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Previous issue date: 2013-02-08 / 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. / O ac?mulo de ferro no c?rebro tem sido observado tanto no envelhecimento normal quanto em muitas doen?as neurodegenerativas. Previamente, mostramos que a sobrecarga de ferro no c?rebro resulta em d?ficits de mem?ria persistentes, acompanhados por estresse oxidativo. Devido ? elevada taxa metab?lica do sistema nervoso, as mitoc?ndrias est?o presentes em grande n?mero em c?lulas nervosas. Tem sido demonstrado que, por meio da fiss?o e fus?o, essas organelas promovem altera??es na sua estrutura e essa din?mica pode afetar a fun??o mitocondrial e vice-versa. D?ficits no fornecimento de energia para as sinapses t?m sido associados a doen?as neurodegenerativas e com a redu??o da funcionalidade de circuitos neurais essas c?lulas podem ativar cascatas de morte neuronal. No presente trabalho, foram analisados os efeitos do tratamento do ferro neonatal sobre os seguintes alvos: prote?na 1 semelhante ? dinamina (DNM1L) e prote?na atr?fica ?ptica 1 (OPA1), envolvidas na regula??o de fiss?o e de fus?o mitocondrial, respectivamente; caspase 3, uma protease essencial da fase efetora da apoptose; e sinaptofisina, um marcador sin?ptico. Al?m disso, n?s investigamos os efeitos do canabidiol (CBD), principal componente n?o psicotr?pico da Cannabis sativa, j? mostrado capaz de melhorar a mem?ria de ratos tratados com ferro, na revers?o dos efeitos induzidos pelo ferro sobre as prote?nas DNM1L, OPA1, caspase 3 e sinaptofisina. Ratos machos receberam ve?culo ou ferro carbonila (30mg/kg) do 12? ao 14? dia p?s-natal. Na idade adulta, foram tratados com ve?culo ou CBD (10mg/kg) durante 14 dias. Os n?veis proteicos e a express?o g?nica no hipocampo e c?rtex foram quantificados atrav?s de Western blotting e RT-qPCR, respectivamente. A quantifica??o das prote?nas foi realizada atrav?s da medida das densidades das bandas individuais, normalizadas pela densidade de β-actina. Para o RT-qPCR, as amostras foram normalizadas para 3 genes de refer?ncia (GAPDH, HPRT1 e RPL13A). Os resultados da an?lise prot?ica indicaram que o tratamento com ferro no per?odo neonatal induziu redu??o de DNM1L no hipocampo e OPA1 no c?rtex. O ferro tamb?m aumentou os n?veis de caspase 3 tanto no hipocampo quanto no c?rtex, acompanhado por redu??o dos n?veis de sinaptofisina no hipocampo. O CBD reverteu os efeitos induzidos pelo ferro, trazendo os n?veis hipocampais de DNM1L, caspase 3 e sinaptofisina de volta aos valores compar?veis ao grupo controle. Os resultados sugerem que o ferro pode afetar a din?mica mitocondrial, possivelmente desencadeando perda sin?ptica e morte celular por apoptose. A revers?o desses efeitos pelo CBD indica o seu potencial efeito neuroprotetor.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.pucrs.br:tede/5461 |
| Date | 08 February 2013 |
| Creators | Silva, Vanessa Kappel da |
| Contributors | Schr?der, Nadja |
| Publisher | Pontif?cia Universidade Cat?lica do Rio Grande do Sul, Programa de P?s-Gradua??o em Biologia Celular e Molecular, PUCRS, BR, Faculdade de Bioci?ncias |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da PUC_RS, instname:Pontifícia Universidade Católica do Rio Grande do Sul, instacron:PUC_RS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 8198246930096637360, 600, 600, 36528317262667714 |
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