cGαo-/- females show irregular estrous cycles that cannot be modified by male urine. (A) Estrous cycles of group-housed cGαo-/-, Gαofx/fx, cGαo+/-, and B6 female mice were monitored for two weeks under no stimulation (left) and two more weeks after male urine exposure (right, grey). Numbers on y-axis correspond to different estrous phases: 2, estrus; 1, proestrus; 0, diestrus and metestrus. Each color line represents individual subjects and black lines the average of all animals. A full cycle is calculated as the event between two estrous phases. In cases where no estrus is detected before return to diestrus/metestrus, the earliest proestrus phase is considered as the beginning/end of the cycle. (B) Male urine exposure during a two-week interval results in a cycle frequency increase in B6, Gαofx/fx, and cGαo+/- but not in cGαo-/- mice (paired t-test: ***P < 0.001 (Gαofx/fx), **P <0.005 (B6 and cGαo+/-), non-significant (ns) P = 0.06 (cGαo-/-)). (C) The number of receptive days (estrus and proestrus) after male urine exposure is increased in adult B6, Gαofx/fx, and cGαo+/- and reduced in cGαo-/-females (paired t-test: *P <0.05, for all strains). The number of days in estrus and proestrus is lower in cGαo-/- when compared to control strains (analysis of variance: F1,63 = 7.83, P <0.01; least significant difference: P <0.001 in all cases; no significant difference is found between control genotypes: P = 0.27 to 0.71). (D) Two-week urine exposure induces an advancement of the third cycle by nearly two days in B6, Gαofx/fx, and cGαo+/- but not in cGαo-/- females (paired t-test: ***P <0.001 (B6), **P <0.01 (Gαofx/fx), *P <0.05 (cGαo+/-), ns P = 0.14 (cGαo-/-)).
Oboti et al. BMC Biology 2014 12:31 doi:10.1186/1741-7007-12-31