A new study shows that the hearts of female and male mice respond differently to stress hormones. This research could contain important implications that play a role in treating cardiovascular diseases, such as arrhythmias and heart failure, in humans. In the study, the mice were exposed to noradrenaline, also known as norepinephrine, which is a hormone and neurotransmitter that is associated with our “fight-or-flight” response. The research team detected how a mouse heart responds to neurotransmitters and hormones in real-time by using a fluorescence imaging system. They also used a special genetically modified mouse, called the CAMPER mouse, that emits light during cAMP binding in the heart. The cAMP molecule acts as an intermediate messenger that turns hormones and neurotransmitters into actions in the heart. The fluorescence imaging system picks up light signals emitted by the CAMPER mouse which allows the researchers to record the heart’s reaction to noradrenaline in real-time, along with its electrical activity.
Woman experimenting on mouse
Image Source: Cultura RM Exlusive/Sigrid Gombert
The results demonstrated that male and female hearts respond in the same way after the first exposure to noradrenaline; however, instead, some areas of the female heart returned to basal rate more quickly than the male heart, thus producing differences in the heart’s electrical activity. This means that the repolarization of the heart differs between female and male mice. One of the lead researchers, Jessica L. Caldwell, stated that “the study reveals a new factor that may contribute to arrhythmia susceptibility to men and women.” Prior to this study, male mice were used exclusively for experiments and studies, but patterns of different reactions revealed that there are sex-based differences. With this in mind, more research must be done to determine how and why the differences in response between both sexes contribute to heart disease in humans.
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