LECTURE 1012 PSYCH 3F03
January 28, 2014
How is Insulin resistance triggered?
− During infection, cytokines trigger insulin resistance
− Inhibit insulin receptors on selected tissues
− Thus, the signaling power of insulin is decreased in those tissues
o Less glucose is taken from the bloodstream
− Resistance in the spleen would not occur, because it is needed in the immune system
Why can your diet trigger the immune system?
− Mechanistically, glucose is the preferred energy source of
Not all aspects of the diet trigger immune response
− What seems to be important in modern diets that trigger immune response – sugars (glucose), some fatty acids (saturated, not unsaturated)
o Saturated fatty acids are more likely to come from animal products; unsaturated fatty acids from plants
Why do we store fat in adipose tissue?
− Energy reserve for
o Other conditions of energetic stress
− During energetic stress – fat mobilized and converted into saturated fatty acids (FAs) for the body to use
o Not only fat that is mobilized; glucose from the liver is also mobilized during energetic stress
Immune response is energetically expensive
− Inactive immune system consumes about 23% of overall metabolism (large amount!)
− When activated by infection, increases even further
o Sepsis > 50%
− Where does energy come from is we’re not eating?
o Less overall food consumption when sick – so where does energy come from?
o Fatty acids stored in adipose tissue and glucose in liver
Lymph nodes are important in the immune response
− Found all over the body
− Often concentrated in regions where pathogens are likely to be encountered
o Eg/ oral cavity, tonsils, digestive tract, genitals – but also in peripheral limbs
− Embedded in adipose tissue – less likely to compete for energy with other tissues
Mobilization of fat and insulinresistance
− Immune response to infection requires both:
o Down regulation of energy expenditure in n