Responses of adrenal function to stimulation of lumbar and thoracic interspinous tissues in the rat

In urethane-anesthetized Wistar rats, the responses of adrenal sympathetic nerve activity and catecholamine secretion were measured following chemical stimulation of lumbar and thoracic interspinous tissues. Injection of normal saline into the lower lumbar or lower thoracic interspinous tissues produced no changes in adrenal sympathetic nerve activity or catecholamine secretion. On the other hand, the injection of capsaicin produced protracted increases in adrenal nerve activity and catecholamine secretion both in CNS-intact animals and in animals acutely spinalized at the Cl-2 level. Repetitive electrical stimulation of the medial branch of a lumbar primary dorsal ramus, the nerve which provides sensation to the lumbar interspinous tissues, produced A- and C-reflex discharges, mediated at the spinal and supraspinal levels, in the adrenal sympathetic nerve.