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The uterus is thought to play no role outside of pregnancy. However, Koebele and colleagues show that a hysterectomy could significantly impact hormonal and cognitive function.
A hysterectomy is a common procedure in which the uterus is surgically removed. Usually, this occurs prior to the onset of menopause, and about half of women also have their ovaries removed at the same time.
Until now, it was believed that the uterus played no role in normal bodily processes outside of pregnancy and that maintaining the ovaries in such surgeries would allow the maintenance of normal hormonal and cognitive function. However, recent clinical studies suggest that women who undergo a hysterectomy have a higher risk of early-onset dementia.
In a new paper published in the journal Endocrinology, the United States researchers Kobele and colleagues describe changes to the hormonal and cognitive function of rats that have undergone a hysterectomy. To study the effects of this surgery, they performed four types of procedures on rats: a sham procedure, in which nothing was removed; an ovary removal; a hysterectomy; and a hysterectomy paired with ovary removal. They then tracked rat behavior starting six weeks after the surgery.
The researchers found that ovary removal improved learning in rats, compared to those who had undergone a sham operation. Rats who had undergone a real hysterectomy also showed improved learning. These effects only applied to the early stages of learning, and not to later stages.
However, rats who had undergone a hysterectomy made more errors in spatial working memory than those who had not, even when compared to rats who had undergone both a hysterectomy and ovary removal. Rats who had undergone ovary removal were heavier than other rats. However, those rats that had undergone a hysterectomy without ovary removal showed no differences in ovarian function from rats who had undergone the sham procedure. Ovary removal reduced estrogen levels, but so did a hysterectomy. Hysterectomy also resulted in increased progesterone levels.
These findings point to the possibility of long-term cognitive and hormonal effects of hysterectomy, independent of removal of the ovaries. This could have important implications for maintaining the long-term health of women who have undergone hysterectomies, and may also impact the decision-making process for women and doctors considering a hysterectomy. Further work is needed to clarify ovarian function after hysterectomy, and the way in which hysterectomy affects cognitive processes.
Written by C.I. Villamil
Reference: Koebele et al. 2019. Hysterectomy uniquely impacts spatial memory in a rat model: a role for the nonpregnant uterus in cognitive processes. Endocrinology 160(1):1-19.