Effects of compensatory growth on the levels of IGF-1, IGFBP-1 and expressions of IGF-1 mRNA, IGF-1R mRNA in Carassius auratus gibelio

We studied the effects of starvation and re-feeding on the levels of plasma IGF-1, IGFBP-1 and expressions of hepatic IGF-1 mRNA and muscle IGF-1R mRNA in Carassius auratus gibelio. During the two week starvation period, both the levels of plasma IGF-1 and IGFBP-1 decreased and were significantly lower on day 14 (P<0.05). On the first day of re-feeding, the level of plasma IGF-1 increased sharply, to the level of control group, and had no significant changes for the remaining days. While the level of plasma IGFBP-1 was still greatly lower than that of control group at the first day of re-feeding, it increased significantly higher than that of control group by day 14 (P<0.05). During the starvation period, expression of IGF-1 mRNA in liver decreased, but it was not statistically different from that of the control group (P>0.05). During the early period of re-feeding, the abundance of IGF-1 mRNA was still significantly lower than that of control group (P<0.05), then increased to the level of control group on day 7. IGF-1R mRNA showed a decreasing trend after starvation, and reached a significantly low value on day 3 (P<0.05). After re-feeding, the abundance of IGF-1R mRNA increased to peak at day 14. These results indicate that the higher level of IGFBP-1 in serum and IGF-1R mRNA in muscle after re-feeding could improve the promoting growth effect of IGF-1 to participate in the regulation of compensatory growth.