Name: Lívia Silveira de Moraes
Type: MSc dissertation
Publication date: 31/07/2014

Namesort descending Role
Cristina Martins e Silva Advisor *

Examining board:

Namesort descending Role
Adair Roberto Soares dos Santos External Examiner *
Cristina Martins e Silva Advisor *
Rita Gomes Wanderley Pires Internal Examiner *

Summary: The Parkinson’s disease (PD) is a neurodegenerative disturbe caused by neuronal loss of the dopaminergic neurons in the substantia nigra pars compacta, afecting by 1% in people >70 years of age. Currently, the main treatment is based on the replacement of the dopamine levels (DA) with administration of levodopa, which mitigates especially the motor impairment. Other drugs, such as dopamine agonists, are now used concomitantly with levopoda but they are not effective and do not prevent disease progression, beside triggers several side effects. Thus, there are efforts focused on the discovery and identification of new molecules with neuroprotective activity of natural origin, especially of the biodiversity of flora. The plant Combretum leprosum has vast medicinal potential with a wide spectrum of biological action, such as anti-inflammatory, analgesic, antiepileptic, among others, but its mechanism of action and its neuroprotective effects have not been fully elucidated. In this study, we explored the potential neuroprotective effect of ethanol extract (EE) of C. leprosum in a murine model of PD, using the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) i.p. at a dose of 30 mg/Kg for 5 consecutive days. Exacerbated hyperlocomotion was observed after injection of amphetamine (2 mg/kg) in the group treated with MPTP, an effect prevented by pretreatment with EE at a dose of 100 mg/kg. The deficit in muscle strength induced by MPTP was also prevented by pretreatment with C. leprosum. In biochemical context, treatment with EE was not able to prevent MPTP-induced dopamine depletion in the striatum. However, interestingly, our data suggest that treatment with EE can prevent depletion of dopamine metabolites, homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC), in the same region. In addition, treatment with EE prevented the alterations in the metabolism of MPTP-induced DA. Regarding the molecular part, treatment with EE was able to increase the expression of tyrosine hydroxylase (TH) gene in the midbrain region of the animals. Although there is a clear tendency that the lower expression of the dopamine transporter (DAT) and the dopamine D2 receptor in this region caused by MPTP can be prevented by treatment with EE, this finding was not statistically significant. In the striatum, the expression of genes TH, D1 and D2 did not differ between groups. Our results show that treatment with EE at a dose of 100 mg/kg prevents motor and molecular alterations induced by MPTP, however partially reversing the biochemical changes. Accordingly, our study demonstrates the therapeutic potential Combretum leprosum in the prevention and treatment of PD.

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