TAC1 and acute kidney injury: Furthermore, when comparing the saline-treated and AcA-treated NHPs to the AKI NHPs, the AKI NHPs demonstrated higher levels of Atf3 and Tac1 mRNA, confirming the presence of nerve injury (Figs. 4B–4C) and indicating the absence of nociception and nerve injury in the saline-treated and AcA-treated NHPs.