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

Abstract

The aim of this investigation was to analyze the effect of urodele limb amputation and blastema growth on the protein synthesis in spinal cord and spinal ganglia neurons corresponding to the 3rd and 4th spinal segment of young, postmetamorphic Triturus vulgaris, in vivo. Protein synthesis was studied on both trunk sides as a function of right forelimb amputation at the distal stylopodium, and blastema development, during a critical period of 22 days post amputation (dpa). Protein synthesis was assessed by counting silver grains on autoradiographs obtained after pulse labeling with tritiated phenylalanine. An electronic image analyzer was used to evaluate the results. During the period of observation, several statistically significant, yet moderate changes were observed in the protein synthesis of motor neurons. In contrast, the studied metabolic parameter exhibited considerable augmentation in sensory neurons and spinal nerve. The main results may be summarized as follows: (a) Limb amputation triggers protein synthesis in both ipsilateral and contralateral neural elements; (b) protein synthesis is higher on the ipsilateral than on the contralateral side; (c) as the aftermath of forelimb amputation, the 4th ipsilateral ganglion responds with an approximately 20% higher protein synthesis in comparison to the 3rd one; (d) peaks in protein synthesis are encountered mainly at two time points: 3 hpa and 14 dpa. Protein synthesis returns to control levels after 22 days of limb regeneration.

Origin of Renewed Spinal Ganglia during Tail Regeneration in Urodeles

“…Soon thereafter it was revealed that spinal ganglia might play a leading role in the latter process [Walter, 1919]. Numerous investigations have since been performed in the hope that elucidation of the cellular and molecular parameters in-volved might be used profitably at the clinical level [Anton and Koussoulakos, 1993;Tong et al, 1998]. …”