Astrocytic Expression of the Immunoreceptor CD300f Protects Hippocampal Neurons from Amyloid-ß Oligomer Toxicity In Vitro.

BACKGROUND: Astrocytes contribute to neuroinflammation that accompanies neurodegenerative disorders such as Alzheimer's disease (AD). In this sense, the toxicity of these diseases might be attenuated through the modulation of astrocytic inflammatory responses. Recently, the CD300f immunoreceptor was described as a new member of the CD300 immunoreceptor family, showing promising modulatory properties. OBJECTIVE: Here, we investigated whether overexpression of hCD300f (the human isoform of CD300f) in astrocytes protects hippocampal neurons against the degeneration induced by amyloid-beta (Aß) oligomer. METHOD: Astrocyte monolayers were transfected with hCD300f before seeding the hippocampal neurons, and then the co-culture was exposed to Aß1-42 oligomers (5 µM, 48h). RESULTS: hCD300f expression significantly abrogated the neuronal loss elicited by Aß. This effect was dependent on neuron-astrocyte cell-cell interactions since no protection was observed using conditioned media from transfected astrocytes. Astrocyte modulation was dependent on the cytoplasmic signaling tail of hCD300f. Furthermore hCD300f expression did not affect the ability of astrocytes to uptake Aß1- 42 oligomers by endocytosis, which discards the possibility that increased Aß1-42 clearance could mediate neuroprotection by hCD300f. CONCLUSION: These results suggest that the astrocyte-directed expression of the hCD300f immune receptor can be a neuroprotective strategy in AD disease.

Staying at the crossroads: assessment of the potential of serum lithium monitoring in predicting an ideal lithium dose.

OBJECTIVE: Lithium has been successfully employed to treat bipolar disorder for decades, and recently, was shown to attenuate the symptoms of other pathologies such as Alzheimer's disease, Down's syndrome, ischemic processes, and glutamate-mediated excitotoxicity. However, lithium's narrow therapeutic range limits its broader use. Therefore, the development of methods to better predict its dose becomes essential to an ideal therapy. METHOD: the performance of adult Wistar rats was evaluated at the open field and elevated plus maze after a six weeks treatment with chow supplemented with 0.255%, or 0.383% of lithium chloride, or normal feed. Thereafter, blood samples were collected to measure the serum lithium concentration. RESULTS: Animals fed with 0.255% lithium chloride supplemented chow presented a higher rearing frequency at the open field, and higher frequency of arms entrance at the elevated plus maze than animals fed with a 50% higher lithium dose presented. Nevertheless, both groups presented similar lithium plasmatic concentration. DISCUSSION: different behaviors induced by both lithium doses suggest that these animals had different lithium distribution in their brains that was not detected by lithium serum measurement. CONCLUSION: serum lithium concentration measurements do not seem to provide sufficient precision to support its use as predictive of behaviors.

Staying at the crossroads: assessment of the potential of serum lithium monitoring in predicting an ideal lithium dose / Em uma encruzilhada: potencial do nível plasmático de lítio como preditor da dose ideal

OBJECTIVE: Lithium has been successfully employed to treat bipolar disorder for decades, and recently, was shown to attenuate the symptoms of other pathologies such as Alzheimer's disease, Down's syndrome, ischemic processes, and glutamate-mediated excitotoxicity. However, lithium's narrow therapeutic range limits its broader use. Therefore, the development of methods to better predict its dose becomes essential to an ideal therapy. METHOD: the performance of adult Wistar rats was evaluated at the open field and elevated plus maze after a six weeks treatment with chow supplemented with 0.255 percent, or 0.383 percent of lithium chloride, or normal feed. Thereafter, blood samples were collected to measure the serum lithium concentration. RESULTS: Animals fed with 0.255 percent lithium chloride supplemented chow presented a higher rearing frequency at the open field, and higher frequency of arms entrance at the elevated plus maze than animals fed with a 50 percent higher lithium dose presented. Nevertheless, both groups presented similar lithium plasmatic concentration. DISCUSSION: different behaviors induced by both lithium doses suggest that these animals had different lithium distribution in their brains that was not detected by lithium serum measurement. CONCLUSION: serum lithium concentration measurements do not seem to provide sufficient precision to support its use as predictive of behaviors.

OBJETIVO: Além de ser usado há décadas para tratar distúrbio bipolar, o lítio, mais recentemente, demonstrou-se eficaz para Alzheimer, síndrome de Down, processos isquêmicos e excitotoxicidade mediada por glutamato. Contudo, a estreita janela terapêutica do lítio limita seu uso. Portanto, o estabelecimento de métodos preditivos de dose torna-se importante. MÉTODO: O desempenho de ratos Wistar adultos foi avaliado no campo aberto e labirinto em cruz elevado após seis semanas de tratamento com uma ração suplementada com 0,255 por cento ou 0,383 por cento de cloreto de lítio ou ração normal. Coletou-se amostras de sangue para dosagem plasmática do lítio. RESULTADOS: Os animais alimentados com a ração com 0,255 por cento de cloreto de lítio fizeram mais rearing no campo aberto e tiveram uma maior freqüência de entradas nos braços do labirinto elevado que os animais que ingeriram a dose mais alta. Apesar disso, verificou-se níveis plasmáticos de lítio semelhantes em ambos os grupos. DISCUSSÃO: A variação nos comportamentos destarte a presença de níveis plasmáticos semelhantes sugere que as diferentes doses produziram diferentes concentrações cerebrais não detectadas pela medida plasmática. CONCLUSÃO: Medidas da concentração plasmática de lítio não permitem prever de forma completa seus efeitos comportamentais.