Alterações nas proteínas de fissão e fusão mitocondriais, caspase 3 e sinaptofisina cerebrais induzidas pela sobrecarga de ferro neonatal : reversão pelo tratamento com canabidiol

• Autor(a) principal: Silva, Vanessa Kappel da
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da PUC_RS
• Texto Completo: http://tede2.pucrs.br/tede2/handle/tede/5461
• topic: BIOLOGIA MOLECULAR; BIOLOGIA CELULAR; MITOCÔNDRIOS; DOENÇAS NEURODEGENERATIVAS; CANABIDIOL; APOPTOSE; FERRO; CNPQ::CIENCIAS BIOLOGICAS::BIOLOGIA GERAL

Iron accumulation in the brain has been observed in both normal aging and in several neurodegenerative diseases. We have previously shown that brain iron loading results in persistent memory deficits, which are accompanied by oxidative stress. Due to the high metabolic rate of the nervous system, mitochondria are present in large numbers in nerve cells. It has been demonstrated that through fission and fusion of mitochondria, these organelles promote changes in their structure and this dynamic can affect mitochondrial function and vice-versa. Deficits in supplying energy to the synapses have been linked to neurodegenerative diseases and once the functionality of neural circuits is reduced, these cells may activate neuronal death cascades. Here, we analyzed the effects of neonatally iron treatment on the following targets: Dynamin-1-like protein (DNM1L) and Optic atrophy 1 (OPA1), proteins involved in regulating mitochondrial fission and fusion, respectively; Caspase 3, a key protease of the effector phase of apoptosis; and Synaptophysin, as a synaptic marker. Additionally, we investigated the effects of Cannabidiol (CBD), the main non-psychotropic component of Cannabis sativa, previously shown to improve memory in iron-treated rats, in reversing iron-induced effects on DNM1L, OPA1, caspase 3, and synaptophysin. Male rats received vehicle or iron carbonyl (30mg/kg) at postnatal days 12-14. At adulthood, they were treated with vehicle or CBD (10 mg/kg) for 14 days. Hippocampal and cortical protein levels and gene expression were quantified using western blotting analysis and RT-qPCR, respectively. Quantitative measurements of proteins were made using densities of individual proteins, normalized to the density of β-actin. On RT-qPCR, samples were normalized to three reference genes (GAPDH, HPRT1 and RPL13A). Western blotting results indicated that neonatal iron treatment induced a significant reduction of DNM1L in the hippocampus and OPA1 in the cortex. Iron was also shown to increase caspase 3 both in the hippocampus and cortex, which was accompanied by a significant reduction of synaptophysin levels in the hippocampus. CBD reversed iron-induced effects, bringing hippocampal DNM1L, caspase 3 and synaptophysin levels back to values comparable to the control group. The present results suggest that iron may affect mitochondrial dynamics, possibly trigging synaptic loss and apoptotic cell death. The reversion of these effects by CBD, indicates its potential neuroprotective effect.