RESUMO
The GluN1 subunit of the N-methyl-D-aspartate (NMDA) receptor shows age-related changes in its expression pattern, some of which correlate with spatial memory performance in mice. Aged C57BL/6 mice show an age-related increase in mRNA expression of GluN1 subunit splice variants that lack the N terminal splice cassette, GluN1(0XX) (GluN1-a). This increase in expression is associated with good performance in reference and working memory tasks. The present study was undertaken to determine if GluN1(0XX) splice variants are required for good performance in reference memory tasks in young mice. Mice were bilaterally injected with either siRNA specific for GluN1(0XX) splice variants, control siRNA or vehicle alone into ventro-lateral orbital cortices. A fourth group of mice did not receive any injections. Starting five days post-injection, mice were tested for their performance in spatial reference memory, associative memory and cognitive flexibility tasks over four days in the Morris water maze. There was a 10-19% reduction in mRNA expression for GluN1(0XX) splice variants within the ventro-lateral orbital cortices in mice following GluN1(0XX) siRNA treatment. Declines in performance within the first half of reference memory testing were seen in the mice receiving siRNA against the GluN1(0XX) splice variants, as compared to the mice injected with control siRNA, vehicle and/or no treatment. These results suggest a role for the GluN1(0XX) splice variants in orbital regions for early acquisition and/or consolidation of spatial reference memory.
Assuntos
Processamento Alternativo/genética , Memória , RNA Mensageiro/análise , Receptores de N-Metil-D-Aspartato/metabolismo , Envelhecimento/genética , Animais , Lobo Frontal/metabolismo , Lobo Frontal/patologia , Expressão Gênica , Masculino , Aprendizagem em Labirinto , Camundongos , Camundongos Endogâmicos C57BL , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Subunidades Proteicas/genética , Subunidades Proteicas/metabolismo , RNA Interferente Pequeno , Receptores de N-Metil-D-Aspartato/genéticaRESUMO
BACKGROUND: Few studies have examined earlier discharge in relation to Canadian guidelines for earlier discharge and infant feeding. We addressed differences in readmission (1 year post-discharge) and exclusive breastfeeding (4 months) for newborns and mothers discharged within 48 hours compared to those with a longer hospital stay. METHOD: A cohort of 1,357 vaginally delivered singleton normal newborns and their mothers (births between January 1, 1996 and March 31, 1997) were studied by linking five databases and a chart audit. RESULTS: Overall there were no differences in infant and maternal readmission or rates of exclusive breastfeeding. CONCLUSION: Canadian guidelines for earlier discharge appear appropriate for vaginally delivered singleton normal newborns and their mothers with timely home visitation.