sentences: "In vivo" evidence indicative of KOR activation, such as elevation of serum prolactin levels due to dopamine suppression and increased hypothalamic-pituitary-adrenal axis activation via enhanced adrenocorticotropic hormone and cortisol secretion, has been observed in humans and animals.Side effects typical of KOR activation such as hallucinations and dissociation have also been observed with nalmefene in human studies.