Animal Rats radioisotope rat 162 Support, Non-U.S. Gov't 128 animal experiment 106 nonhuman 100 Rats, Inbred Strains 96 Male 92 endocrine system 92 Female 90 animal cell 80 central nervous system 58 pharmacokinetics 44 Pineal Gland 42 article 40 pineal body 40 priority journal 40 In Vitro 38 drug receptor binding 38 Estradiol 34 animal 34 estradiol 34 prolactin 34 Castration 32 drug efficacy 32 in vitro study 32 metabolism 32 Kinetics 30 female genital system 30