title: Chronic administration of methylmalonate on young rats alters neuroinflammatory markers and spatial memory.
abstract: The methylmalonic acidemia is an inborn error of metabolism (IEM) characterized by methylmalonic acid (MMA) accumulation in body fluids and tissues, causing neurological dysfunction, mitochondrial failure and oxidative stress. Although neurological evidence demonstrate that infection and/or inflammation mediators facilitate metabolic crises in patients, the involvement of neuroinflammatory processes in the neuropathology of this organic acidemia is not yet established. In this experimental study, we used newborn Wistar rats to induce a model of chronic acidemia via subcutaneous injections of methylmalonate (MMA, from 5th to 28th day of life, twice a day, ranged from 0.72 to 1.67 μmol/g as a function of animal age). In the following days (29th-31st) animal behavior was assessed in the object exploration test and elevated plus maze. It was performed differential cell and the number of neutrophils counting and interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) levels in the blood, as well as levels of IL-1β, TNF-α, inducible nitric oxide synthase (iNOS) and 3-nitrotyrosine (3-NT) in the cerebral cortex were measured. Behavioral tests showed that animals injected chronically with MMA have a reduction in the recognition index (R.I.) when the objects were arranged in a new configuration space, but do not exhibit anxiety-like behaviors. The blood of MMA-treated animals showed a decrease in the number of polymorphonuclear and neutrophils, and an increase in mononuclear and other cell types, as well as an increase of IL-1β and TNF-α levels. Concomitantly, MMA increased levels of IL-1β, TNF-α, and expression of iNOS and 3-NT in the cerebral cortex of rats. The overall results indicate that chronic administration of MMA increased pro-inflammatory markers in the cerebral cortex, reduced immune system defenses in blood, and coincide with the behavioral changes found in young rats. This leads to speculate that, through mechanisms not yet elucidated, the neuroinflammatory processes during critical periods of development may contribute to the progression of cognitive impairment in patients with methylmalonic acidemia.
authors.affiliation: Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Universidade Federal de Santa Maria (UFSM), Brazil.
authors.forename: Leandro Rodrigo
authors.initials: LR
authors.lastname: Ribeiro
authors.forename: Iuri Domingues
authors.initials: ID
authors.lastname: Della-Pace
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: de Oliveira Ferreira
authors.forename: Vinícius Rafael
authors.initials: VR
authors.lastname: Funck
authors.forename: Simone
authors.initials: S
authors.lastname: Pinton
authors.forename: Franciane
authors.initials: F
authors.lastname: Bobinski
authors.forename: Clarissa Vasconcelos
authors.initials: CV
authors.lastname: de Oliveira
authors.forename: Fernando
authors.initials: F
authors.lastname: da Silva Fiorin
authors.forename: Marta Maria Medeiros Frescura
authors.initials: MM
authors.lastname: Duarte
authors.forename: Ana Flávia
authors.initials: AF
authors.lastname: Furian
authors.forename: Mauro Schneider
authors.initials: MS
authors.lastname: Oliveira
authors.forename: Cristina Wayne
authors.initials: CW
authors.lastname: Nogueira
authors.forename: Adair Roberto Soares
authors.initials: AR
authors.lastname: Dos Santos
authors.forename: Luiz Fernando Freire
authors.initials: LF
authors.lastname: Royes
authors.forename: Michele Rechia
authors.initials: MR
authors.lastname: Fighera
mesh_terms: D000592:Amino Acid Metabolism, Inborn Errors / Q000139:chemically induced / Q000276:immunology* / Q000523:psychology*; D000818:Animals; D000831:Animals, Newborn; D015415:Biomarkers / Q000378:metabolism; D002540:Cerebral Cortex / Q000276:immunology / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D053583:Interleukin-1beta / Q000378:metabolism; D008569:Memory Disorders / Q000139:chemically induced*; D008764:Methylmalonic Acid / Q000008:administration & dosage / Q000633:toxicity*; D015213:Neuroimmunomodulation; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013037:Spatial Behavior / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D015415:Biomarkers; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; C002744:3-nitrotyrosine; D014443:Tyrosine; D008764:Methylmalonic Acid; D052247:Nitric Oxide Synthase Type II
keywords: 3-NT; 3-nitrotyrosine; 5-bromo-4-chloro-3-indolyl phosphate and p-nitro blue tetrazolium; BBB; BCIP/NBT; BSA; CNS; COX-2; Cerebral cortex; ELISA; EPM; HPLC–UV; IEM; IL-1β; MCM; MMA; Memory; Methylmalonate; N-methyl-d-aspartate; NFκB; NMDA; Neuroinflammation; OET; PBS; R.I.; Rat; SDS; SEM; TBS; TBS-T; TNF-α; Tris–borate saline; Tween 20 in Tris–borate saline; blood–brain barrier; bovine serum albumin; central nervous system; cyclooxygenase-2; elevated plus maze; enzyme-linked immunosorbent assay; high performance liquid chromatography/ultraviolet; iNOS; inborn error of metabolism; inducible nitric oxide synthase; interleukin-1 beta; methylmalonic acid, methylmalonate; methylmalonyl-CoA mutase; nuclear factor kappa B; objects exploration test; phosphate buffered saline; recognition index; s.c.; sodium dodecyl sulfate-polyacrylamide gels; standard error of the mean; subcutaneously; tumor necrosis factor-alpha