Opioids and sexual reward

• The study of reward states has become increasingly important.
• No direct method exists to measure opioid release during different behaviors.
• Abundant evidence indicates that for humans sexual behavior is rewarding.
• Several lines of research indicate that opioids are released during sexual behavior.
• A common opioid system mediates sexual reward in males and females.

Various lines of research indicate that sexual reward is mediated by opioids in both males and females. In the first part I review basic ideas about sexual reward in humans followed by a description of what is known in rodents, where most of the studies have been done. Although a direct method to measure opioid release during mating is not yet available, there is a substantial amount of indirect evidence in humans and animals indicating that opioids are released during the execution of sexual behavior. Studies using the conditioned place preference (CPP) method where the effects of opioids upon sex induced reward have been evaluated will also be described.Evidence will also be presented indicating that the medial preoptic area (MPOA) plays a crucial role in the expression of opioid mediated sex-reward in males and females. This area is also important in other naturally occurring reward related behaviors such as singing. Opioids might be part of a system that mediates the rewarding properties of natural behaviors that are intrinsically rewarding.