Cerebellar modulation of feeding-related neurons in rat dorsomedial hypothalamic nucleus

Cerebellum has newly been implicated in many more nonsomatic functions other than motor control. Previous studies indicate that the cerebellum is involved in feeding regulation and that the gastric vagal nerves transmit short-term meal-related visceral signals, including cholecystokinin (CCK), into the hypothalamus. Recently, the dorsomedial hypothalamic nucleus (DMN) has been thought to play an important role in feeding control. Here we investigate whether the inputs from cerebellar interpositus nucleus (IN) can reach and converge onto single DMN neurons with some feeding-related visceral signals, including gastric vagal inputs, CCK, and blood glucose, whose concentration is closely linked to food intake. Among the 259 DMN neurons recorded, 120 (46.3%) and 169 (65.3%) responded to the cerebellar IN and gastric vagal stimulations, respectively. Within the 120 DMN neurons responsive to the cerebellar IN stimulation, 98 (81.7%) also responded to the gastric vagal stimulus, and a summation of the responses was observed further (n = 20), suggesting a convergence and interaction of cerebellar and gastric vagal inputs on the cells. Moreover, among the 98 cells receiving convergent inputs from cerebellar IN and gastric vagal nerves, 69 (70.4%) were identified to be glycemia sensitive, and 22 (68.8%) of the 32 tested neurons were also sensitive to systemic CCK. These results demonstrate that the DMN integrates somatic information forwarded by the cerebellar IN and visceral signals related to food intake, including gastric vagal, CCK and glycemia, and electrophysiologically reveal a novel cerebellohypothalamic IN-DMN pathway through which the cerebellum may actively participate in short-term feeding regulation.