Role of Diet Flashcards
What amino acid do cats require in their diet?
Taurine
What neurobiological effect does eating have?
Positive dopamine
What factors influence taste preference?
Experiences and genetics
Give three “popular beliefs” about diet and behaviour in dogs
Hyperactive/aggresive dogs need a low protein diet to calm them
High carbohydrate diets calm anxious dogs
Artificial preservatives eg. ethoxyquin affect behaviour more than natural preservative eg. vit C
What amino acids is serotonin made up from?
Tryptophan and tyrosine
Which NT does tryptophan contribute to?
Serotonin (MOOD)
Which NT does tyrosine contribute to?
Catecholamines (STRESS)
Which NT does histidine contribute to?
Histamine (IMMUNE)
Which factors affect how much the NT levels are affected by food?
Timing of food, composition of diet, Digestability of diet
What have diets high in tryptophan shown?
Conflicting results - Decreased and increased aggression (rodents and primates)
Reduced self injurious behaviour in primates
Increased exploratory behaviour in foxes
What have diets low in tryptophan shown?
^Aggression, anger and frustration in humans
Increased turnover of tryptophan and serotonin in acute stress
Decreased turnover of tryptophan and serotonin in chronic stress/depression
Where does conversion of tryptophan to serotonin occur? How much trypotohan is converted? What is tae of conversion affected by?
1% in GIT
Conversion affected by - trypotphan, other LNAAs, fatty acids, carbohydrates (->insulin release -> aa uptake, often aa other than tryptophan are more favourable)
Why is getting int o the brain difficult?
Has to compete with other Large Neutral Amino Acids (LNAAs) to cross BBB
What happens to free tryptophan?
Binds to albumin in plasma and cants cross BBB
Fat levels important for albumin
How do carbohydrates affect tryptophan levels?
Stimulate relase of insulin -> aa uptake (other aa than tryptophan more favourable so decreased competition at the BBB)
Which enzyme is the rate limited step for trypotophan -> serotonin conversion?
Tyrptophan hydroxylase
What is the purpose of albumen in tryptophan transport?
Binding to tryptophan “keeping it safe” until reaching the BBB
What NTs does tyrosine form?
Catecholamines - Dopamine, noradrenaline, adrenaline
When does NA turnover increase?
During periods of high stress therefore high tyrosine diet protective of effects of acute stress (rodent studies)
How does tyrosine impact other aa levels?
Competes with other AAs at BBB
Generally higher concentration in normal protein than tryptophan so high protein meal ^tyrosine, vtryptophan
What did Dodman et al 1996 show?
No effect of dietary protein levels for dominance aggressive, hyperactive or control dogs
Significant effect of protein level of territorial aggression dogs due to fear (low protein -> v aggression)
What did De Napoli et al 2000 show?
No change in behaviour within each group (dominance/territorial/hyper)
But combined, decrease in territorial aggression for dogs fed low protein + tryptophan supplement (i.e. ^trypotophan)
Increase in dominance aggression for dogs fed high protein no tryptophan supplementation (ie. vtryptophan)
What did Bosch et al 2009 show?
No difference in response in mildly anxious dogs
How may carbohydrates affect behaviour?
Digestible - Starch ->monosaccharides eg. glucose. Fluctuations in blood glucose -> hyperactivity etc. Also impacts aa uptake into muscles by ^insulin release from pancreas. Uptake of other aa leaves ^conc of tryptophan at BBB
Indigestible - Fibre-> fermented in colon to produce fatty acids, lactate and gases, affects feeling of satiety
