Noxious colorectal distention in spinalized rats reduces pseudorabies virus labeling of sympathetic neurons.
The retrograde transsynaptic tracer pseudorabies virus (PRV) has been widely used as a marker for synaptic connectivity in the spinal cord. Notably, the PRV-152 construct expresses enhanced green fluorescent protein (EGFP). We recently reported a significant attenuation of PRV-152 labeling of the intermediolateral cell column (IML) and celiac ganglia after complete T4 spinal cord transection versus sham injury in rats at 96 h after PRV-152 inoculation of the left kidney. Here we found a significant increase in noxious colorectal distention (CRD)-evoked c-Fos expression in spinal cords of injured versus sham rats without PRV infection. In order to assess whether enhancing neuronal activity in spinalized rats might increase PRV-152 labeling, we subjected awake spinalized rats to 1.5 h of intermittent noxious CRD either: (1) just prior to inoculation, or (2) 96 h after inoculation (n = 3/group). Equal numbers of spinalized rats in both groups received PRV-152 inoculations without CRD (non-stimulated; n = 3/group). At 96 h post-inoculation fixed spinal cords and left celiac ganglionic tissues were assessed for the distribution and quantification of EGFP-labeled cells. The injured cohort that received CRD just prior to PRV injection showed a significant reduction in EGFP-labeled cells in both the IML and left celiac ganglion compared to non-stimulated injured rats. In contrast, the injured cohort that received CRD 96 h after PRV-152 inoculation showed no differences in EGFP-labeled cell numbers in the IML or celiac ganglia versus non-stimulated injured rats. Interestingly, microglia near c-Fos-positive cells after acute CRD appeared more reactive compared to non-stimulated spinalized rats, and activated microglial cells markedly reduce viral transduction and progression following PRV inoculation of the CNS. Hence our results imply that increased CRD-induced c-Fos expression in the injured paradigm, prior to but not after PRV injection, further attenuates PRV-152 uptake, perhaps through changes in neuronal activity and/or innate neuro-immune responses.
Duale
Hanad
H
Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536-0509, USA.
Lyttle
Travis S
TS
Smith
Bret N
BN
Rabchevsky
Alexander G
AG
D000818:Animals; D001339:Autonomic Fibers, Preganglionic / Q000473:pathology; D002452:Cell Count; D003106:Colon / Q000502:physiology*; D003655:Decerebrate State / Q000503:physiopathology*; D005260:Female; D005728:Ganglia, Sympathetic / Q000473:pathology; D011558:Herpesvirus 1, Suid / Q000378:metabolism; D007150:Immunohistochemistry; D017628:Microglia / Q000473:pathology; D009474:Neurons / Q000473:pathology*; D010812:Physical Stimulation; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D011557:Pseudorabies / Q000473:pathology*; D051381:Rats; D017208:Rats, Wistar; D012007:Rectum / Q000502:physiology*; D013116:Spinal Cord / Q000378:metabolism / Q000473:pathology; D013119:Spinal Cord Injuries / Q000473:pathology; D013564:Sympathetic Nervous System / Q000473:pathology*
D016760:Proto-Oncogene Proteins c-fos