Characterization of a Neurohypophyseal Hormone‐Like Activity Isolated From Ovine Pineal Glands

Abstract

The milk-ejecting response of lactating mouse mammary gland tissue to ovine pineal extracts indicated the presence of a neurohormone-like bioactivity in this tissue. After successive fractionation on gel permeation chromatography and reversed-phase liquid chromatography (HPLC) in conjunction with radioimmunoassays (RIA), it was demonstrated that the milk-ejection response to ovine pineal components with an Mr less than 1,000 corresponded to a biologically active peptide sequence that probably differs from that of arginine vasopressin, arginine vasotocin, and oxytocin and from peptides with a COOH-terminal Pro-Arg-Gly-amide ending. Gel permeation chromatography in formic acid appeared also to indicate the presence of a noncovalent interaction of the neurohormone-like bioactivity with proteins (Mr greater than 25,000) of the pineal.

Proteomic analysis of day–night variations in protein levels in the rat pineal gland

“…The presence of these molecules was already suggested in early biochemical gel filtration studies of the ovine pineal gland [13] and these peptides were later shown to possess a neurohypophysial hormone activity [14]. In cultured pinealocytes of rats and mice [15] as well as in the hamster [16], ultrastructural studies have suggested a 'peptidergic' secretion from large granular vesicles of the pinealocytes into the culture medium.…”

Generation of the Melatonin Endocrine Message in Mammals: A Review of the Complex Regulation of Melatonin Synthesis by Norepinephrine, Peptides, and Other Pineal Transmitters

“…In addition, it has been reported that the V 1a -R activates not only PLC, but also phospholipases A and D (Thibonnier, 1992;Briley et al, 1994). The presence of VP, OT, and some of their metabolites have been reported in the pineal gland of several mammals (Dogterom et al, 1980;Pévet et al, 1980c;Fisher and Fernstrom, 1981;Geelen et al, 1981;Noteborn et al, 1988). The first studies using radioimmunoassay and high-performance liquid chromatography suggested that these peptides were specific to the pineal gland, giving the gland its antigonadotropic and milk-ejection properties (see Pévet, 1983b;Vaughan, 1984 for review).…”

Isolation and structure elucidation of bovine pineal arginine vasopressin: arginine vasotocin not identified

“…The neurohypophysial hormone-like peptides in the Sephadex G-25 eluates in the approximate MI range 10 000-1 5 000, which were dissociated by treatment with 5% formic acid, were apparently bound to pineal neurophysinlike proteins known to be present in the bovine pineal gland (26,27). It should be pointed out that in the studies by Noteborn et al (13,14) the Amicon UM2 ultrafiltration membrane was used whereas the YM2 membrane was incorporated in the present study. In past studies we have seen that synthetic nonapeptides (OT, AVT) were quantitatively retained by the UM2 membrane (28), whereas they pass readily through the YM2 membrane into the UM05 retentate (unpublished observations).…”

“…Noteborn et al (13,14) have carried out extensive studies on neurohypophysial hormone-like peptides in ovine pineal glands. In addition to separation of pineal extracts by HPLC with postcolumn detection by RIA, these investigators also incorporated the mouse milk ejection bioassay.…”

“…In general, the conclusions drawn from these studies with diverse antibodies of variable specificity has not been conclusive for the presence or absence of AVT in the mammalian pineal gland. On the other hand, the separation of pineal peptides by high performance liquid chromatography (HPLC), coupled with postcolumn RIA, appeared to increase the precision of the assays and revealed the presence of AVP and OT in mammalian pineals, but strongly enhanced the argument against the presence of AVT in the mammalian pineal (10)(11)(12)(13)(14).…”