Short term satiety factor from the GI tract?
Cholecystokinin (CCK)
signal goes on to brainstem via vagus nerve
Long term satiety factor from adipose tissue?
Leptin
Effect of gastric stretch on food intake?
decrease
effect of gastric nutrients (sucrose) on food intake if stomach is already stretched?
none
Effect of intestinal nutrients (sucrose) on food intake?
decrease
Post absorptive satiety factors from sensors in portal vein of the liver to decrease food intake? (two of them)
glucose
free fatty acids
Pathway for gastric distention signal:
activation of mechanoreceptors—>vagal afferents–> solitary nucleus (medulla) –> decreased food intake
Effect on afferent vagal firing rate from leptin?
none
effect on Solitary nucleus (NTS) firing rate from leptin?
increased
Satiety factor from duodenum in response to eating?
CCK
Effects of CCK? (3)
- gallbladder contraction–> bile –> fat digestion
- pyloric constriction –> increased stomach activity, digestion
- gastric constrictions –> increased stomach activity, digestion
Orexigenic satiety factor from stomach increased by fasting that increases appetite?
Ghrelin
Leptin is from which gene?
OB gene
Site of action of leptin?
brainstem- solitary nucleus (NTS)
fetal hypotonia
mental retardation
hypogonadotropic hypogonadism (decreased FSH, LH)
obesity
hyperphagia
hyperghrelinemia
are sx of:
Prader Willi Syndrome
deletion on chromosome 15
Three hypothalamic nuclei involved in food intake regulation:
- lateral hypothalamic area (LHA)
- Paraventricular nucleus (PVN)
- arcuate nucleus (ARC)
Two causes of aphagia with LHA lesion:
- damage to medial forebrain bundle–>reduced motivation to eat (mesolimbic system, dopaminergic)
- loss of neurons that synthesize Orexin
Activation of LHA causes?
release of “anabolic” NT in brainstem –> increased eating and growth
Activation of PVN causes?
release of “catabolic” NT in brainstem (corticotropin) –> decreased eating and growth
Two populations of ARC neurons?
- neuropeptide Y (NPY) –> project to PVN, LHA –> increase eating
- leptin acts on ARC to inhibit NPY and decrease food intake - melanocortin (ProOpioMelanoCortico derived peptide) –> project to PVN and LHA to decrease eating
- leptin acts on ARC to activate melanocortin (decreasing food intake)
Ghrelin site of action in hypothalamus?
ARC –> increases NPY activity to increase food intake