The effect of pro-inflammatory cytokines on the discharge rate of vagal nerve paraganglia in the rat.

Vagal paraganglia resemble the carotid body and are chemosensitive to reduction in the partial pressure of oxygen (P O2) (O'Leary et al., 2004). We hypothesised that they may also mediate communication between the immune system and the central nervous system and more specifically respond to the pro-inflammatory cytokines: interleukin-1 beta (IL-1 beta) and tumour necrosis factor-alpha (TNF-alpha). We recorded axonal firing rate of isolated superfused rat glomus cells - located at the bifurcation of the superior laryngeal nerve - to IL-1 beta or TNF-alpha at concentrations of 0.5 ng/ml, 5 ng/ml and 50 ng/ml. Twenty-three successful single fibre recordings were obtained from 10 animals. IL-1 beta and TNF-alpha had no statistically significant effect on the frequency of action potentials observed (p=0.39 and 0.42, respectively, repeated measures ANOVA). The activity of both cytokines was tested by observing translocation of P65-NF kappaB from cytoplasm to nucleus in cultured HELA cells. In conclusion, an immune role for SLN paraganglia has not been established.