ROLE OF CONDITIONED TASTE AVERSION AND SATIETY IN THE DEPRESSION OF THE ENERGY INTAKE INDUCED BY THE HIGH PROTEIN DIET IN THE RAT
ROLE DE L'AVERSION GUSTATIVE CONDITIONNEE ET DE LA SATIETE DANS LA DEPRESSION DE LA PRISE ENERGETIQUE INDUITE PAR LES REGIMES HYPERPROTEIQUES CHEZ LE RAT
Résumé
IN ORDER TO DETERMINE THE RESPECTIVE ROLES OF CONDITIONED FOOD AVERSION, SATIETY AND PALATABILITY, WE STUDIED BEHAVIORAL RESPONSES OF RATS FED HIGH PROTEIN DIETS (50%) CONTAINING EITHER TOTAL MILK PROTEIN OR WHEAT GLUTEN OR SOYA PROTEIN, COMPARED WITH THOSE TO A NORMAL PROTEIN DIET CONTAINING 14% TOTAL MILK PROTEIN. DIFFERENT PARADIGMS WERE USED, INCLUDING MEAL PATTERN ANALYSIS, TWO CHOICE TESTING, FLAVOR TESTING, A BEHAVIORAL SATIETY SEQUENCE AND TASTE REACTIVITY. OUR EXPERIMENTS SHOWED THAT ONLY BEHAVIORAL AND FOOD INTAKE PARAMETERS WERE DISTURBED DURING THE FIRST DAY WHEN AN ANIMAL ATE THE HIGH PROTEIN DIET, AND THAT MOST PARAMETERS RETURNED TO BASELINE VALUES AS SOON AS THE SECOND DAY OF HIGH PROTEIN DIET. THE TYPES OF PROTEIN USED IN THE DIET DID NOT SEEM TO INFLUENCE BEHAVIORAL RESPONSES. RATS ADAPTED TO HIGH PROTEIN DIET DID NOT ACQUIRE A CONDITIONED TASTE AVERSION BUT EXHIBITED SATIETY, AND A NORMAL BEHAVIORAL SATIETY SEQUENCE. THE INITIAL REDUCTION IN HIGH PROTEIN DIET INTAKE APPEARED TO RESULT FROM THE LOWER PALATABILITY OF THE FOOD COMBINED WITH THE SATIETY EFFECT OF THE HIGH PROTEIN DIET AND THE DELAY REQUIRED FOR METABOLIC ADAPTATION TO THE HIGHER PROTEIN LEVEL. SECONDLY, WE STUDIED SATIETY EFFECTS OF LOADS OF PROTEIN VERSUS CARBOHYDRATE ON SUBSEQUENT FOOD INTAKE IN RATS. WE USED AN INTRA-ORAL CANULA TO DELIVER ISOENERGETIC ISOVOLUMIC LOADS, IN A TIGHTLY CONTROLLED TIME FRAME ALLOWING FOR BOTH METABOLIC RESPONSES AND OROSENSORY COMPONENTS OF THE LOAD. OUR RESULTS SHOWED THAT THE GLUTEN LOAD (GLT-100%) INDUCED A GREATER DEPRESSION IN FOOD INTAKE THAN AN ISOCALORIC WHEAT STARCH LOAD (GLT-0%). THE TYPES OF PROTEIN USED IN THE LOAD (TOTAL MILK PROTEIN VERSUS GLT) DID NOT SEEM TO INFLUENCE THEIR APPETITE SUPPRESSIVE EFFECT. THERE WAS A DOSE DEPENDANT EFFECT OF THE SATIATING EFFECTS OF THE PROTEIN LOADS, THE GLT-100% LOAD BEING MORE EFFECTIVE THAN EITHER THE GLT-50% OR GLT-35% LOADS. AT LEAST ONE DAY WAS NECESSARY BEFORE THERE WAS A SIGNIFICANT DECREASE IN THE ENERGY INTAKE FOLLOWING THE PROTEIN LOADS. THUS, THE ANIMALS HAD TO LEARN THE POST-INGESTIVE EFFECTS OF THE LOADS BEFORE THE RESPONSE WAS STABILIZED. TAKEN TOGETHER, THE PRESENT RESULTS CONFIRM THAT PROTEIN HAS A GREATER SATIATING EFFECT THAN CARBOHYDRATE AND EXTEND THESE RESULTS BY REVEALING THAT THE LARGER THE PROPORTION OF PROTEIN IN THE FOOD, THE LARGER THE SATIATING EFFECT, AND THAT THE QUALITY OF PROTEIN DOES NOT SEEM TO PLAY A SIGNIFICANT ROLE. OUR RESULTS SHOW THAT THE INGESTION OF A HP DIET OR MORE SIMPLY A HP MEAL ARE ACCOMPANIED BY A SATIETY EFFECT WHICH REMAINS TO BE EXPLAINED
