Comparison of some peptidic and proteic ovine pineal fractions with a bovine pineal E5 fraction

Presence of immunoreactive growth hormone and prolactin in the ovine pineal gland

The use of antisera raised against bovine growth hormone (GH) and ovine prolactin (PRL) enabled the detection of related immunoreactive (ir) sequences of proteins in ovine pineal tissue. The isolation of PRL-like ir-material was accomplished using a 0.25 M ammonium sulphate (pH 5.5) extraction followed by ethanol precipitation, whereas the resulting 2.0 M ammonium sulphate (pH 7.0) precipitate contained a GH-like immunoreactivity. Gel chromatography of the GH-like immunoreactivity (Sephadex G-100) indicated the presence of several GH-like fragments ranging in the M(r) range of 7,000 to 55,000. Analyses of the PRL-like ir-material found in pineal tissue on HPLC using a TSK 545-DEAE column led to the resolution into a single peak of immunoreactivity. A single peak of activity was also observed following chromatofocusing and hydrophobic interaction chromatography of the ir-peak from the TSK 545-DEAE column. The PRL-like ir-material inhibited the binding of [125I]ovine PRL-S14 to anti-ovine PRL antibodies without showing an affinity for binding to anti-rat PRL or anti-bovine GH antibodies. Scatchard analysis of the binding of pineal PRL-like ir-material and pituitary ovine PRL-S14 to liver membranes from day-20 pregnant rats revealed similar affinity constants (Ka of 4.7 +/- 0.2 x 10(9) M-1). In addition, the replication of Nb 2 Node rat lymphoma cells was stimulated by pineal PRL-like ir-material, an effect known to be specific for lactogenic hormones. The pineal PRL-like immunoreactivity appeared on sodium dodecyl sulfate polyacrylamide gels as a single major band of M(r) 24,000. The functional status of PRL- and GH-like ir-material in the ovine pineal remains to be determined, but evidence is presented that the overall protein synthesis rate of the rat pineal responded to circulating concentrations of PRL.

Partial purification of a polypeptide extract derived from ovine pineal that suppresses the growth of human melanoma cells in vitro

A combination of gelfiltration and reverse-phase high performance liquid chromatography with postcolumn antitumour assay has been developed. A melatonin insensitive human melanoma cell strain was used to guide the purification of the antitumour effect of an ovine pineal aqueous extract (MW 1,000 to 10,000) that possessed the ability to decrease the hypophysiotropic activity of rat and mice hypothalami in vitro. This allows a specific identification of a pineal factor (MW 2,000 to 6,000) that inhibits the growth of human melanoma cells at a dose of 0.47 mg/ml medium. It was shown that the activity of this pineal compound differs from structures known to be present in the pineal, such as melatonin, pteridines, and beta-carbolines. There appears to be evidence for a peptidic nature of this pineal antitumour factor.

Partial purification of (a) low molecular weight ovine pineal compound(s) with an inhibiting effect on the growth of human melanoma cells in vitro

An in vitro human melanoma cell assay was used to work up the partial purification of (a) low molecular weight (MW) substance(s) from aqueous extracts of ovine pineal tissue shown to contain a growth-inhibiting activity. A combination of paper chromatography, ion-exchange and reverse-phase high performance liquid chromatography with post-column antitumor assay has been developed. This allows a specific identification of an ovine pineal factor (MW less than 500) which inhibits the growth of human melanoma cells in vitro. The substance was partially purified to about 1,000 times as compared to the IC100-value of the starting material (retentate 5). The growth inhibition of human melanoma cells in culture was complete at a dose of 0.1 microgram/ml of purified pineal factor(s). It was demonstrated that the activity of this pineal compound differs from some substances known to be present in the pineal, such as melatonin, serotonin, peridines and beta-carbolines. The activity was not destroyed by treatment with proteolytic enzymes.

