Pressinoic Acid Research Articles

Autoradiographic characterization of binding sites labelled with vasopressin in the brain of a urodele amphibian.

Because arginine vasotocin (AVT) activates male sexual behaviors in the rough-skinned newt (Taricha granulosa), quantitative autoradiography with radiolabelled arginine vasopressin (3H-AVP) was used to characterize putative AVT receptors in the telencephalon of this amphibian. Analyses were restricted to specific binding sites in the medial pallium, although dense binding also was observed in the dorsal pallium and amygdala pars lateralis. Binding of 3H-AVP to these sites was saturable, specific, reversible, of high affinity (Kd = 1 nM) and low capacity (57 fmol/mg protein). The rank order of potency of related peptides in inhibiting 3H-AVP binding was as follows: AVT greater than d(CH2)5[Tyr(Me)2]AVP (a mammalian pressor antagonist) greater than AVP, oxytocin, and [dPen1Tyr(Me)2]AVP (also a pressor antagonist) greater than mesotocin much greater than desGly(NH2)AVP, AVP fragment 4-9 and pressinoic acid. Thus, these binding sites appear to represent authentic central nervous system receptors for AVT. Furthermore, ligand specificity for the binding sites in this amphibian differ from that reported for AVP binding sites in rat brains. The AVT receptors in the medial pallium, dorsal pallium, and amygdala pars lateralis may represent site(s) of action where AVT elicits sexual behaviors in male T. granulosa.

Carrier-mediated transport of vasopressin across the blood-brain barrier of the mouse.

A brain to blood carrier-mediated transport system for arginine vasopressin (AVP) was investigated in mice after intraventricular injection of iodinated AVP and varying amounts of unlabeled material or candidate inhibitors. Residual activity in the brain detected after decapitation was used as the main determinant of transport activity. The half-time disappearance of iodinated AVP from the brain was 12.4 min, the Vmax was 1.41 nmol/g-min, and the apparent Km was 28.7 nmol/g. A 30-nmol dose of AVP, mesotocin, arginine vasotocin, pressinoic amide, pressinoic acid, tocinoic acid, and lysine vasotocin, but not oxytocin, lysine vasopressin, AVP free acid, tocinoic amide, Tyr-MIF-1, or cyclo Leu-Gly, significantly (P less than 0.05) inhibited the transport of iodinated AVP out of the brain. The 30 nmol dose of AVP had no effect on the transport of iodide or iodotyrosine out of the brain. High-performance liquid chromatography showed that 59.2% of the radioactivity found in the blood 2 min after an i.c.v. injection of labeled AVP eluted at the same position as labeled AVP compared with 68.8% of radioactivity eluting at that position after material was infused i.v. for 2 min. This indicates that intact peptide is transported across the blood-brain barrier and that most of the degradation of AVP occurs during circulation in the blood. Calculations based on the appearance of radioactivity in the periphery showed that 56.2% of the material injected centrally would have been transported into the periphery by 10 min. This appearance of material in the periphery was inhibited by the simultaneous injection of an excess of unlabeled peptide. Water loading significantly decreased the brain to blood transport rate of AVP by 40%. It is concluded that a saturable system exists for brain to blood transport of AVP and some structurally similar peptides.

ChemInform Abstract: Amino Acids and Peptides. Part 195. Synthesis of Pressinoic Acid by Enzymatically Catalyzed Formation of Peptide Bonds.

Chemischer InformationsdienstVolume 17, Issue 42 Natural Products ChemInform Abstract: Amino Acids and Peptides. Part 195. Synthesis of Pressinoic Acid by Enzymatically Catalyzed Formation of Peptide Bonds. V. CEROVSKY, V. CEROVSKYSearch for more papers by this author V. CEROVSKY, V. CEROVSKYSearch for more papers by this author First published: October 21, 1986 https://doi.org/10.1002/chin.198642300Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume17, Issue42October 21, 1986 RelatedInformation

Neurohypophysial peptide potencies in cultured anuran epithelia (A6).

