Figure 11. Schematic model depicting the anatomical relationships within rostral and caudal portions of the DMV whereby PrRP is hypothesized to activate vagal efferent pathways to evoke gastric contraction and relaxation, respectively.

In both cases, specific receptors for PrRP are hypothesized to reside presynaptically on the nerve endings of glutamatergic NTS neurones, but not on the cell bodies of DMV or NTS neurones. Dotted line denotes approximate boundary between the NTS and DMV, without reference to anatomical exactness. Note that PrRP is shown to be colocalized with tyrosine hydroxylase (TH) in NTS neurones of noradrenergic phenotype, comprising the A2 cell group. Abbreviations: Chol PPN, cholinergic postganglionic parasympathetic neurone; NANC PPN, non-adrenergic, non-cholinergic postganglionic parasympathetic neurone. Unshaded terminals represent presynaptic elements of excitatory synapses, whereas darkened terminals represent presynaptic inhibitory elements.