Previous studies have indicated that neurons in the dorsomedial hypothalamic nucleus (DMN) receive feeding-related signals from the gastric vagal nerves, glycemia as well as leptin. On the other hand, it is intriguing that the cerebellum participates in regulating nonsomatic visceral activities including food intake via the direct cerebellohypothalamic projections. The present study was designed to examine, by using extracellular recordings in vivo in rats, whether the cerebellar fastigial nucleus (FN) could reach and converge with the feeding-associated gastric vagal, glycemia and leptin signals onto single DMN neurons. Of the 200 DMN neurons recorded, 104 (52%) responded to the cerebellar FN stimulation, in which 95 (91.3%) were also responsive to the gastric vagal stimulation, suggesting a convergence of cerebellar FN and gastric vagal inputs on the DMN neurons. Moreover, a summation of responses was observed (n = 10) when the cerebellar FN and gastric vagal nerve were simultaneously stimulated. Among the 18 DMN neurons receiving convergent inputs from the cerebellar FN and gastric vagal nerves, 16 (88.9%) cells also responded to the systemic administrations of glucose and leptin. These results demonstrated that the cerebellar FN-afferent inputs, together with the feeding signals from the gastric vagal nerves, blood glucose as well as leptin, converge onto single DMN neurons, suggesting that a somatic-visceral integration related to the feeding may occur in the DMN and the cerebellum may actively participate in the feeding regulation through the cerebellar FN-DMN projections.
2009 S. Karger AG, Basel.