title: Synthesis and catabolism of progesterone in placentas from normotensive and severely hypertensive patients before and after parturition.
abstract: We measured the synthesis of progesterone (P) from pregnenolone and its conversion into 20 alpha-dihydroprogesterone (20 alpha-DHP) in placentas obtained from 12 patients with severe pregnancy-induced hypertension and from 24 normotensive patients. There was no significant difference between placentas from hypertensive and normotensive patients with respect to mitochondrial 3 beta-hydroxysteroid dehydrogenase: delta 5-isomerase activity both before and after labor, indicating that the capacity of this organ to synthesize P remains unchanged during labor in both groups of patients. There was a significant (p less than 0.05) difference in 20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSDH) activity in placental supernatants obtained from normotensive patients before (853.58 +/- 293 pmoles of 20 alpha-DHP/mg of protein/hr) and after (1,156.66 +/- 280 pmoles/mg of protein/hr) labor. In contrast, 20 alpha-HSDH activity in placental supernatants obtained from hypertensive women before (644.30 +/- 236 pmoles/mg of protein/hr) and after (697.17 +/- 524 pmoles/mg of protein/hr) labor was not significantly different. As a consequence, the endogenous 20 alpha-DHP concentration, which was significantly increased after labor in placentas from normotensive women, remained unchanged in placenta from women with pregnancy-induced hypertension. These results indicate that premature activation of the P to 20 alpha-DHP pathway causing "in situ" P withdrawal does not seem to be an adequate explanation for the increased contractility and the tendency to preterm labor commonly exhibited by patients with pregnancy-induced hypertension
mesh_terms: D015089:20-Hydroxysteroid Dehydrogenases / Q000378:metabolism; D004092:20-alpha-Dihydroprogesterone / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D006973:Hypertension / Q000378:metabolism*; D007743:Labor, Obstetric; D008931:Mitochondria, Muscle / Q000378:metabolism; D010920:Placenta / Q000378:metabolism*; D011225:Pre-Eclampsia / Q000378:metabolism; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000378:metabolism*; D011284:Pregnenolone / Q000378:metabolism; D011374:Progesterone / Q000378:metabolism*
chemical_list: D004092:20-alpha-Dihydroprogesterone; D011374:Progesterone; D011284:Pregnenolone; D015089:20-Hydroxysteroid Dehydrogenases