Inhibition of neonatal rat growth and circulating concentrations of insulin-like growth factor-I using an antiserum to rat growth hormone.
Treatment of rats for 24 h on day 2, 10 or 20 of age with a specific antiserum to rGH (anti-(rGH], GH, bromocriptine (CB-154) or prolactin failed to influence body weight gain or serum concentrations of insulin-like growth factor-I (IGF-I). On day 28 of age, however, anti-(rGH) completely inhibited body weight gain and markedly reduced circulating IGF-I concentrations, effects which were completely prevented by exogenous ovine GH (oGH). When administered to control rats on day 28 oGH caused supranormal weight gain and serum IGF-I concentrations. These results suggested that GH does not play a significant role in growth or regulation of serum IGF-I until after day 20 of age. By contrast, when anti-(rGH) was given for 4 consecutive days beginning on day 2 of life, body weight gain was reduced within 48 h and remained so until at least 28 days of age. Tail length was also significantly reduced. The effect was due to inhibition of GH effects since serum GH concentrations were low and exogenous GH prevented the effect. Inhibition of growth during the first 14 days of life occurred in the absence of any effect on serum IGF-I although by 21 days of age serum IGF-I was considerably lower than in control rats. The prolonged reduction in growth after treatment has stopped appeared to be due to a cytotoxic effect on the pituitary gland since pituitary weight and GH but not prolactin content were significantly decreased.(ABSTRACT TRUNCATED AT 250 WORDS)
Hannah Research Institute, Ayr.
D J
DJ
Flint
M J
MJ
Gardner
D000818:Animals; D000831:Animals, Newborn / Q000097:blood / Q000254:growth & development*; D013006:Growth Hormone / Q000276:immunology / Q000502:physiology*; D007106:Immune Sera / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000097:blood*; D015430:Weight Gain
D007106:Immune Sera; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone