Neuroestrogenic control of feeding behavior and body weight in rats with kainic acid lesions of the lateral septal area

Abstract

The role of the lateral septal area (LS) in the regulation of energy balance and the estrogenic control of feeding behavior in the female rat has been examined. Food intake (FI) and body weight (BWt) were measured daily following kainic acid (KA) LS lesions (KALS) to assess any regulatory changes in energy balance. In all animals KA lesions of the LS produced major cell loss in the LS; however the extent of damage was variable. Associated with KA lesions of the LS was the concurrent loss of CA3-CA4 cell groups in the hippocampus which was comparable for all the lesioned animals. The extent of septal damage was quantified morphometically and correlated with changes in FI and BWt following estrogen treatment. The significant effects of the KALS lesions, relative to the control animals were: (1) an increase in BWt which was statistically significant 22 days following brain surgery, (2) an increase in daily FI which was significant by day 6 post surgery, (3) an attenuation in the anorexic effects of estrogen on FI and BWt, and (4) a significant decrease in the percent days of vaginal estrus. Moreover, the anorexic effects of estrogen were significantly correlated with the extent of LS damage, but not the amount of hippocampal damage. The present study confirms that an increase in BWt is produced by KA lesions of the LS and further indicates that a sustained period of increased FI precedes the increase in BWt. Also these results verify that cells in the LS are involved in the estrogenic control of energy balance and further suggest that the increase in FI and BWt following KA lesions of the LS is attributable to the concurrent reduction in the anorexic effects of estrogen. The morphometic analysis of the brain lesions further suggest the ventral and/or intermediate subdivisions of the LS as the location of the cell bodies that modulate the estrogenic control of feeding behavior.