Physiology of Eating - L10&11

1. acute stress: inhibits eating: CRF & urocortin act on AgRP/POMC Neurons in ARC

2. chronic stress: increases wanting + consumption of palatable foods via dopaminergic system 

-> Depends on many factors: Nature of stress (physiologic, psychogenic), intensity/duration, prior experiences with food, restraint eating score 

-> independent of whether more/less food is consumed when stressed, there is always a shift toward more comfort foods 

1. increase of wanting/eating palatable foods -> increase in insulin resistance, more FFA release and uptake -> more MESENTERIC AT

2. increased fructose consumption -> activation of 11beta-HSD-1 -> stimulates release of more glucocorticoids

3. increased gluconeogenesis, insulin (resistance), LPL (enzyme that directs energy to various tissues)  -> more MESENTERIC AT

1.

a. endocrine changes (increased ghrelin, decreased leptin) -> increased hunger 

b. Hedonic factors -> increased time/opportunity to eat, increased food reward 

2. 

a. decreased thermogenesis

b. increased fatigue

c. decreased physical activity 

-> increased energy intake + decreased energy expenditure 

(+ another factor is gut dysbiosis -> disrupted intestinal barrier + increased LPS translocation)

1. Inhibiting effect on food intake -> major effect is enhancement of CCK satiation by acting in hindbrain

2. estradiol receptors are all over brain -> also in many areas involved in eating regulation/energy homeostasis

3. Estradiol can act in all these areas! (and thus has an effect on food intake)

1. high fluctuations of estrogen/progesterone 

2. depends on individual differences -> genetics, stress, history of mood disorders 

3. women show disturbed eating! -> changes coincide with changes in serotonin activity (depression..)

1. menopause: dramatic drop in estrogen levels + estrogen dominance (over progesterone) 

2. leads to disrupted estrogen-related systems (e.g. thermoregulation, sleep, circadian rhythm etc.)

3. thus MAINLY neurological symptoms -> hot flushes, insommnia, mood changes, depression, eating, impaired cognitive function

4. Estradiol receptors: ESR1, ESR2, GPER 

estrogen & FSH levels decrease, which leads to a decrease in muscle mass & strength, energy expenditure and adipose cell metabolism -> increased body weight

1. factors that trigger the cycles: genetics, stress, poor diet

-> Neuroendocrine effects (HPA-axis, leptin, insulin dysregulation)

-> Gut Microbiota (Dysbiosis)

-> Adipose tissue (increased lipogenesis, pro-inflammatory cytokines) 

2. All of this leads to neuroinflammation (also via IDO, which is a key enzyme involved in the synthesis of monoamines (serotonine, dopamine)

3. Altered brain activity for mood&food 

4. Depression <-> Obesity