Overexpression of nerve growth factor in epidermis of transgenic mice preserves excess sensory neurons but does not alter the somatotopic organization of cutaneous nerve projections.
To determine how target-derived nerve growth factor (NGF) affects sensory neuronal survival and the development of topographic nerve projections in the spinal cord, anatomical studies were performed on transgenic mice that overexpress NGF in skin and other keratinized epithelial structures. Transgenic animals showed a 100% increase in the number of sensory neurons in specific dorsal root ganglia and exhibited significantly more fibers immunoreactive for calcitonin gene-related peptide in the dorsal horn compared to control animals. This confirms earlier studies which suggested that naturally occurring sensory neuronal death is decreased, or eliminated, in the transgenic mice. Nerve labeling studies showed that the somatotopic organization of cutaneous nerve projections was not altered in the transgenic animals. These data suggest that neuronal death does not act to remove sensory neurons that project to inappropriate regions of the spinal cord.
Mendelson
B
B
Department of Anatomy (Slot 510), University of Arkansas for Medical Sciences, Little Rock 72205-7199, USA.
Albers
K M
KM
Goodness
T P
TP
Davis
B M
BM
D000818:Animals; D002232:Carbocyanines; D016923:Cell Death / Q000502:physiology; D004817:Epidermis / Q000294:innervation / Q000378:metabolism*; D005456:Fluorescent Dyes; D005727:Ganglia, Spinal / Q000166:cytology; D007150:Immunohistochemistry; D051379:Mice; D008822:Mice, Transgenic; D009412:Nerve Fibers / Q000502:physiology; D009414:Nerve Growth Factors / Q000096:biosynthesis* / Q000235:genetics; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology*
D002232:Carbocyanines; D005456:Fluorescent Dyes; D009414:Nerve Growth Factors; C024286:3,3'-dioctadecylindocarbocyanine