Somatic afferent regulation of cytotoxic activity of splenic natural killer cells in anesthetized rats.

The effects of non-noxious and noxious mechanical stimulation of the skin on cytotoxic activity of splenic natural killer (NK) cells and splenic blood flow were examined in anesthetized rats. Bilateral brushing of the body surface between the lateral chest and hindlimb for 30 min did not significantly influence cytotoxic activity of splenic NK cells, splenic blood flow or splenic sympathetic efferent nerve activity. Bilateral pinching stimulation of the skin of the hindpaws for 30 min reduced cytotoxic activity of splenic NK cells and splenic blood flow to 67 +/- 8 and 82 +/- 3% of the control values, respectively. Pinching the hindpaws for 30 min increased splenic sympathetic efferent nerve activity to 143 +/- 15% of control. Electrical stimulation (10 V, 10 Hz) of the splanchnic nerve for 20 min produced a decrease in the cytotoxic activity of splenic NK cells and splenic blood flow. The hindpaw pinching-induced suppression of cytotoxic activity of NK cells was abolished after surgical transection of the splenic sympathetic nerve or the spinal cord at the cervical level. These results indicate that the suppression of cytotoxic activity of NK cells and splenic blood flow following noxious pinching stimulation is a supra-spinal reflex response mediated via the splenic sympathetic nerve.