To characterize the V2 receptor (for antidiuretic hormone), we have studied the effect of a number of neurohypophysial hormone analogues on cyclic AMP (cAMP) accumulation and short-circuit current in cultured epithelia formed by A6 cells. A6 is the designation of a continuous cell line derived from the kidney of Xenopus laevis. The order of potency for stimulating cAMP accumulation and short-circuit current in A6 epithelia is like that for stimulating water permeability in toad urinary bladder. As anticipated, arginine vasotocin (AVT), the antidiuretic hormone of Amphibia, is more potent than arginine vasopressin (AVP), the antidiuretic hormone of most mammals. The two hormones differ only in the third amino acid (Phe-3 in AVP is a substitution for Ile-3 in AVT). However, there are a number of striking differences in the responsiveness of these amphibian V2 receptors and mammalian V2 receptors to changes in the 7th, 8th, and 9th amino acids where AVT and AVP are identical. 1) Substitution of Lys-8 for Arg-8 in AVP results in marked loss of potency in Amphibia, whereas there is only modest loss of potency in mammals. 2) Desglycinamide AVP is nearly as potent as AVP in Amphibia, whereas it is inactive in mammals. 2) Tocinoic acid, lacking amino acids 7, 8, and 9, has activity in Amphibia, but pressinoic acid, lacking the same three amino acids, is inactive.

Structure of pressinoic acid: the cyclic moiety of vasopressin.

Arginine vasopressin consists of a 20-membered, disulfide-linked macrocyclic ring system called pressinoic acid to which is attached a COOH-terminal tripeptide. The molecular conformation of pressinoic acid has been determined from single crystal x-ray diffraction data. The 20-membered macrocyclic ring, stabilized by two intramolecular hydrogen bonds, has a type I beta-bend centered on Gln4 and Asn5 and a highly distorted type II' bend centered on Phe3 and Gln4. In vasopressin the Asn5 side chain extends away from the macrocyclic ring system and hydrogen bonds to the terminal tripeptide, but in pressinoic acid the Asn5 side chain lies over the molecule and forms a strong hydrogen bond to the nitrogen of Tyr2. The absence of pressor activity in pressinoic acid may be a result of both the loss of the COOH-terminal tripeptide and the incorrect orientation of the Asn5 side chain. Whether this class of hormones has pressor or oxytocic activity is determined by the orientation of the Tyr2 side chain, that is, whether it is extended away from or over the ring system, respectively. In pressinoic acid, the Tyr2 side chain is in the expected "pressor conformation," that is, extended away from the ring system, and is stabilized through a hydrophobic interaction with the Phe3 side chain. Thus, the conformation of the pressinoic acid molecule partly explains the activity of vasopressin-like hormones.

Use of carboethoxysulfenyl chloride for disulfide bond formation.

The use of carboethoxysulfenyl chloride for disulfide bond formation and concomitant cyclization of five peptides was investigated. Even though cyclic peptides were obtained very rapidly and in good yields when cyclization was performed in aqueous media at different pHs (4 to 7), the final crude peptides were found to contain closely related impurities which, in the case of somatostatin and pressinoic acid, were not generated by air oxidation. This observation may limit the use of carboethoxysulfenyl chloride to those cases where other methods of disulfide bond formation prove inadequate.

Synthesis of pressinoic acid by enzymatically catalyzed formation of peptide bonds

Three fully enzymatic syntheses of the 1-6 vasopressin hexapeptide were investigated using papain, α-chymotrypsin and thermolysin. Best results were obtained with thermolysin in the 2 + 4 fragment condensation. The α-chymotrypsin-catalyzed 3 + 3 condensation is less advantageous and the 4 + 2 condensation with papain gave only low yield. Using the mentioned enzymes, further fragments of vasopressin molecule were prepared. Amino groups were protected with benzoylcarbonyl or tert-butyloxycarbonyl groups, carboxyl groups as phenylhydrazides or methyl esters, and the cysteine sulfhydryl group as the benzyl derivate. The tyrosine hydroxyl was not protected.

Regulation of lymphokine production by arginine vasopressin and oxytocin: modulation of lymphocyte function by neurohypophyseal hormones

The neurohypophyseal hormones arginine vasopressin (AVP) and oxytocin are capable of replacing the interleukin 2 (IL 2) requirement for T cell mitogen induction of gamma-interferon (IFN-gamma) in mouse spleen cell cultures. The structural basis for the helper signal by these hormones resides in the six N-terminal amino acids of AVP based on the relative ability of AVP, oxytocin, vasotocin, and pressinoic acid (AVP six N-terminal amino acid peptide) to help in IFN-gamma induction. AVP and pressinoic acid provide maximal help at 10(-10) M, while oxytocin and vasotocin with isoleucine at position three in place of phenylalanine are 10-fold less effective. An AVP competitive antagonist of vasopressor activity blocks the AVP helper signal for production of IFN-gamma, while having no effect on IL 2 help. This suggests that the AVP helper signal operates via binding to an AVP vasopressor-type receptor on lymphocytes.

Vasopressin and vasotocin facilitate reversal of a brightness discrimination

Male albino rats received vasopressin, vasotocin, pressinoic acid or placebo and were tested on an aversively motivated brightness discrimination task. Treatment with both vasopressin and vasotocin had no effect on acquisition but facilitated the reversal of the discrimination. Pressinoic acid had an inconsistent effect. The results are interpreted to show that the C terminal of the peptides vasopressin and vasotocin influence potency of these peptides. Furthermore, the results are interpreted as showing that both vasotocin and vasopressin influence selective attention during aversively motivated tasks.

Actions of neurohypophysial peptides on pancreatic hormone release.

The intermittent reports concerning metabolic actions of neurohypophysial extracts or hormones encouraged us to study the effect of these substances on the function of the endocrine pancreas. A surprisingly small amount of neural lobe (NL) extract (0.025 NL eq/ml) stimulated a 425% increase in the release of glucagon from islets isolated from the pancreas of the rat. Gel filtration of the extract produced an elution profile of glucagon-releasing activity that was superimposable on the profiles of oxytocin (OT) and arginine vasopressin (AVP). Synthetic OT and AVP each elicited a concentration-dependent stimulation of glucagon release but failed to influence insulin release in medium 199 containing 5.6 mM glucose. They were effective at 0.2 ng/ml (+55%, +50%) and produced a striking increase (five- to sevenfold) at 20 ng/ml. The response to each peptide was greatly diminished in the presence of a higher concentration of glucose (11 mM). The lysine, desamino-, and 1,6-aminosuberyl analogues of vasopressin, vasotocin, and AVP are equipotent peptides, whereas the desglycinamide analogue, pressinoic acid, and angiotensin II were inactive. Injection of AVP (1 microgram iv) produced a rapid increase in peripheral glucagon (+185% in 5 min). The response to injection of OT was less rapid (+105% in 15 min), but in each case elevation of insulin was also observed. Our results provide evidence that OT and AVP can act directly on the endocrine pancreas and may help explain previous reports of metabolic actions of these peptides.

Activation of pineal acetyl coenzyme A hydrolase by disulfide peptides.

Incubation of pineal acetyl-CoA hydrolase preparations with disulfide peptides activates the enzyme. Activation of somatostatin, the most potent peptide tested, is enhanced at higher pH, indicating that disulfide exchange is probably involved. This interpretation is supported by the observation that activation is reversed by dithiothreitol treatment. The order of potency is somatostatin = [Tyr1]somatostatin greater than or equal to Tyr-somatostatin greater than vasopressin = pressinoic acid = [Arg8]vasotocin greater than oxytocin. Insulin, insulin A, insulin B, and [Asu1,6, Arg8]vasopressin were ineffective. This order of potency is distinctly different from that for the inactivation of pineal N-acetyltransferase (Namboodiri, M. A. A., Favilla, J., and Klein, D. C. (1981) Science 213, 571-573) by these peptides. Examination of the primary structure of the peptides reveals that the above order of potency is consistent with the predictions of the nearest neighbor model as applied to the disulfide group.