LES REGIMES HYPERPROTEIQUES INDUISENT UNE DEPRESSION DE LA PRISE ENERGETIQUE CHEZ LE RAT. LES MECANISMES SOUS-TENDANT CETTE DEPRESSION SONT MAL CONNUS. L'OBJET DE CETTE THESE EST D'ANALYSER LES ROLES RESPECTIFS DE LA PALATABILITE, DE LA SATIETE, ET DE L'AVERSION GUSTATIVE CONDITIONNEE DANS CE PHENOMENE. LAPPLICATION DE LA METHODE DENREGISTREMENT DE LA PRISE ALIMENTAIRE ET DE VIDEO ANALYSE A DES RATS, LORS DE LA TRANSITION DUN REGIME NORMOPROTEIQUE (14%) VERS UN REGIME HYPERPROTEIQUE (>50%), MONTRE DES MODIFICATIONS TRANSITOIRES DU COMPORTEMENT DE LANIMAL LORS DU PREMIER JOUR : REDUCTION DE LA TAILLE DU REPAS, DIMINUTION DE LA VITESSE DINGESTION ET MODIFICATION DE LA SEQUENCE COMPORTEMENTALE DE SATIETE. APRES ADAPTATION AU REGIME HYPERPROTEIQUE, LA QUANTITE DENERGIE INGEREE AVEC LE REGIME HYPERPROTEIQUE RESTE NEANMOINS EN DEÇA DE CELLE INGEREE EN REGIME NORMOPROTEIQUE ET LE POIDS DES ANIMAUX RECEVANT UN REGIME HYPERPROTEIQUE EST PLUS FAIBLE. DES LE SECOND OU TROISIEME JOUR, SELON LA PROTEINE ALIMENTAIRE UTILISEE, LA SEQUENCE COMPORTEMENTALE DE SATIETE N'EST PLUS DIFFERENTE DE CELLE INDUITE PAR UN REPAS NORMOPROTEIQUE. L'ABSENCE D'AVERSION GUSTATIVE CONDITIONNEE ET LA PRESENCE D'UN EFFET SATIETOGENE DES PROTEINES A ETE CONFIRMEE QUAND LES RATS, ELEVES SUR UN REGIME NORMOPROTEIQUE, ET RECEVANT TROIS REPAS PAR JOUR, INGERENT UN EN-CAS PROTEINE. LES PROTEINES DEPRIMENT PLUS LA PRISE ALIMENTAIRE LORS DU REPAS SUIVANT QUE LES GLUCIDES. LANALYSE DE LA SEQUENCE ALIMENTAIRE MONTRE QUE LA DIMINUTION DE LA TAILLE DU REPAS INDUITE PAR LES CHARGES PROTEIQUES 35% ET 50% EST DU A UN EFFET SATIETOGENE ET NON A UNE AVERSION GUSTATIVE CONDITIONNEE. NOTRE ETUDE A AUSSI MONTRE QUE PLUSIEURS PARAMETRES BIOCHIMIQUES (AMINOACIDEMIE TOTALE, ACIDES AMINES BRANCHES ) OU HORMONAUX (LEPTINEMIE) SONT SUSCEPTIBLES DETRE A LA BASE DES SIGNAUX ENVOYES AU CERVEAU POUR INITIER LA BAISSE DE PRISE ALIMENTAIRE. EN RESUME, LES RATS NE DEVELOPPENT PAS UNE AVERSION GUSTATIVE CONDITIONNEE VIS A VIS DU REGIME HYPERPROTEIQUE. LES MODIFICATIONS DE LA PRISE ALIMENTAIRE ET DU COMPORTEMENT, CORRESPONDENT PLUS A UN EFFET SUR-SATIETOGENE DU REGIME HYPERPROTEIQUE COMBINE A SA FAIBLE PALATABILITE ET A UNE NECESSAIRE ADAPTATION METABOLIQUE DE L'ANIMAL A CE REGIME. NOS RESULTATS, QUE CE SOIT DANS LE CADRE DE L'INGESTION D'UN REGIME HYPERPROTEIQUE OU, PLUS SIMPLEMENT LORS D'UN REPAS, MONTRE QUE L'INGESTION DE PROTEINES S'ACCOMPAGNE D'UN EFFET SATIETOGENE QUI RESTE A EXPLIQUER