O Brilliant blue G, antagonista do receptor P2x7, diminui a discinesia induzida por L-DOPA em animais submetidos a modelo experimental de doença de parkinson

• Autor(a) principal: Fonteles, Analu Aragão
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/23973
• topic: Doença de Parkinson; Oxidopamina; Levodopa; Discinesias

Dyskinesia is a serious motor complication associated with the prolonged administration of L-DOPA in patients with Parkinson’s disease. The peak of L-DOPA-induced dyskinesia (LID) greatly coincides with the maximum action of L-DOPA following its administration. Accumulating evidence supports the fact that ATP controls dopamine release in striatum through P2X7 receptor. The aim of this work was to investigate a high affinity P2X7 receptor antagonist (Brilliant Blue G) in ameliorating L-DOPA-induced dyskinesia. We selected a established 6-OHDA animal model of Parkinson’s disease. One hundred and six animals were divided into 7 groups as following: 1. sham-operated, 2. sham-operated treated with BBG (45 mg/kg i.p.), 3. sham-operated treated with L-DOPA (30 mg/kg), 4. exposed to 6-OHDA only, 5. exposed to 6-OHDA and treated with L-DOPA, 6. exposed to 6-OHDA and treated with L-DOPA and BBG at 22,5 mg/kg, 7. exposed to 6-OHDA and treated with L-DOPA and BBG at 45 mg/kg. Treatments were initiated 15 days following 6-OHDA exposure. L-DOPA treatment was performed daily over a period of 22 days, whereas BBG treatment was performed every other day for the same amount of time. BBG treatment significantly improved AIMs scores at 7, 14 and 21 days following L-DOPA treatment and enhanced the motor coordination performance on rotarod test. Neurodegeneration was assessed through TH-imunohistochemistry and flurojade C staining though BBG did not show neuroregeneration activity and no changes were observed in flurojade C staining. We also evaluated changes in DAT levels, D1 and D2 dopaminergic receptors and DARPP-32 protein and noticed that P2X7 inhibition reestablished DAT levels that were initially reduced in L-DOPA-treated animals, and ameliorated D1 receptor and pDARPP-32Thr34 expression in L-DOPA-treated animals. The neuroinflammation was evaluated through the measurement of GFAP/CD11b/COX-2-imunohistochemistry and IL-1β expression with L-DOPA chronic therapy significantly increasing neuroinflammation in 6-OHDA treated animals, and conversely P2X7 receptor blockade diminishing it. Our results suggest that the purinergic system plays an important role in the pathophysiology of LID, with BBG showing a remarkable anti-dyskinetic effect probably by downregulating D1 pathway activation and controlling neuroinflammation.