J Korean Soc Endocrinol.  1994 Sep;9(3):213-218.

Effect of Insulin Like Growth Factor - 1 (IGF - 1) on Energy Restricted Rat - Failure of IGF - 1 injection to promote growth in energy restricted rats despite normalization of serum IGF - 1 concentration -

• Shin JH

Abstract

recombinant human IGF-I in energy-restriction model. Experimental design; Sprague-Dawley rats(n=20) weighing 90-100g were used. Rats were fed a control diet two times a day(AM 8-11, PM 5-8) for four days after arrival and then assigned to one of three groups: control, energy-restricted, energy-restricted IGF-I treatment group. Energy restricted group was given with a decrese of 25% in the energy without changes in the protein by feeding 88% by weight to energy-restricted diet. During the 10days of energy restriction, the growth rate was reduced by 35%(2.70+-0.18g/day in energy restricted group vs. 4.13+-0.75g/day in the control group). At sacrifice, the tail lengh and weight of organs were not significantly decreased except the spleen and thymus(-17%: P<0.05). Serum IGF-I was reduced by 19% at the end of 10days of energy restriction. The glycemia, measured each day by glucometer from blood collected at the tail, was not reduced by energy restriction(105.4+-7.7 in control group vs. 101.3+-4.1mg/dl). The abundance of serum IGF-BPs was unchanged by this restriction.Despite the 1.5 fold increase of IGF-I concentration in energy restricted IGF-I injection group at sacrifice(1994+-172ng/ml vs. 1221+-110 ng/ml energy restricted group), IGF-I treatment(300 ug/day in twice sc injection for 6day) did not significantly accelerate the growth rate(body weight)(2.87+-0.20 vs. 2.70+-0.18g/day in energy restricted group).The glycemia was slightly reduced by IGF-I treatment(91.7+-5.0 mg/dl vs. 101.3+-4.5 mg/dl in energy restricted group), but it was not significant. However, the spleen and thymus weight, decreased by energy restriction, was completely normalized by IGF-I treatment.In summary, lack of a significant anabolic response to injection of IGF-I during energy restriction in this study may be associated with the compensatory growth response(alterations in dietary protein utilization) which followed initial period of energy restriction.

MeSH Terms

Animals
Diet
Dietary Proteins
Humans
Insulin*
Insulin-Like Growth Factor I
Rats*
Rats, Sprague-Dawley
Research Design
Spleen
Tail
Thymus Gland
Dietary Proteins
Insulin
Insulin-Like Growth Factor I