Opioids is known that produce not only analgesia but also hyperalgesia through activation of central glutaminergic system-GABA. At the same time, recently it was found that the main opioid receptor (OPRM1) is present on human granulosa cells and exogenous opiates and their antagonists can influence granulosa cell vascular endothelial growth factor (VEGF) production via OPRM1, causing ovarian hyperstimulation syndrome.