THE RENAL AFFERENT PATHWAYS IN THE RAT - A PSEUDORABIES VIRUS STUDY

Retrograde tract tracing studies have indicated that dorsal root gangl ion cells from T-8 to L-2 innervate the rat's left kidney. Electrophys iology studies have indicated that putative second-order sympathetic a fferents are found in the dorsal horn at spinal segments T-10 to L-1 i n laminae V-VII. Here, the spread of pseudorabies virus through renal sensory pathways was examined following 2-5 days post-infection (PI) a nd the virus was located immunocytochemically using a rabbit polyclona l antibody. Two days PI, dorsal root ganglion neurons (first-order sym pathetic afferents) were infected with PRV. An average of 1.2, 0.8, 2. 1 and 4.4% of the infected dorsal root ganglion neurons were contralat eral to the injected kidney at spinal segments T-10, T-11, T-12 and T- 13, respectively. Four days PI, infected neurons were detected within laminae I and II of the dorsal horn of the caudal thoracic and upper l umbar spinal cord segments. The labeling patterns in the spinal cord a re consistent with previous work indicating the location of renal symp athetic sensory pathways. The nodose ganglia were labeled starting 4 d ays PI, suggesting the involvement of parasympathetic sensory pathways . Five days PI, infected neurons were found in the nucleus tractus sol itarius. In the present study, it was unclear whether the infected neu rons in the nucleus tractus solitarius are part of sympathetic or para sympathetic afferent pathways or represent a convergence of sensory in formation. Renal denervation prevented the spread of the virus into th e dorsal root ganglia and spinal cord. Sectioning the dorsal roots fro m T-10-L-3 blocked viral spread into the spinal cord dorsal horn, but did not prevent infection of neurons in dorsal root ganglion nor did i t prevent infection of putative preganglionic neurons in the intermedi olateral cell column. The present results indicated that renal afferen t pathways can be identified after pseudorabies virus infection of the kidney. Our results suggest that renal afferents travel in sympatheti c and parasympathetic nerves and that this information may converge at the NTS. (C) 1998 Elsevier Science B.V. All rights reserved.