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Experimental pediatric stroke shows age-specific recovery of cognition and role of hippocampal Nogo-A receptor signaling.

ABSTRACT: Ischemic stroke is a leading cause of death worldwide and clinical data suggest that children may recover from stroke better than adults; however, supporting experimental data are lacking. We used our novel mouse model of experimental juvenile ischemic stroke (MCAO) to characterize age-specific cognitive dysfunction following ischemia. Juvenile and adult mice subjected to 45-min MCAO, and extracellular field recordings of CA1 neurons were performed to assess hippocampal synaptic plasticity changes after MCAO, and contextual fear conditioning was performed to evaluate memory and biochemistry used to analyze Nogo-A expression. Juvenile mice showed impaired synaptic plasticity seven days after MCAO, followed by full recovery by 30 days. Memory behavior was consistent with synaptic impairments and recovery after juvenile MCAO. Nogo-A expression increased in ipsilateral hippocampus seven days after MCAO compared to contralateral and sham hippocampus. Further, inhibition of Nogo-A receptors reversed MCAO-induced synaptic impairment in slices obtained seven days after juvenile MCAO. Adult MCAO-induced impairment of LTP was not associated with increased Nogo-A. This study demonstrates that stroke causes functional impairment in the hippocampus and recovery of behavioral and synaptic function is more robust in the young brain. Nogo-A receptor activity may account for the impairments seen following juvenile ischemic injury.

SUBMITTER: Orfila JE

PROVIDER: S-EPMC7026845 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Experimental pediatric stroke shows age-specific recovery of cognition and role of hippocampal Nogo-A receptor signaling.

Orfila James E JE Dietz Robert M RM Rodgers Krista M KM Dingman Andra A Patsos Olivia P OP Cruz-Torres Ivelisse I Grewal Himmat H Strnad Frank F Schroeder Christian C Herson Paco S PS

Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism 20190214 3

Ischemic stroke is a leading cause of death worldwide and clinical data suggest that children may recover from stroke better than adults; however, supporting experimental data are lacking. We used our novel mouse model of experimental juvenile ischemic stroke (MCAO) to characterize age-specific cognitive dysfunction following ischemia. Juvenile and adult mice subjected to 45-min MCAO, and extracellular field recordings of CA1 neurons were performed to assess hippocampal synaptic plasticity chang ...[more]

PMID: 30762478

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Project description:Spontaneous recovery of motor and cognitive function occurs in many individuals after stroke. The mechanisms are incompletely understood, but may involve neurotransmitter systems that support neural plasticity, networks that are involved in learning and regions of the brain that are able to flexibly adapt to demand (such as the 'multiple-demand system'). Forty-two patients with first symptomatic ischaemic stroke were enrolled in a longitudinal cohort study of cognitive function after stroke. High-resolution volumetric, diffusion MRI and neuropsychological assessment were performed at a mean of 70 ± 18 days after stroke. Cognitive assessment was repeated 1 year after stroke, using parallel test versions to avoid learning effects, and change scores were computed for long-term episodic, short-term and working memory. Structural MRI features that predicted change in cognitive scores were identified by a two-stage analysis: a discovery phase used whole-brain approaches in a hypothesis-free unbiased way; and an independent focused phase, where measurements were derived from regions identified in the discovery phase, using targeted volumetric measurements or tractography. Evaluation of the cholinergic basal forebrain, based on a validated atlas-based approach, was included given prior evidence of a role in neural plasticity. The status of the fornix, cholinergic basal forebrain and a set of hippocampal subfields were found to predict improvement in long-term memory performance. In contrast to prior expectation, the same pattern was found for short-term and working memory, suggesting that these regions are part of a common infrastructure that supports recovery across cognitive domains. Associations between cholinergic basal forebrain volume and cognitive recovery were found primarily in subregions associated with the nucleus basalis of Meynert, suggesting that it is the cholinergic outflow to the neocortex that enables recovery. Support vector regression models derived from baseline measurements of fornix, cholinergic basal forebrain and hippocampal subfields were able to explain 62% of change in long-term episodic and 41% of change in working memory performance over the subsequent 9 months. The results suggest that the cholinergic system and extended hippocampal network play key roles in cognitive recovery after stroke. Evaluation of these systems early after stroke may inform personalized therapeutic strategies to enhance recovery.

Project description:BackgroundAdult-onset stressors exert opposing effects on hippocampal neurogenesis and cognition, with enhancement observed following mild stress and dysfunction following severe chronic stress. While early life stress evokes persistent changes in anxiety, it is unknown whether early stress differentially regulates hippocampal neurogenesis, trophic factor expression, and cognition across the life span.MethodsHippocampal-dependent cognitive behavior, neurogenesis, and epigenetic regulation of brain-derived neurotrophic factor (Bdnf) expression was examined at distinct time points across the life span in rats subjected to the early stress of maternal separation (ES) and control groups. We also examined the influence of chronic antidepressant treatment on the neurogenic, neurotrophic, and cognitive changes in middle-aged ES animals.ResultsAnimals subjected to early stress of maternal separation examined during postnatal life and young adulthood exhibited enhanced hippocampal neurogenesis, decreased repressive histone methylation at the Bdnf IV promoter along with enhanced BDNF levels, and improved performance on the stress-associated Morris water maze. Strikingly, opposing changes in hippocampal neurogenesis and epigenetic regulation of Bdnf IV expression, concomitant with impairments on hippocampal-dependent cognitive tasks, were observed in middle-aged ES animals. Chronic antidepressant treatment with amitriptyline attenuated the maladaptive neurogenic, epigenetic, transcriptional, and cognitive effects in middle-aged ES animals.ConclusionsOur study provides novel insights into the short- and long-term consequences of ES, demonstrating both biphasic and unique, age-dependent changes at the molecular, epigenetic, neurogenic, and behavioral levels. These results indicate that early stress may transiently endow animals with a potential adaptive advantage in stressful environments but across a life span is associated with long-term deleterious effects.

Dataset Information

Experimental pediatric stroke shows age-specific recovery of cognition and role of hippocampal Nogo-A receptor signaling.

Publications

Experimental pediatric stroke shows age-specific recovery of cognition and role of hippocampal Nogo-A receptor signaling.

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