**2. Prokineticins and their receptors**

Prokineticins are anorexigenic and angiogenic hormones. Because of the structural, signaling and functional similarities, prokineticins are considered as cytokines/chemokines [5]. They are released principally by macrophages and reproductive organs [6]. Recently, prokineticin is considered as an adipokine because a high level of prokineticins has been found in obese human WAT [7]. These small peptides (80–120 amino acids) are called prokineticins, because these molecules were first identified as potent contractile factors in the gastrointestinal tract [8]. Two isoforms of prokineticins have been identified: prokineticin‐1 and prokineticin‐2. Prokineticin‐1 has been originally called as endocrine gland‐derived vascular endothelial growth factor (EG‐VEGF), [9] because of its functional similarity to VEGF. Prokineticin‐2 is also called as Bv8. Both of these peptides are 45% identical with highly conserved N‐terminal AVITGA motif essential for their biological activity [6, 10]. Prokineticin activity is mediated by two G‐protein‐coupled receptors, PKR1 and PKR2 [11].
