Blood-Brain Barrier Disruption Mediated by FFA1 Receptor-Evidence Using Miniscope

Modulation of the Blood-Brain Barrier by Sigma-1R Activation

Sigma non-opioid intracellular receptor 1 (Sigma-1R) is an intracellular chaperone protein residing on the endoplasmic reticulum at the mitochondrial-associated membrane (MAM) region. Sigma-1R is abundant in the brain and is involved in several physiological processes as well as in various disease states. The role of Sigma-1R at the blood-brain barrier (BBB) is incompletely characterized. In this study, the effect of Sigma-1R activation was investigated in vitro on rat brain microvascular endothelial cells (RBMVEC), an important component of the blood-brain barrier (BBB), and in vivo on BBB permeability in rats. The Sigma-1R agonist PRE-084 produced a dose-dependent increase in mitochondrial calcium, and mitochondrial and cytosolic reactive oxygen species (ROS) in RBMVEC. PRE-084 decreased the electrical resistance of the RBMVEC monolayer, measured with the electric cell-substrate impedance sensing (ECIS) method, indicating barrier disruption. These effects were reduced by pretreatment with Sigma-1R antagonists, BD 1047 and NE 100. In vivo assessment of BBB permeability in rats indicates that PRE-084 produced a dose-dependent increase in brain extravasation of Evans Blue and sodium fluorescein brain; the effect was reduced by the Sigma-1R antagonists. Immunocytochemistry studies indicate that PRE-084 produced a disruption of tight and adherens junctions and actin cytoskeleton. The brain microcirculation was directly visualized in vivo in the prefrontal cortex of awake rats with a miniature integrated fluorescence microscope (aka, miniscope; Doric Lenses Inc.). Miniscope studies indicate that PRE-084 increased sodium fluorescein extravasation in vivo. Taken together, these results indicate that Sigma-1R activation promoted oxidative stress and increased BBB permeability.

Two-pore channel-2 and inositol trisphosphate receptors coordinate Ca2+ signals between lysosomes and the endoplasmic reticulum

Lysosomes and the endoplasmic reticulum (ER) are Ca2+ stores mobilized by the second messengers NAADP and IP3, respectively. Here, we establish Ca2+ signals between the two sources as fundamental building blocks that couple local release to global changes in Ca2+. Cell-wide Ca2+ signals evoked by activation of endogenous NAADP-sensitive channels on lysosomes comprise both local and global components and exhibit a major dependence on ER Ca2+ despite their lysosomal origin. Knockout of ER IP3 receptor channels delays these signals, whereas expression of lysosomal TPC2 channels accelerates them. High-resolution Ca2+ imaging reveals elementary events upon TPC2 opening and signals coupled to IP3 receptors. Biasing TPC2 activation to a Ca2+-permeable state sensitizes local Ca2+ signals to IP3. This increases the potency of a physiological agonist to evoke global Ca2+ signals and activate a downstream target. Our data provide a conceptual framework to understand how Ca2+ release from physically separated stores is coordinated.

Potential Mechanisms Underlying the Dysfunction of the Blood-Brain Barrier

The blood-brain barrier (BBB) comprises a highly specialised complex of cells within the neurovascular unit, and is responsible for tightly regulating homeostasis within the central nervous system, which is critical for maintaining neuronal function [...].

Controllable blood–brain barrier (BBB) regulation based on gigahertz acoustic streaming

The blood–brain barrier (BBB) is a structural and functional barrier necessary for brain homeostasis, and it plays an important role in the realization of neural function and in protecting the brain from damage by circulating toxins and pathogens. However, the extremely dense BBB also severely limits the transport of molecules across it, which is a great hindrance to the diagnosis and treatment of central nervous system (CNS) diseases. This paper reports a new method for controllable opening of the BBB, based on the gigahertz acoustic streaming (AS) generated by a bulk acoustic wave resonant device. By adjusting the input power and working distance of the device, AS with tunable flow rate can be generated to disrupt tight junction proteins (TJs) between endothelial cells. The results obtained with this method show that the gigahertz AS promotes the penetration of dextran molecules with different molecular weights across the BBB. This work provides a new platform for studying the mechanical regulation of BBB by fluid shear forces and a new method for improving the efficiency of drug delivery.

How Alpha Linolenic Acid May Sustain Blood-Brain Barrier Integrity and Boost Brain Resilience against Alzheimer's Disease

Cognitive decline, the primary clinical phenotype of Alzheimer's disease (AD), is currently attributed mainly to amyloid and tau protein deposits. However, a growing body of evidence is converging on brain lipids, and blood-brain barrier (BBB) dysfunction, as crucial players involved in AD development. The critical role of lipids metabolism in the brain and its vascular barrier, and its constant modifications particularly throughout AD development, warrants investigation of brain lipid metabolism as a high value therapeutic target. Yet, there is limited knowledge on the biochemical and structural roles of lipids in BBB functionality in AD. Within this framework, we hypothesize that the ApoE4 genotype, strongly linked to AD risk and progression, may be related to altered fatty acids composition in the BBB. Interestingly, alpha linolenic acid (ALA), the precursor of the majoritarian brain component docosahexaenoic acid (DHA), emerges as a potential novel brain savior, acting via BBB functional improvements, and this may be primarily relevant to ApoE4 carriers.