BIOPSYCH 0505 Edition 1nd Lecture 20 Outline of Last Lecture I Serotonin and Satiety A Serotonin agonists B Rats reactions C Associated with the shift in food preference D Fenfluramine and dexfenfluramine II Theories A Set Point Theories B Glucostatic Theory C Lipostatic Model D Positive Incentive Theory E Setting Point model Outline of Current Lecture I Brain Mechanisms A Original view 1 Ventromedial hypothalamus 2 Lateral hypothalamus B New research 1 Ventral noradrenergic bundle II From the lateral hypothalamus A Melanin concentrating hormone and orexin B Paraventricular nuclei Current Lecture III Brain Mechanisms C Original view 3 Ventromedial hypothalamus a The satiety center b Lesions result in hyperphagia which made the rats eat more and become obese c They ate all the food in front of them and eat on going if food was available 4 Lateral hypothalamus These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute a Feeding and hunger center b Lesions result in aphagia stopped eating and adipsia stopped drinking c Slowly started to eat and drink again yet they never went back to the normal weight d If the lateral hypothalamus was stimulated it increased the eating and drinking significantly D New research 2 Ventral noradrenergic bundle a Close to the lateral hypothalamus b Lesions through the bundle decreased food reinforcement c Rats stopped working for food because the pleasurable effects of food decrease IV From the lateral hypothalamus C Melanin concentrating hormone and orexin that increase arousal and motivation 1 Both stimulate increased hunger and decreased metabolic rate 2 Increase and preserve body energy stores 3 Food deprivation results in increase MCH and orexin 4 Stimulated by the arcuate nuclei contain Neuropeptide Y neurons 5 NPY neurons have receptors for ghrelin a Released from the digestive tract during the fasting phase b An increase in ghrelin means an increase in NPY which leads to more hunger and eating behavior c Leptin released from fat cells and slow down one s eating increase in leptin leads to a decrease in NPY inhibitory d Peptide YY satiety peptide from the deuadmen and as it increases it decreases NPY D Paraventricular nuclei 1 The MCH and orexin go to the NPY pathway right to this part of the brain as well as NPY receptors 2 PVN stimulation leads to activation of brain stem nuclei that control the autonomic nervous system and other digestive functions 3 Decrease in insulin and break down of fatty acids
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