Similar results have been observed showing dysphoria-like responses accompanying acute opioid and ethanol withdrawal (Liu and Schulteis, 2004; Schulteis and Liu, 2006). Here, naloxone administration following single injections of morphine increased reward thresholds, measured by ICSS, and increased thresholds with repeated morphine and naloxone-induced withdrawal experience (Liu and Schulteis, 2004). Similar results were observed during repeated acute withdrawal from ethanol (Schulteis and Liu, 2006).
