Localization of TGF-beta receptors [type II] in the adult rat muscles

To date, signal transduction of transforming growth factor-beta [TGF-beta] members is well known to occur through three main identified types of protein receptors. Type II receptors [T beta R-II] were found to be prime movers of the signaling process of TGF-beta candidates. Because TGF-beta 2 localizes a neuromuscular junctions [nmjs] of the adult Wistar rats, it would be expectable accumulation of TGF-beta receptors at the same location, i.e. nmjs. Two groups of six Wistar rats were subject to both confocal immunohistochemistry and immunoelectronmicroscopy studies. The main objective of this study was to localize T beta R-II particularly at the nmjs. The results do not prove a clear-cut evidence of T beta R-II accumulation at the nmjs. The receptors would rather scatter near and around the intracellular organelles such as mitochondria in a variable manner. Several assumptions were put forward to explain such variability

Schwann cells of peripheral motor nerve endings undergoing early apoptosis after a brief period of ischemia / reperfusion in wistar rats

Apoptosis is a gene-based programmed death of cells during physiological conditions such as development and aging. Also, apoptotic pathways can be activated in different kinds of tissues under different pathological background such as hormonal changes, toxic agents, or ischemia / reperfusion injury. In this study we tested the effect of ischemia / reperfusion injury for a brief period on terminal Schwann cells of peripheral motor nerve endings. We hypothesize that terminal Schwann cells are sensitive and undergo apoptotic changes under ischemic insult. Therefore, we subjected 8 Wistar rat left legs to 30 min ischemia followed by 15 min reperfusion. The right legs were used as controls. Extensor digitorum longus muscles were dissected and processed for transmission electron microscopic study. Results demonstrated apoptotic changes in terminal Schwann cells and disappearance of basal lamina of neuromuscular junctions. In contrast, muscle fibers did not show any concurrent pathological changes. This indicates that apoptotic changes in Schwann cells would trigger delayed pathological response in muscle fibers. Therefore, more attention would be paid to motor axon terminals as a starting point for pathogenesis and perhaps therapy of motoneuron and neuromuscular diseases

Cellular dynamics of transforming growth factor beta-2 [TGF-beta [2]] in the postnatal developing rat muscles

Transforming growth factor beta-2 [TGF-beta2] is a multifunctional superfamily. TGF-beta2 has been found to be involved in multiple cellular functions including; cell growth, proliferation, differentiation and death. However, the specific function of muscle-derived TGF-beta2 has not been determined. The localization as well as the study of time course of muscle-derived TGF-beta2 is a crucial step towards understanding the role of TGF-beta in the postnatal developing skeletal muscle. Extensor digitorum longus muscles of Wistar rats at ages 0,2,4,7,13,16,19,21,42 and 90 postnatal days were used. The muscles were processed for double labeling immunohistochemistry and confocal examination. Anti-TGF-beta2 antibodies and alpha-bungarotoxin were used to localize TGF-beta 2 in the muscle fibers of the different age groups. The results showed that TGF-beta2 localizes at the mature neuromuscular junction [nmj] after being diffuse throughout the immature muscle cell. The time curse of muscle derived TGF-beta2 can be divided into 3 phases; the first plateau phase, second fluctuant phase and third plateau phase. The second phase demonstrated a sudden increase of muscle derived TGF-beta2 ratio at the nmj coinciding with the timing of synaptic eliminate on phenomenon of the muscle fibers