Biochemical specificity of septal hyperreactivity: a behavioral discrimination.

Intra-septal injections of specific monoamine and cell body neurotoxins were used to determine the anatomical and biochemical elements critical to both short and longer term changes in reactivity normally seen after septal lesions. A multivariate discrimination performed on the basis of tactile, foot-shock and heat responsiveness revealed that septal lesions have a unique effect not accounted for by specific monoamine induced degeneration. Injections of 6-hydroxydopa and monosodium glutamate had slight effects on heat and shock responsiveness not at all comparable in degree or kind to septal lesion effects. Decreased hippocampal, but not hypothalamic, levels of norepinephrine may be associated with the longer term increased responsiveness to shock and heat in animals with septal lesions.