FMT The Effect of Cross-Sex Fecal Microbiota Transplantation on Metabolism and Hormonal Status in Adult Rats (Jan 2024) "cross-sex male recipients displayed a significantly lower testosterone concentration compared to the males that received same-sex FMT"

[Michael Harrop]

https://www.mdpi.com/1422-0067/25/1/601

Abstract​

Increasing evidence of sexual dimorphism in the pathophysiology of metabolic complications caused by sex steroids is under investigation. The gut microbiota represents a complex microbial ecosystem involved in energy metabolism, immune response, nutrition acquisition, and the health of host organisms. Gender-specific differences in composition are present between females and males. The purpose of this study was to use cross-sex fecal microbiota transplantation (FMT) for the detection of sex-dependent metabolic, hormonal, and gut microbiota changes in female and male recipients.

Healthy non-obese female and male Wistar rats were divided into donor, same-sex, and cross-sex recipient groups. After a 30-day period of FMT administration, biochemical markers (glucose and lipid metabolism) and sex hormones were measured, and the gut microbiota was analyzed. The cross-sex male recipients displayed a significantly lower testosterone concentration compared to the males that received same-sex FMT.

Sex-dependent changes caused by cross-sex FMT were detected, while several bacterial taxa correlated with plasma testosterone levels. This study represents the first to study the effect of cross-sex changes in the gut microbiome concerning metabolic and hormonal changes/status in adult non-obese Wistar rats. Herein, we present cross-sex FMT as a potential tool to modify sex-specific pathologies.

This is interesting. It's the first study that I recall that suggests sex-matching for FMT is important. The existing evidence has largely supported universal donors. Mice, rats, and other animals naturally eat each other's poop and I've never heard of them having sex-specific preferences. The humanmicrobes.org results don't seem to show an effect like this either.