Abstract
Orexin increases blood pressure and orexin-immunoreactive (IR) axons robustly innervate the spinal cord. Seeking anatomical evidence for direct effects of orexin on sympathetic preganglionic neurons (SPN), we used immunohistochemistry to study the relationships between orexin-IR axons and SPN identified by immunoreactivity for choline acetyltransferase (ChAT) or for cholera toxin B retrogradely transported from the superior cervical ganglion (SCG). In the intermediolateral cell column (IML), varicose, orexin-positive axons closely apposed almost all SPN in segments T1 and T2, but appositions were rare in T4-L2. Orexin fibers also apposed ChAT-IR cell bodies in the intercalated nucleus and the central autonomic area from T1 to L2. Orexin-IR synapses were identified ultrastructurally on SPN projecting to the SCG. Since SPN involved in cardiovascular control cluster in the IML of mid- and lower thoracic cord, these findings suggest that orexin affects blood pressure by acting on supraspinal neurons rather than SPN.
Original language | English (US) |
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Pages (from-to) | 115-119 |
Number of pages | 5 |
Journal | Neuroscience letters |
Volume | 351 |
Issue number | 2 |
DOIs | |
State | Published - Nov 13 2003 |
Keywords
- Autonomic regulation
- Blood pressure
- Hypocretin
- Immunocytochemistry
- Spinal cord
- Superior cervical ganglion
- Ultrastructure
ASJC Scopus subject areas
- General Neuroscience