The effect of nerve growth factor and limb regeneration on the spinal and sympathetic ganglia of Triturus

Abstract

In Triturus administration of NGF causes hypertrophy of neuronal perikarya of third dorsal root ganglia and post-subclavian sympathetic ganglia. Two classes of neurons were characterized cytologically in the third dorsal root ganglia. Some evidence is presented which indicates that Class I neurons respond more vigorously to NGF. It is suggested that Class I neurons are similar to the medio-dorsal neuroblasts of chick embryos in their response to NGF. Forelimb amputation did not cause neuronal hypertrophy in either third dorsal root ganglia or post-subclavian sympathetic ganglia. The incorporation of (3H)-uridine increases to a highly significant extent in third dorsal root ganglia following NGF treatment or limb amputation. When NGF treatment and limb amputation were combined, no further increase in (3H)-uridine incorporation was noted. This suggests that RNA synthesis is maximally stimulated by either NGF treatment alone or limb amputation alone.

Unilateral Forelimb Amputation Affects Protein Synthesis in Ipsilateral and Contralateral Spinal Cord and Spinal Ganglia Neurons of the Newt in vivo

“…In this respect, our results coincide with findings reported in the relevant literature [21] and, in agreement with others [8,15], they do not differ signifi cantly from those obtained from nonamputated animals. Thus, this issue will be not discussed further.…”

“…by reflux) and/or turnover vari ations between individual animals, the mean nuclear area and silver grain density were estimated at 300 basal layer cell nuclei of the adjacent, dorsal epidermis [18], The values estimated in the nerve tissues were divided by these corresponding values found in the epidermis. The merit of the epidermis as a reference tissue is well documented [8,19], For convenient reading, the ratios obtained by the division of areas were abbreviated as RA (relative area) whereas, the ratios between silver grain counts were termed RS (relative silver grain density). In the text, the numbers representing RA and RS are accompanied by a parenthesis, wherein the values of the measured parameters are expressed as percentages of the control values (100%).…”

“…The perikarya of the affected fibers respond to these lesions by chromatolysis [6] and alterations in RNA [7,8] and protein [4,9] synthesis in vitro. In this respect, it was early recognized that the presence of a regeneration blastema on a limb amputation stump prevents retro grade nerve degeneration and exerts other influences on the nerves as well [10,11].…”

A brief history of the study of nerve dependent regeneration

“…Nevertheless, more recent approaches have strongly supported the notion that nerves supply one or more growth factors which are crucial for blastemal proliferation. Implicated factors include substance P, 49,50 insulin, [51][52][53] transferrin, 54,55 nerve growth factor, 56,57 and fibroblast growth factors with BMPs. -61 Much of this work has been conducted on cultured blastemal cells, and together these findings suggest that there is a constellation of factors working in conjunction to communicate proliferative signals from the nerve to the regenerating blastema.…”

“…56 Treatment with NGF increases the labeling index of dorsal root ganglia, as does amputation of the limb, although the effects are not combinatory. 57 Newt anterior gradient Expressed in the blastema and lost upon denervation; stimulates blastemal cell proliferation in culture; electroporation into denervated newt limbs rescues regeneration. 62 Stimulation of blastemal cells can be blocked with a mutation to the anterior gradient active site or the addition of antibody to the receptor Prod1.…”