Abstract
The effect of the somatotropic hormone on the « in vitro » growth of explants from chick embryos are studied. According to literature data, it would be suggested that the peripheral effects of the somatotropic hormone (diabetogenous and growth promoting effect) may be indirect, that is related, at least in part, to the glucagone secretion.
Aim of the present study is the demonstration of a possible direct action of the hypophyseal growth hormone.
The growth was determined by micrometric meauserements of the migration area of explants in 4 days old cultures.
A 26,98 per cent growth increase was exerted by STH at a concentration of 1/1.000.000, no action at a concentration of 1/200.000 and a 33,11 per cent growth inhibition at a concentration of 1/100.000.
The apparently paradoxical action of high doses could be likely related to the glycoinhibiting effect of the growth hormone (prevention of glucokinase reaction). Such effect may be subliminal with low doses, which would therefore demonstrate only the growth promoting action (stimulation of the protein anabolism); with increased doses it would reach the sensitivity threshold of the cell by abolishing at first and by inverting later the hormone activity.
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