You’ve Come a Long Way Baby.- The evolution of concepts of opioid receptors.- Pharmacology of opioid drugs.- Opioid receptors: the early years.- Endogenous opioids.- Molecular biology of mu opioid receptors.- Delta Opioid Receptors.- Kappa opioid receptor gene and the regulatory mechanisms of its protein expression.- Opioid receptor signal transduction mechanisms.- Mu opioid receptor mediated analgesia and reward.- Kappa opioid receptor function.- Delta opioid receptor function.- Genetics of opioid receptor functions in mice.- Opioid receptor trafficking.- Opioid receptor dimerization.- Molecular modulation of in vivo tolerance.- Genetics of opioid actions.