Evidence for reduced accumulation of exogenous neurotrophin by aged sympathetic neurons.
The present study investigated the potential for neurotrophin uptake by cerebrovascular axons and subsequent accumulation in the aged superior cervical ganglion (SCG) following a two week intracerebroventricular infusion of nerve growth factor (NGF). In the SCG from aged rats, NGF protein levels declined significantly compared with the SCG from young adult rats. Following NGF infusion, perivascular axons from both young adult and aged rats showed intense NGF immunostaining. In addition, significant increases in NGF protein were shown using enzyme-linked immunosorbent assay (ELISA) and in counts of NGF immunopositive cell bodies in the SCG when compared with age-matched controls. NGF accumulation in ganglia from aged rats, however, was significantly less when compared with ganglia from young adult rats. The results of the present study suggest that NGF protein is significantly reduced in aged ganglia with the neurons retaining some capacity to take up and transport exogenous neurotrophin. Even so, the potential for NGF accumulation is dramatically reduced in aged rats when compared with that of young adult rats. While previous results have shown robust NGF-induced neurotransmitter responses by sympathetic neurons from the aged animal, the present finding of reduced accumulation of NGF in aged sympathetic neurons suggests an age-related difference in the utilization or transport of NGF.
Kudwa
A E
AE
Center for Neuroscience, Department of Zoology, 280 Pearson Hall, Miami University, Oxford, OH 45056, USA.
Shoemaker
S E
SE
Crutcher
K A
KA
Isaacson
L G
LG
D000375:Aging / Q000378:metabolism*; D000818:Animals; D020771:Anterior Cerebral Artery / Q000166:cytology / Q000294:innervation; D001369:Axons / Q000378:metabolism; D002452:Cell Count; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007150:Immunohistochemistry; D007276:Injections, Intraventricular; D020932:Nerve Growth Factor / Q000493:pharmacokinetics*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D017207:Rats, Sprague-Dawley; D017783:Superior Cervical Ganglion / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D013995:Time
D020932:Nerve Growth Factor