Neonatal damage to the rat's infraorbital nerve upregulates both galanin and neuropeptide Y in individual vibrissae-related primary afferent axons

Abstract

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.

Prevention of galanin upregulation following neonatal infraorbital nerve transection or attenuation of axoplasmic transport does not rescue central vibrissae‐related patterns in the rat

“…The efficacy of V ganglionic injections of antisense oligonucleotides in preventing the upregulation of galanin normally observed following ION transection or vinblastine application was assessed using immunocytochemical staining procedures that are well established in our laboratory (Boylan et al ., 1996; Chiaia et al ., 1996a,b). Animals were killed with CO 2 , perfused transcardially with saline followed by a 4% paraformaldehyde fixative, and the brains and spinal cords removed and postfixed for 18–36 h. The brainstems were then cut on a freezing microtome into two sets of 50‐μm coronal sections.…”

Prevention of galanin upregulation following neonatal infraorbital nerve transection or attenuation of axoplasmic transport does not rescue central vibrissae-related patterns in the rat

“…The ef®cacy of V ganglionic injections of antisense oligonucleotides in preventing the upregulation of galanin normally observed follow-ing ION transection or vinblastine application was assessed using immunocytochemical staining procedures that are well established in our laboratory (Boylan et al, 1996;Chiaia et al, 1996a,b). Animals were killed with CO 2 , perfused transcardially with saline followed by a 4% paraformaldehyde ®xative, and the brains and spinal cords removed and post®xed for 18±36 h. The brainstems were then cut on a freezing microtome into two sets of 50-mm coronal sections.…”