOD1G93A mice.

Highlights

The development of new therapeutic strategies to treat amyotrophic lateral sclerosis (ALS) is of utmost importance
Tempol delays the bodyweight loss and the motor deficit in the Rotarod test associated with ALS progression The behavioral analyses were performed with experimenters blinded to treatment groups twice a week, starting at 10 weeks of age until 17 weeks
The data obtained from the behavioral tests revealed an earlier loss of body weight (12 weeks) in the SOD1G93A mice treated with riluzole and vehicle compared to the NTG group, starting from the asymptomatic phase of the disease (Fig. 2a)

Summary

Introduction

The development of new therapeutic strategies to treat amyotrophic lateral sclerosis (ALS) is of utmost importance. The clinical signs emerge when neuronal degeneration reaches a critical point beyond compensatory mechanisms, generating denervation and muscular weakness. Such partial degeneration is compensated for by the surviving neurons, which, through axonal sprouting, increase the size of the motor units. This mechanism eventually fails, and the cell bodies of the motoneurons become visibly abnormal and completely degenerate [4]. The disease progression is fast, with 50% of patients dying due to respiratory complications within 2 to 5 years after the onset of symptoms [5]

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