The proportion of tracer-labeled neurons that also were Fos-positive (i.e., double-labeled) was significantly increased within the NTS, VLM, lateral PBN, lCEA, and dlBNST in LPS-treated rats (n=8) compared to saline-injected controls (n=6). Small but still significant increases in activation also were observed within the rPVT in LPS-treated rats vs. controls. Conversely, there was no significant effect of LPS treatment on Fos activation of retrogradely labeled neurons within either the mCEA or the cPVT.