Similar to previous studies (Harris and Gewirtz, 2004; Harris et al., 2004; Cabral et al., 2009; Lee et al., 2017), testing 4 h after the final dose of 2 weeks of repeated escalating morphine increased the acoustic startle response in mice regardless of Tat exposure, suggesting an anxiogenic negative affect response that is characteristic of opioid dependence (Harris and Gewirtz, 2005). This evidence concerns the gene TAT and opiate dependence.