Short-chain fatty acids and microbiota metabolites attenuate ghrelin receptor signaling.

The gastrointestinal microbiota is emerging as a unique and inexhaustible source for metabolites with potential to modulate G-protein coupled receptors (GPCRs). The ghrelin receptor [growth hormone secretagogue receptor (GHSR)-1a] is a GPCR expressed throughout both the gut and the brain and plays a crucial role in maintaining energy balance, metabolism, and the central modulation of food intake, motivation, reward, and mood. To date, few studies have investigated the potential of the gastrointestinal microbiota and its metabolites to modulate GPCR signaling.

Mitochondrial toxicity of microcystin-LR on cultured cells: application to the analysis of contaminated water samples.

Microcystins (MC) are potent hepatic toxins delivered into the cells by organic anion transporting peptides (OATP) where they target protein phosphatases and mitochondria. We analyzed the effects of MC-LR on primary hepatocytes, HepG2, and Jurkat T cells, and isolated rat liver mitochondria by measuring changes in O(2) consumption by optical oxygen sensing technique. Respiration of fresh primary hepatocytes was inhibited by MC-LR with EC50 = 2.