Supporting information for Mogil et al. (2003) Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0730053100

Supporting Figure 5

Fig. 5.

Switching of analgesia mechanisms in female B6 and e/e mice depending on estrogenic status. C57BL/6 (B6) and mutant (e/e) mice of both sexes (n = 4–14 per genotype per sex per status per drug) were either left intact or ovariectomized (OVX), via surgical removal (dorsal incision) of both ovaries under isoflurane/oxygen anesthesia. No testing occurred for at least 2 weeks after surgery. Some OVX mice were given chronic estrogen replacement (OVX+E2; 5.0 μg/day, i.p., in sesame oil vehicle, for 6–7 days), following our original protocol (1). After baseline testing on the 49ΊC tail-withdrawal test, all mice received a s.c. injection of MK-801 (0.075 mg/kg) or saline (10 ml/kg), followed immediately by an i.p. injection of U50,488 (50 mg/kg). Percent analgesia scores were calculated as described. *, Significant blockade of analgesia by MK-801, P < 0.05. †, Significantly different from intact male and OVX female group, P < 0.05. Note that both B6 and e/e females display evidence of estrogenic control of analgesic magnitude. Only B6 females display evidence of neurochemical switching of analgesia (i.e., MK-801 sensitivity), because e/e mice appear to be using the male-like, MK-801 sensitive system regardless of hormonal status.

1. Mogil, J. S., Sternberg, W. F., Kest, B., Marek, P. & Liebeskind, J. C. (1993) Pain 53, 17–25.