Gastrointestinal function is known to be regulated by steroid molecules produced by the gonads, the adrenal glands and the gut microbiota. However, we have a limited knowledge on the functional significance of local steroid production by gastrointestinal tract tissue. On this basis, we have here evaluated, as a first methodological approach, the expression of steroidogenic molecules and the local levels of key steroids in the male rat colon. Our findings indicate that the colon tissue expresses molecules involved in the early steps of steroidogenesis and in the consecutive synthesis and metabolism of steroid hormones, such as progesterone, testosterone and 17β-estradiol. In addition, the levels of the steroid hormone precursor pregnenolone and the levels of active metabolites of progesterone and testosterone, such as dihydroprogesterone, tetrahydroprogesterone, dihydrotestosterone and 17β-estradiol, were higher in colon than in plasma. Higher levels of the androgen metabolite 3α-diol were detected in the colon in comparison with another non-classical steroidogenic tissue, such as the cerebral cortex. These findings suggest the existence of local steroid synthesis and metabolism in the colon, with the production of active steroid metabolites that may impact on the activity of the enteric nervous system and on the composition of the gut microbiota.

众所周知，胃肠功能受性腺，肾上腺和肠道菌群产生的类固醇分子调节。但是，我们对胃肠道组织产生局部类固醇的功能意义的认识有限。在此基础上，我们在这里评估了雄激素大鼠结肠中类固醇生成分子的表达和关键类固醇的局部水平，作为第一种方法学方法。我们的发现表明，结肠组织表达的分子参与类固醇生成的早期步骤以及类固醇激素（如孕酮，睾丸激素和17β-雌二醇）的连续合成和代谢。此外，类固醇激素前体孕烯醇酮的水平以及孕酮和睾丸激素（例如二氢孕酮）的活性代谢物的水平，结肠中的四氢孕酮，二氢睾酮和17β-雌二醇高于血浆。与其他非经典的类固醇生成组织（例如大脑皮层）相比，在结肠中检测到更高水平的雄激素代谢物3α-二醇。这些发现表明结肠中存在局部类固醇的合成和代谢，以及活性类固醇代谢产物的产生，这可能会影响肠神经系统的活动以及肠道菌群的组成。