Caractérisation d’outils pharmacologiques pour l’étude des récepteurs centraux de la vasopressine

Abstract

Neuropeptides(such(as(vasopressin(and(oxytocin,(besides(their(well8known(peripheral( actions,( regulate( many( cognitive( and( behavioral( functions( via( a( central( action.( Recently,( it( has( been( shown( that( vasopressin( mediate,( through( V1A,( V1B( and( OT( receptor,( mood,( learning(and(emotional(disorders(occurring(in(the(limbic(system.(However,(the(V1A(and(V1B( receptor(sub8types(remain(the(least(studied(because(of(the(lack(of(selective(pharmacological( tools.( In(the(rat,(one(of(the(most(used(animals(in(laboratory,(no(high(affinity(agonist(selective( for(the(V1A(receptor(has(been(characterized(yet.(Similarly(for(V1B,(we(lack(radio8labbel(ou( fluorescent(tools(to(localize(selectively(this(receptor(in(the(central(nervous(system.(( This(led(us,(in(this(work,(to(focus(on(two(targets(:( ( V1A$receptor$ This( part( concerns( the( pharmacological( characterization( of( a( new( compound,( the( FE( 201874.( This( compound,( derived( from( the( F8180( was(first(described(as( a( short8acting( selective(agonist(of(the(human(V1A(receptor.( Our(results(confirmed(that(FE(201874(is(a(good(ligand(and(V1B/V1A,(V2/V1A(selective( concerning(binding( experiments( and( OT/V1A( unselective.(FE( 201874( binds( to( the( oxytocin( receptor(but(with(a(moderate(affinity(and(behaves(as(an(oxytocin(antagonist(in(vitro,(but(not( in(vivo.(Our(study(has(allowed(the(characterization(of(the(first(selective(V1A(receptor(agonist( in(rats.( This( selective( peptide( would( be( particularly( useful( in( developing( new( therapeutic( strategies(or(pharmacological(studies(aimed(at(better(understanding(of(the(central(roles(of( these(receptors(in(behavior(and(pathologies.( ( V1B$receptor$ This( section(concerns( the( characterization( of( the( labeling( and( pharmacological( properties(of(fluorescent(ligands(derived(from(d([Leu4,(Lys8](VP,(the(first(selective(agonist(of( the(rat(V1B(receptor,(to(study(the(distribution(of(central(V1B(receptors(in(rats.( Our(results(showed(that(the(3(fluorescent(ligands(tested(are(good(agonists,(V1A/V1B( and(V2/V1B(selective(and(OT/V1B(unselective.(Their(ability(to(label(the(V1B(receptors(in(a( heterologous(cell(culture(system(and(primary(cell(culture(was(also(evaluated,(demonstrating( that( these( fluorescent( ligands( are( excellent( tools(to( label( and( study( the(V1B( receptors( localization.( These( ligands( were( then( used( on( fresh( rat( brain( slices( to( study( the( V1B( receptors(distribution(in(central(regions(involved(in(different(behavioral(processes.(Several( sites( have( been( identified( including( the( hippocampus,(the(cortex,(the( amygdala,( the( hypothalamus,(the(olfactory(bulb.(In(addition,(taking(advantage(of(the(agonist(nature(of(the( fluorescent( ligands,( the( activation( of( the( Map( kinase( pathway( in( living( brain( slices( by( the( fluorescent( agonists(could(also(be(evidenced( using( a( specific( anti8pERK( antibody.( Thus,( mapping(the(in#situ(expression(of(V1b(receptors(in(connection(with(their(function(in(normal( and(stressed(animals(will(become(possible(using(these(tools.(