We studied the effect of regeneration, altered innervation and thyroid hormone (TH) levels on fiber type transitions in slow soleus (SOL) muscles grafted (GRAFT) into host extensor digitorum longus (EDLh) muscles of euthyroid (EU), hyperthyroid (HT) and hypothyroid (HY) Lewis strain rats. SOL muscles were excised from 3-week to 4-week-old inbred Lewis rats and intramuscularly transplanted into EDLh muscles of 2-month-old female rats of the same strain. The proportions of type 1, 2A, 2X and 2B fibers of GRAFT were determined by immunohistochemistry and compared with those of EDLh muscle and EDL and SOL muscles of the unoperated contralateral hind limb. After an average regeneration period of 6-7 months and after being reinnervated by the "fast" peroneal nerve of EDLh muscle, GRAFT was transformed into a fast muscle. However, the extent of GRAFT transformation varied with different TH states. In the EU rats, GRAFT contained about 95 % of fast fibers, among which type 2X and 2B fibers predominated (about 75 %). The transition toward fast muscle phenotype was more pronounced in HT status, where the fastest type 2B fibers predominated. On the contrary, in HY status, the slow to fast transformation was less pronounced, as GRAFT contained less type 2B and 2X but more type 2A and 1 fibers. We conclude that the type of innervation is the crucial factor for the slow to fast fiber type transitions in GRAFT, but the extent of muscle transformation is further modulated by altered TH status.

Institute of Physiology Academy of Sciences of the Czech Republic v v i Vídeňská 1083 142 20 Prague Czech Republic

Zobrazit více v PubMed

FEBS Lett. 1996 Dec 16;399(3):220-2 PubMed

Int Rev Cytol. 1997;170:143-223 PubMed

Muscle Nerve. 1997 Dec;20(12):1487-96 PubMed

Horm Metab Res. 2004 May;36(5):286-90 PubMed

Physiol Res. 2004;53 Suppl 1:S57-61 PubMed

Physiol Res. 2012;61(6):575-86 PubMed

J Muscle Res Cell Motil. 1996 Aug;17(4):401-9 PubMed

Physiol Res. 2005;54(6):691-6 PubMed

Gen Physiol Biophys. 1999 Dec;18 Suppl 1:84-6 PubMed

Horm Metab Res. 2013 Jul;45(7):507-12 PubMed

News Physiol Sci. 1991 Feb;6:1-6 PubMed

Physiol Res. 2014;63(Suppl 1):S133-40 PubMed

Acta Neuropathol. 2000 Oct;100(4):435-44 PubMed

J Appl Physiol (1985). 1994 Aug;77(2):493-501 PubMed

Eur J Histochem. 2008 Jul-Sep;52(3):179-90 PubMed

Physiol Res. 2014;63(Suppl 1):S119-31 PubMed

Acta Neuropathol. 2001 Nov;102(5):473-84 PubMed

Am J Physiol. 1998 Mar;274(3):R864-7 PubMed

Histochem J. 1999 May;31(5):277-83 PubMed

Physiol Res. 2001;50(6):619-26 PubMed

J Appl Physiol (1985). 1997 Feb;82(2):552-7 PubMed

Rev Physiol Biochem Pharmacol. 1992;120:115-202 PubMed

Acta Histochem. 2002;104(4):399-405 PubMed

J Appl Physiol (1985). 1987 Jun;62(6):2507-11 PubMed

Physiol Res. 2009;58(2):253-262 PubMed

Horm Metab Res. 2011 Jan;43(1):43-7 PubMed

Can J Appl Physiol. 2002 Aug;27(4):423-48 PubMed

Histochem Cell Biol. 2001 May;115(5):359-72 PubMed

Anat Embryol (Berl). 1995 Sep;192(3):283-91 PubMed

FASEB J. 1991 Dec;5(15):3064-70 PubMed

Muscle Nerve. 2000 May;23(5):661-79 PubMed

Physiol Res. 2007;56(6):833-6 PubMed

Acta Physiol (Oxf). 2010 Aug;199(4):451-63 PubMed

Physiol Res. 2013;62(4):445-53 PubMed

Physiol Res. 2000;49(6):617-33 PubMed

J Muscle Res Cell Motil. 1995 Jun;16(3):295-302 PubMed

Physiol Rev. 1996 Apr;76(2):371-423 PubMed

Histochemistry. 1979 Feb 26;60(1):71-84 PubMed

Altered thyroid status affects myocardial expression of connexin-43 and susceptibility of rat heart to malignant arrhythmias that can be partially normalized by red palm oil intake

Effect of altered innervation and thyroid hormones on myosin heavy chain expression and fiber type transitions: a mini-review