Presentation is loading. Please wait.

Presentation is loading. Please wait.

GENETIC AND DEVELOPMENTAL FACTORS ON FEEDING MAIN TOPICS b GENETICS b SOCIAL FACTORS b ECOLOGICAL.

Similar presentations


Presentation on theme: "GENETIC AND DEVELOPMENTAL FACTORS ON FEEDING MAIN TOPICS b GENETICS b SOCIAL FACTORS b ECOLOGICAL."— Presentation transcript:

1

2 GENETIC AND DEVELOPMENTAL FACTORS ON FEEDING

3 MAIN TOPICS b GENETICS b SOCIAL FACTORS b ECOLOGICAL

4 GENETICS b PAPER #I b “SPECIFICITY OF LEPTIN ACTION ON ELEVATED BLOOD GLUCOSE LEVELS & HYPOTHALAMIC NEUROPEPTIDE Y GENE EXPRESSION”

5 SOCIAL FACTORS b PAPER #I b “SUSCEPTIBILITY OF ARTIFICIALLY REARED RAT PUPS TO SOCIAL INFLUENCES ON FOOD CHOICE” b PAPER #II b “INTERACTION WITH DEMONSTRATORS RATS CHANGES OF OBSERVER RAT’S AFFECTIVE RESPONSE TO FLAVOURS ”

6 b PAPER #III b “A HISTORICAL PERSPECTIVE ON RECENT STUDIES OF SOCIAL LEARNING ABOUT FOODS BY NORWAY RATS”

7 ECOLOGICAL b “FOOD SELECTION: PROBLEMS IN UNDERSTANDING HOW WE CHOOSE WE EAT”

8 GENETICS: PAPER #I INTRODUCTION: LEPTIN CAUSES A DECREASE IN FOOD INTAKE & NPY CAUSES AN INCREASE IN FOOD INTAKE. LEPTIN CAUSES A DECREASE IN FOOD INTAKE & NPY CAUSES AN INCREASE IN FOOD INTAKE. STUDIES HAVE RECENTLY SHOWN THAT SYSTEMATIC ADMINISTRATION OF LEPTIN RESULTED IN NORMALIZATION OF FOOD INTAKE IN BODY WEIGHT OF OB/OB MICE.STUDIES HAVE RECENTLY SHOWN THAT SYSTEMATIC ADMINISTRATION OF LEPTIN RESULTED IN NORMALIZATION OF FOOD INTAKE IN BODY WEIGHT OF OB/OB MICE. STUDIES HAVE ALSO SHOWN THAT LEPTIN IN THE BRAIN & NPY IN THE ARCULATE NUCLEUS ARE RESPONSIBLE FOR MEDIATING THESE EFFECTS.STUDIES HAVE ALSO SHOWN THAT LEPTIN IN THE BRAIN & NPY IN THE ARCULATE NUCLEUS ARE RESPONSIBLE FOR MEDIATING THESE EFFECTS.

9 PROBLEMS: b RESULTS OF PREVIOUS STUDIES HAVE SHOWN THAT THE REVERSAL OF THE OBESE CONDITION OF THE OB/OB MICE RESULTS IN A DECREASE IN HYPOTHALAMIC NPY. b GOAL OF THIS RESEARCH IS TO DETERMINE THE CAUSE FOR THE ABOVE STATED RESULTS. b HYPOTHESIS: 1.DUE TO THE SPECIFIC ACTION OF LEPTIN (DIRECT EFFECT)

10 b LEPTIN ADMINISTRATION RESULTS IN NORMALIZATION OF OBESITY & OVER EXPRESSION OF NPY IN THE ARCULATE NUCLEUS 2.DUE TO THE REVERSAL OF THE OBESE STATE IN ITSELF (IN DIRECT EFFECT) b LEPTIN LOWERS FOOD INTAKE & BODY WEIGHT THROUGH UNRELATED MECHANISMS. b THIS RESULTS IN A REVERSAL OF OBESITY CONDITION (LOSS OF WEIGHT) b AS A RESULT OF THIS REVERSAL, NPY LEVELS IN THE HYPOTHALAMUS ARE NORMALIZED.

11 HOW WILL THIS QUESTION BE ANSWERED???? THE EXPERIMENTERS LOOKED AT: - EFFECT OF LEPTIN INJECTIONS ON HYPOTHALAMIC NPY LEVELS IN OB/OB MICE BEFORE CHANGES IN BODY ADIPOSITY. - ASSESED SPECIFICITY OF LEPTIN ACTION BY MEASURING NPY LEVELS IN ARCULATE NUCLEUS & IN TWO CONTROL SITES : (A) CEREBRAL CORTEX (B) HIPPOCAMPUS

12 - EFFECT OF LEPTIN ON PVN LEVELS OF CRH (CONTROL MEASURE FOR NP GENE EXPRESSION & CRH INCREASES INSULIN WHICH DECREASES FOOD INTAKE.

13 METHODS: SUBJECTS: b MALE OB/OB MICE N=24 b MALE DB/DB MICE N=12 b 12 HR DAY/NIGHT SCHEDULE b INDIVIDUAL CAGES WITH CONTINUES ACCESS TO WATER.

