Neuroscience
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Platelet-activating factor (PAF) is a potent phospholipid mediator that exerts various pathophysiological effects by interacting with a G protein-coupled receptor. PAF has been reported to increase the permeability of the blood-brain barrier (BBB) via incompletely characterized mechanisms. We investigated the effect of PAF on rat brain microvascular endothelial cells (RBMVEC), a critical component of the BBB. ⋯ PAF produced a decrease in RBMVEC monolayer electrical resistance assessed with Electric Cell-Substrate Impedance Sensing (ECIS), indicative of a disruption of endothelial barrier function. In vivo studies indicate that PAF increased the BBB permeability, assessed with sodium fluorescein and Evans Blue methods, via PAF receptor-dependent mechanisms, consequent to Ca2+ influx and increased NO levels. Our studies reveal that PAF alters the BBB permeability by multiple mechanisms, which may be relevant for central nervous system (CNS) inflammatory disorders.
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Aging is associated with a substantial decline in the expression of social behavior as well as increased neuroinflammation. Since immune activation and subsequent increased expression of cytokines can suppress social behavior in young rodents, we examined age and sex differences in microglia within brain regions critical to social behavior regulation (PVN, BNST, and MEA) as well as in the hippocampus. Adult (3-month) and aged (18-month) male and female F344 (N = 26, n = 5-8/group) rats were perfused and Iba-1 immunopositive microglia were assessed using unbiased stereology and optical density. ⋯ When morphological features of microglia were assessed, aged rats exhibited increased soma size in the BNST, MEA, and CA3. Together, these findings provide a comprehensive characterization of microglia number and morphology under ambient conditions in CNS sites critical for the normal expression of social processes. To the extent that microglia morphology is predictive of reactivity and subsequent cytokine release, these data suggest that the expression of social behavior in late aging may be adversely influenced by heightened inflammation.
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Recently, it has been shown that serotonin 5-HT1A receptor interacts with dopamine D2 receptor in vitro. However, the existence of 5-HT1A-D2 heteromers in native tissue remains unexplored. In the present study, we investigated 5-HT1A-D2 receptor heteromerization in mice treated acutely or chronically with paroxetine (10 mg/kg) or risperidone (0.05 mg/kg). ⋯ These changes were not accompanied by any changes in the expression of mRNAs (measured by in situ hybridization) or densities of 5-HT1A and D2 receptors (quantified by receptor autoradiography with [3H]8-OH-DPAT and [3H]domperidone, respectively), what all indicated that paroxetine and risperidone facilitated 5-HT1A-D2 heteromer formation independently of the receptor expression. In vitro homogenous time-resolved FRET (HTRF) study confirmed the ability of tested drugs to influence the human 5-HT1A-D2 heteromer formation. The obtained data indicate that the increase in 5-HT1A-D2 receptor heteromerization is a common molecular characteristic of paroxetine and low-dose risperidone treatment.
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Semantically congruent sounds can facilitate perception of visual objects in the human brain. However, the manner in which semantically congruent sounds affect cognitive processing for degraded visual stimuli remains unclear. We presented participants with naturalistic degraded images and semantically congruent sounds from different conceptual categories in three modalities: degraded visual only, auditory only, and auditory and degraded visual. ⋯ Our results demonstrate that the visual association cortex and STS/STG are involved in the integration of auditory and degraded visual information. In addition, the pattern classification results imply that semantically congruent sounds may facilitate identification of degraded images in both coarse and fine groups. Importantly, when naturalistic visual stimuli were further subdivided, facilitation through auditory modulation exhibited category selectivity.
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Both chemical and physical microenvironments appear to be important for lineage specification of umbilical cord mesenchymal stem cells (UCMSCs). However, physical factors such as the elastic modulus in traumatic brain injury (TBI) are seldom studied. Intracranial hypertension and cerebral edema after TBI may change the brain's physical microenvironment, which inhibits neural lineage specification of transplanted UCMSCs. ⋯ The results showed that mild hypothermia significantly reduced intracranial pressure and brain water content, indicating modulation of the elastic modulus by mild hypothermia. An examination with atomic force microscopy (AFM) in a cell injury model in vitro further verified hypothermia-regulated elastic modulus. In this study, we found a novel role of mild hypothermia in modulating the elastic modulus of the injured brain, resulting in the promotion of neural lineage specification of UCMSCs, which suggested that the combination of mild hypothermia had more advantages in cell-based therapy after TBI.