Abstract
The long term effect of daily injections of GRF (1μg/kg bw,sc) was studied in developing male rats.In two additional groups GRF was stopped on day 30 and on day 50.Weight and length were measured at 5 days intervals,GH and somatomedin were measured at diverse time points by RIA.When compared to the controls,GRF treated animals did not differ in length at the end of the observation period (day 75) .On the other hand, the growth pattern was markedly different.GRF treated animals grew faster from day 15 to day 25,and had significantly lower GH levels than the controls on day 30(3.0±1 vs 23.0±12 ng/ml,p < 0.01).Growth velocity in the GRF group decreased slightly until day 45,on which experimental and control group did not differ any more in length.On the contrary,a significant catch up in length(p < 0.001),followed by a decrease in growth velocity was observed when GRF was stopped on day 30,final length not differing from the controls.This pattern was not observed when treatment was stopped on day 50 .On the other hand,a significant and lasting increase in weight was observed after GRF withdrawal in both groups.These animals were on day 75 significantly heavier than the chronically treated and the controls(286±16 and 287±8 vs 272±7 and 264±12 gr,p < 0.05).The results indicate that chronic GRF administration might alter GH secretion possibly by down regulation of pituitary receptors, and affects the pubertal growth pattern,but not the final length.
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Attanasio, A., Hausch, S., Blum, W. et al. 47 EFFECT OF CHRONIC GRF ADMINISTRATION ON MALE RATS DURING PUBERTAL DEVELOPMENT. Pediatr Res 19, 611 (1985). https://doi.org/10.1203/00006450-198506000-00067
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DOI: https://doi.org/10.1203/00006450-198506000-00067