Distribution of dopamine receptors D sub(1)- and D sub(2)-immunoreactive neurons in the dorsal motor nucleus of vagus in rats

The dorsal motor nucleus of vagus (DMV) plays an important role in the regulation of gastrointestinal function. Dopamine (DA) exerts potent neuromodulatory effects on the motoneurons in the DMV via dopamine receptors (DRs). However, the distribution of DRs and their neurochemical phenotypes in the DMV are unclear. In the present study, the distribution of DRs D sub(1)- and D sub(2)-immunoreactive (IR) neurons and their neurochemical phenotypes in the DMV of rats were investigated using a double-labeling immunofluorescence technique combined with confocal microscopy. The results indicated that a considerable quantity of D sub(1) and D sub(2) was expressed throughout the DMV. A large amount of choline acetyltransferase (ChAT)-IR and a few tyrosine hydroxylase (TH)-IR neurons were observed in the DMV. Nearly all of the neurons were also D sub(1)-IR and D sub(2)-IR. In conclusion, the present study demonstrates the wide distribution of D sub(1) and D sub(2) in the cholinergic and catecholaminergic neurons in the DMV of rats. The DRs might play an important role in the regulation of DA on the activity of cholinergic and catecholaminergic neurons in the DMV.