Although we focus on identifying genetic factors affecting OIH, we previously noted (using data obtained from a smaller number of strains) that the strain dependencies of OIH, tolerance and physical dependence were correlated [13]. Furthermore, the genes identified by analysis of one opioid adaptive trait were found to affect other adaptive traits when subsequently tested using pharmacologic agents and transgenic animals [8, 12, 13]. We therefore analyzed the correlations between the opioid adaptive traits, and found moderate levels of correlation between the index trait (mechanical OIH) and several opioid adaptive phenotypes (Table 1). After correction for false discovery, however, only the correlation between mechanical and thermal OIH remained significant. Strains displaying more OIH assessed using a mechanical stimulus tended to show morphine-induced hyperalgesia to thermal stimuli as well. Moreover, stains developing more hyperalgesia also tended to show more tolerance and physical dependence on morphine. These correlations are consistent with the hypothesis that some of the same genetic variants affect diverse opioid adaptive traits.Table 1 Correlations between mapped traits OIH MechOIH TFOIH ThermToleranceDependence OIH Mech 10.46*0.58†-0.50*-0.21 OIH TF 10.43*-0.180.24 OIH Therm
