Faculty Bibliography

Toxicity of prenatal ethanol leading to fetal alcohol spectrum disorders (FASDs) has been linked to disturbances in retinoic acid (RA) signaling necessary for embryonic development. While ethanol exposure in the postnatal day 7 (P7) mice, which induces immediate neurodegeneration and long-lasting GABAergic cell loss and behavioral deficits, has been used for the third trimester FASD model, involvement of RA signaling in the process has not been well explored. Using RARE-LacZ reporter mice that express β-galactosidase (β-Gal) under the control of retinoic acid response element (RARE), we examined RA signaling activity of the forebrains of P8 and P30 mice with or without P7 ethanol treatment. In all experimental groups, β-Gal was expressed mainly in the hippocampus with the strongest expression in the granule cell layer of dentate gyrus. In addition, β-Gal was expressed in pyramidal neurons and parvalbumin (PV) neurons in CA1-3 pyramidal layer and in astrocytes scattered around the CA1-3 region although PV neurons were only examined at P30 because of the low PV expression at P8. β-Gal was also expressed in the anteroventral/anteromedial (AV/AM) thalamus and the retrosplenial (Rs) and Tbr1-positive (+) layer 6 cortices. β-Gal-expressing PV neurons were also found in the cortex such as Rs, while β-Gal was barely detected in somatostatin neurons in any brain regions examined. Such region and cell specific β-Gal expression was significantly higher in P8 brains than P30 brains in various brain regions. P7 ethanol reduced β-Gal expression in the CA1-3 pyramidal layer, Tbr1 + cortical layer 6, and the AV/AM thalamus at P8 or P30 or both. Although P7 ethanol decreased PV cells in CA2-3 pyramidal layers as reported, it decreased β-Gal+ PV cells more drastically. The active RA signaling found in PV neurons and the effects of P7 ethanol on the signaling suggest that reduced RA signaling by P7 ethanol may disturb PV cell maturation and enhance long-lasting brain abnormalities.

BACKGROUND: ("Dutch") transgenic mice develop aging-related learning deficits and accumulate endogenously generated non-fibrillar aggregates (NFAs) of amyloid beta (Aβ) and amyloid precursor protein α-carboxy terminal fragments. NFA-Aβ correlates with synaptic loss and memory deficits more closely than does fibrillar Aβ. METHODS: mice. RESULTS: mice developed physiological abnormalities in post-tetanic potentiation, synaptic fatigue, synaptic vesicle replenishment, and an aging-related reduction in mitochondrial complex I activity. Single-cell RNA sequencing showed that excitatory neurons exhibited an altered transcriptomic profile involving "protein translation" and "oxidative phosphorylation." DISCUSSION/CONCLUSIONS:Accumulation of NFA-Aβ alters neuronal metabolism but does not activate inflammation. Depletion of all forms of Aβ may be required to eliminate Aβ toxicity with anti-amyloid antibodies.

BACKGROUND:Raghib syndrome is a congenital anomaly that is caused by a persistent left superior vena cava draining into the left atrium, unroofed coronary sinus, and atrial septal defect. It can lead to cyanosis, cryptogenic strokes, pulmonary hypertension, and arrythmias. CASE SUMMARY/METHODS:A 60-year-old woman presented with palpitations due to atrial flutter. Cardiac imaging, including computed tomography, transesophageal echocardiography, and magnetic resonance imaging, confirmed bilateral superior vena cavae, with the left superior vena cava draining into the left atrium and minimal right-to-left shunting (3%). She was managed with anticoagulation and underwent regular follow-up without complications. DISCUSSION/CONCLUSIONS:Diagnosis of Raghib syndrome relies on multimodality imaging. In cases with minimal symptoms and left-to-right shunting, conservative management with biannual follow-up may be sufficient. TAKE-HOME MESSAGES/CONCLUSIONS:Multimodality imaging is crucial in confirming anatomy and characterizing flow dynamics in cyanotic congenital heart disease. In patients with Raghib syndrome without cyanosis, conservative management with anticoagulation may be a safe alternative to surgical intervention.

RATIONALE/BACKGROUND:Aggression is an innate social behavior prevalent across animal species. However, in modern human society, inter-personal aggression is considered disruptive and detrimental to both families and communities. Clinically, antipsychotics, which primarily target dopamine (DA) receptors, have been widely used to suppress hyper-aggression. However, the mechanisms underlying the effect of the antipsychotics remain incompletely understood. OBJECTIVES/OBJECTIVE:We reviewed key steps in brain DA synthesis and summarized genetic and pharmacological evidence supporting the role of the mesolimbic DA system in aggression. Next, we discussed recent circuit studies that elucidate the DA action in modulating aggression-related brain regions. These lines of evidence collectively suggest that DA acts on different brain regions to facilitate aggression and self-learning, and signals the valence of the fighting experience.

