| It has been reported that the EP-1, a contraceptive compound composed of levonorgestrel and quinestrol with the ratio of1:2, has negative effects on the breeding and reproductive behaviors in some species of mice and rats. However, little is known that the effects of EP-1on spatial memory and anxiety in mice. Here, the effects of treatment time (15d and30d) and dose (0mg/kg (control),1.0mg/kg,2.0mg/kg,3.0mg/kg) of EP-1on spatial memory and anxiety in Mus musculus were tested using Morris water maze and elevated plus maze separately. Negative effects of2.0mg/kg EP-1on spatial memory of the subjects were found in15days, and this ability recovered in30days, implying the2.0mg/kg EP-1can decrease the ability of spatial memory of M. musculus within a period of time. No significant effects were found in all treatments of time and dose of EP-1on anxiety of the subjects. The results might help to evaluate the effects of EP-1on mice in respect to non-reproductive behaviors.Parental care absence absolutely threatens survival and growth of pups, and subsequently influences population density in rodents. The EP-1, a kind of bisexual sterility compounds, has been reported can constrain birth and breeding behaviors in some species of rats and mice. However, little is known whether/how EP-1suppresses parental care behaviors of females during the period of lactation, and subsequently affects survival and growth of pup in mice. Here, we used0(control group) and1/20000dose EP-1rat chow (experimental group, EP-1group) to feed Mus musculus individuals to test how EP-1influences the parental care behaviors during the period of lactation. During the21days of experiment, we measured the daily intake, body weight of mothers, and recorded the daily weight and number of pups. We also measured the abilities of spatial learning and memory, anxiety behaviors of mothers during the experimental period using Morris water maze and elevated plus maze. At the end of lactation, we feed all of the experimental animals with normal rat chows in two weeks, and then let them mate with health males to test their reproductive capacity after EP-1processing in the prior period of reproduction. We found, compared with control group, both daily intake and weight of females that feed with EP-1rat chow decreased significantly. Meanwhile, the weight of pups also decreased dramatically. All pups of EP-1group were killed, due to the infanticide behavior of females. Different from control group, the escaping latency (searching for the hidden platform) of EP-1group in Morris water maze was elongated, even though the difference was not significant. Compared to control group, the anxiety behaviors showed at specific time points in elevated plus maze. Time spent in open arms of EP-1group decreased significantly at day5, day18, and day19, and the mice displayed anxiety behaviors. The entries into open arms of female mice also reduced significantly at day5, and the mice showed anxiety behaviors. After mating experiment, the pregnant period of the female mice of EP-1group was elongated. Also, the success rates of pregnancy and the number of pups decreased significantly. In the mean time, the sex ratio imbalance of pups of EP-1group was notable. All together, these results indicated the strong anti-fertility of EP-1. In conclusion, our results suggest that EP-1could efficiently control the population density of rodent by affecting parental care. |
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