OPRK1 and Anxiety: Thus, KOR activation was linked to aversion, chronic anxiety, hallucinations and malaise, and activation of noradrenalin (NE) during chronic stress, but not to acute, situational stress, or specific phobias (Reyes et al., 2008; Schwarzer, 2009; Wittmann et al., 2009; Tejeda et al., 2012).