Author/Editor		Pregelj, P; Črne-Finderle, N; Sketelj, J
Title		Effect of thyroid hormones on acetylcholinesterase mRNA levels in the slow soleus and fast extensor digitorum longus muscles of the rat
Type		članek
Source		Neuroscience
Vol. and No.		Letnik 116
Publication year		2003
Volume		str. 657-67
Language		eng
Abstract		In the rat, the level of acetylcholinesterase messenger RNA in the typical slow soleus musctes is only about 20-30% of that in the fast extensor digitorum longus muscles. The expression of contractile proteins in muscles is influenced by thyroid hormones and hyperthyroidism makes the slow soleus muscle faster. The influence of thyroid hormones on the leveis of acetylcholinesterase messenger RNA level in the slow soleus and fast extensor digitorum longus muscle of the rat was studied in order to examine the effect of thyroid hormones on muscle acetylchoiinesterase expression. Hyperthyroidism was induced in rats by daily thyroid hormone injection or thyroid hormone releasing tablet impiantation. Hind-limb suspension was applied to produce muscle unloading. Muscle denervation or reinnervation was achieved by sciatic nerve transection or crush. Acetylcholinesterase messenger RNA levels were analyzed by Northern blots and evaluated densitometrically. Hyperthyroidism increased the levels of acetylcholinesterase messenger RNA in the slow soleus muscles close to the levels in the fast extensor digitorum longus. The effect was the same In the unloaded soleus muscles. Acetylcholinesterase expression increased also in the absence of innervation (denervation), in the presence of changed nerve activation pattern (reinnervation), and under enhanced tonic neural activation of the soleus muscle (electrical stimulation). However, the changes were substantially smaller than those observed in the control soleus muscies. Enhancement of acetylcholinesterase expression ln the soleus muscles by the thyroid hormones is, therefore, at last ln part due to hormonai effect on the muscle itself. On the contrary, Increased level of the thyroid hormones had no infiuence on acetylcholinesterase expression in the normal fast extensor digitorum longus muscles. (Abstract truncated at 2000 characters).
Descriptors		MUSCLE, SKELETAL MUSCLE FIBERS, FAST-TWITCH MUSCLE FIBERS, SLOW-TWITCH ACETYLCHOLINESTERASE RATS, WISTAR RNA, MESSENGER HYPERTHYROIDISM ELECTRIC STIMULATION MUSCLE DENERVATION HINDLIMB SUSPENSION BLOTTING, NORTHERN