Author/Editor		Pregelj, Peter
Title		Vpliv dejavnikov mišične preobrazbe na izražanje acetilholinesteraze v skeletnih mišicah
Translated title		Influence of muscle transformation factors on acetylcholinesterase expression in skeletal muscles
Type		monografija
Place		Ljubljana
Publisher		Medicinska fakulteta
Publication year		2002
Volume		str. 168
Language		slo
Abstract		Acetylcholinesterase (AChE) is essential for normal synaptic transmission in the neuromuscular junction. In the rat, the level of AChE mRNA in the typical slow soleus muscle is only about 20-30% of that in the predominantly fast extensor digitorum longus (EDL) muscles. Accordingly, AChE activity in rat fast muscles is much higher than that in the slow soleus. Motor units in the soleus muscle are activated tonically with long trains of low-frequency impulses, whereas those in the EDL are excited phasically with rare, short, high frequency bursts of neural discharges. Tonic low-frequency electrical stimulation of fast muscles makes them slower and decreases their AChE expression. We hypothesized that, accordingly, treatments that make the slow soleus muscle faster would increase AChE mRNA levels in this muscle. We, therefore, examined how four such treatments (muscle unloading, treatment with thyroid hormones, the phasic pattern of electrical muscle stimulation and treatment with cyclosporin A, a calcineurin phosphatase inhibitor) influence AChE mRNA levels in the soleus muscle. AChE mRNA levels in muscles were analyzed by Northern blots and evaluated densitometrically. In the soleus muscles, unloaded by hindlimb suspension for 8 days, AChE mRNA levels were not statistically significantly different from the control. A small elevation of AChE mRNA level was indicated only after combination of hindlimb suspension with hindlimb immobilization which maintained the soleus muscle at a medium length. Unexpectedly, tenotomy of the synergistic gastrocnemius muscle, which overloaded the soleus muscle, significantly increased its AChE mRNA level. AChE mRNA level increased greatly in the soleus muscles of rats, treated for 8 days with the thyroid hormone (T3). (Abstract truncated at 2000 characters).
Descriptors		MUSCLE, SKELETAL ACETYLCHOLINESTERASE NEUROMUSCULAR JUNCTION SCIATIC NERVE MUSCLE DENERVATION RATS, WISTAR NERVE CRUSH CALCIUM RNA, MESSENGER ELECTRIC STIMULATION HINDLIMB SUSPENSION CYCLOSPORINE DENSITOMETRY HYPERTHYROIDISM RNA, MESSENGER BLOTTING, NORTHERN