Neonatal damage to the rat's infraorbital nerve upregulates both galanin and neuropeptide Y in individual vibrissae-related primary afferent axons.
Previous studies in adult animals have suggested that the peptides galanin and neuropeptide Y (NPY) may be upregulated in the same primary afferent neurons after peripheral axotomy. The present study was undertaken to determine whether such upregulation occurred in vibrissae-related primary afferent neurons and their axons after damage to the infraorbital nerve [ION; the trigeminal (V) branch that innervates the vibrissae follicles]. Double-labelling experiments demonstrated that approximately 75% of axotomized V ganglion cells and the central arbors of vibrissae-related primary afferents expressed both galanin and NPY after perinatal, but not adult, nerve damage. However, additional experiments demonstrated that the sensitive periods for lesion-induced upregulation of the two peptides and the period over which they were expressed after neonatal ION transection differed substantially. Staining for both peptides was increased after ION damage on P-0 through P-14, but only galanin staining was increased in vibrissae-related primary afferents after lesions on P-21. Galanin expression was elevated in vibrissae-related primary afferents in rats killed 3, 8, and 15 days after neonatal ION transection, while increased NPY was observed at only the middle time point. The lesion-induced increases in galanin and NPY in vibrissae-related ION primary afferents suggest that these peptides may modulate central V reorganization after such damage.
Boylan
C B
CB
Department of Anatomy and Neurobiology, Medical College of Ohio, Toledo 43699, USA.
Davis
K
K
Bennett-Clarke
C A
CA
Rhoades
R W
RW
D000344:Afferent Pathways / Q000378:metabolism*; D000818:Animals; D001369:Axons / Q000378:metabolism*; D019004:Galanin / Q000378:metabolism*; D007150:Immunohistochemistry; D009478:Neuropeptide Y / Q000378:metabolism*; D009916:Orbital Diseases / Q000378:metabolism; D051381:Rats; D061221:Trigeminal Nerve Injuries
D009478:Neuropeptide Y; D019004:Galanin