Regulation of Energy Intake & Body Weight Regulation

Question 1

Lateral hypothalamus: stimulation and lesions

Answer 1

hunger center

stimulation: voracious eating
lesions: aphagia (no eating)

Question 2

Two peptides produced in LH

Answer 2

MCH: melanin concentrating hormone

Orexins

Question 3

MCH and Orexins function and projection

Answer 3

induce feeding

1. brainstem motor systems: chewing, licking, swallowing
2. reticular surrounding: pattern generators
3. sympathetic/ parasympathetic pregang. nuclei in medulla and spinal cord

Question 4

ventromedial nucleus:

stimulation & lesions

Answer 4

satiety center
stimulation: cessation of eating

lesions: eat excessively–> obesity
- lesioned animals have reset baseline weight at 3-4 times normal

Question 5

arcuate nucleus

Answer 5

-contains first order neurons that promote either food intake or satiety

Promote feeding:
-NPY & AgRP

Promote Satiety:
-a-MSH & CART

Question 6

what is the precursor to a-MSH?

Answer 6

POMC

Question 7

what do a-MSH & CART neurons innervate?

Answer 7

• PVN and LH

- sympathetic pregang. neurons in the spinal cord

Question 8

MCR: melanocortin receptor

Answer 8

Activation: satiety

• activated by a-MSH
• inhibited by AgRP

Question 9

NPY

Answer 9

• increases hunger when injected into hypothalamus

- decrease energy expenditure: inhibit sympathetic nervous system/ thyroxin & GH secretion

Question 10

Arcuate nucleus:

NPY & AgRP

Answer 10

Anabolic: Hunger
-increased food intake, decreased energy expenditure

NPY–> NPYR in PVN/ LH
AgRP inhibits MCR in PVN/LH

Question 11

Arcuate nucleus:

POMC & CART

Answer 11

Catabolic: Satiety
-decreased food intake, increased energy expenditure

–>aMSH–> MCR in PVN/ LH

Question 12

Gherkin effects on hypothalamic nuclei

Answer 12

Anabolic: hunger

Activates: NPY/ AgRP in Arc
Inhibits: POMC/CART in ARC

Question 13

4 several satiety signals from GI tract

Answer 13

Vagal afferents
CCK (doudenum)
GLP-1 (L cells distal ileum)
PYY (L cells distal ileum)

Question 14

vagal afferents

Answer 14

Rapid eaters: gastric distention in addition to glucose and lipids

vagal afferents
-->
Tractus solitarius nucleus (NTS)
-->
PVN, Arcuate Nucleus, LH, Amygdala & Visceral sensory of Thalamus
--> 
conscious fullness (Thalamus)

Question 15

CCK: cholecystokinin

Answer 15

• doudenum
• activates vagal afferents in peritoneum
• area postrema to activate brainstem pthwys projecting to hypothalamus

Question 16

GLP-1: glucagon like peptide

Answer 16

• L cells of distal ileum
• acts in area postrema via NTS
• activate pathways 4 reduced food intake

Question 17

PYY: Peptide YY

Answer 17

• L cells of distal ileum

- anorexic effects by inhibiting NYP/AGRP neurons

Question 18

Glucose Sensitive Neurons

Answer 18

LH: hunger center
-inhibited by glucose

VMN: satiety center
-stimulated by hyperglycemia

Question 19

selective destruction of glucose sensitive cells in VMN

Answer 19

-mice develop obesity

Question 20

lipectomy/ removal of adipose tissue in rats

Answer 20

increased appetite: due to reduced appetite depressing signal

Question 21

serum from obese rats fed a high-fat diet

Answer 21

appetite depressing effect when injected into control rats

Question 22

parabiotic animal experiments

Answer 22

surgical connection 2 rats:

• if one made fat (lesion VMH)
• 2nd rat will under eat and lose weight

*circulating factor in fat rats that suppresses appetite

Question 23

cultured fat cells from obese rats injected into brain ventricles of normal rats

Answer 23

depresses appetite

Question 24

ob/ob type mice

Answer 24

-deficient in leptin and can be cured of obesity via systemic injection of leptin

Question 25

injecting leptin into normal mice

Answer 25

1. systemic: decreased appetite, increased metabolic rate, weight loss
2. minute amounts into brain ventricles: weight loss

Question 26

db/db strain mice

Answer 26

• mutated leptin receptor

- supernormal amount of circulating leptin but are insensitive to it

Question 27

leptin in the hypothalamus

Answer 27

-Leptin receptor in Arcuate and VMN

NPY/AgRP: Hunger
-inhibited

a-MSH/ CART: Satiety
-activated

Question 28

Insulin

Answer 28

• levels parallel body fat mass
• insulin receptors: glucose sensitive regions of hypothalamus and brainstem
• transported to brain by specific transporters

Question 29

insulin in the hypothalamus

Answer 29

POMP/CART: satiety
-activates

NPY/AgRP: hunger
-inhibits

Question 30

NPY/AgRP

Activators and Inducers

Answer 30

Anabolic/ Hunger

Activated:
-Ghrelin

Inhibited:

• leptin
• insulin
• PYY

Question 31

Wanting of Food

Answer 31

Nucleus Accumbens:

• related to drug addiction
• injected opioid agonists into nucleus accumbens: Feeding Induced
• nucleus accumbens and LH are interconnected

Question 32

d-fenfluramide

Answer 32

-serotonin re-uptake inhibitor was part of when/fen weight loss combination in humans

Question 33

lorcaserin

Answer 33

• selective serotonin 2c receptor agonist

- activates POMC (a-MSH/CART): satiety

Question 34

liking of food

Answer 34

• endogenous opioid system
• agonists: increase food intake
• antagonists: suppress intake

Question 35

naltrexone

Answer 35

-opioid receptor blocker: reduces food intake

Question 36

other effects on eating

Answer 36

• cognitive/ executive
• emotions
• environmental
• social

Question 37

POMP/CART

Activators and Inhibitors

Answer 37

Satiety

Activated:

• leptin
• insulin

Inhibitors:
-Ghrelin