Effect of adrenalectomy or gonadectomy on affective behavior changes following septal lesions in the rat.

Abstract

Adrenaleotomy or gonadectomy was performed ia conjunction with a septal lesion in order to test the hypothesis that changes in affective behavior following a septal lesion in the rat (septal syndrome) result from altered brain function due to hyperfunction of the adrenal cortex and/or gonads. Neither adrenalectomy nor gonadectomy was found to alter the characteristic appearance or duration of the septal syndrome, even when manipulations were performed to maximize the behavior changes observed following septal lesions. Results are discussed in terms of the ability of the animals to cope with stress. It is concluded that although adrenal hypertrophy frequently follows septal damage, intactness of the adrenal glands or testes is not necessary for manifestation of the septal syndrome, Drastic behavioral changes characterized by hyperreactivi ty and hyperemotionality (septal syndrome) have been reported in rats following septal ablation (Brady & Nauta, 1953). These behaviors included postural rigidity and explosive startle reaction to unexpected stimuli, and fierce struggling and biting in response to capture. Once present, however, the septal syndrome is a self-limiting condition observed to persist for postoperative periods of 7-75 days (Krieckhaus, Simmons, Thomas, & Kenyon, 1964; Reynolds, 1965). Investigations of this transitory property have indicated that environmental as well as neural factors influence the duration of the syndrome. Normal attenuation of the syndrome requires that the neocortex be intact (Yutzey, Meyer, & Meyer, 1967), while somatosensory stimulation facilitates the reduction of changes in affective behavior following septal damage (Seggie, 1968). Conversely, an amygdaloid lesion prior to septal damage prevents the appearance of a full1 This research was supported by Grant APA133 from the National Research Council of Canada and funds from the Clarke Institute of Psychiatry. Thanks are expressed to G. M. Brown of the Clarke Institute for his help with the present manuscript. J. Seggie is a holder of an Ontario Mental Health Foundation Research Fellowship.