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Systemic LPS resulted in a transient hippocampus malfunction but a prolonged corpus callosum injury.

ABSTRACT: To investigate the effect of systemic lipopolysaccharide (LPS) on function of hippocampus and corpus callosum (CC) in adult rats.Adult rats with mature white matter tract were divided into systemic LPS and saline injection groups. Animal were euthanized following 3 daily injections (day 3) and 3-day after cessation of injections (day 6). At both time points, hippocampal long term potentiation (LTP) and CC compound action potentials (CAP) were recorded, beta amyloid precursor protein (β-APP) level in CC tissue was measured by Western blot, and microglia activation was examined by immunostaining and proportional area analysis.Systemic LPS significantly decreased amplitude of both post tetanic potentiation (PTP) and LTP at day 3, but PTP and LTP turned to be normal at day 6. CAP was significantly declined at day 3 but was further declined at day 6. The β-APP levels in CC tissues of LPS injected rats were significantly higher than that of saline group at both time-points. Interestingly, proportional area measurement disclosed that microglial areas in both hippocampus and CC significantly expanded at day3, but at the day 6, microglial area decreased in hippocampus but further increased in CC.Systemic LPS resulted in a transient hippocampus malfunction but a prolonged CC injury. Microglia activation may correlate with such LPS induced white matter injury.

SUBMITTER: Zhang J

PROVIDER: S-EPMC5557561 | biostudies-other | 2017 Aug

REPOSITORIES: biostudies-other

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Project description:The Corpus Callosum (CC) is an important structure that includes the majority of fibers connecting the two brain hemispheres. Several neurodegenerative diseases may alter CC size and morphology leading to its atrophy and malfunction which may play a role in the pathological manifestations found in these diseases. The purpose of the current study is to determine any possible changes in CC size in patients suffering from Alzheimer's disease. The Study also investigated the effect of acetylcholinesterase inhibitors (AChEIs) on the size of CC and its association with improvement in the Alzheimer disease severity scores. Midsagittal size of CC were recorded prospectively from 439 routine T1-weighted MRI brain images in normal individuals. The internal skull surface was measured to calculate CC/ internal skull surface ratio. Two groups of patients were studied: 300 (150 male / 150 female) were healthy subjects and 130 (55 males / 75 females) had Alzheimer disease. Out of the 130 Alzheimer disease pateints, 70 patients were treated with Donepezil or Rivastigmine or both. The size of the CC was measured based on T1-weighted MRI images after the treatment to investigate any possible improvement in CC size. The mean surface area of CC in controls was 6.53±1.105 cm2. There was no significant difference between males and females (P < 0.627), and CC/ internal skull surface ratio was 4.41±0.77%. Patients with mild or severe Alzheimer disease showed a significant reduction in CC size compared to healthy controls. Treating mild Alzheimer patients with either Donepezil or Rivastigmine exerts a comparable therapeutic effect in improving the CC size. There was more improvement in the size of CC in patients with severe Alzheimer disease by using combined therapy of Donepezil and Rivastigmine than using single a medication. we measured the mean size of the various portions of the corpus callosum in normal individuals and Alzheimer patients before and after taking Donepezil and Rivastigmine. Alzheimer patients have pronounced reduction in CC which is corrected after taking Donepezil and Rivastigmine leading to remarkable improvement in Alzheimer disease severity scores.

Project description:Increasing evidence for the cumulative effects of head trauma on structural integrity of the brain has emphasized the need to understand the relationship between tissue mechanic properties and injury susceptibility. Here, diffusion tensor imaging, helmet accelerometers and amplified magnetic resonance imaging were combined to gather insight about the region-specific vulnerability of the corpus callosum to microstructural changes in white-matter integrity upon exposure to sub-concussive impacts. A total of 33 male Canadian football players (meanage = 20.3 ± 1.4 years) were assessed at three time points during a football season (baseline pre-season, mid-season and post-season). The athletes were split into a LOW (N = 16) and HIGH (N = 17) exposure group based on the frequency of sub-concussive impacts sustained on a per-session basis, measured using the helmet-mounted accelerometers. Longitudinal decreases in fractional anisotropy were observed in anterior and posterior regions of the corpus callosum (average cluster size = 40.0 ± 4.4 voxels; P < 0.05, corrected) for athletes from the HIGH exposure group. These results suggest that the white-matter tract may be vulnerable to repetitive sub-concussive collisions sustained over the course of a football season. Using these findings as a basis for further investigation, a novel exploratory analysis of strain derived from sub-voxel motion of brain tissues in response to cardiac impulses was developed using amplified magnetic resonance imaging. This approach revealed specific differences in strain (and thus possibly stiffness) along the white-matter tract (P < 0.0001) suggesting a possible signature relationship between changes in white-matter integrity and tissue mechanical properties. In light of these findings, additional information about the viscoelastic behaviour of white-matter tissues may be imperative in elucidating the mechanisms responsible for region-specific differences in injury susceptibility observed, for instance, through changes in microstructural integrity following exposure to sub-concussive head impacts.

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Systemic LPS resulted in a transient hippocampus malfunction but a prolonged corpus callosum injury.

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