Abstract
Summary
The results of our experiments indicate a significant difference between the rate of disappearance of TRH from plasma of adult male, pregnant female, and fetal rhesus macaques. In fetal rhesus plasma, TRH exists in an immunoreactive state for a significantly longer period of time than in either pregnant, spayed female, or adult male plasma. If TRH of maternal origin does cross the placenta in physiologically effective quantities, the slower degradation rate does increase the potential effectiveness of the hormone, since it would remain active in the circulation for a longer period of time.
Our evidence also suggests that the estrogen level is not a determining factor in the enzymatic inactivation of TRH. We found no significant difference between inactivation rates in plasma from spayed and pregnant rhesus macaques. Neither did we find a significant difference in the rate of TRH degradation in pregnant rhesus macaques and pregnant women. Therefore, the rhesus macaque should prove to be an acceptable model of TRH influence on fetal development.
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