Characterization and regulation of the expression of scyllatoxin (Leiurotoxin I) receptors in the human neuroblastoma cell line NB-OK 1

Abstract125I-[Tyr2]scyllatoxin allowed to label a single class of high-affinity receptors in membranes from the human neuroblastoma cell line NB-OK 1. The Kd of these receptors was 60 pM for scyllatoxin (Leiurotoxin I) and 20 pM for apamin and the Bmax was low (3.8 fmol/mg membrane protein). K+ increased toxin binding at low concentrations but exerted opposite effects at high concentrations. Ca2+, guanidinium and Na+ exerted only inhibitory effects on binding. Scyllatoxin binding sites were overexpressed 2.5-fold after a 24-h cell pretreatment with 2 mM butyrate. This effect was suppressed by cycloheximide

SDI-118, a novel procognitive SV2A modulator: First-in-human randomized controlled trial including PET/fMRI assessment of target engagement

Background: Current treatments for progressive neurodegenerative disorders characterized by cognitive impairment either have limited efficacy or are lacking altogether. SDI-118 is a small molecule which modulates the activity of synaptic vesicle glycoprotein 2A (SV2A) in the brain and shows cognitive enhancing effects in a range of animal models of cognitive deficit.Methods: This first-in-human study evaluated safety, tolerability, and pharmacokinetics/pharmacodynamics of SDI-118 in single ascending oral doses up to 80 mg administered to 32 healthy male subjects. Brain target occupancy was measured in eight subjects using positron emission tomography with PET-ligand [11C]-UCB-J. Food effect was assessed in seven subjects. Mood state was regularly evaluated using standardized questionnaires, and resting state fMRI data were analyzed as exploratory objectives.Key Results: At all doses tested, SDI-118 was well tolerated and appeared safe. Adverse events were mainly dizziness, hypersomnia, and somnolence. All were mild in intensity and increased in frequency with increasing administered dose. No dose-limiting adverse reactions were observed at any dose. SDI-118 displayed a linear pharmacokinetic profile with no significant food effect. Brain penetration and target engagement were demonstrated by a dose-proportional SV2A occupancy.Conclusion: Single oral doses of SDI-118 up to 80 mg were very well tolerated in healthy male subjects. Dose-proportional SV2A occupancy in the brain was demonstrated with brain imaging. Adverse effects in humans mainly occurred in higher dose ranges, with high occupancy levels, and were all mild and self-limiting. These data support further clinical exploration of the compound in patients with cognitive disorders.Clinical Trial Registration:https://clinicaltrials.gov/, identifier NCT0548619

Molecular architecture of secretin receptors: The specific covalent labelling of a 51 kDa peptide after cross-linking of [125I]iodo-secretin to intact rat pancreatic acini

p-Azidophenylglyoxal (APG), a heterobifunctional reagent with one group reacting selectively with arginine residues and another group photoactivable, was used to cross-link [125I]secretin prebound to intact rat pancreatic acini. The best yield was obtained when the [125I]secretin-acini complex was incubated under dim light with 2 mM APG at 37°C and pH 8.0, followed by photolysis at 312 nm. The main secretin binding peptide cross-linked under reducing conditions, when tested by SDS-PAGE and autoradiography: (i) had a molecular mass of 51 kDa and was not a subunit of a larger, disulfide-linked structure, and (ii) was distinct from the main VIP binding peptide coexisting in the same preparation.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Secretin receptors in the neuroglioma hybrid cell line NG108-15. Characterization and regulation of their expression

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Effects of various secretins and PACAP on amylase secretion from rat and rabbit pancreatic acini

info:eu-repo/semantics/publishe

Characterization and regulation of atrial natriuretic peptide (ANP)-R1 receptors in the human neuroblastoma cell line NB-OK-1

We characterized in membranes from the human neuroblastoma cell line NB-OK-1, an ANP-R1 receptor (Mr 130 kDa) for the atrial natriuretic peptide (ANP). This receptor recognized biologically active forms of ANP with high affinity but showed no affinity for truncated ANP forms. It was functional in that binding correlated with guanylate cyclase activation (a 2-fold increase in Vmax) with the following rank order of potency: rat ANP-(99-126) > human ANP-(99-126) > human ANP-(102-126) > porcine BNP (brain natriuretic peptide). The enzyme required free Mn2+ in addition to the Mn-GTP substrate (Km of about 0.3 mM for both basal and ANP-stimulated activity). In the presence of dithiothreitol, the dose-response curve of guanylate cyclase activation was shifted rightward by a factor of 30. ANP-R1 receptors were upregulated through protein synthesis in cells exposed to 1 mM carbamylcholine or 1 mM dibutyryl cyclic AMP for 8-24 h (ANP was ineffective). © 1991 Elsevier Science Publishers B.V. All rights reserved.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Influence of fluoxetine on olanzapine pharmacokinetics.

