Animal Support, Non-U.S. Gov't radioisotope Rats 128 rat 120 nonhuman 116 animal cell 90 Rats, Inbred Strains 84 animal experiment 82 endocrine system 78 Female 72 Male 64 central nervous system 48 priority journal 46 article 38 drug receptor binding 38 pharmacokinetics 38 In Vitro 36 Pineal Gland 36 pineal body 36 drug efficacy 32 Kinetics 30 female genital system 28 animal 26 estradiol 26 in vitro study 26 metabolism 26 Norepinephrine 24 female 24 prolactin 24