Figure 2.

Writhing responses in COX-deficient male (a) and female (b) mice. The number of writhing responses in 15 min in the stretching test for COX-1-deficient homozygous or heterozygous mice injected i.p. with 1.2% acetic acid was less than the number of responses by WT animals. This indicated a decrease in nociception in these mice. COX-2-deficient heterozygous females also showed fewer writhing responses and decreased nociception. Histograms represent means for 4–6 animals (males) and 7–10 animals (females) ± SEM; *, P < 0.05 when compared with WT controls.