14 PROCEDURE: b MICE TREATED FOR FIVE DAYS WITH INTRA PERITONEAL INJECTIONS OF EITHER SALINE (CONTROL) OR LEPTIN (TREATMENT) b ALL INJECTIONS WERE A 150 ug. b SALINE GROUP, OB GROUP, PAIR FED GROUP OB/OB GROUP: b EXPERIMENTAL GROUP: “OB” - LEPTIN INJECTED, FREE FED. b CONTROL GROUP: “SAL” - SALINE INJECTED FREE FED b CONTROL GROUP: “PAIR FED” - SALINE INJECTED BUT PAIRED WITH MEMBERS OF THE OB GROUP WITH RESPECT TO THE AMOUNTS OF FOOD EATEN.

15 DB/DB GROUP: b EXPERIMENTAL GROUP : “OB” - LEPTIN INJECTED FREE FED b CONTROL GROUP : “ SAL” - SALINE INJECTED FREE FED b DAILY MEASUREMENTS TAKEN OF EACH MOUSE : (A) BODY WEIGHT (B) FOOD INTAKE b AFTER 5 DAY TREATMENT, ANIMALS WERE SACRIFICED b SLIDES WERE SELECTED FROM MID REGION OF THE ARCULATE NUCLEUS IN THE PVN

16 RESULTS: OB/OB GROUP “OB” TREATMENT GROUP b DECREASE FOOD INTAKE BY 56% b DECREASE BODY WEIGHT BY 4.1% b DECREASE NPY LEVELS IN ARN BY 42.3% b THESE RESULTS FOR “OB” GROUP ARE STATED RELATIVE TO THE “SAL” CONTROL GROUP WHICH SHOWED NO SIGNIFICANT DECREASE IN FOOD INTAKE AND NPY LEVELS IN ARN. FURTHER MORE, “SAL” GROUP EXPERIENCED AS INCREASE IN BODY WEIGHT OF 1.2%. WHICH SHOWED NO SIGNIFICANT DECREASE IN FOOD INTAKE AND NPY LEVELS IN ARN. FURTHER MORE, “SAL” GROUP EXPERIENCED AS INCREASE IN BODY WEIGHT OF 1.2%.

17 “PAIRED” CONTROL GROUP b DECREASE IN BODY WEIGHT (3.4%) b NO CHANGE IN NPY LEVELS IN ARN b FOR ALL GROUPS LEPTIN INJECTIONS HAD NO AFFECT ON NPY LEVELS IN CEREBRAL CORTEX OR HIPPOCAMPUS OR LEVELS OF CRH IN THE PVN DB/DB GROUP b LEPTIN ADMINISTRATION DID NOT AFFECT FOOD INTAKE, BODY WEIGHT OR NPY LEVELS EITHER IN THE ARN, CEREBRAL CORTEX OR HIPPOCAMPUS

18 CONCLUSIONS: b REMEMBER THAT: NPY INCREASES FOOD INTAKE LEPTIN DECREASES FOOD INTAKE b THUS, INCREASED NPY=DECREASED LEPTIN AND INCREASED LEPTIN=DECREASED NPY b FINDING HIGH LEVELS OF NPY IN OB/OB MICE IS EXPECTED BECAUSE THEY DON’T PRODUCE LEPTIN b HOWEVER, SYSTEMATIC ADMINISTRATION OF LEPTIN DECREASES NPY LEVELS IN THE ARN OF OB/OB MICE

19 b THIS IS DIRECT EVIDENCE THAT THE ARN-PVN NPY SYSTEM IS SUPPRESSED BY CIRCULATING LEPTIN

20 EVIDENCE b REDUCTION OF NPY IN ARN (43%) AFTER 4.1% WEIGHT LOSS IN “OB” GROUP CAN CONCLUDE THAT THE EFFECT OF LEPTIN TO DECREASE NPY IN OB/OB MICE OCCURS BEFORE SIGNIFICANT CHANGES IN BODY ADIPOSITY. b THE PAIRFED GROUP, WHICH LOST SIMILAR AMOUNT OF WEIGHT AS “”OB” GROUP DID NOT EXPERIENCE DECREASE IN ARN NPY LEVELS.

21 b CAN CONCLUDE THAT BODY WEIGHT DOES NOT DIRECTLY AFFECT LEVELS OF NPY, BUT IT MUST BE DUE TO SPECIFIC ACTION OF LEPTIN. b IT APPEARS THAT A REVERSAL IN OBESE CONDITION OF OB/OB MICE RESULTS IN A DECREASE OF HYPOTHALAMIC NPY AS A DIRECT EFFECT O F LEPTIN AND NOT TO THE INDIRECT AFFECT OF WEIGHT LOSS. b CONSEQUENTLY, REDUCED FOOD INTAKE AND BODY WEIGHT DO NOT MEDIATE EFFECT OF LEPTIN TO LOWER HYPOTHALAMIC NPY. RATHER LEPTIN ACTS DIRECTLY TO DECREASE NPY.

22 3 ADDITIONAL OBSERVATIONS IN SUPPORT OF THIS CONCLUSION. b NPY DID NOT DECREASE IN CEREBRAL CORTEX OR HIPPOCAMPUS SUGGESTING THAT THE EFFECTS OF LEPTIN IS REGIONALLY SPECIFIC TO ARN NEURONS. b LEPTIN DID NOT ALTER NPY LEVEKS IN THE ARN OF DB/DB MICE WHICH DID NOT RESPOND TO LEPTIN b A. THIS SUGGESTS THAT INHERITED RESISTANCE TO LEPTIN RESULTS IN ARN NPY

23 NEURONS TO BE UNRESPONSIVE TO LEPTIN, THUS LEPTIN’S AFFECT N OB/OB MICE WAS NOT DUE TO A NONSPECIFIC OR TOXIC AFFECT. b LEPTIN DID NOT INFLUENCE CRH LEVELS IN PVN OF EITHER OB/OB OR DB/DB MICE THUS INHIBITION OF NPY BY LEPTIN IS NOT CAUSED BY A GENERALIE HYPOTHALAMIC REACTION OF LEPTIN TO ALTER NEUROPEPTIDE GENE EXPRESSION.

