Animals controlled study physiology rat nonhuman 72 animal 71 Rats 62 metabolism 55 article 52 priority journal 52 animal experiment 47 animal cell 37 drug effect 36 Rats, Sprague-Dawley 30 female 30 animal tissue 29 Sprague Dawley rat 27 Female 26 male 25 unclassified drug 25 Article 24 protein expression 23 Rats, Wistar 22 Wistar rat 22 Male 21 Humans 18 human 18 Cells, Cultured 16 cell culture 16 signal transduction 16