How does the body‘s energy storage system stores energy?
mostly triglycerids and glycogen
What is the phase after eating called, when nutrients are abundant in the blood stream?
prandial state —> storage molecules are synthetized (anabolic phase)
What is the fasting phases between meals called?
postabsorptive state —> storage molecules are broken down (catabolized)
What brain area has the control of feeding?
Hyperthalamus
What are the three functional regions of the hyperthalamus?
The autonomic nervous system can be divided into …
a sympathetic , a parasympathetic and an enteric branch
Activation of the sympathetic branch prepares the body for activity. What activities?
four „F“s: fight, flight, fright, and …sex
Activation of the parasympathetic branch prepares for …
rest: digestion, regeneration, growth etc
What is the enteric nervous system also called?
„little brain“ of the gut.
What is produced in fat cells when these are sufficiently filled with lipids?
Leptin
Control of feeding with leptin levels
Lesions in the lateral area lead to the disruption of food intake. What is this phenomenon called?
anorexia
-In humans, the following hypothalamic structures are involved in feeding control
nucleus arcuatus, nucleus paraventricularis and the area hypothalamica lateralis
-Nucleus arcuatus is a „brain sensor“ that responds to varying levels of leptin in the blood stream.
What peptide was discovered which is highly concentrated in the stomach wall and released into the blood when the stomach is empty?
ghrelin
Short term regulation of feeding
(Don’t study the details of the signals)
Summary feeding
What are the three major brain areas that control ingestive behavior?
Hedonic evaluation of food.
What are the different areas in the brain and what are their functions?
What is the relation of dopamine and food intake? (shown in experiments)
Animals enjoy food, but don’t look for it anymore
How dynamic is the evaluation of food in the brain?
How can you test that?
What is the conclusion?
It depends on the availability.
When an animal has extended access to very „yummy“ food (or drugs), the brain gets less sensitive towards the reward associated with the food. This increase in reward threshold is reflected in the increase of electrical stimulation necessary to maintain the self-stimulation.
Thus overconsumption of yummy food (and weight gain) can induce deficits in brain reward circuitry
more and more food is needed to reach the same level of reward, thus further increasing the energy imbalance
In humans that gained weight during a controlled 6 months study, weight gain was associated with decreased …
striatal activation in fMRI, and decreased availability of dopamine D2 receptors (D2R)
Striatal Responses to Weight Gain in Humans
Knock-down of D2R in rat striatum …
accelerates the emergence of reward dysfunction and compulsive overeating (=binge eating) in this situation
Food, mood, and serotonin
Some food components also have a direct influence on the level of serotonin in the brain. Serotonin is a cricital neurotransmitter for mood control, and involved in depression and anxiety.
Serotonin levels rise in anticipation of food and spike during a meal, especially if the food is rich in carbohydrates (noodles as „soul food“)
Serotonin is derived from tryptophan in the food, and levels of tryptophan vary with the amount of carbohydrates in the food. This could be the explanation for the „mood-rising“ effect of a „carbs“ meal; this effect is stronger in times of stress.
Drugs that elevate serotonin levels are also strong appetite suppressants. One of these substances (dexfenfluramine) was particularly successful in treating obesity, but had severe toxic side-effects.
Involvement of the Amygdala
Metabolic and hedonic drive – who‘s the boss?
What are the biological, psychological and social factors in eating disorders?
Patient has low weight, restricts himself to certain foods, has fear of gaining weight, and a strong desire to be thin. (Young) women 10x more affected than men. Patients see themselves as overweight, control weight frequently, often exercise much, eat little and sometimes vomit afterwards. Complications: osteoporosis, infertility, heart damage etc.
How is this disorder called?
Anorexia nervosa
frequent and recurrent binge eating episodes with associated negative psychological and social problems, but without subsequent purging episodes. Binge eating could be a “milder” version of
Binge eating
How is Binge eating with subsequent purging (e.g., vomiting) called?
Bulimia nervosa
Neurobiology of anorexia nervosa. What gets changed in the brain?
Diet and weight can influence both Dopamine (DA) and Serotonin (5- HT) metabolism. Findings indicate that in AN patients, 5-HT is increased and DA is decreased.
As DA is involved in reward and motivation, and 5-HT in punishment and inhibition, AN patients may have a skew towards aversive or inhibitory responses, rather than reward or motivation.
This correlates with typical AN traits such as anxiety, perfectionism, anhedonism, ascetism, self-denial.
Neurobiology of binge eating (BE)
THe microbiota can get altered through Western-type diet, and go towards …
dysbiosis
Differences in food consumption between gender are statistically signi-ficant, with men eating more meat and women preferring vegetables and fruits. To study the cognitive control of food intake, hungry men and women were scanned while looking at food images.
What were the results?
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