Dopamine internalization via Uptake and stimulation of intracellular D-receptor-dependent calcium mobilization and CDP-diacylglycerol signaling.

Dopamine stimulates CDP-diacylglycerol biosynthesis through D-like receptors, particularly the D subtype most of which is intracellularly localized. CDP-diacylglycerol regulates phosphatidylinositol-4,5-bisphosphate-dependent signaling cascades by serving as obligatory substrate for phosphatidylinositol biosynthesis. Here, we used acute and organotypic brain tissues and cultured cells to explore the mechanism by which extracellular dopamine acts to modulate intracellular CDP-diacylglycerol.

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.

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

Lysosomes and the endoplasmic reticulum (ER) are Ca stores mobilized by the second messengers NAADP and IP, respectively. Here, we establish Ca signals between the two sources as fundamental building blocks that couple local release to global changes in Ca. Cell-wide Ca signals evoked by activation of endogenous NAADP-sensitive channels on lysosomes comprise both local and global components and exhibit a major dependence on ER Ca despite their lysosomal origin.

Progesterone receptor membrane component 1 facilitates Ca signal amplification between endosomes and the endoplasmic reticulum.

Membrane contact sites (MCSs) between endosomes and the endoplasmic reticulum (ER) are thought to act as specialized trigger zones for Ca signaling, where local Ca released via endolysosomal ion channels is amplified by ER Ca-sensitive Ca channels into global Ca signals. Such amplification is integral to the action of the second messenger, nicotinic acid adenine dinucleotide phosphate (NAADP). However, functional regulators of inter-organellar Ca crosstalk between endosomes and the ER remain poorly defined.

Convergent activation of Ca permeability in two-pore channel 2 through distinct molecular routes.

TPC2 is a pathophysiologically relevant lysosomal ion channel that is activated directly by the phosphoinositide PI(3,5)P and indirectly by the calcium ion (Ca)-mobilizing molecule NAADP through accessory proteins that associate with the channel. TPC2 toggles between PI(3,5)P-induced, sodium ion (Na)-selective and NAADP-induced, Ca-permeable states in response to these cues. To address the molecular basis of polymodal gating and ion-selectivity switching, we investigated the mechanism by which NAADP and its synthetic functional agonist, TPC2-A1-N, induced Ca release through TPC2 in human cells.

Convergent activation of two-pore channels mediated by the NAADP-binding proteins JPT2 and LSM12.

The second messenger nicotinic acid adenine dinucleotide phosphate (NAADP) evokes calcium ion (Ca) release from endosomes and lysosomes by activating two-pore channels (TPCs) on these organelles. Rather than directly binding to TPCs, NAADP associates with proteins that indirectly confer NAADP sensitivity to the TPC complex. We investigated whether and how the NAADP-binding proteins Jupiter microtubule-associated homolog 2 (JPT2) and like-Sm protein 12 (LSM12) contributed to NAADP-TPC-Ca signaling in human cells.

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

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), obtained from diet and dietary supplements, have been tested in clinical trials for the prevention or treatment of several diseases. n-3 PUFAs exert their effects by activation of free fatty acid (FFA) receptors. FFA1 receptor, expressed in the pancreas and brain, is activated by medium- to long-chain fatty acids.

Choline-Sigma-1R as an Additional Mechanism for Potentiation of Orexin by Cocaine.

Orexin A, an endogenous peptide involved in several functions including reward, acts via activation of orexin receptors OX and OX, Gq-coupled GPCRs. We examined the effect of a selective OX agonist, OXA (17-33) on cytosolic calcium concentration, [Ca], in neurons of nucleus accumbens, an important area in the reward circuit. OXA (17-33) increased [Ca] in a dose-dependent manner; the effect was prevented by SB-334867, a selective OX receptors antagonist.

Essential requirement for JPT2 in NAADP-evoked Ca signaling.

Nicotinic acid adenine dinucleotide phosphate (NAADP) is a second messenger that releases Ca from acidic organelles through the activation of two-pore channels (TPCs) to regulate endolysosomal trafficking events. NAADP action is mediated by NAADP-binding protein(s) of unknown identity that confer NAADP sensitivity to TPCs. Here, we used a "clickable" NAADP-based photoprobe to isolate human NAADP-binding proteins and identified Jupiter microtubule-associated homolog 2 (JPT2) as a TPC accessory protein required for endogenous NAADP-evoked Ca signaling.

Assessment of Blood-Brain Barrier Permeability Using Miniaturized Fluorescence Microscopy in Freely Moving Rats.

We report here the method of visualization of brain microcirculation and assessment of blood-brain barrier (BBB) permeability changes using the miniature integrated fluorescence microscope (i.e., miniscope) technology in awake, freely moving rats.

Direct evidence of bradycardic effect of omega-3 fatty acids acting on nucleus ambiguus.

Docosahexaenoic acid (DHA) an omega-3 polyunsaturated fatty acid, is an agonist of FFA1 receptor. DHA administration reduces the heart rate via unclear mechanisms. We examined the effect of DHA on neurons of nucleus ambiguus that provide the parasympathetic control of heart rate.

A Rare Case of Bleeding Epiphrenic Esophageal Diverticulum From Arteriovenous Malformations.

Epiphrenic esophageal diverticula (EED) is a rare condition that usually presents with dysphagia in patients with a known motility disorder. In this article, we present a unique case of EED presenting with hemoptysis with clinical workup negative for any pulmonary pathology. Esophagogastroduodenoscopy revealed arteriovenous malformations within the EED successfully managed with argon plasma coagulation (APC), leading to a resolution of the patient's symptoms.

