Periodontal and gastric convergences within the hypothalamic ventromedial nucleus area — single unit study on anesthetized rats

Unitary activities were recorded in the ventromedial nucleus of the hypothalamus (VHM) of anesthetized rats. Cells responding to periodontal stimulation (100–200 g disto-mesial traction applied to an upper incisive) were selected. The effects of gastric stimulation (2–5 ml distension) were then investigated. Out of the 40 cells activated (22 cells) or inhibited (18 cells) by periodontal stimulation, only seventeen were influenced by gastric stimulation. Eight of them responded in the same way and nine in the opposite way. Unlike the periodontal stimulation, which elicited specific spatio-temporal patterns, the gastric stimulation had only weak effects. These data nevertheless demonstrate that periodontal-gastric convergences exist in the VHM nucleus, which is consistent with the role previously ascribed to this area in alimentary behaviour.