In previous studies, we have shown that a traumatic lesion to the hippocampus of adult mice induces the transitory expression of TNFα and IL-1α by neurons of different brain areas and also by glial cells at the site of injury. The aim of the present study was to establish whether the expression of TNFα and IL-1α is restricted to defined subpopulations, or else is common to most of the central neuronal populations. Using polyclonal anti-GAD 67, anti-TH and monoclonal anti-ChAT, and anti-5-HT antibodies in a double-labeling immunohistochemical procedure in combination with murine anti-TNFα and anti-IL-1α polyclonal antibodies, we show that most GABAergic, catecholaminergic, and serotoninergic neurons, and a subgroup of the cholinergic neurons, express these cytokines. Although not immunohistochemically characterized, neurons in some glutamatergic structures such as the hippocampus and the prefrontal cortex also express these cytokines. Thus, we conclude that the capacity of central neurons to express cytokines like TNFα and IL-1α in reaction to a brain Injury is not restricted to peculiar neuronal subtypes, but could include most of the neuronal populations of the brain. © 1996 Wiley-Liss, Inc.