Role of the septal area in feeding behavior elicited by electrical stimulation of the lateral hypothalamus of the rat.

1. The present study was undertaken to investigate the influence of the septal area on neural mechanisms involved in feeding behavior elicited by electrical stimulation of the lateral hypothalamic area of the rat. 2. Electrolytic damage to medial and lateral septal nuclei induced a significant increase (18.29 +/- 1.69 to 25.05 +/- 2.31 g, P less than 0.05, N = 14) in food intake elicited by hypothalamic stimulation. The threshold current for stimulus-induced eating decreased by 20% after septal lesion. 3. A significant decrease in food ingestion was observed after electrical stimulation of the septal nuclei, either preceding (27.47 +/- 1.57 to 19.30 +/- 2.06 g, P less than 0.05, N = 13) or simultaneous (26.20 +/- 1.60 to 12.10 +/- 2.40 g, P less than 0.05, N = 11) with hypothalamic stimulation. 4. The results indicate an inhibitory effect of the septum on the lateral hypothalamic area and also suggest that the functional state of the lateral hypothalamus, which is responsible for the feeding behavior, depends on the activity pattern of the septal area.