Distribution and relative density of p75 nerve growth factor receptors in the rat spinal cord as a function of age and treatment with antibodies to nerve growth factor.
It has been postulated that nerve growth factor (NGF) binding to the low-affinity fast-dissociating NGF receptor (p75 NGFR) on Schwann cells and growing neurites is involved with the molecular feedback necessary for continued neurite extension during development and regeneration. Since central projections of somatosensory fibers sprout into the spinal cord after daily neonatal injections of antibodies to NGF (ANTI-NGF) for a one month period, it is of interest to determine if the distribution of p75 NGFR correlates with the occurrence of sprouting. Spinal cords from three groups of rats: untreated, preimmune sera treated and ANTI-NGF treated were examined on postnatal days (PD) 0, 14 and 30. The p75 NGFR distribution was determined using the monoclonal antibody 192 with standard immunohistochemical techniques and the optical density of the immunoreaction product was quantified using an Amersham image analysis system. The 192 immunoreaction product was localized to laminae I-IV, the dorsal columns, the dorsolateral funiculus, Lissauer's tract (LT) and the ventral horn on PD 0; to laminae I-III and medial IV and LT on PD 14; and laminae I-II and LT on PD 30. The untreated and preimmune sera treated groups show no difference in distribution. In the ANTI-NGF treated group, the 192 immunoreaction product was localized to laminae I-V and LT on PD 14 and to laminae I-III and medial IV and LT on PD 30. Similarly, the optical density of the ANTI-NGF treated group was significantly greater than same aged untreated and preimmune sera treated groups, but was not statistically different from these two groups examined 14 days earlier. Thus, ANTI-NGF treatment interferes with the postnatal downregulation of p75 NGFR in the dorsal horn and may provide for continued neurite growth.
Urschel
B A
BA
Department of Neuroscience, McMaster University, Hamilton, Ont., Canada.
Hulsebosch
C E
CE
D000375:Aging / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D000906:Antibodies / Q000494:pharmacology*; D005728:Ganglia, Sympathetic / Q000254:growth & development* / Q000378:metabolism; D007150:Immunohistochemistry; D009414:Nerve Growth Factors / Q000276:immunology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017475:Receptors, Nerve Growth Factor / Q000032:analysis / Q000378:metabolism*; D013116:Spinal Cord / Q000254:growth & development* / Q000378:metabolism
D000906:Antibodies; D009414:Nerve Growth Factors; D017475:Receptors, Nerve Growth Factor