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Updated: Aug 14, 2026

Use of the Operant Orofacial Pain Assessment Device (OPAD) to Measure Changes in Nociceptive Behavior
Published on: June 10, 2013
Effect of ACTH and vasopressin on extinction: evidence of opiate mediation
Abstract:
These experiments demonstrated that both ACTH and arginine vasopressin (AVP) delay the extinction of a shuttle box avoidance response in intact rats. Furthermore, the effect of ACTH (2.5 IU) and AVP (0.2 IU) on extinction was the same when these hormones were administered daily throughout the course of extinction testing. Doses of naloxone, which did not affect this behavior, differentially blocked the effects of these hormones, ACTH being more easily blocked than AVP. The results are interpreted in terms of opiate mediation of the effects of the hormones and do not support the assertion that ACTH works through motivation whereas vasopressin works through memory.
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