Activity of Cardiorespiratory Networks Revealed by Transsynaptic Virus Expressing GFP

Abstract

A fluorescent transneuronal marker capable of labeling individual neurons in a central network while maintaining their normal physiology would permit functional studies of neurons within entire networks responsible for complex behaviors such as cardiorespiratory reflexes. The Bartha strain of pseudorabies virus (PRV), an attenuated swine alpha herpesvirus, can be used as a transsynaptic marker of neural circuits. Bartha PRV invades neuronal networks in the CNS through peripherally projecting axons, replicates in these parent neurons, and then travels transsynaptically to continue labeling the second- and higher-order neurons in a time-dependent manner. A Bartha PRV mutant that expresses green fluorescent protein (GFP) was used to visualize and record from neurons that determine the vagal motor outflow to the heart. Here we show that Bartha PRV-GFP-labeled neurons retain their normal electrophysiological properties and that the labeled baroreflex pathways that control heart rate are unaltered by the virus. This novel transynaptic virus permits in vitro studies of identified neurons within functionally defined neuronal systems including networks that mediate cardiovascular and respiratory function and interactions. We also demonstrate superior laryngeal motorneurons fire spontaneously and synapse on cardiac vagal neurons in the nucleus ambiguus. This cardiorespiratory pathway provides a neural basis of respiratory sinus arrhythmias.

Synaptic and extrasynaptic transmission of kidney-related neurons in the rostral ventrolateral medulla

“…There are number of studies that have employed PRV-152 to demonstrate electrophysiological properties of specific neuronal populations (Derbenev et al 2004(Derbenev et al , 2010Gao et al 2012;Glatzer and Smith 2005;Irnaten et al 2001;. Whole cell recordings from cardiac vagal neurons in the nucleus ambiguus labeled with PRV-Bartha or rhodamine revealed that the electrophysiological properties of the virusand rhodamine-labeled neurons were indistinguishable from each other.…”

“…Whole cell recordings from cardiac vagal neurons in the nucleus ambiguus labeled with PRV-Bartha or rhodamine revealed that the electrophysiological properties of the virusand rhodamine-labeled neurons were indistinguishable from each other. Furthermore, the baroreflex pathway controlling the heart rate was functionally unaltered (Irnaten et al 2001). These observations indicate that the PRV infection does not alter neuronal function, at least at this time period.…”

Endogenous Acetylcholine and Nicotine Activation Enhances GABAergic and Glycinergic Inputs to Cardiac Vagal Neurons

“…This nicotinic facilitation of inhibitory synaptic inputs to cardioinhibitory vagal neurons may be one mechanism for the increased heart rate prevalent in smokers. The nicotinic augmentation of inhibitory neurotransmission to cardiac vagal neurons may also be involved in the respiratory modulation of heart rate, since one cholinergic input to cardiac vagal neurons originates from neurons active in respiration (Irnaten et al 2001).…”

Molecular Biology of Pseudorabies Virus: Impact on Neurovirology and Veterinary Medicine

“…Infection with EGFP-expressing PRV-Bartha recombinants allows visualization of live infected neurons by fluorescence without any fixative staining. Recent studies have gone beyond the mere tracing of neuronal circuits to actually record the electrophysiological properties of infected neurons from live brain slices or retinal tissue of infected animals (98,151,188,371,422). The attenuated phenotype of the PRV strain used means reduced cytopathic effects and more physiologically intact neurons.…”