Figure 2
From: Intravenous fentanyl self-administration in male and female C57BL/6J and DBA/2J mice
Dose–response of intravenous fentanyl self-administration in C57BL/6J and DBA/2J mice. (a, b, d, e) Male and female mice from both strains pressed the active lever significantly more than the inactive lever on almost all doses, and active lever pressing increased as fentanyl dose decreased (lowest dose vs highest dose: p < .001). (c, f) Number of infusions did not differ as a function of strain or sex. Data are presented as the mean ± S.E.M. *p < .05.
