TY - JOUR
T1 - The expression of insulin and insulin receptor mRNAs is regulated by nutritional state and glucose in rainbow trout (Oncorhynchus mykiss)
AU - Caruso, Michael A.
AU - Sheridan, Mark A.
N1 - Funding Information:
We would like to thank Jeff Kittilson, Chad Walock, Katie Reindl, and Sarah Danielson for their technical assistance. This research was supported by Grants from the National Science Foundation, USA ( EPS 0814442 , IOS 0920116 ) to M.A.S. M.A.C. was supported by a fellowship from ND EPSCoR .
PY - 2012/1/15
Y1 - 2012/1/15
N2 - Many species of fish, including rainbow trout, possess multiple INS- and IR-encoding mRNAs. In this study, rainbow trout (Oncorhynchus mykiss) were used as a model to study the regulation of INS (INS1, INS2) and IR (IR1, IR2, IR3, and IR4) mRNA expression by nutritional state and glucose. In the nutritional state study, fish were either fed continuously, fasted (4 or 6. weeks), or fasted 4. weeks, then refed for 2. weeks. Nutritional state regulated INS and IR mRNA expression in a subtype- and tissue-specific manner. A 4-week fast reduced INS1 expression in endocrine pancreas (Brockmann body) and of INS1 and INS2 in brain, whereas a 6-week fast reduced the expression of both INS1 and INS2 in pancreas but only of INS1 in brain. Refeeding only restored INS2 levels in pancreas. In adipose tissue, by contrast, a 4-week fast increased INS1 expression, and a 6-week fast increased the expression of both INS1 and INS2. Nutritional state also modulated the pattern of IR mRNA expression. Fasting for 4. weeks resulted in no significant change in IR expression. Prolonged fasting (6. weeks) increased the expression of IR4 mRNA in the pancreas, adipose tissue, cardiac muscle, and gill; however, fasting decreased expression of IR3 mRNA in liver. Refeeding restored fasting-associated increases in IR4 expression in pancreas, adipose tissue, cardiac muscle, and gill, but had no effect on the fasting-associated decrease in IR3 expression in liver. Glucose differentially regulated the expression of INS and IR mRNAs in Brockmann bodies and liver pieces incubated in vitro, respectively. Low glucose (1. mM) reduced pancreatic expression of both INS1 and INS2 mRNAs compared to levels observed at 4 or 10. mM glucose. In the liver, IR1 and IR2 mRNA expression was insensitive to glucose concentration, whereas expression of IR3 and IR4 was attenuated at 1 and 10. mM compared to 4. mM glucose. These findings indicate that the pattern of INS and IR expression in selected tissues is regulated by nutritional state and glucose.
AB - Many species of fish, including rainbow trout, possess multiple INS- and IR-encoding mRNAs. In this study, rainbow trout (Oncorhynchus mykiss) were used as a model to study the regulation of INS (INS1, INS2) and IR (IR1, IR2, IR3, and IR4) mRNA expression by nutritional state and glucose. In the nutritional state study, fish were either fed continuously, fasted (4 or 6. weeks), or fasted 4. weeks, then refed for 2. weeks. Nutritional state regulated INS and IR mRNA expression in a subtype- and tissue-specific manner. A 4-week fast reduced INS1 expression in endocrine pancreas (Brockmann body) and of INS1 and INS2 in brain, whereas a 6-week fast reduced the expression of both INS1 and INS2 in pancreas but only of INS1 in brain. Refeeding only restored INS2 levels in pancreas. In adipose tissue, by contrast, a 4-week fast increased INS1 expression, and a 6-week fast increased the expression of both INS1 and INS2. Nutritional state also modulated the pattern of IR mRNA expression. Fasting for 4. weeks resulted in no significant change in IR expression. Prolonged fasting (6. weeks) increased the expression of IR4 mRNA in the pancreas, adipose tissue, cardiac muscle, and gill; however, fasting decreased expression of IR3 mRNA in liver. Refeeding restored fasting-associated increases in IR4 expression in pancreas, adipose tissue, cardiac muscle, and gill, but had no effect on the fasting-associated decrease in IR3 expression in liver. Glucose differentially regulated the expression of INS and IR mRNAs in Brockmann bodies and liver pieces incubated in vitro, respectively. Low glucose (1. mM) reduced pancreatic expression of both INS1 and INS2 mRNAs compared to levels observed at 4 or 10. mM glucose. In the liver, IR1 and IR2 mRNA expression was insensitive to glucose concentration, whereas expression of IR3 and IR4 was attenuated at 1 and 10. mM compared to 4. mM glucose. These findings indicate that the pattern of INS and IR expression in selected tissues is regulated by nutritional state and glucose.
KW - Fasting
KW - Glucose
KW - Insulin
KW - Insulin receptor
KW - Nutritional state
KW - Quantitative real-time RT-PCR
KW - Rainbow trout
UR - http://www.scopus.com/inward/record.url?scp=84855210940&partnerID=8YFLogxK
U2 - 10.1016/j.ygcen.2011.11.029
DO - 10.1016/j.ygcen.2011.11.029
M3 - Article
C2 - 22154645
AN - SCOPUS:84855210940
SN - 0016-6480
VL - 175
SP - 321
EP - 328
JO - General and Comparative Endocrinology
JF - General and Comparative Endocrinology
IS - 2
ER -