Endocannabinoids Measurement in Human Saliva as Potential Biomarker of Obesity

et al. (2012) Endocannabinoids Measurement in Human Saliva as Potential Biomarker of Obesity. PLoS ONE 7(7): e42399. doi:10.1371/journal.pone.0042399 Endocannabinoids Measurement in Human Saliva as Potential Biomarker of Obesity Isabelle Matias 0 Blandine Gatta-Cherifi 0 Antoine Tabarin 0 Samantha Clark 0 Thierry Leste- 0 Lasserre 0 Giovanni Marsicano 0 Pier Vincenzo Piazza 0 Daniela Cota 0 Silvana Gaetani, Sapienza University of Rome, Italy 0 1 Group ''Energy Balance and Obesity'', Institut National de la Sante et de la Recherche Me dicale (INSERM) , Neurocentre Magendie, Physiophatologie de la Plasticite Neuronale, Bordeaux , France , 2 Group ''Endocannabinoids and Neuroadaptation'', Institut National de la Sante et de la Recherche Me dicale (INSERM) , Neurocentre Magendie, Physiophatologie de la Plasticite Neuronale, Bordeaux , France , 3 Group ''Physiopathology of Addiction'', Institut National de la Sante et de la Recherche Me dicale (INSERM) , Neurocentre Magendie, Physiophatologie de la Plasticite Neuronale, Bordeaux , France , 4 University of Bordeaux , Neurocentre Magendie, Physiopathologie de la Plasticite Neuronale, Bordeaux , France , 5 Endocrinology Department, Haut-Le veque Hospital , Pessac , France Background: The discovery of the endocannabinoid system and of its role in the regulation of energy balance has significantly advanced our understanding of the physiopathological mechanisms leading to obesity and type 2 diabetes. New knowledge on the role of this system in humans has been acquired by measuring blood endocannabinoids. Here we explored endocannabinoids and related N-acylethanolamines in saliva and verified their changes in relation to body weight status and in response to a meal or to body weight loss. Methodology/Principal Findings: Fasting plasma and salivary endocannabinoids and N-acylethanolamines were measured through liquid mass spectrometry in 12 normal weight and 12 obese, insulin-resistant subjects. Salivary endocannabinoids and N-acylethanolamines were evaluated in the same cohort before and after the consumption of a meal. Changes in salivary endocannabinoids and N-acylethanolamines after body weight loss were investigated in a second group of 12 obese subjects following a 12-weeks lifestyle intervention program. The levels of mRNAs coding for enzymes regulating the metabolism of endocannabinoids, N-acylethanolamines and of cannabinoid type 1 (CB1) receptor, alongside endocannabinoids and N-acylethanolamines content, were assessed in human salivary glands. The endocannabinoids 2-arachidonoylglycerol (2-AG), N-arachidonoylethanolamide (anandamide, AEA), and the N-acylethanolamines (oleoylethanolamide, OEA and palmitoylethanolamide, PEA) were quantifiable in saliva and their levels were significantly higher in obese than in normal weight subjects. Fasting salivary AEA and OEA directly correlated with BMI, waist circumference and fasting insulin. Salivary endocannabinoids and N-acylethanolamines did not change in response to a meal. CB1 receptors, ligands and enzymes were expressed in the salivary glands. Finally, a body weight loss of 5.3% obtained after a 12-weeks lifestyle program significantly decreased salivary AEA levels. Conclusions/Significance: Endocannabinoids and N-acylethanolamines are quantifiable in saliva and their levels correlate with obesity but not with feeding status. Body weight loss significantly decreases salivary AEA, which might represent a useful biomarker in obesity. - Funding: This work was supported by INSERM/AVENIR (DC and GM), INSERM/ interface (DC), Aquitaine Region (DC and GM), French Society of Endocrinology (BGC), Fondation Recherche Medicale, EU-FP7 HEALTH-F2-2008-223713 and EU-FP7 ENDOFOOD ERC-2010-StG (GM). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. . These authors contributed equally to this work. The discovery of the endocannabinoid system (ECS) and of its impact on the regulation of energy homeostasis represents a significant advance in the study of obesity and type 2 diabetes [1 4]. The ECS comprises two distinct membrane cannabinoid receptors, CB1 and CB2, specific ligands named endocannabinoids, such as anandamide (AEA) and 2-arachidonoylglycerol (2AG), and enzymes for ligand biosynthesis and inactivation [5]. Endocannabinoids have known appetite-stimulating effects in animals by acting at cannabinoid CB1 receptors [1,2]. Furthermore, there is evidence for an up-regulation of endocannabinoids and endocannabinoid-related N-acylethanolamines oleoylethanolamide (OEA) and palmitoylethanolamide (PEA) in both blood and adipose tissue of obese humans [69]. Recently, we have shown that changes in plasma AEA levels might have physiological relevance in the anticipatory or preparatory phase of the meal in humans, since both normal weight and obese subjects have a (...truncated)