Regulation of Food Intake

Question 1

What are neuronal centers that conttrol feeding and satiety?

Answer 1

• lateral nucleus
• ventromedial nucleus
• paraventricular nucleus
• dorsomedial nucleus
• arcuate nucleus

Question 2

Where are the centers that control feeding and satiety located?

Answer 2

hypothalamus

Question 3

What is key to maintaining energy balance?

Answer 3

cross-talk between neural and hormonal regulation via hypothalamus

Question 4

What signals converge in hypothalamus?

Answer 4

neural from GI tract

chemical from nutrients in blood

GI hormones

adipose tissue

cerebral cortex (small, taste, sight)

Question 5

Where is most of the integration of signaling that regulates food intake and energy expenditure?

Answer 5

arcuate nucleus of hypothalamus

Question 6

What is the anorexigenic pathway of the arcuate nucleus?

Answer 6

first part of arcuate nucleus pathway

–> alpha-melanocortin (a-MSH) released by POMC neurons

–> bind to MCR-4 present in second order neurons

*****DECREASE food intake

Question 7

What is the orexigenic pathway of the arcuate nucleus?

Answer 7

second part of arcuate nucleus pathway

–> neuropeptide Y (NPY) stimulated by hunger signals

–> bind Y1R

–> AGRP released which is an antagonist of MCR-4

**INCREASE food intake

Question 8

What is related to mutations in POMC and MCR-4 genes?

Answer 8

some cases of obesity

Question 9

Do the arcuate nucleus pathways antagonize each other?

Answer 9

Yes–> what activates one inhibits the other

Question 10

Describe the appetite-inhibiting pathway

Answer 10

POMC (appetite-inhibiting neurons) release a-MSH–> bind MC4 receptors on second-order neurons to inhibit food intake and increase metabolism

Question 11

Describe the appetite-stimulating pathway

Answer 11

hunger signals stimulate release of neuropeptide Y–> bind Y1 receptors to increase feeding behavior and storage of calories

Question 12

What is an antagonist of the MC4 receptor?

Answer 12

AgRP released by NPY

Question 13

Peptides that stimulate satiety and decrease feeding activate receptors on?

Answer 13

Vagal afferents

Question 14

What circuit produces responses related to feeding behavior and metabolism?

Answer 14

Vagus–>NTS–>hypothalamus

Question 15

When does the amount of material in the stomach no longer influence meal size?

Answer 15

when vagal activity is blocked

–>also eliminates effects of satiety hormones

Question 16

What is crucial in interpretation and relaying of peripheral signals from vagus N?

Answer 16

NTS

–> nucleus tractus solitarius

Question 17

What percent of vagal fibers are afferent?

Answer 17

75%

Question 18

What is the purpose of the vagal–>NTS–>hypothalamus pathway?

Answer 18

alter feeding behavior and metabolic responses

Question 19

What is able to regulate food intake in response to peripheral signals even in absence of higher brain center input?

Answer 19

NTS (hindbrain)

Question 20

What nucleus contains neurons that project to cerebral cortex and areas of brainstem?

Answer 20

PVN

Question 21

What is the hunger center?

Answer 21

Lateral hypothalamic area

Question 22

What peptides do the lateral hypothalamic neurons release?

Answer 22

orexigenic peptides

–> MCH, orexins A and B

Question 23

What is the satiety center?

Answer 23

ventromedial hypothalamic nucleus

Question 24

Hormones released from what areas regulate feeding behavior?

Answer 24

GI tract
Pancreas
Adipose tissue

Question 25

Describe Ghrelin in feeding behavior

Answer 25

- secreted in stomach, bind to growth hormone secretagogue receptors - stimulate neurons that release NPY - increase appetite, gastric motility and acid secretion, adipogenesis - decrease insulin secreition - initiates feeding response

Question 26

Describe insulin in feeding behavior

Answer 26

- bind receptors in POMC and NPY systems - ----->inhibits NPY, + POMC - decreases appetite - increases metabolism

Question 27

Describe insulin effects in Type 1 DM related to food intake

Answer 27

increased food intake is associated with decreased insulin in type 1 DM

Question 28

Describe CCK in feeding behavior

Answer 28

Released by I cells in duodenum - elicits satiety by acting on vagal-NTS-hypo pathway - ---------> decreases ghrelin - decreases gastric emptying - ------->increases gastric distention

Question 29

Describe PYY in feeding behavior

Answer 29

Released by L cells of ileum and colon after meal -binds YR2 in hypothalamus to INHIBIT NPY neurons and + POMC neurons

Question 30

Describe Leptin in feeding behavior

Answer 30

Secreted by adipose tissue - bind receptors on POMC and NPY systems - ------> inhibits NPY - -----> + POMC * *Appetite-suppressing hormone - ---------> decreases appetite and ghrelin release - -------> increases metabolism

Question 31

Injection of what hormone in obese children reduces fat mass, hyperinsulinemia and hyperlipidemia?

