GASTRIC PROJECTING NEURONS OF DORSAL (MOTOR) NUCELUS OF THE VAGUS NERVE (DMV) AND THEIR ARBORIZATION

Objective: The purpose of this study is to locate the gastric projecting neurons in the DMV and examine their dendritic arborization.Material and methods: To achieve these objectives aqueous solution of cholera toxin conjugated horseradish peroxidase (CT-HRP) was injected in to the walls of the stomach using Hamilton syringe. The retro-gradely labelled gastric projecting neurons and their dendritic arborization was mapped in the DVC. The anterograde labelling was also observed in the DMV and subnuclei of the nucleus of the tractus solitarius (NTS).Results: This light microscopic study revealed the areas where overlapping between the DMV, its dendritic tree and afferent terminals of the central nucleus of the Amygdala (CeA) could occur. These areas will be taken up for future ultrastructural evidence for synapses between the axon terminals of the CeA and gastric projecting neurons. In addition vago-vagal connections were observed.Conclusion: The results from this study and the previous experiments1-2 indicate that the most likely areas for such contacts to occur are within and across the dorsal border of the DMV, in the dorsomedial and dorsal parts of the NTSm, and in the commissural nucleus of the NTS. In these regions, input from the CeA overlaps the distribution of labelled cell bodies and dendrites of gastric projecting neurons. It was in these areas; therefore that ultrastructural evidence for synapses between CeA axon terminals and gastric vagal motor neurons was sought (in preparation).