Presence of Acetylated and Shortened Endorphins in Human Fetal Pituitary Gland

Abstract

A total of 21 human fetal pituitaries was collected from spontaneous abortions (11 cases) or prostaglandin (PG)-induced abortions at the second trimester. Pituitaries were homogenized, fractionated by HPLC, and the fractions were tested by specific RIA for alpha-endorphin (EP) (beta-EP 1-16), gamma-EP (beta-EP 1-17), beta-EP (beta-EP 1-31), and their alpha-N-acetylated derivatives. In the fetal pituitaries collected after spontaneous abortion, the contents of alpha-EP (23.4 +/- 7.5 pmol/mg protein, mean +/- SE) and gamma-EP (28.9 +/- 9.7) were similar to those of beta-EP (28.6 +/- 7.4). Both beta-EP/alpha-EP (1.2 +/- 0.3) and beta-EP/gamma-EP (1.1 +/- 0.3) ratios approached unity. Although 35.7 and 30.2% of alpha-EP and gamma-EP were acetylated, acetyl-beta-EP was only 8.4% of the total beta-EP immunoreactivity. In the five cases of PG-induced abortion that were more than 20 wk of pregnancy, the pituitary content of beta-EP (75.9 +/- 21.2) and gamma-EP (26.2 +/- 7.5) were significantly higher than in samples collected after spontaneous abortion (13.3 +/- 8.2 and 5.9 +/- 1.8, respectively, p less than 0.01). On the contrary, neither alpha-EP (31.3 +/- 5.2), acetyl-alpha-EP (0.94 +/- 0.28), acetyl-gamma-EP (0.65 +/- 0.07), acetyl-beta-EP (0.35 +/- 0.05) pituitary contents in PG-induced abortions differed from those measured after spontaneous abortion (alpha-EP: 25.6 +/- 6.6; acetyl-alpha-EP: 0.92 +/- 0.41; acetyl-gamma-EP: 0.82 +/- 0.30; acetyl-beta-EP: 0.96 +/- 0.44).(ABSTRACT TRUNCATED AT 250 WORDS)