Molecular regulation of sympathetic neuron activity in cardiovascular disease

University Of Nevada Reno, Reno NV

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Abstract

The autonomic nervous system is a key regulator of the cardiovascular system including cardiac output. During disease states such as cardiac failure, autonomic input becomes unbalanced such that the sympathetic branch is overactivated and the parasympathetic branch shows decreased activity. However, the molecular mechanisms underlying these changes in neuronal activity are largely unknown. Increased sympathetic activation is characterized by increased plasma levels of neurotransmitters and are associated with poor clinical outcomes in human patients with heart failure. This includes the primary neurotransmitter norepinephrine (NE) that acts through beta-adrenergic receptors to increase heart rate and contractility, as well a 36 amino-acid co-transmitter neuropeptide Y (NPY) that is co-released under conditions of higher stimulation. We hypothesize that inflammatory signals that are elevated during cardiovascular disease potentiate NPY trafficking and release, contributing to disease progression. Although treatments such as the use of beta-blockers can help stabilize or slow disease progression for patients with heart failure, currently disease progression cannot be reversed in most cases. Thus, understanding the molecular changes that underly the dynamic regulation of sympathetic neurons will enable the development of novel therapeutic interventions. We recently developed a novel imaging technique, optical pulse-chase axonal long-distance (OPAL) imaging, that enables the visualization of axonal trafficking of low-abundance proteins such as ion channels with single-molecule resolution. Using this and other imaging techniques, we propose to investigate the alterations to NPY trafficking in cardiac sympathetic neurons from neonatal mice cultured in compartmentalized microfluidic chambers. We will investigate the molecular motors and trafficking machinery involved in the long-distance axonal transport of NPY-containing vesicles, including Rab-GTPases and kinesin motors. Elucidation of this pathway will provide targets of opportunity for therapeutic interventions for conditions such as cardiac failure. Additionally, we propose to investigate the dynamic upregulation of cardiac sympathetic neurons in response to inflammatory agents (inflammatory cytokines or byproducts of inflammation), using alterations to NPY vesicular trafficking as measure of neuronal activation.