According to a study published in Cell Metabolism, premenopausal women with depression have a higher prevalence of gut bacteria than premenopausal women without depression, which is linked to worse clinical outcomes in hospitals. The authors discovered a crucial enzyme in the bacteria's genome that breaks down the ovarian hormone estradiol. Compared to control mice, mice fed this bacterium or another bacterium modified to express the enzyme showed reduced estradiol levels and signs of depressive-like behavior.
Estradiol Level from Causes of Depression in Women
In humans, female depression has been associated with decreased estradiol levels. A study of the influence of the gut microbiome on these differences, after a team from Wuhan University Renmin Hospital in China discovered that levels of these steroid hormones were significantly lower in 91 menopausal women with depression compared to 98 menopausal women without this mood disorder. conducted.
When the team incubated samples from both groups with estradiol, they discovered that stool bacteria from depressed patients were significantly more effective at metabolizing estradiol than those from the non-depressed group. Also, depression-like behavior was seen in mice that received faecal transplants from the depressed group.
The researchers grew stool samples from the depressed group in an environment where estradiol was the sole carbon source to identify the species that carried out this disruptive activity. In response to these conditions, a "pale white colony with fuzzy borders and smooth surface" developed, which the researchers termed the Gram-negative strain of K. aerogenes. Decoding the organism's genome, scientists discovered the existence of an enzyme that breaks down estradiol; A team led by the same researchers had previously shown that this enzyme also breaks down testosterone, causing depressive-like behaviors in male mice.
Female mice were fed this enzyme engineered into a strain of Escherichia coli, which was sufficient to suppress the animals' blood, brain, and hippocampal estradiol levels and induce depressive-like behaviors. According to Brittany Needham, a microbiologist and neuroscientist at Indiana University School of Medicine who was not involved in the study, by performing this final step, the team was able to confirm that this enzyme is "very important" to what they observed and that it was its activity that "caused these effects."
Finally, studies on both groups of premenopausal women showed that depressed subjects had significantly higher levels of K. aerogenes and the enzyme that breaks down estradiol in stool samples.
According to Needham, they "proved extremely conclusively for causation in mice" and showed how feeding the mice with enzyme-containing bacteria altered the animals' estradiol levels and behavior. However, this has yet to be proven in humans, where there has been only one correlation so far.
According to David Rubinow, of the University of North Carolina-Chapel Hill School of Medicine, "although animal studies like this one certainly provide indications that [changes] in gut bacteria can have quite striking phenotypic effects", "there's more smoke than fire for humans right now." Rubinow was not involved in this study. “These discoveries will motivate further study [the function of the microbiota in depressive disorders],” he continues.
Source: the-scientist.com/news
Günceleme: 18/03/2023 18:59