Presence of Acetylated and Shortened Endorphins in Human Fetal Pituitary Gland

Abstract

ABSTRACT. A total of 21 human fetal pituitaries was parturition (4-6). Moreover, a significant secretion of P-EP occollected from spontaneous abortions (11 cases) or pros-curs in the neonatal period, both in vaginally delivered babies taglandin (PG)-induced abortions at the second trimester. and in those born by cesarean section in the absence of labor, Pituitaries were homogenized, fractionated by HPLC, and suggesting that neonatal P-EP secretion is an important factor of the fractions were tested by specific RIA for a-endorphin extrauterine adaptation (7,8). Fetal pituitary contains ACTH (9) (EP) (P-EP 1-16), y-EP (P-EP 1-17), P-EP (P-EP 1-31), and P-EP from the early stages of development (10-12), and and their a-N-acetylated derivatives. In the fetal pituitaries secretion has been documented in vitro after the 20th wk of collected after spontaneous abortion, the contents of a-EP pregnancy (1 3). However, the biologic activity of 0-EP may (23.4 f 7.5 pmol/mg prot, mean f SE) and y-EP (28.9 f change during fetal life because P-EP represents the precursor for 9.7) were similar to those of P-EP (28.6 2 7.4). Both P-smaller peptides, such as a-and y-endorphins with psychostim-EP/a-EP (1.2 f 0.3) and P-EP/y-EP (1.1 f 0.3) ratios ulant and neuroleptic-like profiles, respectively (14, 15). Moreapproached unity. Although 35.7 and 30.2% of a-EP and over, P-EP may be acetylated at its N-terminus, losing its opioid y-EP were acetylated, acetyl-P-EP was only 8.4% of the properties (16). In some mammals, the a-N-acetyltransferase total P-EP immnoreactivity. In the five cases of PG-induced activity is lacking in anterior pituitary and is typical of the abortion that were more than 20 wk of pregnancy, the neurointermediate lobe (17,18). This is present in the human pituitary content of P-EP (75.9 f 21.2) and y-EP (26.2 f fetus but involutes after birth and is normally absent as an 7.5) were significantly higher than in samples collected anatomically differentiated structure in the adult human pituiafter spontaneous abortion (13.3 f 8.2 and 5.9 f 1.8, tary (19). ~i~~~~~. ~~~~l pituitaries were immediately after the 17th wk pregnancy, no differences were seen abortion in 1 1 cases (five cases between the 13th and the 17th paring PG-induced and spontaneous abortions. 'IXese data wk and six between the 20th and the 25th wk of pregnancy). demonstrate that in the fetal pituitary: 1 ) P-EP retains its Spontaneous abortions were due to oligohydramnios (five cases) opioid biologic activity because only a small percentage is 0, to cervical incompetence (4). In two other cases, hysterotomy acet~lated, 2) shortened endorphins are quantitatively as for multiple myomas was performed at the 13th and 14th wk of important as @-EP, and 3) after mid-gestation, the fetal pregnan,y. Then 10 additional pituitaries were collected after proopiomelanocortin synthesis or processing may be sen-p~-induced abortion during the second trimester (five cases sitive to endocrine or environmental stimuli. (Pediatr Res between the 14th and 17th wk and the oth...

The Posttranslational Processing of β‐Endorphin in Human Hypothalamus

“…Of particular interest in this regard is substitution of a tyrosine residue in position 27 of human P-endorphin for histidine in the 0-endorphin sequence of the rat and many other species. Indeed, the reported absence of @-endorphin 1-26 from the human pituitary gland Facchinetti et al, 1989) suggests that it is not. Whether carboxypeptidase H is capable of removing the C-terminal tyrosine from human P-endorphin 1-27, however, remains to be established.…”

“…Nevertheless, immunoreactive P-endorphin ($-endorphin) neurons have been identified in human brain, and several studies have characterized the regional distribution of $-endorphin and other proopiomelanocortin-derived peptides. Although P-endorphin 1-3 1, a-N-acetyl-&endorphin 1-3 1, and a-N-acetyl-Pendorphin 1-27 have been identified in the human pituitary, P-endorphin 1-26 does not appear to be a product of the processing pathway Facchinetti et al, 1989). Also, as in rat brain, chromatographic analyses have shown that the @-endorphin detected in human brain is predominantly attributable to 0-endorphin-sized molecules rather than to @-lipotropin, its immediate precursor (Gramsch et al, 1980;Wilkes et al, 1980;Emson et al, 1984).…”