24 MODEL: NEGATIVE FEEDBACK LOOP b OB GENE EXPRESSION IN ADIPOSITYINCREASES WITH INCREASED LEVELS OF ADIPOSITY. b NPY ACTS IN THE HYPOTHALAMAS TO PROMOTE WEIGHT GAIN IN FAT DEPOSITION BY INCREASING FOOD INTAKE. b BUT, b BUT, HICH LEVELS OF NPY WILL EVENTUALLY LEAD TO AN INCREASE IN LEPTIN WHEN ADIPOSITY LEVELS HAVE REACHED HIGH LEVELS

25 LEPTIN INHIBITS NPY SYSTEM BY NEGATIVE FEEDBACK LOOP AND CAUSES A DECREASE IN NPY AND FOOD INTAKELEPTIN INHIBITS NPY SYSTEM BY NEGATIVE FEEDBACK LOOP AND CAUSES A DECREASE IN NPY AND FOOD INTAKE b THUS, WHEN WEIGHT LOSS HAS OCCURRED LEPTIN LEVELS ALSO DECREASE b WHEN LEPTIN DECREASES NPY INCREASES b NPY THEN SIGNALS EATING TO RECOVER THE LOST WEIGHT.

26 SOCIAL INFLUENCES: PAPER #I EXPERIMENT #1 b b HYPOTHESIS: NORMALLY REARED ANIMALS EXHIBIT A PROFOUND SOCIAL INFLUENCE OF THEIR DIET SELECTION THAN ANIMALS REARED IN SOCIAL ISOLATION. METHODS: b b SUBJECTS b b A. OBSERVERS: THIRTY 42-DAY-OLD RAT PUPS WHERE USED.

27 b 15 IN EXPERIMENTAL GROUP AND 15 IN CONTROL b DEMONSTRATORS: THIRTY RAT PUPS 7-10 DAYS OLDER THAN OBSERVER PUPS APPARATUS: b b FOOD PREFERENCES OF INDIVIDUAL OBSERVER RATS WERE TESTED IN LARGE, WIRE MESH HANGING CAGES THAT WERE DIVIDED INTO TWO EQUAL COMPARTMENTS BY A HARDWARE - CLOTH PARTITION.

28 PROCEDURE: ISOLATION REARING: b REARED IN VISUAL AND TACTILE ISOLATION b 15 OBSERVER RAT PUPS IN THE EXPERIMENTAL GRP. b TAKEN AWAY FROM THEIR MOTHERS 2-3 DAYS AFTER THEIR BIRTH b CANNULATION b MAINTAINED ON A POLYSTYRENE CUP FLOATING IN A CONSTANT TEMP. BATH

29 b UNTIL 18 DAYS OF AGE, FED ENRICHED MILK THROUGH CANNULA b RAT PUPS PLACED ALONE IN SMALL, SHOE BOX CAGE b WEANED FROM MILK TO PELLET OF PURINA CHOW NORMAL REARING b 15 OBSERVER AT PUPS IN THE CONTROL GRP b REARED BY THEIR MOTHER b WEANED AT 21 DAYS OF AGE b AD-LIB PELLETS OF PURINA CHOW b GRPS OF 3 OR 4 IN SHOE BOX CAGES

30 AT 42 DAYS OF AGE, THE IDENTICAL PROCEDURE WAS EMPLOYED WITH ALL 30 OBSERVER PUPS: b 1. EACH OBSERVER PUP WAS INTRODUCED TO ONE COMPARTMENT OF A HANGING CAGE - ACCESS TO PELLETS OF PURINA CHOW - WATER -UNDISTURBED FOR 2 DAYS b 2. DEMONSTRATED RAT PUPS WERE PLACED IN INDIVIDUAL CAGES IN A SEPARATED ROOM. ON EACH OF 2 CONSECUTIVE DAYS - FOOD DEPRIVED FOR 23 DAYS -POWDERED PURINA CHOW FOR ONE HR.

31 b 3. FOLLOWING THE THIRD, 23 HR PERIOD OF FOOD DEPRIVATION EACH DEMONSTRATOR WAS FED EITHER ONE GRAM OF DIET ANI OR 2.4 GRAMS OF DIET MAR TO b 100GMS OF POWDERED PURINA CHOW FOR 1 HR. b 4. IMMEDIATELY AFTER EATING EITHER DIETS EACH DEMONSTRATOR RAT WAS PLACED IN A HANGING CAGE ON THE OTHER SIDE OF THE HARDWARE-CLOTH BARRIER FROM ITS OBSERVER- INTERACTIVE FOR 30 MIN. b 5. AFTER THE 30 MIN PERIOD OF INTERACTION - DEMONSTRATORS REMOVED FROM EXPERIMENT -FOR 22 HRS OBSERVER RATS WERE OFFERED A CHOICE OF DIET ANI OR DIET MAR.

