preliminary communication animal experiment 46 rat 38 Animal 34 Support, Non-U.S. Gov't 34 Rats 32 nonhuman 30 in vitro study 28 Male 26 priority journal 22 endocrine system 20 radioisotope 20 article 16 drug comparison 16 Animalia 14 Female 14 blood and hemopoietic system 14 drug analysis 14 drug efficacy 14 drug mechanism 14 Rats, Inbred Strains 12 drug administration 12 drug identification 12 unclassified drug 12 animal cell 10 human cell 10 methodology 10 prostaglandin 10 Animals 8 Dose-Response Relationship, Drug 8