Conventional antidepressant treatment fails for up to 30% of patients with major depression. When there are concomitant psychotic symptoms, response rates are even worse. Thus, subsequent treatment often includes combinations of antidepressants or augmentation with antipsychotic agents. Atypical antipsychotic agents such as olanzapine cause fewer extrapyramidal adverse effects than conventional antipsychotics; for that reason, they are an advantageous augmentation strategy for treatment-resistant and psychotic depression. The purpose of this study was to assess the potential for pharmacokinetic interaction between olanzapine and fluoxetine, a popular antidepressant that is a selective serotonin reuptake inhibitor. The pharmacokinetics of 3 identical single therapeutic doses of olanzapine (5 mg) were determined in 15 healthy nonsmoking volunteers. The first dose of olanzapine was taken alone, the second given after a single oral dose of fluoxetine (60 mg), and the third given after 8 days of treatment with fluoxetine 60 mg, qd. Olanzapine mean Cmax was slightly higher (by about 18%) and mean CL/F was slightly lower (by about 15%) when olanzapine was coadministered with fluoxetine in single or multiple doses. Olanzapine mean t((1/2)) and median t(max) did not change. Although the pharmacokinetic effects of fluoxetine on olanzapine were statistically significant, the effects were small and are unlikely to modify olanzapine's safety profile. The mechanism of influence is consistent with an inhibition of CYP2D6, which is known to control a minor pathway of olanzapine metabolism.Clinical TrialJournal ArticleScopus ID 52449095078info:eu-repo/semantics/publishe

Isolation and primary structure of rat secretin

A major form of rat secretin was purified to homogeneity from small intestine, being detected with a porcine secretin radioimmunoassay throughout 7 chromatographic steps. The sequence of the heptacosapeptide amide H-S-D-G-T-F-T-S-E-L-S-R-L-Q-D-S-A-R-L-Q-R-L-L-Q-G-L-V-NH2 shows that rat secretin has a glutamine residue in position 14 instead of arginine as in pig secretin.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

The novel VIP-like hypothalamic polypeptide PACAP interacts with high affinity receptors in the human neuroblastoma cell line NB-OK

We investigated the ability of two forms of Pituitary Adenylate Cyclase Activating Polypeptide [PACAP-38, the 38 amino acid peptide isolated from ovine hypothalamus, and PACAP-27, a shorter N-terminal (1-27) amidated version] to interact with specific receptors in membranes from the human neuroblastoma cell line NB-OK. [125I]PACAP-27 bound rapidly and specifically to one class of high affinity sites (K(d) 0.5 nM). VIP inhibited [125I]PACAP-27 binding 300- to 1000-fold less potently than PACAP-27 and PACAP-38. One μM PHI prevented tracer binding only partially and secretin, glucagon and GRF(1-29)NH2 were ineffective in this respect. PACAP-27 and PACAP-38 stimulated adenylate cyclase activity dose dependently and with similar efficacy (K(act) 0.2-0.3 nM), this activation being compatible with the occupancy of specific high affinity PACAP receptors. VIP was markedly less potent and less efficient on this enzyme than PACAP. Chemical cross-linking of [125I]PACAP-27 followed by SDS-PAGE and autoradiography revealed specific cross-linking with a 68 kDa protein.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Presence of highly selective receptors for PACAP (pituary adenylate cyclase activating peptide) in membranes from the rat pancreatic acinar cell line AR 4-2J

We characterized highly selective receptors for PACAP, the pituitary adenylate cyclase activating peptide, in the tumoral acinar cell line AR 4-2J derived from the rat pancreas. PACAP, a novel hypothalamic peptide related to vasoactive intestinal peptide (VIP), was tested as the full natural 38-residue peptide (PACAP-38) and as an N-terminal amidated 27-residue derivative (PACAP-27). The binding sites showed considerable affinity for [125I]PACAP-27 (K(d) = 0.4 nM) and PACAP-38, while their affinity for VIP and the parent peptide helodermin was 1000-fold lower. These receptors were coupled to adenylate cyclase, the potency of PACAP-38 and PACAP-27 (K(act) = 0.2 nM) being much higher than that of VIP (K(act) = 100 nM) and helodermin (K(act) = 30 nM). Chemical cross-linking of [125I]PACAP-27 followed by SDS-PAGE and autoradiography revealed a specifically cross-linked peptide with an M(r) of 68 000 (including 3000 for one PACAP-27 molecule).SCOPUS: ar.jinfo:eu-repo/semantics/publishe