TABLE 4.

Tissue-specific effects of adipokines on lipid metabolism and flux

Adipokine	Food Intake (Energy Intake)	Fat Utilization, β-Oxidation, Thermogenesis (Energy Expenditure)	Fat Storage, Adipogenesis, Nonadipose Lipogenesis (Excess Energy Storage Capacity)	Levels in Common Forms of Obesity
Leptin	Anorexigenic	Enhances β-oxidation via AMPK activation in muscle and liver; reduces intracellular lipids; promotes thermogenesis in BAT	Antiadipogenic in vitro, promotes adipose lipolysis in vivo via the sympathetic nervous system	High (but evidence of leptin resistance)
Adiponectin	No effect on food intake, but ICV leads to increased energy expenditure; present in human cerebrospinal fluid	Enhances via AMPK activation in muscle and liver; reduces intracellular lipids	Promotes lipogenesis in adipocytes in vitro	Low
TNF-α	Anorexigenic	Inhibits muscle AMPK; increased FA incorporation into diacylglycerol, and increase in intracellular ceramide levels; reduces BAT function and promotes BAT atrophy	Antiadipogenic and stimulates lipolysis via TNFR1-mediated transcriptional signals; increases hepatic de novo synthesis of fatty acid and triglycerides	High (but with autocrine/paracrine activity)
IL-6	Anorexigenic	Stimulates fat oxidation via AMPK activation	Stimulates adipose tissue lipolysis; increases hepatic de novo synthesis of fatty acid and cholesterol	High
Resistin	Potentially anorexigenic; present in human cerebrospinal fluid	Decreases fatty acid uptake and metabolism in muscle in vitro	Antiadipogenic and stimulates lipolysis in adipocytes	High
RBP4	Unknown	Unknown	Promotes liver steatosis	High
PBEF/visfatin	Unknown	Unknown	Promotes lipogenesis in adipocytes	Controversial: may be higher in visceral fat
Omentin (humans, not mice)	Unknown	Unknown	Unknown	Increased in human visceral fat

BAT, brown adipose tissue.