Avaliação de parâmetros comportamentais, bioquímicos e morfológicos no sistema nervoso central e músculoesquelético em um modelo de doença de huntington induzido pelo ácido-3-nitropropiônico em peixe-zebra

Abstract

Huntington’s disease (HD) is a devastating, progressive, and fatal neurodegenerative disorder. It is characterized by a neurobehavioral triad consisting of motor dysfunction, neuropsychiatric disturbance and cognitive decline. In HD the striatal neurons are degenerated leading to a decrease in dopamine D2 (D2R) and D1 (D1R), and adenosine A2A (A2AR) and A1 (A1R) leading to impaired movements such as chorea, bradykinesia, rigidity and locomotor incoordination. Furthermore, other molecular and biochemical mechanisms such as mitochondrial dysfunction, oxidative stress, neuroinflammation, neurodegeneration and changes in different neurotransmitter systems are involved in the pathophysiology of the disease. The 3-nitropropionic acid (3-NPA), a toxin derived from fungi and plants, can reproduce the behavioral phenotypes and biochemical alterations of HD. In the current study, we investigated the behavioral and morphological mechanisms in the brain and musculoskeletal system in adult zebrafish with 3-NPA-induced HD phenotype. For the biochemical and morphological analyses, adult zebrafish received a total of 7 intraperitoneal (i.p) injections (one injection every 4 days) of 3-NPA (60 mg/kg) for 28 days. On the 29th day, the brains were collected for histological, biochemical and molecular analyses. For the pharmacological modulation, on the 29th day after starting treatment, the animals receive a single i.p. injection of the following compounds: antioxidants, such as vitamin C (100 mg/kg); creatine (50 mg/kg) and melatonin (10 mg/kg); dopaminergic drugs, such as quinpirole (selective D2R agonist, 5 mg/kg) and eticlopride (selective D2R antagonist, 0.1 mg/kg); adenosinergic drugs such as CPA (selective A1R agonist, 1 mg/kg), CGS 21680 (selective A2AR agonist, 1 mg/kg), caffeine (non-selective antagonist of A1R e A2AR, 10 mg/kg), ZM 241385 (selective A2AR antagonist, 10 μg/kg), DPCPX (selective A1R antagonist, 0.5 mg/kg), dipyridamole (nucleoside transporter inhibitor, 10 mg/kg), EHNA (adenosine deaminase inhibitor, 100 μg/kg). After 30 min of i.p. injection, the locomotor activity and memory of the animals were evaluated. The histological results demonstrated that 3-NPA caused neurodegeneration and a decrease in granular cell in the brain tissue, but did not cause histological change in the cardiac and muscular tissue. Also, the results showed that there was not alteration in the TBARS and NPSH levels in the brain of adult zebrafish following 3-NPA treatment. Moreover, we observed that antioxidants vitamin C and creatine reversed the hypolocomotor effect induced by 3-NPA, while the memory deficit caused by 3-NPA was reversed by vitamin C and melatonin. Regarding the dopaminergic modulation, the 3-NPA caused decrease in dopamine, glutamate, and serotonin levels, but not did alter the gene expression of dopamine receptors. Also, the hypolocomotor effect and memory deficit induced by 3-NPA were reversed with quinpirole, but not with eticlopride. Caffeine and ZM 241385 reversed the hypolocomotor effect and memory deficit induced by 3-NPA, while the CGS 21680 potentiated the hypolocomotion and did not reverse the memory deficit induced by 3-NPA. In addition, CPA, DPCPX, dipyridamole and EHNA reversed the memory deficit induced by 3-NPA. Taken together, these data indicate that the 3-NPA treatment induces to behavioral phenotypes, histological and biochemical alterations as those observed in HD patients in the late stage. Also, the results demonstrate that adenosinergic and dopaminergic signaling modulation and the antioxidant action can be promising pharmacological strategies against end-stage symptoms of HD.