PubMed · 4935303
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D Rimoin. 1971. New knowledge about HGH.. https://pubmed.ncbi.nlm.nih.gov/4935303/
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Insomnia is associated with gut microbial dysbiosis, but the specific microbial metabolites mediating gut-brain communication remain elusive. Here, we integrate metagenomic sequencing from 171 individuals (primary insomnia, post-COVID insomnia, and controls) with functional pathway analysis and preclinical validation. We identify Faecalibacterium prausnitzii depletion and reduced L-arginine biosynthesis as consistent features in both insomnia subtypes, accompanied by elevated cortisol levels. Genomic and in vitro analyses confirm that F. prausnitzii is a key microbial contributor to L-arginine production. In a chronic mild stress mouse model, administration of either F. prausnitzii or L-arginine restores sleep duration, normalizes corticosterone levels, and reverses stress-induced gut dysbiosis. Mechanistically, L-arginine suppresses POMC gene expression and dampens adrenocorticotropic hormone (ACTH)-stimulated corticosterone release, implicating the POMC-ACTH-cortisol axis as a key target. These findings uncover a gut-brain axis driven by F. prausnitzii-derived L-arginine that modulates sleep through endocrine signaling, positioning this metabolite as a potential therapeutic avenue for insomnia.
OBJECTIVE: This meta-analysis aimed to evaluate the effect of oral l-arginine supplementation on ambulatory blood pressure (ABP). METHODS: A systematic search of PubMed, Cochrane Library, Embase, and Web of Science databases was conducted from their inception through March 1, 2026. Randomized controlled trials (RCTs) assessing the effects of oral l-arginine intervention were included. Outcome measures included 24-h systolic blood pressure (24h SBP), 24-h diastolic blood pressure (24h DBP), daytime systolic blood pressure (dSBP), daytime diastolic blood pressure (dDBP), nighttime systolic blood pressure (nSBP), and nighttime diastolic blood pressure (nDBP). Meta-analysis was performed using Stata 17.0. The weighted mean difference (WMD) was used as the effect size, and the results were pooled with 95% confidence intervals (CIs). RESULTS: A total of 5 RCTs comprising 202 participants were included. Meta-analysis results demonstrated that oral l-arginine significantly reduced 24h SBP (WMD = -4.23 mmHg, 95% CI [-5.87, -2.58]; P < 0.01) and 24h DBP (WMD = -3.04 mmHg, 95% CI [-4.48, -1.59]; P < 0.01). Significant reductions were also observed for dSBP (WMD = -4.16 mmHg, 95% CI [-5.90, -2.41]; P < 0.01) and dDBP (WMD = -4.25 mmHg, 95% CI [-5.85, -2.66]; P < 0.01). Furthermore, oral l-arginine significantly lowered nSBP (WMD = -5.70 mmHg, 95% CI [-7.81, -3.58]; P < 0.01) and nDBP (WMD = -4.18 mmHg, 95% CI [-6.27, -2.09]; P < 0.01). CONCLUSION: Oral l-arginine supplementation significantly reduces ABP. However, the number of included studies was limited, and further validation through additional relevant research is warranted.
The production of human proinsulin in its disulfide-intact, native form in Escherichia coli requires disulfide bond formation and the periplasmic space is the favourable compartment for oxidative folding. However, the secretory expression of proinsulin is limited by its high susceptibility to proteolysis and by disulfide bond formation, which is rate-limiting for proinsulin folding. In this report we describe a method for the production of high amounts of soluble, native human proinsulin in E. coli. We fused proinsulin to the C-terminus of the periplasmic disulfide oxidoreductase DsbA via a trypsin cleavage site. As DsbA is the main catalyst of disulfide bond formation in E. coli, we expected increased yields of proinsulin by intra- or intermolecular catalysis of disulfide bond formation. In the context of the fusion protein, proinsulin was found to be stabilised, probably due to an increased solubility and faster disulfide bond formation. To increase the yield of DsbA-proinsulin in the periplasm, several parameters were optimised, including host strains and cultivation conditions, and in particular growth medium composition and supplement of low molecular weight additives. We obtained a further, about three-fold increase in the amount of native DsbA-proinsulin by addition of L-arginine or ethanol to the culture medium. The maximum yield of native human proinsulin obtained from the soluble periplasmic fraction after specific cleavage of the fusion protein with trypsin was 9.2 mg g(-1), corresponding to 1.8% of the total cell protein.