FIGURE 6. Synthetic MTMT enhances the attractiveness of urine to female mice.

In a Y-maze preference test, females strongly prefer urine from intact males compared with castrated male mice, as indicated by investigation time of the different samples (shown as mean s.e.m.). Addition of 20 p.p.b. synthetic MTMT to castrated urine roughly doubles investigation time. Much higher concentrations of acetophenone (ACE, 1 p.p.m. or 10 p.p.m.) have no effect. Although 50 p.p.b. MTMT in water slightly increased investigation time compared with water alone, the absolute investigation time is much lower than that of MTMT presented in a castrated urine background. Asterisks indicate statistically significant differences (Wilcoxon signed-ranks test, P < 0.01).