Sympathetic nerve sprouting fails to occur in the trigeminal ganglion after peripheral nerve injury in the rat.
Peripheral nerve injury induces sprouting of sympathetic nerve fibers in dorsal root ganglia after spinal nerve injury. In the present study, we sought to determine the extent of intraganglionic noradrenergic sprouting in the trigeminal system. The inferior alveolar nerve, a major branch of the mandibular division, or the infraorbital nerve of the maxillary division was either ligated or chronically constricted in Sprague-Dawley rats and recovery permitted for either 2-3 or 6-9 weeks. In some animals both nerves were injured. Using immunohistochemistry with tyrosine hydroxylase antibodies, we found no signs of sympathetic nerve fiber sprouting in the trigeminal ganglion after injury. In contrast, sciatic nerve injury in rat littermates induced a widespread autonomic nerve outgrowth in affected DRGs. Thus, sensory ganglion sympathetic nerve sprouting does not seem to be a general outcome of PNS injury, but is restricted to certain specific locations. Sympathetic nerve fiber networks that surround primary sensory neurons have been suggested to form a structural basis for interactions between the sympathetic and sensory nervous systems after PNS injury. Such interactions, sometimes resulting in paraesthesia or dysaesthesia in patients, appear to be less common in territories innervated by the trigeminal nerve than in spinal nerve regions. The lack of injury-induced intraganglionic sympathetic sprouting in the trigeminal ganglion may help to explain this observation.
Bongenhielm
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U
Dept of Neuroscience, Karolinska Institutet, S-171 77 Stockholm, Sweden Department of Oral and Maxillofacial Surgery, Huddinge Hospital, Karolinska Institute S-18146 Huddinge, Sweden Department of Oral and Maxillofacial Surgery, School of Clinical Dentistry, University of Sheffield, Sheffield, S10 2TA, UK Department of Oral and Maxillofacial Surgery, Karolinska Hospital, S-171 76 Stockholm, Sweden.
Boissonade
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FM
Westermark
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A
Robinson
P P
PP
Fried
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K
D000818:Animals; D003250:Constriction; D007150:Immunohistochemistry; D009416:Nerve Regeneration; D009915:Orbit / Q000294:innervation; D059348:Peripheral Nerve Injuries; D051381:Rats; D017207:Rats, Sprague-Dawley; D013564:Sympathetic Nervous System / Q000502:physiology*; D012668:Trigeminal Ganglion / Q000502:physiology*; D061221:Trigeminal Nerve Injuries; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis
D014446:Tyrosine 3-Monooxygenase