Hindbrain Neuroactive Substances Controlling Gastrointestinal Function
This chapter reviews the anatomical basis for hindbrain control of the entire gastrointestinal (GI) tract. It presents the evidence for neuroactive substances in the hindbrain to control GI function. For some neurotransmitters there is overwhelming anatomical and pharmacological evidence for their importance in control GI function, whereas for others there is very patchy or contradictory evidence. The chapter reviews specific aspects of several interesting questions about neurotransmitter control of GI function, such as the effects of coadministration of colocalized substances in specific nuclei on gastric motor function. Investigators have focused on the issue of viscerotopic organization of the vagal motor nuclei, and anatomical evidence for this viscerotopy is often supported by microinjection or microstimulation studies. Within the rat dorsal motor nucleus of the vagus (DMV) there is a medial-lateral organization such that the gastric branch of the vagus is represented in the medial DMV, and the celiac branch is represented in the lateral DMV.