Neurotensin decreases high affinity [3H]-ouabain binding to cerebral cortex membranes

• Published in: Regulatory peptides Vol. 172; no. 1-3; pp. 35 - 40
• Main Authors: Rosin, Carina, López Ordieres, María Graciela, Rodríguez de Lores Arnaiz, Georgina
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 10-12-2011; Elsevier
• Subjects: [3H]-ouabain binding; Animals; Biological and medical sciences; Cerebral Cortex - metabolism; CNS membranes; Fundamental and applied biological sciences. Psychology; Male; Neurotensin; Neurotensin - pharmacology; NTS1 receptor; NTS2 receptor; Ouabain - metabolism; Piperidines - pharmacology; Protein Binding - drug effects; Pyrazoles - pharmacology; Quinolines - pharmacology; Rats; Rats, Wistar; Receptors, Neurotensin - agonists; Receptors, Neurotensin - antagonists & inhibitors; Receptors, Neurotensin - metabolism; SR 48692; Vertebrates: endocrinology; SR 48692; Neurotensin; [3H]-ouabain binding; NTS2 receptor; CNS membranes; NTS1 receptor; Cerebral cortex; H]-ouabain binding; Ouabain; Central nervous system; Neuropeptide; Encephalon; Affinity; Glycoside; [; Biological receptor
• ISSN: 0167-0115; 1873-1686
• DOI: 10.1016/j.regpep.2011.08.004

Previous work from this laboratory showed the ability of neurotensin to inhibit synaptosomal membrane Na+, K+-ATPase activity, the effect being blocked by SR 48692, a non-peptidic antagonist for high affinity neurotensin receptor (NTS1) [López Ordieres and Rodríguez de Lores Arnaiz 2000; 2001]. To further study neurotensin interaction with Na+, K+-ATPase, peptide effect on high affinity [3H]-ouabain binding was studied in cerebral cortex membranes. It was observed that neurotensin modified binding in a dose-dependent manner, leading to 80% decrease with 1×10−4M concentration. On the other hand, the single addition of 1×10−6M, 1×10−5M and 1×10−4M SR 48692 (Sanofi-Aventis, U.S., Inc.) decreased [3H]-ouabain binding (in %) to 87±16; 74±16 and 34±17, respectively. Simultaneous addition of neurotensin and SR 48692 led to additive or synergic effects. Partial NTS2 agonist levocabastine inhibited [3H]-ouabain binding likewise. Saturation assays followed by Scatchard analyses showed that neurotensin increased Kd value whereas failed to modify Bmax value, indicating a competitive type interaction of the peptide at Na+, K+-ATPase ouabain site. At variance, SR 48692 decreased Bmax value whereas it did not modify Kd value. [3H]-ouabain binding was also studied in cerebral cortex membranes obtained from rats injected i. p. 30min earlier with 100μg and 250μg/kg SR 48692. It was observed that the 250μg/kg SR 48692 dose led to 19% decrease in basal [3H]-ouabain binding. After SR 48692 treatments, addition of 1×10−6M led to additive or synergic effect. Results suggested that [3H]-ouabain binding inhibition by neurotensin hardly involves NTS1 receptor.
► Neurotensin decreases high affinity [3H]-ouabain binding. ► NTS1 antagonist SR 48692 decreases high affinity [3H]-ouabain binding. ► [3H]-ouabain binding decrease by neurotensin does not involve NTS1 receptor.