Behavioral functions of narcotic antagonists: response-drug contingencies.

Behavioral effects of the narcotic antagonist naloxone are discussed in terms of stimulus functions. As an eliciting stimulus, the effects of naloxone depend on prior administration of narcotic. Administered independently of responding, naloxone can increase or decrease rates of narcotic-reinforced responding depending on the dose of naloxone. When naloxone is administered as a consequence of narcotic self-injection, the further probability of that behavior is reduced; thus, naloxone can function as a punishing stimulus. As a negatively-reinforcing stimulus, naloxone can maintain behavior which terminates or prevents delivery in morphine-dependent monkeys. In animals with previous naloxone avoidance-escape experience, unavoidable-inescapable injection of naloxone produce increases in avoidance-escape response rates. In these animals, responding subsequently can be maintained, at least temporarily, when naloxone is administered only as the consequence of responding.