appetite Flashcards
leptin: explain the role of leptin in regulating energy balance and reproduction
abnormalities in recessive mutation causing profound obesity and diabetes which are similar to starved animals (thinks it is starving to death, so eats tremendous amount)
infertility, stunted linear growth, decreased body temperature, decreased energy expenditure, decreased immune function
leptin secretion: what does it do and what neurons does it stimulate/inhibit
coded for in adipose tissue, so low when low body fat and high when high body fat (circulates in plasma in concentrations proportional to fat mass); central or peripheral administration decreases food intake and increases thermogenesis, as it activates POMC and inhibits NPY/Agrp neurons
obesity due to leptin resistance: pathophysiology and consequence of treatment
leptin is present but doesn’t signal effectively if chronic, so leptin is ineffective as a weight control drug here, but can be given if leptin absence with no resistance
effects of leptin absence
starvation mechanisms: hyperphagia, lowered energy expenditure, sterility
effect of leptin administration on LH (more focus on survival so switches off reproductive cycles by lowering LH)
leptin administration restores LH pulsatility in leptin deficient children and in women with hypothalamic amenorrhoea
what does presence of leptin indicate to brain
anti-starvation hormone, so informs brain there are sufficient fat reserves for normal functioning (high leptin has little effect in suppressing body weight)
insulin secretion: receptor location and effect of central administration
circulates at levels proportional to body fat, with receptors in hypothalamus, with central administration reducing food intake (as well as affecting carbohydrate, protein and lipid metabolism)
insulin co-ordination of glucose and energy intake
in periphery suppresses glucose production etc., but also acts centrally in hypothalamus to reduce food intake
