A generation of junior faculty is at risk from the impacts of COVID-19

For junior investigators starting their independent careers, the challenges of the Coronavirus Disease 2019 (COVID-19) pandemic extend beyond lost time and are career threatening. Without intervention, academic science could lose a generation of talent

Constitutive Activation of Kappa Opioid Receptors at Ventral Tegmental Area Inhibitory Synapses Following Acute Stress.

Stressful experiences potently activate kappa opioid receptors (κORs). κORs in the ventral tegmental area regulate multiple aspects of dopaminergic and non-dopaminergic cell function. Here we show that at GABAergic synapses on rat VTA dopamine neurons, a single exposure to a brief cold-water swim stress induces prolonged activation of κORs. This is mediated by activation of the receptor during the stressor followed by a persistent, ligand-independent constitutive activation of the κOR itself. This lasting change in function is not seen at κORs at neighboring excitatory synapses, suggesting distinct time courses and mechanisms of regulation of different subsets of κORs. We also provide evidence that constitutive activity of κORs governs the prolonged reinstatement to cocaine-seeking observed after cold water swim stress. Together, our studies indicate that stress-induced constitutive activation is a novel mechanism of κOR regulation that plays a critical role in reinstatement of drug seeking

Two-Pronged Control of the Dorsal Raphe by the VTA.

© 2019 Elsevier Inc. In this issue of Neuron, Li et al. (2019) distinguish two separable GABAergic projections from the ventral tegmental area (VTA) to the dorsal raphe nucleus (DRN), with differential μ-opioid receptor regulation, each targeting different postsynaptic neurons and promoting opposing behavioral states

Yin and Yang: Unsilencing Synapses to Control Cocaine Seeking

In this issue of Neuron, Ma et al. (2014) show that long-term depression of two independent prefrontal cortical inputs to nucleus accumbens modifies behavioral responses controlling incubation of cocaine craving. Intriguingly, one input increases while the other attenuates behavioral responses, hinting that both “prorelapse” and “antirelapse” pathways are strengthened after cocaine self-administration

Behavioral impact of the disinhibition of the dopaminergic neurons in the VTA via inhibition of VTA GABAergic neurons using the subchronical variable stress paradigm

Depression is the leading cause of disability worldwide, with over 300 million people affected by the disorder (World Health Organization, 2018). Women are twice as likely to be diagnosed with depression as men, yet most animal research into the disorder and its symptoms is performed in only males. This creates a gap between preclinical experiments and their potential clinical use. Females display different neurobiological, behavioral and transcriptional responses when dealing with stress that leads to depressive phenotypes (Dalla et al., Physiology and Behavior , 2008; Hodes et al., Journal of Neuroscience , 2015; La Plant et al., Biol Psychiatry , 2009). Subchronic variable stress (SCVS) is a stress paradigm that induces depression and anxiety like symptoms in female mice, and leaves male mice behaviorally unaffected. The ventral tegmental area (VTA) is a crucial hub in the mesolimbic reward pathway, sending dopaminergic projections to regions like the nucleus accumbens (NAc) and prefrontal cortex. Due to its role in reward seeking behavior and motivation, dysregulation of the VTA circuitry has been implicated in mood disorders. The function of dopaminergic neurons within the VTA is controlled by the GABAergic networks both locally, in the VTA, and by inputs from outside the VTA. In the VTA, GABAergic neurons are activated by stress and inhibit the dopaminergic VTA neurons that are involved in reward seeking and motivation. In addition, several studies using animal models of depression have found that there is altered activity of the dopaminergic neurons of the VTA (Nestler, E., Carlezon, W A., Biol Psychiatry , 2006). The role of VTA GABAergic neurons in stress-induced depressive behavior has not been studied. In this project, we used SCVS to study the effect of chemogenetic inhibition of local GABAergic neurons in the VTA on the behavioral responses to stress. AAVs encoding Cre-dependent inhibitory designer receptors exclusively activated by designer drugs (DREADDs) were injected into the VTA of VGAT-cre mice, allowing VTA GABA neurons to be selectively inhibited by the otherwise-inert ligand CNO. The impact of this manipulation was tested through a variety of behavioral tests that assayed for anxiety and depressive-like phenotypes. We hypothesized that disinhibition of the dopaminergic neurons in the VTA via inhibition of VTA GABAergic neurons will alleviate the behavioral effects of SCVS in female mice

VTA GABA Neurons at the Interface of Stress and Reward

© Copyright © 2019 Bouarab, Thompson and Polter. The ventral tegmental area (VTA) is best known for its robust dopaminergic projections to forebrain regions and their critical role in regulating reward, motivation, cognition, and aversion. However, the VTA is not only made of dopamine (DA) cells, as approximately 30% of cells in the VTA are GABA neurons. These neurons play a dual role, as VTA GABA neurons provide both local inhibition of VTA DA neurons and long-range inhibition of several distal brain regions. VTA GABA neurons have increasingly been recognized as potent mediators of reward and aversion in their own right, as well as potential targets for the treatment of addiction, depression, and other stress-linked disorders. In this review article, we dissect the circuit architecture, physiology, and behavioral roles of VTA GABA neurons and suggest critical gaps to be addressed

Patch-Clamp Proteomics of Single Neurons in Tissue Using Electrophysiology and Subcellular Capillary Electrophoresis Mass Spectrometry

Understanding of the relationship between cellular function and molecular composition holds a key to next-generation therapeutics but requires measurement of all types of molecules in cells. Developments in sequencing enabled semiroutine measurement of single-cell genomes and transcriptomes, but analytical tools are scarce for detecting diverse proteins in tissue-embedded cells. To bridge this gap for neuroscience research, we report the integration of patch-clamp electrophysiology with subcellular shot-gun proteomics by high-resolution mass spectrometry (HRMS). Recording of electrical activity permitted identification of dopaminergic neurons in the substantia nigra pars compacta. Ca. 20-50% of the neuronal soma content, containing an estimated 100 pg of total protein, was aspirated into the patch pipette filled with ammonium bicarbonate. About 1 pg of somal protein, or ∼0.25% of the total cellular proteome, was analyzed on a custom-built capillary electrophoresis (CE) electrospray ionization platform using orbitrap HRMS for detection. A series of experiments were conducted to systematically enhance detection sensitivity through refinements in sample processing and detection, allowing us to quantify ∼275 different proteins from somal aspirate-equivalent protein digests from cultured neurons. From single neurons, patch-clamp proteomics of the soma quantified 91, 80, and 95 different proteins from three different dopaminergic neurons or 157 proteins in total. Quantification revealed detectable proteomic differences between the somal protein samples. Analysis of canonical knowledge predicted rich interaction networks between the observed proteins. The integration of patch-clamp electrophysiology with subcellular CE-HRMS proteomics expands the analytical toolbox of neuroscience