animal experiment article unclassified drug nonhuman 270 controlled study 235 Animals 216 priority journal 181 mouse 141 animal model 136 animal cell 133 animal tissue 131 rat 120 Mice 116 Male 108 Rats 102 female 98 male 98 Female 97 protein expression 81 animal 71 metabolism 64 human 57 Humans 56 Animalia 50 messenger RNA 49 Mice, Inbred BALB C 45 Rats, Sprague-Dawley 45 in vitro study 45 drug effect 42 enzyme activity 42