PROJECTIONS FROM THE RENAL NERVE TO THE CATS LATERAL SOMATOSENSORY THALAMUS

The representation of the kidney in the lateral somatosensory thalamus was mapped using electrical stimulation of the renal nerve in pentoba rbitone-anesthetized cats. Ninety-five of 197 thalamic neurons studied responded to renal nerve stimulation. The responsive neurons were loc ated in the periphery of the ventral posterolateral nucleus (42%; VPLp ) and the neighboring dorsal and lateral aspects of the posterior comp lex (58%; POd and POl). No visceroceptive neurons were found within VP L proper. The mean response latency of the thalamic neurons to electri cal nerve stimulation was 9.5 +/- 2.6 ms (mean +/- S.D.), suggesting a n involvement of A delta, and possibly A beta fibers in the primary af ferent pathway. The visceroceptive neurons were further characterized with innocuous mechanical stimulation of the body surface, and for 94 of the 95 neurons a somatic receptive field could be determined. Of th ese, 35% were located on the lower back and belly, i.e., the dermatome s of the lower thoracic and upper lumbar spinal projection areas of th e renal nerve. 52% of the somatic receptive fields were located on the contralateral foot, thigh, tail, or hind leg (lower lumbar, sacral an d coccygeal dermatomes) and 13% covered the arm and upper body (upper thoracic and lower cervical dermatomes). Comparison between the thalam ic representations of the renal and pelvic nerves showed that both cov ered comparable areas adjacent and around, but not within VPL proper. It is concluded that VPLp, POd and POl play a role in processing visce ral, possibly including nociceptive, information from the kidney of th e cat. (C) 1997 Elsevier Science B.V.