32 b6b6b6b6. AT THE END OF THE 22HR PERIOD, EXPERIMENTERS MEASURING THE AMOUNT OF EACH OF THE TWO DIETS EATEN.

33 RESULTS OBSERVERS ASSIGNED TO BOTH CONTROL & ISOLATION REARED CONDITIONS: 1. ATE A GREATER % OF THE DIET THAN THEIR RESPECTIVE DEMONSTRATORS HAVE EATEN. 2. THERE WAS NOT A SIGNIFICANT DIFFERENCE BETWEEN THE MEAN % EATEN OF THE OBSERVERS DIET IN COMPARISON TO WHAT THEIR DEMONSTRATORS HAD EATEN.

34 b THEREFORE, RAT PUPS REARED IN SOCIAL ISOLATION ARE AS SENSITIVE TO SOCIAL INFLUENCES OF THEIR FOOD CHOICES AS ARE NORMALLY REARED RAT PUPS.

35 EXPERIMENT #2 HYPOTHESIS: TO DETERMINE WHETHER SIMPLE EXPOSURE OF 42-DAY-OLD ISOLATION REARED RATS TO THE TASTE & SMELL OF FOOD WOULD BE ENOUGH TO ENHANCE THEIR LATER FOOD PREFERENCES. METHODS:SUBJECTS: - 14 ISOLATION REARED RAT PUPS & 14 NORMALLY REARED RAT PUPS.

36 APPARATUS: - LARGE WIRE-MESH HANGING CAGES DIVIDED INTO 2 COMPARTMENTS BY HARDWARE-CLOTH COMPARTMENT- ALSO USED IN EXP. #1 PROCEDURE: SAME AS EXP. #1 EXCEPT FOR : b NO DEMONSTRATORS WERE USED b DURING STEP 4, RAT PUPS WERE EXPOSED FOR 30 MIN TO A SEMI-CIRCULAR, STAINLESS STEEL DISH CONTAINING EITHER DIET ANI OR DIET MAR.

37 RESULTS: b ISOLATION REARED & NORMALLY REARED RAT PUPS WERE SIMPLY EXPOSED TO A DIET: 1. DID NOT EAT A GREATER % OF THE DIET THEY WERE EXPOSED TO 2. DID NOT DIFFER FROM ONE ANOTHER IN THE MEAN % EATEN OF THE DIET TO WHICH THEY WERE EXPOSED

38 b THEREFORE, b THEREFORE, THE PREFERENCES BY RAT PUPS REARD IN ISOLATION FOR DIET EATEN BY THEIR DEMONSTRATORS IN EXP.#1, CANNOT BE EXPLAINED BY SIMPLE EXPOSURE TO DIET ANI OR DIET MAR DURING THE PERIOD OF INTERACTION BETWEEN DEMONSTRATORS & OBSERVERS.

39 SUMMARY b THE SUSCEPTIBILITY TO SOCIAL INFLUENCE ON FOOD CHOICE IS VERY RESISTANT TO AN ABNORMAL EARLY LIFE. b PREVIOUS SOCIAL EXPERIENCES DO NOT APPEAR TO PLAY A MAJOR ROLE IN THE DEVELOPMENT TO USE DEMONSTRATORS AS SOURCES OF INFORMATION ABOUT WHAT FOODS TO EAT. b THIS TENDENCY SEEMS TO BE A SPECIES TYPICAL BEHAVIOUR

40 SOCIAL INFLUENCES: PAPER #2 EXPERIMENT #1 BACKGROUND INFORMATION: b THE GRILL & NORGENS TASTE REACTIVITY TEST MEASURES BOTH POSITIVE & NEGATIVE RESPONSES TO FLAVOUR. HOW IS IT ADMINISTERED??? b A FLAVOURED FLUID IS INTRODUCED INTO THE ORAL CAVITY OF A RAT (VIA CHRONIC CANNULA)

41 b RATS OROFACIAL & GENERAL MOTOR RESPONSES TO THE INFUSION ARE VIDEO TAPED FOR ANALYSIS b POSITIVE RESPONSES: 1. TONGUE PROTRUSIONS 2. LATERAL TONGUE PROTRUSIONS 3. PAW LICKING

42 bNbNbNbNEGATIVE RESPONSES: 1. GAPING 2. PASSIVE DRIPPING OF FLUID FROM MOUTH 3. PAW FLAILING 4. HEAD SHAKING 5. CHIN RUBBING

43 PURPOSE: b TO EXAMINE WHETHER THE EFFECTS OF DEMONSTRATOR RATS ON THE FOOD CHOICES OF THEIR OBSERVERS, REFLECTED CHANGES IN THE OBSERVERS PERCEPTION OF THE PABILITY OF FOODS

44 METHODS SUBJECTS: b 35 OBSERVERS THAT ARE EXPERIMENTALLY NAÏVE RATS ( BORN IN CAPTIVITY ) b 35 DEMONSTRATOR RATS ( PREVIOUS SUBJECTS IN OTHER EXPERIMENTS) APPARATUS: b WIRE-MESH HANGING CAGES (HOUSED RATS INDIVIDUALLY )

45 b CIRCULAR PLEXI GLASS TEST CHAMBER WHICH HOUSED RATS DURING TASTE REACTIVITY TEST b PANASONIC COLOUR VIDEO CAMERA TEST FLUIDS: b 2 DISTINCT, EQUALLY PALLITABLE FLUID WERE USED IN THE EXPERIMENT b FIRST FLUID CONSISTED OF 20 GMS OF UNSWEETENED COCOA & 50 GMS OF SUGAR IN 1 LITRE OF WATER (FLUID COS)