Neurohypophyseal hormone-like peptides in the ovine pineal gland using reverse-phase liquid chromatography and radioimmunoassay

A method is described for the determination of the neurohormone contents of ovine pineal tissue by radioimmunoassay (RIA) after successive fractionation on gel filtration in formic acid and reverse-phase liquid chromatography (HPLC). This method gives a good resolution for the neurohormones vasopressin, vasotocin and oxytocin, without a significant interference of aspecific cross-reacting of peptides with the RIA. An acid extract from ovine pineal tissue was found to contain amounts of immunoreactive AVP- and OXT-like peptides, whereas an AVT-like peptide was not detectable over background levels after HPLC with post-column RIA. It is concluded from our results that an AVT-like peptide is not present in ovine pineal tissue, and the pineal AVP- and OXT-like peptides appeared to be associated to neurophysin molecules.

Characterization of a neurohypophyseal hormone-like activity isolated from ovine pineal glands

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.

Modified forms of vasopressin and oxytocin in a bovine pineal preparation

A bovine pineal acid extract displays a vasotocin-like bioactivity in several bioassays, and is recognized by antibodies against the Pro-Arg-Gly-amide ending common to vasopressin and vasotocin. By using molecular sieve filtration and reversed-phase HPLC, a vasopressin- and oxytocin-like peptide was isolated from this pineal preparation, while no evidence for a vasotocin-like peptide was obtained. The isolated neuropeptides contain a modified amino acid at position 2. This structural difference with authentic pituitary vasopressin and oxytocin may alter their biological and immunological properties, which have been interpreted as vasotocin-like, and thus underlies the controversy concerning the existence of vasotocin in the mammalian pineal gland.

Characterization of vasopressin and oxytocin immunoreactivity in the sheep and rat pineal gland: absence of vasotocin and detection of a vasopressin-like peptide

The presence of arginine-vasopressin (VP), arginine-vasotocin (VT) and oxytocin (OT) were studied in sheep and rat pineal gland by the combination of HPLC and radioimmunoassays. Three immunoreactive substances, which had the same retention time as OT, VP and VT, were detected in sheep and rat pineal extracts after HPLC separation. Parallelism of dilution curve and standard curve demonstrated that two of them were identical to OT and VP respectively. The third component was distinct from VT on basis of its immunological reaction with two different antibodies; it resembled the immunoreactivity of VP. This substance was also detected in the hypothalamus, brain cortex and pituitary gland, but not in the hippocampus and adrenal gland. The results support the notion that VT is absent in the adult mammalian pineal gland and point to the existence of another, possibly related peptide.

Presence of immunoreactive neurophysins of a higher molecular weight in addition to the 10.000 form in the ovine pineal gland

Using an aqueous extraction followed by ultrafiltration through Amicon Diaflo membranes, two ovine pineal fractions were obtained, which contain immunoreactive neurophysin. The presence of neurophysin was monitored by radioimmunoassay, employing an antiserum raised against pituitary bovine neurophysin and selected because it reacts with neurophysins of many other mammals. From 50 g of wet ovine pineal glands 552 micrograms of immunoreactive neurophysins were obtained. About 5% of these immunoreactive neurophysins are eluted from three different Sephadex columns with an elution volume corresponding to Mr above 10,000 between bovine serum albumin and pituitary neurophysin. The remaining 95% of ovine immunoreactive pineal neurophysin (Mr 10,000) shares immunological and physico-chemical properties with highly purified bovine pituitary neurophysin used as a reference. From the results of gel filtration and affinity chromatography on LVP-Sepharose it was concluded that ovine pineal gland may contain a neurophysin precursor molecule in addition to the neurophysin Mr 10,000.

Arginine vasotocin (AVT), an alleged hormone of the mammalian pineal gland

Arginine vasotocin has been proposed as a hormone of the mammalian pineal gland. This claim is largely based on biological and immunological results, although some chemical evidence has also been provided. Yet, more and more researchers have recently disclaimed the presence of this nonapeptide in mammalian tissue. The currently available evidence is critically reviewed exposing the dispute as a real one urgently requiring final settlement.