Repeated acoustic stimulation (audiogenic kindling) induces estrous arrest in the Wistar audiogenic Rat (WAR) strain. A model of pseudopregnancy?

Background

Epilepsy is a chronic disorder characterized by a predisposition to epileptic seizures, affecting more than 50 million people worldwide.

Methods

Wistar and Wistar Audiogenic Rats (WAR) females were evaluated regarding estrous cycle and seizures episodes during repeated (kindling) acoustic stimulation at different stages of the estrous cycle.

Results

Acoustic stimulation did not affect the estrous cycle of most Wistar females in either control (91.6 %) or kindled (70.0 %) groups. They also had no seizures episodes. In WAR females, most of the control group (91.6 %) showed regular cycles during acoustic stimulation. In the kindling group, all females showed irregular cycles during acoustic stimulation with diestrus arrest for several days (11.8 ± 1.46 days) and 12 of them (92.3 %) showed, at least, four mesencephalic seizure behaviors during the acoustic stimulation (1 ≤ cSI ≤ 8). In this group, 7 females (53.84 %) also showed limbic seizures (2 ≤ LI ≤ 4). When WAR females were stratified by estrous cycle stage, the group that started the acoustic stimulation during estrus had five females (45.4 %) with diestrus arrest for several days (11.4 ± 0.89 days) and, eight females (72.7 %) exhibited, at least, two seizure behaviors (1 < cSI < 8). When acoustic stimulation was started in the metestrus stage, six females (54.5 %) exhibited diestrus arrest for several days (10.5 ± 3.27 days). In the metestrus group, ten females (90.9 %) presented five or six seizure episodes (1 < cSI < 8).

Conclusion

Our results showed that chronic audiogenic seizures (audiogenic kindling) affect the estrous cycle of WAR females, resulting in a consistent diestrus arrest for 10–12 days, which is consistent with the phenomenon of pseudopregnancy.