The probiotic Lactobacillus rhamnosus mimics the dark-driven regulation of appetite markers and melatonin receptors' expression in zebrafish (Danio rerio) larvae: Understanding the role of the gut microbiome

The use of probiotics has been recently considered a novel therapeutic strategy to prevent pathologies such as obesity; however, the specific mechanisms action by which exert their beneficial effects on metabolic health remain unclear. aim present study was investigate short-term probiotic Lactobacillus rhamnosus supplementation (PROB) appetite regulation, growth-related markers, and microbiota diversity in zebrafish (Danio rerio) larvae, compared group subjected constant darkness photoperiod (DARK), well evaluate both treatments melatonin receptors' expression. After 24 h treatment, PROB DARK conditions caused significant increase leptin Moreover, mRNA abundances b proopiomelanocortin were elevated group, showed similar tendency, supporting negative regulation markers treatments. also enhanced receptors transcript (melatonin receptor 1 ba bb) protein 1) suggesting potential involvement mediating these effects. Nevertheless, did not exhibit effect expression most growth hormone/insulin-like factor axis genes evaluated. Finally, only condition significantly modulated gut at short time, altogether highlighting rapid this modulating regulatory expression, without concomitant variation microbiota.