Stimulation of rat pituitary phospholipid methyltransferase by vasopressin but not oxytocin

Rat pituitary extracts contain two methyltransferases that catalyze stepwise methylation of phosphatidyl-ethanolamine to phosphatidylcholine using S-adenosylmethionine as the methyl donor. The activities of both of these enzymes were stimulated by 40 μM lysine or arginine vasopresin but not oxytocin, arginine vasotocin and Pro-Leu-Gly NH 2. The concentration of lysine-vasopressin required for the half-maximal stimulation of phospholipid methylation was 27 μM. A comparison of the chemical structure of different peptides with their ability to stimulate phospholipid methylation suggests that the stimulatory activity resides in the covalent ring structure (pressinoic acid) of the vasopressin molecule.

Synthesis and some pharmacological properties of [I-β-mercaptopropionic acid, 2-(3,5-dibromo- l-tyrosine)]-8-lysine-vasopressin

The title compound, [1-β-mercaptopropionic acid, 2-(3,5-dibromo- l-tyrosine)]-8-lysine-vasopressin (X), was synthesized by condensation of Pro-Lys(Boc)-Gly-NH 2 with the cyclic peptide [1-β-mercaptopropionic acid, 2-(3,5-dibromo- l-tyrosine)]-pressinoic acid. X has no oxytocic, avian vasodepressor, pressor, or antipressor activities, but is a weak inhibitor of the responses to oxytocin in the oxytocic and avian vasodepressor assays. Its pharmacological properties are qualitatively identical to those of the corresponding analog of oxytocin, although it is a less potent antagonist than the latter compound.

A semi-automated in vitro assay for CRF: activities of peptides related to oxytocin and vasopressin.

The CRF-like activity of peptides related to vasopressin and oxytocin was estimated using a semi-automated in vitro bioassay. Rat pituitary halves were incubated for 1 h with the test material in 1.0 ml of Krebs-Ringer bicarbonate buffer. The ACTH released from the pituitary tissue was estimated using adrenal quarters in an automated superfusion system. The pituitary tissue was standardized with median eminence extract, and adrenal tissue was standardizeed with ACTH. Vasopressin and its analogues release ACTH in order of their pressor potency. Most of the ring or tail fragments of oxytocin and vasopressin did not stimulate the release of ACTH. In some experiments, deaminopressinamide and pressinoic acid had CRF-like activity.

Pressinoic acid: A peptide with potent corticotrophin-releasing activity

Pressinoic acid, a synthetic hexapeptide that corresponds to the ring of vasopressin, exhibited corticotrophin-releasing activity in , vitro in doses of 3 and 30 nanograms per ml. The related peptide, deaminopressinamide, released lesser amounts of corticotrophin in doses of 30 to 30,000 ng. Two other hexapeptides, pressinamide and deaminopressinoic acid, were devoid of corticotrophin-releasing activity at doses of 30 to 30,000 ng.

Melanophore stimulating hormone: release inhibition by ring structures of neurohypophysial hormones.

Tocinamide and tocinoic acid, ring structures of oxytocin, are potent inhibitors of the release of melanophore stimulating hormone from the rat and hamster pituitary in vitro. Tocinamide is effective at concentrations as low as 10-(14)M on the mammalian pituitary. These peptides do not affect release of the hormone on the frog (Rana pipiens) pars intermedia, but they do inhibit release in the bullfrog (Rana catesbeiana) and the toad (Bufo marinus). The specificity of the peptides on inhibition of the hormone is demonstrated by the fact that oxytocin, lysine vasopressin, and pressinoic acid and pressinamide (ring structures of the vasopressins) do not show such inhibitory activity. Hypothalamic extracts of either the frog (Rana pipiens) or the rat inhibit release of the hormone from pituitaries of either species. The inhibitory effects of tocinamide and tocinoic acid, like that of hypothalamic extracts, are reversible.