The present invention provides an arrestin knockout mouse useful for screeni ng compounds for efficacy in controlling pain, methods of controlling pain in subjects by inhibiting binding of arrestin to .mu. opioid receptors, and methods of screening a compound for activity in potentiating .mu. opioid receptor agonist activity (e,g., morphine activity) by determining whether o r not said compound inhibits arrestin binding to a .mu. opioid receptor.</SDOA B>
INHIBITION OF .BETA.ARRESTIN MEDIATED EFFECTS PROLONGS AND POTENTIATES OPIOID RECEPTOR-MEDIATED ANALGESIA