Analgesia in phasic and tonic pain tests in a pharmacological model of autotomy.

Self-mutilation or self-injurious behaviour is a well known behavioural disorder in humans. The proposition that this behaviour in animals is a response to chronic pain of peripheral nerve injury has been met with controversy. In the present study a pharmacological model, which produces no sensory or motor loss was used to study how autotomy is related to pain. In a group of rats autotomy was induced by amphetamine in phenoxybenzamine and reserpine treated animals. The pain tests, both phasic and tonic were then performed. The results of this study showed that a total analgesia was produced in both phasic and tonic pain tests, in animals that exhibited autotomy. Injection of naloxone in these animals prevented autotomy. A correlation between autotomy and no pain is suggested in this pharmacological model of autotomy.