Brain monoamines during footshock-induced aggression in paired rats.

Regional brain monoamine concentrations were investigated following footshock induced fighting behaviour in paired rats, by a spectrophotofluorometric method. The dopamine (DA) levels of the diencephalon-midbrain (DM), and that of the caudate nucleus (CN), were significantly augmented as compared to unshocked but paired rats, the increase being substantially more in DM. Noradrenaline (NA) concentrations of both DM and pons-medulla (PM) increased to almost similar extents, though the data remained statistically insignificant in comparison to controls. The 5-hydroxytryptamine (5HT) of both DM and PM, however, recorded a decrease, which was statistically significant in the latter brain area. The biochemical data are consonant with the reported facilitatory effect of central DA, and the inhibitory role of central 5HT, in experimental aggression. The observed changes in NA levels, for which a role in experimental aggression remains equivocal, may be due to the stress of footshock kept minimal due to the coping factor of fighting in response to the shock.