APLN and Obesity: Novel adipokines of apelin with receptor APJ [154], (angiotensin II receptor like-1), vaspin, and nesfatin-1, when bound to G-protein, coupled receptors (GPCRs) and cannabinoid receptors (CR), are known to maintain glucose tolerance [155,156] Additionally, in some studies of obesity, vaspin levels are low along with suppression of leptin and TNF-α synthesis [157].