Hunger, Satiety and the Brain Flashcards
What did early studies of hunger show when they decerebrated the Brain Stem in rats?
The rats showed fairly normal eating
What early studies were done on the hypothalamus?
Old lesion and stimulation studies
What were the findings of the early studies on the Hypothalamus?
1.) Lateral Hypothalamus: feeding centre
2.) Ventromedial Hypothalamus: satiety centre
What happened when they lesioned the VMH?
The rats developed “VMH syndrome”
What does VMH syndrome cause?
Hyperphagia
What is hyperphagia?
Excessive Eating
What did the rats develop a preference for?
Palpable Food
What is Palpable food?
Any food that is reading to the palate
What happened when rats were in their dynamic phase?
Excessively Eating which lead to rapid weight gain
What happened when rats were in their stable phase?
Stabilized (but still high) eating which lead to a new stable weight
What happen when you lesion the LH?
“LH syndrome”
What does “LH syndrome” consist of?
Aphagia: stop eating
Adipsia: stop drinking
What did they also notice when they lesioned the LH?
Motor deficits and the lack of responsiveness to sensory inputs
What did new researchers look at when studying the hypothalamus in regards to hunger?
Paraventricular Nucleus of the Hypothalamus
Arcuate Hypothalamus Nuclei
What does the Lateral Hypothalamus produce?
Melanin Concentrating Hormone and Orexins/Hypocretins (Orexin A and B)
What do the Orexins/Hypocretins do?
Enhance your appetite which enhances your feeding
What are Accurate NPY Neurons?
Feeding enhancers (NPY and Agouti Related Peptide)
What are your Arcuate POMC Neurons
Feeding Inhibitors (Melanocortins - MCR-4)
What is your PVN?
Feeding Inhibitor (MCR-4)
What is your Lateral Nucleus?
Feeding Enhancer (MCH and Orexin A + B/Hypocretins)
What is the role of the Hypothalamic nuclei?
Regulating food intake, energy expenditure, glucose and lipid metabolism in the peripheral tissues by leptin
What does Leptin do?
Decrease your appetite
What happens when Leptin acts on the POMC neurons of the Arcuate Nucleus?
It signals to the PVN to reduce food intake
What happens when Leptin isn’t present?
It signals to the Arcuate nucleus to increase food intake at other sites
