In normal rate, after 2 min Restraint stress, plasma ACTH and β-Endorphine were significantly increased in 5 min, thereafter, gradually decreased to the normal.
In adrenalectomized rats, after 2 min restraint stress, plasma ACTH and β-Endorphine were similary significantly increased in 5 min, threafter gradually decreased to the normal.
In pregnant female, during pregnancy ACTH and β-Endorphine were maintained the same level without fluctuation. But, in labor, at the beginning (less than 4 cm dilatation of cervical os)they began to rise through the period (more than 4 cm
dilatation of
cervical os) and reached to the peak at the time of delivery.
The serum ACTH land β-Endorphine from cord blood of newborn infants showed the similar level to those of mid-labor of mothers.
As the 2 min restraint stress to the rats, the stress like labor in human show the increased secretion of ACTH, β-Endorphine. Subsequently, 2 min restraint stress in rats, and labor in human appear to act the similar mechanism, Since, in
adrenalectomized rats, the ACTH and β-Endorphine were markedly increased, 2 min restraint stress stimulus the increased secretion. In human, the pituitary is also suspected for that.
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