INTERFERON-GAMMA AND A FACTOR DERIVED FROM TRYPANOSOMES CAUSE BEHAVIORAL-CHANGES IN THE RAT

A newly isolated interferon-gamma (IFN-gamma) immunoreactive molecule, ''neuronal IFN-gamma'', and recombinant lymphocyte-derived IFN-gamma were injected intracerebroventricularly (i.c.v.) through a previously implanted cannula into adult male rats during both the light and the d ark phases of the light/dark cycle. The two molecules caused a reducti on in both frequency and duration of rearing and locomotion during the dark, but not the light, phase. A molecule isolated from Trypanosoma brucei brucei, a parasite of the same subspecies of trypanosomes which causes African sleeping sickness, can induce production and release o f IFN-gamma and ''neuronal IFN-gamma'' from lymphocytes and neurons, r espectively. I.c.v. injection of this factor also reduced rearing duri ng the dark period, but to a less extent. Thus, ''neuronal IFN-gamma'' appears to have effects on animal behaviour in common with lymphocyte -derived IFN-gamma. This study highlights the potential role of these cytokines in behaviour disturbances.