progesterone nonhuman 220 article 186 Progesterone 182 Female 176 priority journal 166 rat 146 Animals 144 controlled study 144 animal experiment 142 female 120 Rats 116 animal cell 100 protein expression 90 animal tissue 86 estradiol 84 animal model 68 Animal 66 unclassified drug 64 Rats, Sprague-Dawley 62 human 62 Humans 60 Support, Non-U.S. Gov't 56 mouse 56 Male 54 animal 54 Mice 52 Estradiol 48 Ovary 48 metabolism 48