A new study in rats is challenging the long-held dogma that the uterus has no function outside of pregnancy. A series of experiments carried out by scientists at Arizona State University suggest that the organ influences working memory – the type of short-term information processing involved in performing complex tasks such as learning, reasoning, and navigation.
“People talk a lot about the connection between the ovary and the brain because we now know that estrogen and progesterone have such dramatic effects on things like memory. But hopefully scientists will start thinking about the brain-related utero-ovarian system instead. of just thinking about the ovary-brain system,” said Heather Bimonte-Nelson, senior author of the study. published.
According to Bimonte-Nelson's team, about a third of women had their uterus removed before age 60, and most of these surgeries occur before menopause begins. The most common reasons for hysterectomy are fibroids (painful benign lesions), endometriosis, prolapse uterine, hyperplasia (when the uterine lining is abnormally thick, causing heavy bleeding) and cancer.
The evidence available up to this point implied that the uterus had no purpose outside of maternity, causing doctors to generally recommend a hysterectomy for postpartum women (or those who are not interested in having more children), with the aim of improving quality of life.
Approximately half of women who undergo hysterectomy have their ovaries removed (oophorectomy), while the other half retain their ovaries. In addition to producing eggs, the ovaries are the main source of estrogen and progesterone in the female body, hormones that regulate the menstrual cycle and have widespread impacts on other organs and processes physiological.
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In their study, the team randomized rats into four interventions: a hysterectomy group, a hysterectomy plus oophorectomy group, a group of control without surgery and a sham surgery group, which allowed researchers to separate the potential effects of invasive opening of the cavity. abdominal. Each group contained 14 to 15 rats.
After a six-week recovery period, each animal's working memory was tested in a water maze with eight passages radiating from a central point. At the end of four passages, there were hidden platforms on which rats could crawl. Rats were placed in the center of the maze and, if they swam to a platform, were pulled out of the maze. Each rat was then placed in the maze again so they could learn which arms contained platforms.
The team was surprised to find that the hysterectomy rats fared far worse at remembering where the platforms were. Those who had a hysterectomy plus oophorectomy performed similarly to those with sham surgery, leading the authors to theorize that the uterus may, by itself, have a “detrimental impact on the ability to handle a high working memory load. demand".
"Performance did not differ between groups on reference memory tasks," noted the authors, “suggesting that the working memory domain is particularly sensitive to variations in menopause surgical procedure”.
The results were so unexpected that scientists decided to redo the experiments with new groups of mice.
“When the results of the second study had the same effect and the same pattern was present, we knew we had found something important,” Bimonte-Nelson told Discover. "No matter how we look at it, the data told us that removing the uterus was affecting cognition."
In light of these unprecedented findings, the team called for further investigation into the uterus' effects on memory.
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