Glucose-monitoring neurons in the mediodorsal prefrontal cortex

The mediodorsal prefrontal cortex (mdPFC), a key structure of the limbic neural circuitry, plays important roles in the central regulation of feeding. As an integrant part of the forebrain dopamine (DA) system, it performs complex roles via interconnections with various brain areas where glucose-monitoring (GM) neurons have been identified. The main goal of the present experiments was to examine whether similar GM neurons exist in the mediodorsal prefrontal cortex. To search for such chemosensory cells here, and to estimate their involvement in the DA circuitry, extracellular single neuron activity of the mediodorsal prefrontal cortex of anesthetized Wistar and Sprague–Dawley rats was recorded by means of tungsten wire multibarreled glass microelectrodes during microelectrophoretic administration of d-glucose and DA. One fourth of the neurons tested changed in firing rate in response to glucose, thus, proved to be elements of the forebrain GM neural network. DA responsive neurons in the mdPFC were found to represent similar proportion of all cells; the glucose-excited units were shown to display excitatory whereas the glucose-inhibited neurons were demonstrated to exert mainly inhibitory responses to dopamine. The glucose-monitoring neurons of the mdPFC and their distinct DA sensitivity are suggested to be of particular significance in adaptive processes of the central feeding control.

► To search for special chemosensory cells, single neuron activity was recorded in the mediodorsal prefrontal cortex (mdPFC).
► Evidence has been obtained for the existence of glucose-monitoring (GM) neurons.
► Differential dopamine sensitivity of the mdPFC neurons has been elucidated.
► The GM neurons were shown to be more likely to change in activity to DA than the glucose-insensitive cells.
► The glucose-excited units displayed excitatory, whereas the glucose-inhibited ones exerted mainly inhibitory responses to DA.