Insulin-like growth factor-I and -II messenger RNA expression in muscle, heart, and liver of streptozotocin-diabetic swine.
We have investigated the effects of streptozotocin-diabetes and fasting in juvenile swine by monitoring IGF-I and -II gene expression in muscle, heart, and liver tissues. In diabetic pigs, IGF-I messenger RNAs (mRNA) were decreased by 50% in muscle and liver tissues, and by 70% in heart. The imposition of fasting on diabetic animals tended to further decrease IGF-I mRNA levels, and fasting alone also decreased IGF-I mRNA abundance in the three tissues (P less than 0.05). Insulin therapy restored IGF-I mRNA levels to normal in muscle and livers but was less effective in hearts of diabetic pigs. Relative IGF-I mRNA expression in heart and muscle tissues was 2-fold and 4-fold higher, respectively, than in liver tissues under normal conditions in these animals. Serum IGF-I concentrations and tissue extractable immunoreactive IGF-I levels were also measured. Serum IGF-I was markedly decreased in the diabetic state, dropping to 70% below control levels (P less than 0.01). Extractable IGF-I in liver declined by 50% with diabetes (P less than 0.01), and by 30% in muscle with diabetes and fasting (P less than 0.05), but no significant changes in heart levels of IGF-I protein were detected. Expression levels of IGF-II mRNAs in the three tissues were unaffected by diabetes or fasting. These results are consistent with earlier observations in rat liver and further demonstrate that IGF-I expression in muscle and heart is altered by diabetes and fasting, whereas IGF-II mRNAs do not change.
Department of Animal Science, Ohio State University, Columbus 43210.
D W
DW
Leaman
F A
FA
Simmen
T G
TG
Ramsay
M E
ME
White
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D015342:DNA Probes; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D005215:Fasting; D015870:Gene Expression; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D008099:Liver / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000235:genetics*; D013002:Somatomedins / Q000235:genetics*; D013552:Swine
D001786:Blood Glucose; D015342:DNA Probes; D007328:Insulin; D012333:RNA, Messenger; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II