Anterograde Transneuronal Viral Tracing of Central Viscerosensory Pathways in Rats

Abstract

Previous studies demonstrated that strain H129 of herpes simplex virus-1 undergoes anterograde transneuronal transport in mice and primates after peripheral or central injection. In this study, H129 was used in rats to identify CNS regions that receive relayed viscerosensory inputs from the stomach wall. We also examined whether transneuronal viral transport in this model is exclusively anterograde. H129 or an established retrograde transneuronal viral tracer, pseudorabies virus (PRV), was injected into the ventral stomach wall in intact rats or in rats with previous subdiaphragmatic vagal sensory deafferentation. Rats were perfused with fixative 3-5 d later, and tissues were processed for immunocytochemical detection of transported virus. In intact rats, H129 was transported transneuronally via vagal and spinal viscerosensory neurons to postsynaptic target cells in the medullary dorsal vagal complex and thoracic dorsal horn, respectively, with subsequent transport to discrete regions of the medullary and pontine reticular formation, cerebellum, parabrachial nucleus, periaqueductal gray, thalamus, hypothalamus, amygdala, bed nucleus of the stria terminalis, and other central sites. Comparison of labeling patterns in intact and vagal deafferented rats indicated that H129 also produced first-order retrograde infection of autonomic neurons that project directly to virus injection sites, similar to PRV. Unlike PRV, however, H129 was not transported transneuronally in the retrograde direction from infected neurons to central sources of presynaptic input. We conclude that transneuronal transport of H129 occurs exclusively in the anterograde direction to reveal CNS regions that receive direct and relayed viscerosensory signals.

Anterograde transneuronal viral tract tracing reveals central sensory circuits from white adipose tissue

“…The labeling of T13 postganglionic SNS cells may have occurred because they also are first-order neurons, and H129 initially infects all first-order neurons, as was shown with stomach injections of H129 (33). Further progression into the CNS via the WAT SNS circuits would require retrograde spread of the virus across synapses, which the H129 is not capable of doing (17,33,50). In addition, the labeling of the Fig.…”

“…To this end, we used the H129 strain of the herpes simplex virus-1 (HSV-1), a transneuronal viral tracer that spreads anterogradely (6,17,33,43,50), in contrast to the retrograde of PRV, to trace the multi-synaptic ascending afferent circuit from inguinal WAT (IWAT) or epididymal WAT (EWAT) through the CNS of Siberian hamsters. Immunohistochemical detection of H129 has been previously used in this manner to successfully identify CNS regions that receive viscerosensory inputs from the rat stomach wall (33). In the present study, Siberian hamsters were chosen because the SNS and sensory innervation of WAT have been most extensively studied in this species both histologically (e.g., 3,20,36,39,41,48) and functionally (e.g., 10,10,49).…”

Herpes simplex virus type 1 induces filopodia in differentiated P19 neural cells to facilitate viral spread

“…Efforts to use HSV-1 to trace multisynaptic pathways in vivo also rely heavily on our implicit understanding of viral movement strategies. Previous studies with the herpes virus family have focused on pathway tracing and internal axonal transport of viruses in the nervous system [32], [7], [5], [17], and [26]. Our live cell imaging of GFP-tagged HSV-1, however, has captured, for the first time, viral "surfing" behavior along the outer membrane of dendrites and dendritic filopodia.…”

Anterograde transneuronal viral tract tracing reveals central sensory circuits from brown fat and sensory denervation alters its thermogenic responses

“…Specifically, using the Bartha's K strain of the pseudorabies virus (PRV), we provided the first demonstration of the SNS outflow circuits to BAT in rodents using Siberian hamsters (3), with the first report in laboratory rats following relatively soon thereafter (44). By contrast to PRV, the H129 strain of the herpes simplex virus type 1 (HSV-1), an anterograde traveling virus, allows mapping of central sensory circuits from peripheral tissues such as the stomach (48), or in our hands, white adipose tissue [WAT; (54)]. Thus the first aim of this study was to delineate BAT central nervous system (CNS) sensory circuitry after H129 inoculation of BAT.…”