Cardiorespiratory responses to interleukin-1beta in adult rats: role of nitric oxide, eicosanoids and glucocorticoids.

Interleukin-1beta (IL-1beta) receptors are abundantly expressed in brain stem regions involved in respiratory control. We hypothesized that systemic administration of IL-1beta would increase ventilation (V(E )), and that nitric oxide, eicosanoids, and glucocorticoid receptors would modulate IL-1beta-induced cardioventilatory responses. Intravenous injections of three doses (37.5 ng kg(-1), 75 ng kg(-1 ) and 150 ng kg(-1)) of IL-1b induced monophasic increases in (V(E)), heart rate (HR), and blood pressure (BP) which had a distinctly different onset and duration of action compared to IL-1beta-induced body temperature elevations. Pre-treatment with the nitric oxide inhibitor L-NAME was associated with decreased peak V(E) responses, without affecting the latency and duration of IL-1beta. L-NAME also enhanced HR responses while pressor responses were attenuated. Eicosanoid inhibition with indomethacin resulted in markedly attenuated V responses. However, cardiovascular responses to IL-1beta were not modified by indomethacin. In contrast, pre-treatment with dexamethasone, was not associated with any changes in the IL-1beta-induced V(E), HR, or BP responses. We conclude that IL-1beta increases of V(E) are dose-dependent and are not time-locked with the pyrexic response suggesting the possibility that distinct neural pathways may underlie these responses. In addition, nitric oxide and eicosanoid-dependent mechanisms modulate IL-1beta ventilatory effects.