According to a study presented at the 25th European Congress of Endocrinology, female mice can be put to shift work-like patterns for only four weeks before their biological clocks are thrown off and their ability to conceive is diminished. The study adds to our understanding of how circadian disruptions affect female fertility and may potentially aid in the development of prophylactic strategies for women who work irregular hours.
The body’s internal clocks, which are synced to a 24-hour period primarily by changes in light throughout days, produce the circadian rhythm. The sleep-wake cycle, hormone secretion, digestion, and reproduction are just a few of the biological processes and functions that these clocks control, but they are readily thrown off by inappropriate light exposure, such as light at night. The ‘master biological clock’ is located in the suprachiasmatic nuclei, a small region in the centre of the brain called the hypothalamus. The hypothalamus is also the regulatory centre for reproductive function by acting on the pituitary gland – attached to the bottom of the hypothalamus – which in turn regulates ovarian activity to promote ovulation. Numerous studies in both mice and humans indicate a negative impact on female reproduction when the circadian rhythm is disrupted. However, the underlying mechanisms are not yet fully understood.
Researchers from the Institute of Cellular and Integrative Neurosciences (INCI) and the University of Strasbourg have previously shown that shift work-like patterns for several weeks lead to a reduced pregnancy rate in female mice. Now, in this study, the researchers mimicked long-term shift work conditions in female mice by constantly shifting the light-dark cycle, delaying and advancing light exposure by 10 hours across four weeks, and found that the massive release of the pituitary hormone called luteinising hormone – which triggers ovulation – was abolished, subsequently reducing fertility in these mice. Source: ANI