46 bSbSbSbSECOND FLUID CONSISTED OF 20 MIL LIT OF ALMONDS EXTRACTS & 70 GMS OF SUGAR IN 1 LITRE OF WATER ( FLUID ALS)

47 PROCEDURE: b DAY 1: ALL OBSERVER RATS WERE IMPLANTED WITH A CHRONIC CANNULA b DAY 2-3: RATS LEFT UNDISTURBED FOR 2 DAYS TO RECOVER FROM SURGERY b DAY 4: HABITUATION DAY - RATS PLACED IN TEST APPARATUS FOR 10 DAYS -FOLLOWING 10 MIN. HABITUATION, RATS WERE PLACED ON WATER DEPRIVATION SCHEDULES

48 b DEMONSTRATORS RATS DEPRIVED OF WATER FOR 23.5 HRS /DAY FOR 4 DAYS b OBSERVER RATS DEPRIVED OF WATER FOR 23 HRS A DAY FOR NEXT 3 DAYS, SO THEY COULD BE TAUGHT A TASTE AVERSION TO FLUID COS FOR DAY 8 b DURING HALF HR. DRINKING PERIODS, WATER WAS GIVEN TO 19 DEMONSTRATOR RATS (CONTROL GRP.) & FLUID COS WAS GIVEN TO THE REMAINING 16 DEMONSTRATOR RATS (EXPERIMENTAL GRP.)

49 b DAY 5-7: TO HABITUATE RATS TO TEST PROCEDURES b BEFORE EACH OBSERVER RATS 1 HR DRINKING PERIOD, IT WAS PLACED IN THE TEST CHAMBER FOR 4 MIN. b WHILE IN CHAMBER RAT WAS INFUSED WITH WATER 1 MIL LIT/ MIN. b DAY 8: TASTE AVERSION TOOK PLACE b EACH OBSERVER RAT WAS GIVEN FLUID COS. INSTEAD OF WATER 1 HR., & INJECTED WITH LITHIUM CHLORIDE SOLUTION

50 b DAY 9: TESTING b FOR 30 MIN, 19 DEMONSTRATORS (ASSIGNED TO INTERACT WITH CONTROL GROUP) WERE GIVEN WATER. REMAINING 16 DEMONSTRATORS RATS (ASSIGNED TO EXPERIMENTAL GROUP) WERE GIVEN FLUID COS b UPON COMPLETION 30 MIN PERIOD, DEMONSTRATOR RATS WERE TRANSFERRED TO CAGES OF ASSIGNED OBSERVER RATS AND LEFT TO INTERACT FOR 30 MIN. b AFTER INTERACTION, OBSERVER RATS A TASTE REACTIVITY TEST (RECOREDE D ON VIDEOTAPE)

51 b SCORING OF VIDEOTAPES WAS CARRIED BY AN EXPERIMENTER WHO WAS UNAWARE OF OBSERVER RAT GROUP ASSIGNMENT b UPON COMPLETION OF TEST RATS WERE RETURNED TO THEIR CAGES AND OFFERED A CHOICE FOR 22 HOURS BETWEEN 2 WEIGHED CUPS: ONE CONTAINING COS AND THE OTHER ALS. b AT THE END OF THE PREFERENCE TEST CUPS WERE WEIGHED AND OBSERVER RATS INTAKE WAS DETERMINED

52 RESULTS: PREFERENCE TEST b OBSERVERS ASSIGNED TO EXPERIMENTAL GROUP SHOWED SIGNIFICANTLY WEAKER AVERSION TO FLUID COS OVER THE 22 HR. PERIOD THAN OBSERVER RATS IN THE CONTROL GROUP

53 TASTE REACTIVITY TEST: b OBSERVERS IN EXPERIMENTAL AND CONTROL GROUPS WERE EQUALLY LIKELY TO EXHIBIT POSITIVE RESPONSES (THAT IS WHEN THEY WERE GIVEN WATER) b THOUGH OBSERVERS IN THE EXPERIMENTAL GROUP WERE SIGNIFICANTLY LESS LIKELY THAN THE OBSERVERS ASSIGN TO THE CONTROL TO EXHIBIT THE MOST COMMON NEGATIVE RESPONSES

54 EXPERIMENT #2 BACKGROUND INFORMATION: IRWIN’S 2 POSSIBLE CAUSES OF DIFFERENTIAL RESPONSES EXHIBITED BY ANIMALS WHEN MAKING A CHOICE: 1. A REFLEXIVE RESPONSE TO THE STIMULI PRESENT WHEN THE CHOICE IS MADE 2. A MOTIVATED RESPONSE THAT REFLECTS AN ANIMALS EXPECTANCIES REGARDING THE OUTCOMES OF THE BEHAVIOURS IT MIGHT EXHIBIT

55 IRWIN PROPOSED CHOICES MADE IN THE PRESENCE OF THE GOAL OBJECTS WERE BIASES (NUMBER 1 ABOVE), AND THAT DIFFERENCE RESPONSES MADE BY AN ANIMAL NOT DIRECTLY EXPOSED TO GAL OBJECTS WERE PREFERENCES (NUMBER 2 ABOVE).

