animal controlled study nonhuman rat Animals 135 metabolism 117 Rats 113 priority journal 94 animal experiment 90 article 79 animal cell 78 physiology 69 Article 62 female 57 drug effect 56 animal tissue 55 Rats, Sprague-Dawley 52 Sprague Dawley rat 52 Female 51 unclassified drug 51 male 46 Male 42 protein expression 41 drug effects 36 animal model 35 Humans 33 Rats, Wistar 33 Wistar rat 33 human 33 chemistry 30