Both Gw501516 and AICAR are not true SARM (androgen receptor modulators), but agonists of other receptors. When we talk about GW501516 vs AICAR, we need to know which class of agonists they belong to at first.
Gw501516 is a PPARδ agonist, also known as PPAR-Delta agonist, which is a completely synthetic design substance.
Aicar is an AMPK (AMP-activated protein kinase) activator, also known as PPAR-delta AMPK axis agonist, which is naturally produced in the body.
PPAR, Peroxisome proliferator-activated receptor. In the molecular domain, PPAR is a group of nuclear receptor proteins that function as transcription factors to regulate gene expression. PPAR plays a key role in cell differentiation, development and metabolism (Carbohydrate metabolism, lipid metabolism, Protein Protein metabolism) and carcinogenesis of higher organisms, and it can control environmental and dietary stimuli.
Among them, PPARα is mainly expressed in liver, heart and kidney, and induces peroxisome proliferation, fatty acid oxidation and ketone body production by agonists or fatty acids.
Pparδ /β is involved in energy metabolism and is highest in bone and muscle. Pparδ /β is involved in membrane lipid synthesis/turnover, cell proliferation and differentiation. Pparδ /β promotes fatty acid oxidation in muscle and regulates a range of fatty acid catabolism and obesity genes. In skeletal muscle, forced expression of constitutively active PPARδ/β enhances oxidized muscle fibers and enhances running endurance.
Pparγ is mainly expressed in adipose tissue and less in liver. Pparγ activation increases insulin sensitivity and decreases intracellular lipid levels in liver and muscle.
AMPK plays a key role in sensing and regulating energy homeostasis in cells. Physiologically responds to changes in the ratio of cellular AMP to ATP.
AMPK plays an important role in glucose metabolism. Therefore, drugs that activate AMPK are beneficial in the treatment of insulin resistance and diabetes. In addition, insulin induces the expression and translocation of glucose transporters, thereby promoting glucose uptake into cells.
AMPK is involved in maintaining lipid and cholesterol homeostasis and stimulates the oxidation of fatty acids in mitochondria to utilize lipids, which leads to fat burning in liver and muscle.
Even under normal conditions, the vascular endothelium is usually subjected to physical stresses (such as blood pressure or shear stress). AMPK can affect vascular physiology, respond to external stress and regulate cellular homeostasis, enabling endothelial cells to resist severe stress.
It can be seen from the above that PPAR-delta mainly regulates metabolism (especially glucose and lipid) and the maintenance of energy homeostasis, which can reverse the characteristic of human body's preferential consumption of muscle, burn fat as energy, reduce body fat, provide continuous power for Bodybuilder, and guarantee muscle quality in the case of energy shortage. Therefore, both GW501516 and AICAR can greatly improve Bodybuilder endurance.
AICAR acts as an AMPK agonist and promotes glucose uptake and translocation of sugar transporters in skeletal muscle; thus, even in sedentary mice, 4 weeks of AICAR treatment stimulated metabolic genes and increased running endurance by 44%.
In study, the synergistic use of GW501516 and AICAR increased the transcription of several oxidative genes (such as ATP citrate lyase, hormone-sensitive lipase, muscle fatty acid binding protein, etc.) in mouse muscle, enhanced the activity of receptors, and contributed to the regulation of body metabolism.