56 PURPOSE b TO DETERMINE WHETHER SOCIAL INTERACTIONS CAUSE AN INCREASE IN OBSERVER MOTIVATION TO SEEK OUT FOODS THAT THEIR DEMONSTRATORS ATE. METHODS METHODS SUBJECTS:- EIGHT 42 DAY-OLD OBSERVER RATS BORN IN CAPTIVITY AND EIGHT ADDITIONAL DEMONSTRATORS RATS (PREVIOUS SUBJECTS IN OTHER EXPERIMENTS).

57 APPARATUS b SHOE BOX CAGES (HOUSED RATS INDIVIDUALLY) b A T-MAZE CONSTRUCTED OF PLEXIGLASS WITH STAINLESS STELL GRID FLOOR b 2 FOOD CUPS, ONE AT EACH END OF THE ARM MAZE b A LINE 5CM INSIDE THE ENTRANCE TO EACH ARM OF THE MAZE ( TO SERVE AS A BOUNDARY)

58 PROCEDURE b BOTH OBSERVER AND DEMONSTRATOR RATS WERE FED WELL BALANCED DIETS b DURING FINAL 9WKS. OF EXPERIMENT, DEMONSTRATOR RATS WERE EITHER FED BANANA OR CHOW FLAVOURED PELLETS DURING THEIR ONE HOUR FEEDING PERIOD (OCCURRED TUESDAY AND FRIDAY OF FINAL 9 WKS.)

59 b TRAINING: OBSERVER RATS WERE TAUGHT TO RUN FROM THE START BOX OF THE MAZE TO BOTH GOAL BOXES b EACH OBSERVER RAT RAN 10 TRIALS/DAY, UNTIL ALL WERE CONSISTANTLY ENTERING THE ARM OF THE MAZE CONTAINING THE BANANA FLAVOURED PELLETS MORE OFTEN THAN THE ARM CONTAINING THE CHOW FLAVOURED PELLETS b TESTING: OBSERVER RATS CONTINUED TO RUN MAZE 10 TRIALS/DAY, 7 DAY/WKS b TUESDAYS AND FRIDAYS OF EACH WEEK WAS ALLOWED TO INTERACT IN THEIR HOME CAGE WITH A DEMONSTRATOR FOR THIRTY MIN.

60 b HALF OF THE DEMONSTRATOR RATS ATE BANANA FLAVOURED PELLETS OR CHOW FLAVOURED PELLETS THE HOUR PROIR TO INTERACTING b EACH OBSERVER RAT WAS GIVEN 10 TRIALS/DAY IN THE T-MAZE WITH BANANA AND CHOW FLAVOURED PELLETS IN THEIR USUAL POSITIONS.

61 RESULTS b EXPERIMENT REVEALED THAT 6 OF THE 8 OBSERVER RATS WERE SIGNIFICANTLY NORE LIKELY TO ENTER THE ARM OF THE MAZE CONTAINING BANANA FLAVOURED PELLETS ON DAYS THEIR DEMONSTRATORS HAD EATEN BANANA THAN ON DAYS WHEN DEMONSTRATORS HAD EATED CHOW FLAVOURED PELLETS

62 b ACCORDING TO IRWIN’S DEFINITION OF PREFERENCE, CHOICES OF OBSERVERS INDUCED BY INTERACTION WITH DEMONSTRATORS WERE DUE TO CHANGES IN PREFERENCE AND NOT BIASES.

63 SOCIAL INFLUENCES: PAPER#III BACKGROUND b STUDIES OF THE PAST 20 YEARS HAVE FOCUSED ON THE GOAL OF SOCIAL INTERACTION IN THE DEVELOPMENT OF ADAPTIVE PATTERNS OF FOODSELECTION BY NORWAY RATS

64 b THEIR IMMEDIATE GOAL OF RESEARCH: TO DETERMINE THE BEHAVIOURAL PROCESSES THAT CAUSE ONE RAT TO DIRECT ITS FEEDING BEHAVIOUR TOWARDS THE SAME FOODS THAT OTHERS OF ITS SOCIAL GROUP ARE EATING AND TO IGNORE POTENTIAL FOODS THAT OTHERS ARE NOT EATING OTHERS OF ITS SOCIAL GROUP ARE EATING AND TO IGNORE POTENTIAL FOODS THAT OTHERS ARE NOT EATING

65 STUDIES b GALEF AND CLARK (1971) STUDIED THE PHENOMENON DESCRIBED BY STEINIGER (1950) (POISON BAIT) b CONDUCTED EXPERIMENTS WITH COLONIES OF WILD NORWAY RATS IN THE LAB. b COLONIES LIVED IN SMALL (1 X 2 M) ENCLOSURES.

66 b NON LETHAL, NAUSEAUTING CONCENTRATIONS OF MILD TOXINS INTRODUCED INTO DIET B (THE MORE PALLITABLE OF THE 2 DIETS, A & B PRESENTED FOR 3 HRS EACH DAY b AVERSION TO DIET B DEVELOPED b LITTERS OF RATS BORN TO THOSE WHO LEARNED AVERSION TO DIET B b FOOD CHOICES OF WEANING RAT PUPS OBSERVED

67 FINDINGS: b AS LONG AS YOUNG WERE LEFT IN CONTACT WITH ADULT MEMBERS OF THE COLONY, JUVENILES RAISED, ATE ONLY DIET A. b ADULT WILD RATS COULD BIAS THEIR YOUNG TO EAT A RELATIVELY UNPALLITABLE SAFE FOOD (DIET A) AND TO IGNORE THE MORE PALLITABLE POTENTIALLY DANGEROUS FOOD (DIET B). b AVOIDANCE OF DIET B IS NOT DUE TO THE SCENT MARKINGS BY ADULTS.

