Leptin and Adiponectin Flashcards
(51 cards)
what is the only adipokine to decrease with obesity
adiponectin
what does the co-culture experiment show
Co-incubation study = incubate 2 cell types together
- Muscle cells, culture and grow it (from rectus abdominis)
- Fat depot is mammary = from breast (representative depot of visceral fat) more realistic compared to going deep to get the viscera
- Let mix and make contact or make layers with a fine screen between, stopping physical mending - If they coincubation, after 48hrs if you then isolate muscle cells and give an insulin challenges, and look you see impairment
two ways that fat cells increase
hypertrophy or new cells
what way is worse increase size or quantity
size
why is an increase in visceral adipose cell size bad
we hit a threshold due to certain size and we create a stress response sending out cytokines and peptides that recruit immune cells (macrophages)
what do the macrophages change (altered secretory profile)
Pro-inflammatory response
- increased TNF, resistin, IL6, IL8 and FA
- decrease in adiponectin
Causes problems with insulin response over all and now the muscle is unable to clear glucose
what do toll like receptors do
triggers immune response when FA bind
what did the removal of VF but not subcutaneous fat from aging/diabetic rats show
as the rats aged they became more insulin resistant
- VF removal saw an increase in glucose clearance similar to that of caloric restriction
- sub-Q fat removal was only similar to the sham group (less than young)
what is lipoatrophy
absence of peripheral adipose tissue
- associated with severe insulin reisstance
why is the absence of peripheral adipose tissue a bad thing
we are still consuming fat so it is converted and then needs to be stored which is in tissue instead like heart and liver
what does the study done where they transplanted AT from either a normal or leptin deficient mouse into a lipoatrophic mouse show
lipoatrophic mice = elevated bld glucose, insulin, TG-insulin resistant, liver TG
Transplanted with wildtype AT = improvement (decrease in all and more insulin sensitive)
Transplanted with no leptin = no improvement
leptin =
the anti obesity hormone
t or f leptin has both central and peripheral effects
true
what positive correlations does leptin have
positive correlation to adiposity and BMI
what are the central effects of leptin
decrease NPY and appetite
increase SNS activity
leptin stimulates
FA oxidation in muscle
how does leptin increase FA oxidation
activates AMPK
- AMPK detects the disturbance in energy charge (increase ATP)
what happens when AMPK is activated
ACC produces malonyl CoA
- puts a break on the carnitine system
- malonyl CoA is an inhibitor of this
= AMPK deactivates this so there is less malonyl CoA = less of a break = more fat in
the important peripheral role of leptin is to prevent
lipotoxicity in non-adipocytes
- increase AMPK and PGC1a = increases FA oxidation and mitochondrial content
what does an increase in HSL (ERK) and lipolysis do to lipid content
decreases it
(leptin turns on the HSL = fat breakdown)
how does leptin correct a HF diet (insulin resistance)
leptin increases insulin stimulated glucose uptake
- increases IRS-1, insulin stimulated PI3Kinase activity, Akt phosphorylation, plasma membrane and total GLUT4
decreases = muscle lipid content (TG, DAG, ceramides)
how is adiponectin related to obesity and insulin resistance
inversely
adiponectin functions much like leptin as it increases
AMPK/FA oxidation
mitochondrial biogenesis
restores insulin stimulated glucose uptake in HF fed rodents
Adiponectin gene therapy ____ mice from a HF High sucrose diet
protects
- improves glucose tolerance and lose fat mass
