Spinally projecting preproglucagon axons preferentially innervate sympathetic preganglionic neurons.
Bottom Line: These results show that brainstem PPG neurons innervate spinal autonomic and somatic motor neurons.SPN receive the densest PPG innervation.Brainstem PPG neurons could directly modulate sympathetic outflow through their spinal inputs to SPN or interneurons.
Affiliation: Cardiovascular Medicine, Physiology and Centre for Neuroscience, Flinders University, Bedford Park, SA 5042, Australia.Show MeSH
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Mentions: Varicose YFP-containing axons had clearly delineated varicosities and fine intervaricose segments (Figs. 4–9). Some of the axons had large varicosities; others had small fine varicosities and some axons had both large and small varicosities (e.g., Figs. 6B, C and 7E). All three types of axons made close appositions on immunohistochemically identified spinal neurons. In segments T1–L2 (Figs. 4 and 5), which contain SPN, many varicose, YFP-immunoreactive axons traveled rostrocaudally along the IML and mediolaterally between the IML and the intercalated nucleus (ICN). There was also a dense plexus of varicose axons containing YFP-immunoreactivity that ran rostrocaudally through the dorsal portion of lamina X, the location of SPN cell bodies in the spinal autonomic subnucleus called the central autonomic area (CAA). Smaller numbers of varicose YFP-positive axons occurred through lamina VII and in laminae VIII and IX; areas containing limb motor neurons (Figs. 4D and 7). There were fewer immunoreactive axons in laminae IV and V than in laminae containing autonomic and somatic motor neurons (Fig. 4A, E). The number of YFP-containing axons decreased from lamina IV to lamina II, where there were almost no YFP-immunoreactive axons. YFP-positive axons were never found in lamina I.
Affiliation: Cardiovascular Medicine, Physiology and Centre for Neuroscience, Flinders University, Bedford Park, SA 5042, Australia.