68 RESULTS: b DURING INTERACTION WITH ADULTS, WILD RAT PUPS WERE LEARNING ONLY TO EAT THE FOODS THE ADULTS WERE EATING, NOT TO AVOID FOODS THAT ADULTS WERE AVOIDING

69 MECHANISMS FOR SOCIAL LEARNING ABOUT FOODS IN NORWAY RATS 1. PRESENCE OF ADULTS AT FEEEDING SITES e.g. - FOOD BOWL WITH ANAESTHESIZED FEMALE VS FOOD BOWL WITHOUT. - PUPS ATE 4X AS MUCH FOOD FROM BOWL WITH ANESTHESIZED FEMALE. -PUPS ATE FIRST MEALS OF SOLID FOOD IN PRESENCE OF ADULT 2. RESIDUAL OLFACTORY CUES e.g. - MARKING OF BOTH FOOD EATEN & AREAS AROUND FOOD % OF FOOD EATEN TAKEN FROM SOILED END OF CAGE

70 3. FLAVOUR CUES & MOTHER’S MILK e.g. - CUES IN HER MILK REFLECTING FLAVOUR OF DIET. -AVERSION TO MILK FED FROM FEMALE EATING DIET OTHER THAN THEIR MOTHER -SIMILARITIES TO HUMANS IN DEVELOPING TASTES FOR CULTURALLY SPECIFIC FOODS; ie. SPICY FOODS

71 4. OLFACTORY CUES ON THE BREATH OF ADULT RATS e.g. - CUES FROM DIGESTIVE TRACT & FOOD CLINGING TO FUR b SIMPLE EXPOSURE OF OBSERVERS TO THE SMELL OR TASTE OF FOOD IS NOT SUFFICIENT TO ENHANCE OBSERVERS PREFERENCE FOR THAT FOOD. b RAT PRODUCED ODOURS (SEMIOCHEMICALS )& SMELL OF FOOD PRESENTED TOGETHER INCREASES OBSERVERS PREFERENCES FOR THAT FOOD.

72 IMPLICATIONS OF SOCIAL LEARNING FOR THE DEVELOPMENT OF ADAPTIVE FORAGING BEHAVIOURS b FEEDING BEHAVIOUR OF OTHER RATS INFLUENCES CHOICES OF FEEDING SITES & FOODS b THIS MAY HELP OUTSIDE THE LAB. IN LOCATING NUTRITIONALLY ADEQUATE FOODS, IDENTIFYING TOXINS, FORAGING MORE EFFICIENTLY. b THEY CANNOT DO THIS WITHOUT SOCIAL CUES.

73 b PUPS CANNOT LOCATE OR DEVELOP PREFERENCE FOR NUTRITIONALLY ADEQUATE FOOD ON THEIR OWN b LEARNED FOR FOOD AVERSIONS DUE TO TOXICOSIS CAN BE ABANDONED AFTER EXPOSURE TO RATS THAT HAD EATEN THE AVERTED FOOD.

74 ECOLOGICAL: PAPER #I FOOD SELECTION b b REQUIRES MORE THAN A NATURAL - SCIENCE BASED, REDUCTIONIST ANALYSIS LOOKING AT THE PHYSIOLOGY & THE FEEDING BEHAVIOUR OF THE INDIVIDUAL b b INVOLVES ALSO THE INTERACTION BETWEEN THE INDIVIDUAL, ECOLOGICAL & SOCIAL ENVIRONMENT.

75 b ECOLOGY - WHICH FOODS THE ORGANISM EATS b SOCIAL - FOODS AVAILABLE b EVOLUTION SHAPES THE HEDONIC RESPONSES TO FLAVOURS & THE TEXTURES b PROBLEMS IN FEEDING BEHAVIOUR- INAPPROPRIATE AMOUNTS & INAPPROPRIATE CHOICES OF FOOD

76 FOOD CHOICE b 2 CLASSES OF ANIMALS : 1. DIETARY SPECIALISTS - SINGLE TYPE OF FOOD 2. DIETARY GENERALISTS- VARIETY OF DIFFERENT SUBSTANCES IN DIET b ONCE ASSIGNED AS A SPECIALIST, WRONG TO ASSUME FOOD CHOICES MADE BY MEMBERS OF THAT SPECIES IS UNDERSTOOD

77 FEEDING STRATEGIES EVOLVED IN ANIMALS : 1. FOOD SELECTORS: b CHOOSE FOOD ITEMS WITH SIMILAR NUTRITIONALLY VALUE (SPECIALIST) b PREDATORS SELECT PREY THAT WILL PROVIDE MORE ENERGY THAN WAS USED IN THEIR CAPTURE & CONSUMPTION, THUS MAXIMIZING THE RATE OF NET ENERGY GAIN.

