Fat: an endocrine organ Flashcards
How does RBP4 induce insulin resistance?
It prevents phosphorylation of insulin receptor substrate 1 which prevents GLUT4 levels. (RBP4 is inversely proportional to GLUT4).
What is RBP4 produced by?
Adipocytes (specifically visceral adipocytes and macrophages
What evidence is there that suggests people may become leptin resistant?
Increased adipose mass correlated with high plasma leptin levels, that would normally be associated with an annorexigenic effect.
What are the characteristics of Ob/Ob mice?
Hyperphagic, obese and insulin resistant.
Is Leptin inflammatory or antiinflammatory?
Inflammatory and is increased by pro-inflammatory mediators.
Other than adipocytes, what does adipose tissue consist of?
Macrophages
Pre-adipocytes
T-cells
Blood vessls
How do adipocytes and macrophages regulate each other?
Adipocytes - secreted-frizzled related protein 5(SFRP5)
- adiponectin
these are both anti-inflammatory
Macrophages -WNT5a which interacts with SFRP5
- TNF which interacts with adiponectin.
How does the above vary with obesity?
In the obese state, pro-inflammatory cytokines predominate.
How does obesity affect blood vessels?
It leads to rarefaction of capillaries which causes ischeamic necrosis of the fat. (crown like structures) This becomes a viscous cycle as the capillary enothelium expresses more adhension molecules increasing inflammation.
Why could obesity = insulin resistance?
There is less delivery of insulin to the fat cells due to the reduction in capillaries.
How do adipocytes interact with each other?
Cell-cell junctions
Adipokines
Soluble factors and microvesicles.
All of the above tell small adipocytes to start taking over from big ones.
How is the above information useful/how could it be used?
Pharmacological manipulation of some of the cell signal pathways could prevent obesity and be useful in treatment of metabolic disease.
