The Effect of Septal Lesions on the Threshold of Adrenal Stress Response

Previous studies have indicated that septal ablation produces an exaggeration of adrenal activation in response to stress and have suggested further that the threshold for activation might be lowered. In order to examine the threshold for activation, rats lesioned in the septal area were subjected to various levels of electric shock, after which corticosterone and prolactin responses were examined. Although baseline corticosterone values were unaltered, plasma corticosterone concentrations in lesioned animals were elevated in response to stimuli that did not produce a corresponding elevation in sham-lesioned and unlesioned animals. Neither baseline nor stress levels of prolactin were affected by septal lesions at the times studied. It is concluded that a septal lesion lowers the stimulation threshold for activation of the pituitary adrenal axis and is suggested that corticosterone and prolactin stress responses are under different neural control.