To test the hypothesis that response to
insulin by regulating
glucose and lipid metabolism in gibel carp A strain may be different from that in DT strain, bovine
insulin was injected into both strains of gibel carp after previous fasting for 48h. The results showed that
insulin induced
hypoglycemia at 3h in 2 strains, and that this was coupled with increased expression of
glucose transporters (GLUT2 in the liver and GLUT1, GLUT4 in the muscle) and glycolytic
enzyme (HK2 in the muscle) in both strains.
Insulin induced increased glycolysis (GK) and
fatty acid oxidation (ACO3 in the liver and CPT1a, ACO3 in the muscle) in the DT strain. Conversely, very strong lipogenic capacity, as indicated by higher
mRNA levels of
transcription factor of
fatty acid anabolism (SREBP1) and lipogenic
enzymes (ACC, ACLY, and FAS) and decrease lipolytic capacity as indicated by lower
mRNA levels of
fatty acid oxidation
enzymes in the liver (ACO3) and muscle (CPT1a and ACO3) detected in the A strain after
insulin injection. Higher plasma
insulin levels and decreased plasma
free fatty acid levels were detected at 8h post
insulin injection in A strain induced
hypoglycemia. However, plasma
glucose levels returned to baseline and no effect on
fatty acid levels in the DT strain was observed in response to
insulin treatment at the same point in time. These
insulin-strain interactions demonstrated that
insulin induced different changes in
glucose and lipid metabolism in these 2 strains as expected.