In a new study published in the journal Cell Metabolism on March 17, scientists at the University of Wuhan, China, report that a single enzyme may be responsible for depression in some women who are in their reproductive years.
Previous surveys have already revealed that there is an interaction between hormones, gut and a healthy mind. In the research, the authors reveal to have discovered an enzyme responsible for connecting these three points, causing depression: 3β-HSD.
hormones and depression
For over a century, science has linked estradiol levels to depression in fertile women. Natural hormone drops during menopause and puerperium are linked to negative mood swings, for example.
Estradiol is produced in the ovaries and is responsible for some tasks, such as regulating the menstrual cycle. It is metabolized in the liver and passes into the intestine before being partially reabsorbed by the body and back into the bloodstream.
The researchers studied the action of estradiol in the gut by comparing the blood serum and fecal microbiome of 91 women with depression and 98 without the condition. All of them were between 18 and 45 years old.
They added estradiol to fecal microbiome samples from women with depression and found that within two hours of addition, there was a 78% degradation of the hormone. For women without depression, this decline was only 20%.
The scientists also transplanted the fecal microbiome of five women with depression into mice. They observed a 25% drop in blood serum estradiol levels compared to a control group.
Then, to detect and isolate the microorganism responsible for the degradation, the researchers placed the microbiome samples from the women with depression on an agar plate and fed them only estradiol. After two hours, more than 60% of the hormone was degraded into estrone and they identified the microorganism: a strain of bacteria called Klebsiella aerogenes TS2020.
“These results show that K. aerogenes TS2020 can reduce the serum estradiol level in mice and induce depressive-like behaviors,” the researchers stated.
Enzyme discovery
Scientists have also observed that the K. aerogenes It works by converting estradiol into estrone with an enzyme called 3β-HSD. When added to the gut microbiome and “injected” into mice, the substance caused a drop in estradiol and the onset of depression. The mice also had lower levels of estradiol in their brains, including in the hippocampus – a region known to be strongly associated with the disease.
The hormone given alone to mice in the control group did not have depressive effects, which rules out the possibility of excess estradiol causing depression.
“We believe that the K. aerogenes in faeces is not the only intestinal bacteria that can produce 3β-HSD. Our metagenomic sequencing data showed that bacteria thetaiotaomicron Bacteroides It is Clostridia have 3β-HSD. However, there may be other 3β-HSD producing bacteria below the detection limit of metagenomic sequencing”, point out the scientists, who suggest further studies to map new enzyme-manufacturing microorganisms.
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