78 2. DIET COMPOSERS: b SELECT FOOD OF VARYING NUTRITIONAL VALUE (GENERALIST ) b MORE COMPLEX PROCESS INVOLVED THAN FOOD SELECTORS b OFTEN FAIL TO HAVE AN ADEQUATE DIET WITH ALL THE REQUIRED NUTRIENTS b POSSESS BEHAVIOURAL MECHANISMS USED TO SELECT & AVOID CERTAIN TYPES OF FOOD

79 CONGENITAL HEDONIC RESPONSES b OLFACTORY & GUSTATORY SYSTEMS DISCRIMINATE & RESPOND TO CHEMICAL STIMULI OF FOOD. b ANIMALS IN NEW ENVIRONMENT - GUSTATORY SYSTEM PROVIDES NO PROTECTION AGAINST INGESTING TOXINS. b FOOD PYRAMID - HEDONIC SCALE OF PALATABILITIES OF VARIOUS FOODS.

80 b MOTIVATED TO EAT - BODY NOT DESIGNED TO COPE WITH THE HEDONICALLY DRIVEN SELECTION OF FOODS. b RESULTS IN DISEASES- e.g. -TOOTH DECAY, OBESITY, CANCER OF GASTROINTESTINAL SYSTEM ASSOCIATE TO HIGH LEVELS OF FAT INTAKE.

81 SUMMARY b ALTHOUGH A CONGENITAL PATTERN OF HEDONIC RESPONSES EVOLVED TO GUIDE US IN FOOD SELECTION YOU CANNOT RELY ON “WISDOM OF THE BODY” FOR THESE CHOICES. b EXPOSURE TO DIFFERENT FOODS INCREASED DIFFERING FROM THOSE EATEN BY OUR ANCESTORS

82 b THEREFORE NOT VERY RELIABLE IN IDENTIFYING BETWEEN DESIRABLE OR TOXIC FOODS BASED ON THEIR SENSORY QUALITIES b HARD TO SELECT HEALTHY FOOD DUE TO THE LARGE MARKET DEVOTED TO ADVERTISING JUNK FOOD.

83 SELECTING FOODS b PROLONG EXPOSURE TO AN UNPALATABLE FLAVOUR WILL PRODUCE AN EXCEPTANCE & A PERVERSE PREFERENCE FOR THAT FLAVOUR. b HOWEVER, FREQUENTLY EXPOSED TO A FOOD DURING A MEAL CAN LEAD TO A DECREASED LIKING TO THE FOOD. b PREFERENCE FOR A FLAVOUR WILL BE ENHANCED WHEN PAIRED WITH A POSITIVE EVENT.

84 b PREFERENCE FLAVOUR WILL CAUSE A TASTE AVERSION IF PAIRED WITH A NEGATIVE EVENT b AN INDIVIDUAL IS MOST LIKELY TO INGEST CERTAIN FOODS IF AFFECTED BY THE INTERACTION WITH CONSPECIFICS EATING THAT FOOD.

85 CONCLUSION b ENVIRONMENTAL INFLUENCES AN INDIVIDUALS’ BIAS SELECTION OF FOOD - EXTERNAL CUES b NEED TO EXAMINE FOOD SELECTION ACCORDING TO THE BIOLOGICAL & SOCIAL ENVIRONMENT THE INDIVIDUAL IS EATING IN - NOT JUST THE PHYSIOLOGY OF FOOD INTAKE.

86 SUMMARY b GENETICS: PAPER #1 b NPY INCREASES FOOD INTAKE AND LEPTIN DECREASES FOOD INTAKE b HIGH LEVELS OF NPY IN OB/OB MICE IS EXPECTED BECAUSE THEY DO NOT PRODUCE LEPTIN b HOWEVER, SYSTEMIC ADMINISTRATION OF LEPTIN DECREASES NPY LEVELS IN ARN OF OB/OB MICE

87 b ARCULATE PVN-NPY SYSTEM IS SUPPRESSED BY CIRCULATING LEPTIN b SOCIAL INFLUENCES: PAPER #1 b b SOCIAL INFLUENCE ON FOOD CHOICE IS RESISTANT TO AN ABNORNAL EARLY LIFE b b SOCIAL INFLUENCES ON FOOD INTAKE SEEMS TO BE A SPECIES TYPICAL BEHAVIOUR.

88 b SOCIAL INFLUENCES: PAPER #2 b OBSERVERS IN THE EXPERIMENTAL AND CONTROL GROUP ARE EQUALLY LIKELY TO EXHIBIT POSITIVE RESPONSE (TASTE REACTIVITY TEST) b IRWIN’S DEFINITION OF PREFERENCE SHOWS THAT CHOICES OF OBSERVERS INDUCED BY INTERACTION WITH DEMONSTRATORS WERE DUE TO CHANGES IN PREFERENCE AND NOT BIAS

89 b SOCIAL INFLUENCES: PAPER #3 b 4 MECHANISMS FOR SOCIAL LEARNING ABOUT FOODS IN NORWAY RATS ARE: b 1. PRESENCE OF ADULTS AT FEEDING SITES b 2. RESIDUAL OLFACTORY CUES b 3. FLAVOUR CUES IN MOTHER’S MILK b 4. OLFACTORY CUES ON THE BREATH OF ADULT RATS

90 b ECOLOGICAL: PAPER #1 b FOOD INTAKE OR SELECTION OF FOOD INTAKE DEPENDS ON ENVIRONMENTAL INFLUENCES, BIOLOGICAL, AND SOCIAL ENVIRONMENT THE INDIVIDUAL IS EATING IN.


Download ppt "GENETIC AND DEVELOPMENTAL FACTORS ON FEEDING MAIN TOPICS b GENETICS b SOCIAL FACTORS b ECOLOGICAL."

Similar presentations


Ads by Google