Acute cocaine administration alters permeability of blood-brain barrier in freely-moving rats- Evidence using miniaturized fluorescence microscopy.

Background: Cocaine has a variety of negative effects on the central nervous system, including reports of decreased barrier function of brain microvascular endothelial cells. However, few studies have directly shown the effects of cocaine on blood-brain barrier (BBB) function in vivo. The miniature integrated fluorescence microscope (i.

GPR55-mediated effects on brain microvascular endothelial cells and the blood-brain barrier.

GPR55, an atypical cannabinoid receptor activated by lysophosphatidylinositol (LPI) has been involved in various physiological and pathological processes. We examined the effect of GPR55 activation on rat brain microvascular endothelial cells (RBMVEC), an essential component of the blood-brain barrier (BBB). GPR55 was detected in RBMVEC by western blot and immunocytochemistry.

Choline Is an Intracellular Messenger Linking Extracellular Stimuli to IP-Evoked Ca Signals through Sigma-1 Receptors.

Sigma-1 receptors (Sig-1Rs) are integral ER membrane proteins. They bind diverse ligands, including psychoactive drugs, and regulate many signaling proteins, including the inositol 1,4,5-trisphosphate receptors (IPRs) that release Ca from the ER. The endogenous ligands of Sig-1Rs are unknown.

Thinking through acidic Ca stores.

Glutamate signaling regulates neuronal activity and synaptic plasticity, which underlies learning and memory. In this issue of , Foster found that metabotropic glutamate receptors mediate long-term potentiation in hippocampal neurons by mobilizing acidic endolysosomal Ca stores through the intracellular messenger NAADP.

Effects of Platelet-Activating Factor on Brain Microvascular Endothelial Cells.

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.

NAADP-evoked Ca signals through two-pore channel-1 require arginine residues in the first S4-S5 linker.

Two-pore channels (TPCs) are two-domain members of the voltage-gated ion channel superfamily that localize to acidic organelles. Their mechanism of activation (ligands such as NAADP/PI(3,5)P versus voltage) and ion selectivity (Ca versus Na) is debated. Here we report that a cluster of arginine residues in the first domain required for selective voltage-gating of TPC1 map not to the voltage-sensing fourth transmembrane region (S4) but to a cytosolic downstream region (S4-S5 linker).

Modulation of cardiac vagal tone by bradykinin acting on nucleus ambiguus.

Bradykinin (BK), a component of the kallikrein-kininogen-kinin system exerts multiple effects via B1 and B2 receptor activation. In the cardiovascular system, bradykinin has cardioprotective and vasodilator properties. We investigated the effect of BK on cardiac-projecting neurons of nucleus ambiguus, a key site for the parasympathetic cardiac regulation.

Interfacially Engineered Pyridinium Pseudogemini Surfactants as Versatile and Efficient Supramolecular Delivery Systems for DNA, siRNA, and mRNA.

This article presents the synthesis, self-assembly, and biological activity as transfection agents for pDNA, siRNA, and mRNA of novel pyridinium pseudogemini surfactants, interfacially engineered from the most efficient gemini surfactants and lipids generated in our amphiphile research program. Formulation of novel amphiphiles in water revealed supramolecular properties very similar to those of gemini surfactants, despite their lipidlike charge/mass ratio. This dual character was found also to enhance endosomal escape and significantly increase the transfection efficiency.

Effects of Suvorexant, a Dual Orexin/Hypocretin Receptor Antagonist, on Impulsive Behavior Associated with Cocaine.

Hypothalamic hypocretin (orexin) peptides mediate arousal, attention, and reward processing. Fibers containing orexins project to brain structures that govern motivated behavior, including the ventral tegmental area (VTA). A number of psychiatric conditions, including attention deficit hyperactivity disorder (ADHD) and substance use disorders, are characterized by deficits in impulse control, however the relationship between orexin and impulsive behavior is incompletely characterized.

N-arachidonoyl glycine, another endogenous agonist of GPR55.

Interest in lipoamino acids as endogenous modulators of G-protein coupled receptors has escalated due to their involvement in a variety of physiologic processes. In particular, a role for these amino acid conjugates has emerged in the endocannabinoid system. The study presented herein investigated the effects of N-arachidonoyl glycine (NAGly) on a candidate endocannabinoid receptor, GPR55.

HIV Tat excites D1 receptor-like expressing neurons from rat nucleus accumbens.

Background: HIV-1 infection and drug abuse are frequently co-morbid and their association greatly increases the severity of HIV-1-induced neuropathology. While nucleus accumbens (NAcc) function is severely perturbed by drugs of abuse, little is known about how HIV-1 infection affects NAcc.

Methods: We used calcium and voltage imaging to investigate the effect of HIV-1 trans-activator of transcription (Tat) on rat NAcc.

Effects of VPAC1 activation in nucleus ambiguus neurons.

The pituitary adenylyl cyclase-activating polypeptide (PACAP) and its G protein-coupled receptors, PAC1, VPAC1 and VPAC2 form a system involved in a variety of biological processes. Although some sympathetic stimulatory effects of this system have been reported, its central cardiovascular regulatory properties are poorly characterized. VPAC1 receptors are expressed in the nucleus ambiguus (nAmb), a key center controlling cardiac parasympathetic tone.