Beta-endorphin and met-enkephalin in plasma of cattle during pregnancy, parturition and the neonatal period.
Plasma concentrations of beta-endorphin and met-enkephalin were measured, with appropriate radioimmunoassays, in cows during gestation and at parturition and in newborn calves. During pregnancy beta-endorphin immunoreactivity (IR) concentration increased, but values during the last month of gestation were not different from those at parturition. Highest met-enkephalin IR levels were obtained in cows during calving. A term Caesarean section caused an increase in plasma beta-endorphin and met-enkephalin IR concentrations, but no such increase occurred in cases of a preterm Caesarean section. In calves beta-endorphin IR values were lower before umbilical cord rupture than immediately after birth. Values decreased continuously thereafter. This was also the case for met-enkephalin IR concentrations in calves born at term. In preterm calves met-enkephalin IR values were low immediately after delivery and increased during the first hour of life. A significant correlation existed between the degree of acidosis and plasma levels of both opioid peptides in the calves. We conclude that a direct stimulation of peripheral beta-endorphin release by the pain or stress associated with calving does not seem to exist in cattle, whereas met-enkephalin seems to be more directly related to parturition. In calves the change to the extrauterine environment causes an immediate, increased release of both opioids.
Aurich
J E
JE
Klinik für Geburtshilfe, Hannover, FRG.
Dobrinski
I
I
Hoppen
H O
HO
Grunert
E
E
D000818:Animals; D000831:Animals, Newborn / Q000097:blood*; D002417:Cattle / Q000097:blood*; D004744:Enkephalin, Methionine / Q000097:blood*; D005260:Female; D007743:Labor, Obstetric / Q000097:blood*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000097:blood*; D011863:Radioimmunoassay; D001615:beta-Endorphin / Q000097:blood*
D004744:Enkephalin, Methionine; D001615:beta-Endorphin