Myostatin expression in porcine tissues: tissue specificity and developmental and postnatal regulation. Ji, Shaoquan, R. L. Losinski, S. G. Cornelius, G. R. Frank, G. M. Willis, D. E. Gerrard, F. F. S. Depreux and M. E. Spurlock, Purina Mills, Inc. St. Louis, Mo and Purdue University, West Lafayette, In . Michael Spurlock, Purina Mills, Inc. Research Center, 100 Danforth Drive, Gray Summit, MO 63039, Telephone: (314) 768-4437, Facsimile: (314) 768-4108, email: mike_spurlock@purina-mills.com
APStracts 5:0257R, 1998.
The objective of this study was to establish the developmental pattern and tissue specificity of porcine myostatin expression, and to evaluate expression in skeletal muscle during circumstances in which muscle growth was altered. Northern blot analysis revealed two transcripts (1.5 and 0.8 kb). Myostatin mRNA was detected in whole fetuses at 21 and 35 days and was markedly increased (P < 0.05) by 49 d. At birth, mRNA abundance in longissimus muscle had declined significantly (P < 0.05) from that at day 105 of gestation and continued to decrease (P < 0.05) to its lowest level 2 weeks postnatally (4 kg body weight). Myostatin expression was higher (P < 0.05) at 55, 107, and 162 kg body weight than at 4 kg body weight. Postnatally, myostatin mRNA was detected in skeletal muscle and mammary gland. Expression at birth was 65% higher (P < 0.04) in longissimus muscle of low birth weight piglets (0.57 ( 0.052 kg body weight) vs. normal (1.37 ( 0.077 kg body weight) littermates, irrespective of gender. However, suppression of longissimus muscle growth by food deprivation (3 days) did not alter (P > 0.15) myostatin expression in either 4- or 7-week old piglets. Additionally myostatin mRNA abundance was not changed by porcine growth hormone administration in growing animals. These data indicate that myostatin expression in skeletal muscle peaks prenatally and that greater expression is associated with low birth weight. Expression in mammary gland indicates a possible role for myostatin in mammary gland development and(or) lactation. 

Received 24 March 1998; accepted in final form 8 July 1998.
APS Manuscript Number R177-8.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 30 July 1998