Support, Non-U.S. Gov't endocrine system Animal 134 Rats 118 rat 110 animal experiment 86 nonhuman 86 Rats, Inbred Strains 84 radioisotope 80 Female 70 Male 70 animal cell 52 drug efficacy 44 central nervous system 42 Pineal Gland 36 female genital system 36 pineal body 36 Castration 32 estradiol 30 priority journal 30 In Vitro 28 Estradiol 26 Prolactin 26 pharmacokinetics 26 progesterone 26 Kinetics 24 Progesterone 24 drug receptor binding 24 male genital system 24 Testosterone 22