Effect of PICALM rs3851179 polymorphism on the default mode network function in mild cognitive impairment.

Alterations in default mode network (DMN) functional connectivity (FC) might accompany the dysfunction of Alzheimer's disease (AD). Indeed, episodic memory impairment is a hallmark of AD, and mild cognitive impairment (MCI) has been associated with a high risk for AD. Phosphatidylinositol-binding clathrin assembly protein (PICALM) (rs3851179) has been associated with AD; in particular, the A allele may serve a protective role, while the G allele serves as a strong genetic risk factor. Therefore, the identification of genetic polymorphisms associated with the DMN is required in MCI subjects. In all, 32 MCI subjects and 32 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging (rs-fMRI) and a genetic imaging approach. Subjects were divided into four groups according to the diagnosis (i.e., MCI and HCs) and the PICALM rs3851179 polymorphism (i.e., AA/AG genotype and GG genotype). The differences in FC within the DMN between the four subgroups were explored. Furthermore, we examined the relationship between our neuroimaging measures and cognitive performance. The regions associated with the genotype-by-disease interaction were in the left middle temporal gyrus (LMTG) and left middle frontal gyrus (LMFG). These changes in LMFG FC were generally manifested as an "inverse U-shaped curve", while a "U-shaped curve" was associated with the LMTG FC between these four subgroups (all P<0.05). Furthermore, higher FC within the LMFG was related to better episodic memory performance (i.e., AVLT 20min DR, rho=0.72, P=0.044) for the MCI subgroups with the GG genotype. The PICALM rs3851179 polymorphism significantly affects the DMN network in MCI. The LMFG and LMTG may be associated with opposite patterns. However, the altered LMFG FC in MCI patients with the GG genotype was more sensitive to episodic memory impairment, which is more likely to lead to a high risk of AD.

Neuroprotective effects of edaravone on early brain injury in rats after subarachnoid hemorrhage.

BACKGROUND: The underlying mechanism of early neurobiological impairment after subarachnoid hemorrhage (SAH) is not well understood, but the system of reactive oxygen superoxide (ROS) might be involved. Edaravone (MCI-186), a potent free radical scavenger that prevents apoptosis of neurons, was thus used in this study to see its possible therapeutic effect in early brain injury due to SAH in a rat model. METHODS: One hundred and twenty male Sprague-Dawley rats were randomly assigned to four groups: group 1, control rats receiving sham operation only; group 2, rats with SAH treated by saline; group 3, rats with SAH treated with 1 mg/kg MCI-186 injected intraperitoneally; and group 4, rats with SAH treated with 3 mg/kg MCI-186. Treated with either saline or MCI-186 twice daily for two consecutive days after SAH, the rats were sacrificed for measurements of malondialdehyde (MDA) and activity of superoxide dismutase (SOD) and histological analysis of caspase-3 protein by Western blotting and immunohistochemical staining. In addition, mortality and neurological scores were statistically analyzed by the chi-square test and Dunn's procedure respectively for each group. One-way analysis of variance followed by the Tukey's procedure was also used in data analysis. RESULTS: The rats in group 2 that received saline only showed neurological impairment as well as elevated mortality, and were found to have significantly increased levels of MDA and caspase-3, but reduced SOD activities in brain tissues (P < 0.05). When treated with MCI-186 at two different dosages, the rats in groups 3 and 4 had markedly decreased levels of MDA and caspase-3 but increased SOD activities in the brain tissue (P < 0.05), along with improved scores of neurological evaluation (P < 0.05). CONCLUSIONS: This study sheds some lights on the therapy of SAH-induced early brain injury by providing the promising data indicating that MCI-186, a radical scavenger, can efficiently diminish apoptosis of neurons and thus prevent the function loss of the brain in rats with SAH.