Endocrinology and metabolism vol:4 issue:5 pages:321-328
The effects of a single intravenous injection of insulinlike growth factor(IGF)-I, IGF-II, or antiserum against either IGF on plasma hormone and glucose levels, respiratory quotient (RQ) and heat production (HP) were measured over 24 h in meat-type chickens. Plasma levels of IGF-I were elevated by administration of exogenous IGF-I, and circulating IGF-I was immuno-neutralized using a potent, specific antiserum to IGF-I. The same experimental protocol was repeated on other chickens using IGF-II, and anti-IGF-ll. Following IGF-I administration, plasma IGF-I concentrations were elevated for 6 h. Plasma growth hormone (GH), triiodothyronine (T-3) and glucose concentrations were all decreased in the first 3h after IGF-I, and then followed by a rebound to higher than initial levels. There was no significant effect on 24 h HP, but a sharp drop in RQ was observed in the first 6 h. Administration of anti-IGF-I serum produced decreased plasma IGF-I and elevated plasma glucose and T-3 concentrations. After an initial rise, plasma GH levels were decreased with anti-IGF-l treatment. Anti-IGF-l treatment was also associated with a lower (P<0.05) 24 h HP, but there was no clear effect on RQ. Injection of IGF-II or anti-IGF-ll serum resulted in similar hormonal changes as those seen following IGF-I and anti-IGF-l, respectively. Also, RQ values dropped markedly after IGF-II administration.