Educational initiatives that address the gap between basic/preclinical and clinical practices are important to effectively translate basic science discoveries to benefit patients. The ILAE Neurobiology Commission conducted a pilot project aimed at exposing basic and preclinical scientists engaged in epilepsy research to general clinical issues pertaining to the diagnosis and care of people with epilepsy. This aim was addressed through a two-week-long, on-site clinical training program for 50 basic scientists in 21 epilepsy centers across 18 countries in the six ILAE regions (with a maximum of 3 basic scientists per center). The learning objectives and the training module were discussed and defined by the project organizing committee, which consisted of Neurobiology Commission members and a team of epileptologists representing different geographical regions. The training activities were conducted at each epilepsy center under the local supervision of clinical tutors. Each basic scientist was exposed to 50.3 ± 23.3 (range 16-89) hours of intensive and dedicated clinical training, coordinated by 2-3 tutors per center, assisted by 6.8 ± 3.6 colleagues. A structured test consisting of 17 general clinical epilepsy questions was completed by the trainees before and after the training activity. The learning assessment was based on the comparison between responses to the exit and entry tests. After the on-site clinical exposure, the proportion of correct answers increased to 87% compared to 61% in the entry test. Structured post-training questionnaires demonstrated very high satisfaction of trainees and all involved tutors across the different aspects of the training module. This global pilot study demonstrated that on-site attendance by basic scientists in specialized clinical settings up-scaled their knowledge of clinical epileptology and facilitated networking with clinicians. Expansion of this pilot to further centers should be considered to understand how exposure to clinical practice affects research direction and quality of translational epilepsy research. PLAIN LANGUAGE SUMMARY: Epilepsy research has long benefitted from collaboration between scientists and clinicians. Early exposure of researchers to people with epilepsy and their care teams may strengthen future impact. This pilot study tested a two-week immersive experience where small teams of basic scientists shadowed clinicians during their work at hospitals around the world. Questionnaires showed high satisfaction among both groups. Results support expanding such training, with the backing of the International League Against epilepsy and aligned centers, to build understanding, interest, and long-term commitment, ensuring bench research is informed by and translates to clinical practice and improved quality of life for patients.

De novo protein synthesis is required for long-lasting synaptic plasticity and memory, but it comes with a great metabolic cost. In the mammalian brain, it remains unclear which cell types and biological mechanisms are critical for sensing and responding to increased metabolic demand. Here, we demonstrate that microglia, the resident macrophages of the brain, are required for metabolic coupling between endothelial cells, astrocytes, and neurons, which fuels protein synthesis in active neurons. Increasing metabolic demand via a motor task stimulates microglia to secrete the hypoxia-responsive protein CYR61, which increases glucose transporter expression in brain vasculature. Depleting microglia reduces training-induced metabolic fluxes and neuronal protein synthesis, which can be reproduced by blocking CYR61 signaling. Thus, we define a neuroimmune metabolic circuit that is required for on-demand protein synthesis in mouse motor cortex.

Ameloblasts are specialized epithelial cells that form enamel during the secretory and maturation stages, the latter involving an increase in Ca²⁺ transport to mineralize the enamel crystals. During enamel formation, ameloblasts travel several microns while secreting a matrix and are surrounded by several cell layers in the confined space of the enamel organ. Presumably, ameloblasts are subjected to mechanical stimuli e.g. pressure, stretch. Mechanosensitive (MS) or stretch-gated channels are expressed in the membranes of many cells including mineralizing cells. The opening of MS channels occurs in response to physical stimuli and results in the influx of ions. Piezo1 is a non-selective class of MS channel permeable to Ca²⁺ and hence it may contribute to Ca²⁺ homeostasis in ameloblasts. Here we show that secretory and maturation stage ameloblasts express similar protein levels of Piezo1. Cultured rat primary secretory and maturation stage ameloblasts showed stretch-activated currents by patch-clamp. Ameloblasts loaded with the cytosolic Ca²⁺ indicator Fura-2 were also stimulated with the Piezo1-selective activator Yoda1. We show that ameloblasts are sensitive to Piezo1 stimulation which evoked an increase in cytosolic Ca²⁺. This effect was inhibited by Piezo1 blockers. Mechanical analysis of the incisors of Piezo1 cKO mice showed no alterations in hardness or elastic modulus relative to littermate control mice. Our work provides the first evidence that Piezo1 channels are functional in both ameloblast stages and their activation leads to an elevation in cytosolic Ca²⁺, however, Piezo1 does not appear to be essential for enamel mineralization.