Straub tail phenomenon

To illustrate this point, we consider an experiment in which the subjects individually respond in all-or-none fashion, as in the Straub tail phenomenon... 

The observation that the analgesic action, despite the Straub tail phenomenon, cannot be inhibited by the opiate antagonist Naloxone, but by the non-competitive nAChR antagonist mecamylamine, indicates that epibatidine binds not at opiate receptors, but instead at nicotinic acetylcholine receptors. [547, 549, 550]... 

Pethidine attracted attention as a possible analgesic because it caused the tails of laboratory mice to stand erect (Straub phenomenon), a characteristic of morphine-like drugs caused by spasm of the anal sphincter. 

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