Stress during Lactation Affects Fatty Acid Amide Hydrolase Protein Expression in Adipose Tissue and Liver of Adult Mice

Abstract

CIntroduction: Early stress alters the endo-cannabinoid system of tissues involved in energy homeostasis, leading to long term consequences associated to hormonal and metabolic disruptions associated to overweight/obesity and insulin resistance. We have previously reported a decreased Anandamide (AEA)-hydrolysing activity in liver and epididymal fat of adult mice previously subjected to stress during lactation, a result that may indicate reduced activity of the enzyme fatty acid amide hydrolase present in both tissues (FAAH; able to hydrolyse the endocannabinoid AEA). Objective: Since at present it is unknown whether early stress affects FAAH gene and/or protein expression in liver and adipose tissue during adulthood, we have performed studies with the aim of evaluating these parameters. Methods: Male mice pups were subjected to a soft nociceptive stress during the first 21 days of life (whole lactation period) with a subcutaneous injection of saline solution in the back, and sacrificed when adults (130 days old) to extract liver and epididymal fat. Results: Data obtained from real time PCR demonstrate that stress during lactation do not affect FAAH mRNA expression either in liver or epididymal adipose tissue of adult animals; however, Western Blot analyses indicates that FAAH protein amount was decreased by 35 and 65% in liver and epididymal fat, respectively. Conclusion: Present results demonstrate that nociceptive stress during lactation leads to decreased FAAH protein expression in liver and epididymal fat of adult mice, which may be associated to the low AEA- hydrolysing activity previously reported by us in both tissues. Low levels and activity of FAAH should result in increased availability of AEA, leading to a sustained activity of type 1 cannabinoid receptors associated to undesirable cellular and physiological consequences