Acute Electrical Stimulation of Nucleus Ambiguus Enhances Immune Function in Rats

Abstract

Up to now, many "immunoactive" brain areas have been identified, such as hypothalamic nuclei, brain reward system; but the nucleus ambiguous (Amb), a nucleus nervi vagis of medulla oblongata, was less well studied in neuroimmunomodulation. In order to obtain more profound comprehension and more knowledge on Amb, we studied the effect of acute electrical stimulation of Amb on thymus and spleen activity in rat. A stimulator was applied to stimulate the Amb of the anaesthetic rats using the parameter at 100 microgA x 5 ms x 100 Hz every 1 s for 1 min. The levels of TGF-13 and thymosin-beta4 mRNA in thymus, the release of IL-2 and IL-6 at splenocyte in vitro and splenic lymphocyte proliferation were measured at hour 0.5, 1, 2, 3 following the electrical stimulation. The results showed that concanavalin A (Con A)-induced splenic lymphocyte proliferation and the release of IL-2 and IL-6 were all significantly enhanced at 0.5, 1, and 2 h following effective Amb stimulation as compared to in the control group. However, as compared to in the control group, the levels of TGF-beta and thymosin-beta4 mRNA in the thymus were both remarkably reduced at 0.5, 1, and 2 h following effective Amb stimulation. These findings reveal that the Amb participates in the modulation of animal immune functions.