Septal lesions block sympathetic activation following frontal cortex stimulation in the rat

The rates of oxygen consumption, colonic and interscapular brown adipose tissue temperature, and discharge of sympathetic nerves innervating the same tissue were recorded before and after orbital frontal cortex stimulation in three groups of rats. These groups consisted of animals with electrolytic lesions of the nucleus medialis septi, with lesions of nucleus lateralis septi or with sham lesions. The values of all the variables considered were similar during the pre-stimulation time in the three groups of rats. There was an increase in all the parameters in sham-lesioned animals after electrical stimulation, while no changes were found in the two groups of injured rats. The results showed that the frontal cortex is involved in the control of thermogenesis through the activation of the sympathetic nervous system. Medial and lateral septal nuclei, in spite of their neurochemical and pharmacological differences, share a common role in the pathway from the frontal cortex to the hypothalamic area and the amygdala, which in turn drive the sympathetic nervous system.