TNF and meningitis: Microglia activation in turn would contribute to the increase in TNFα in hippocampal neurons of these rats, as occurs in rats with chronic hyperammonemia and hepatic encephalopathy [15,16,17,20,24,48,49,50], in meningitis [51], in dorsal horn neurons and the spinal cord [52,53], or in propofol-induced neurotoxicity [54].