Effects of postnatal anti-NGF on the development of CGRP-IR neurons in the dorsal root ganglion.
Experiments were undertaken to examine anatomical correlates of physiological effects of rabbit sera raised against nerve growth factor (anti-NGF) on nociceptive afferents. This antiserum has been shown to deplete the population of A-delta high threshold mechanoreceptors and to reduce neurogenic vasodilatation. Because numerous studies implicate calcitonin gene related peptide (CGRP)-containing sensory neurons in these effects, immunocytochemical and anatomical techniques were used to examine the normal development of CGRP-immunoreactive (-IR) neurons in the dorsal root ganglion (DRG) of rats from 13 days to 19 weeks of age, and to compare this to the development in rats treated neonatally (postnatal days 2-14) with anti-NGF. In controls the rate of increase in the mean diameter of CGRP-IR cells was substantially greater between 13 days and 5 weeks of age than it was between 5 weeks and 19 weeks, in contrast to CGRP-negative neurons whose rate of growth remained relatively constant. Anti-NGF had no significant effect on growth rate, but rats treated with anti-NGF exhibited a reduced proportion of CGRP-IR neurons at 5 weeks. This deficit was reversed by 19 weeks unlike the physiological changes. These results indicate independent regulation of CGRP expression and nociceptor physiology by NGF.
Tonra
J R
JR
Department of Physiology and Biophysics, SUNY at Stony Brook, New York 11794, USA.
Mendell
L M
LM
D000818:Animals; D000906:Antibodies / Q000494:pharmacology*; D015740:Calcitonin Gene-Related Peptide / Q000032:analysis*; D002454:Cell Differentiation / Q000502:physiology; D048429:Cell Size; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology / Q000502:physiology*; D009414:Nerve Growth Factors / Q000276:immunology*; D009474:Neurons / Q000737:chemistry / Q000166:cytology*; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley
D000906:Antibodies; D009414:Nerve Growth Factors; D015740:Calcitonin Gene-Related Peptide