Schwann cell-neuronal interactions in the rat involve nerve growth factor.
To gain some insight into possible functions of nerve growth factor (NGF), we suppressed the endogenous levels of NGF in newborn rats by subcutaneous injections (3 microliters/g body weight) of rabbit antibodies to purified mouse beta-NGF (ANTI-NGF). Fiber and axonal areas and perimeters were measured for unmyelinated and myelinated sensory fibers in T9 dorsal roots (DR) in three groups of animals: 1) ANTI-NGF treated littermates, 2) preimmune sera treated littermates (PREIMM), and 3) untreated littermates (UNTR). In some rats, fibers in ventral roots (VR) were measured and, in other rats, sensory processes in peripheral nerves (PN) were measured following radical ventral rhizotomy. The only outer area and perimeter measurements that were statistically different were those in the ventral root (P less than 0.013 and P less than 0.043, respectively). However, myelin thickness was significantly thinner in the dorsal roots of the ANTI-NGF group than in the dorsal roots of the UNTR and PREIMM groups (P less than 0.000009 and P less than 10(-6), respectively). Myelin thickness in the ventral roots of the ANTI-NGF group was also statistically thinner than that in the UNTR group (P less than 0.001). There were no statistically significant differences when comparing the UNTR group to the PREIMM group. In the peripheral nerves studied, there was no significant change in the myelin thickness between the ANTI-NGF and UNTR groups of animals. These results indicate that Schwann cell-neuronal interactions are altered by the inactivation of NGF, and that 1) the central processes of sensory fibers are affected and not the peripheral processes and 2) motor fiber myelination is altered.(ABSTRACT TRUNCATED AT 250 WORDS)
Urschel
B A
BA
Department of Anatomy and Neuroscience, University of Texas Medical Branch, Galveston 77550-2772.
Hulsebosch
C E
CE
D000818:Animals; D000831:Animals, Newborn; D007106:Immune Sera / Q000494:pharmacology; D009186:Myelin Sheath / Q000187:drug effects / Q000502:physiology*; D009414:Nerve Growth Factors / Q000276:immunology / Q000502:physiology*; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012583:Schwann Cells / Q000187:drug effects / Q000502:physiology*; D013126:Spinal Nerve Roots / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
D007106:Immune Sera; D009414:Nerve Growth Factors