Answer 31

Leptin

Question 32

Obesity in general is associated with high _____ levels and failure to respond to exogenous ____

Answer 32

leptin -->AKA leptin resistance

Question 33

What is released from pancreatic B cells?

Answer 33

Insulin

Question 34

What is the site of action of insulin r/t feeding behavior?

Answer 34

hypothalamus

Question 35

What hormone decreases appetite and increases metabolism?

Answer 35

insulin

Question 36

What hormone is released from fat cells and endocrine cells of the stomach?

Answer 36

leptin

Question 37

What are the sites of action of leptin?

Answer 37

Hypothalamus and Vagal Afferents

Question 38

What are the effects of leptin on the hypothalamus?

Answer 38

Increase POMC Decrease NPY and AgRP

Question 39

What decreases appetite and ghrelin release, increases metabolism?

Answer 39

leptin

Question 40

What is secreted from I cells of duodenum?

Answer 40

CCK

Question 41

What is the site of action of CCK in feeding behavior?

Answer 41

Vagal afferents

Question 42

What decreases appetite and gastric emptying?

Answer 42

CCK

Question 43

What is secreted from L cells of ileum and colon?

Answer 43

PYY

Question 44

What are the sites of action of PYY?

Answer 44

Hypothalamus | Stomach

Question 45

What are the effects of PYY on the hypothalamus?

Answer 45

decrease NPY and AgRP Increase POMC

Question 46

What decreases appetite and gastric emptying, increases metabolism?

Answer 46

PYY

Question 47

What is secreted from endocrine cells of stomach, hypothalamus, LI and SI?

Answer 47

Ghrelin

Question 48

What are the sites of action of ghrelin?

Answer 48

Hypothalamus | Vagal afferents

Question 49

What are the effects of ghrelin on the hypothalamus?

Answer 49

Increase NPY, AgRP

Question 50

What increases appetite, decreases metabolism and leptin release?

Answer 50

Ghrelin

Question 51

What is the difference between fat and gut peptide signal in the modulation of food/energy?

Answer 51

Adiposity signals--> long-term regulation of energy balance Gut peptides--> modulate food intake on meal-by-meal basis

Question 52

What reduces food intake, suppresses glucagon secretion and delays gastric emptying?

Answer 52

Glucagon-like peptide 1 (GLP-1)

Question 53

What is co-secreted with PYY from L cells in intestine and is also an incretin?

Answer 53

GLP-1

Question 54

How are GLP-1 levels affected by meals and fasting?

Answer 54

rise after meal, fall during fasting -->d/t reduces food intake and inhibits glucagon

Question 55

What is released from L cells of intestine in response to ingested food/caloric intake?

Answer 55

Oxyntomodulin -->anorectic effect

Question 56

What decreases food intake directly through Y4R in brainstem and hypothalamus?

Answer 56

Pancreatic peptide

Question 57

Where is pancreatic peptide secreted from?

Answer 57

pancreatic islets of Langerhans

Question 58

What can act on the vagus nerce to produce anorectic effects?

Answer 58

pancreatic peptide

Question 59

What is stored and released with insulin in response to food intake and inhbits NPY release?

Answer 59

Amylin

Question 60

What molecules have anorectic effects?

Answer 60

Amylin Pancreatic Peptide Oxyntomodulin

Question 61

Define anorexia nervosa

Answer 61

self-starvation and excessive weight loss

Question 62

What are some biological factors that support habits of patients with anorexia nervosa?

Answer 62

- morphs in genes involved in eating attitudes and behavior - secretion of leptin reduced - ghrelin resistance - elevated levels of PYY (contributes to decreased nutrient intake)

Question 63

What are genetic causes of obesity?

Answer 63

- Leptin receptor gene deficiency - MC4R receptor gene mutation - Prader Willi syndrome - POMC deficiency

Question 64

What causes early-onset SEVERE obesity, hyperphagia, and infertility?

Answer 64

Leptin deficiency

Question 65

What causes early-onset SEVER obesity, hyerinsulinemia and is the MOST COMMON cause of genetic obesity

Answer 65

MC4R mutation

Question 66

What is the most common known genetic cause of obesity?

Answer 66

MC4R gene mutation food inhibition pathway

Question 67

What leads to severe obesity and MR in children with paradoxically elevated ghrelin?

Answer 67

Prader-Willi syndrome -->partial deletion chromosome 15

Question 68

What is related to obesity, red hair, jaundice and adrenal insufficiency?

Answer 68

POMC deficiency food inhibition pathway