Fatty acid binding proteins and their involvement in anxiety and mood disorders

Anxiety and mood disorders represent the most prevalent neuropsychiatric conditions. Nevertheless, current pharmacotherapies often have a host of adverse side effects. Emerging evidence suggests modulation of lipid signaling pathways - particularly those involved in the endocannabinoid (eCB) system, may offer promising new targets for the treatment of anxiety and depression. Polyunsaturated fatty acids (PUFA) and their metabolic derivatives, including the eCB ligands, have garnered significant attention for their roles in neuropsychiatric disease mechanisms. Intracellular transportation of these lipids is facilitated by fatty acid binding proteins (FABP), which are increasingly recognized as key regulators of lipid signaling. Accumulating evidence indicates that FABPs may impact the development of neuropsychiatric disorders by mediating the signaling pathways of PUFAs and eCB ligands. In this review, we investigate the role of FABPs in two major categories of neuropsychiatric conditions - anxiety disorders and clinical depression. We begin by examining several neuropathophysiological mechanisms through which FABPs can impact these conditions, focusing on their role as lipid chaperones. These mechanisms include the trafficking of eCB ligands, as well as oleoylethanolamide and palmitoylethanolamide; modulation of inflammatory responses through PUFA transport and PPAR activation; regulation of PUFA availability to support neurogenesis; influence on stress-related pathways, including NMDA receptor activation and the hypothalamic-pituitary-adrenal axis; and the facilitation of dopamine receptor trafficking and localization. Next, we discuss preclinical evidence linking FABP function to anxiety- and depression-related behaviours. Finally, we propose that pharmacologically targeting FABP-mediated pathways holds considerable potential as a novel therapeutic strategy for addressing the symptoms associated with mood and anxiety disorders.

From Obesity to Mitochondrial Dysfunction in Peripheral Tissues and in the Central Nervous System

Obesity is a condition of chronic low-grade inflammation affecting peripheral organs of the body, as well as the central nervous system. The adipose tissue dysfunction occurring under conditions of obesity is a key factor in the onset and progression of a variety of diseases, including neurodegenerative disorders. Mitochondria, key organelles in the production of cellular energy, play an important role in this tissue dysfunction. Numerous studies highlight the close link between obesity and adipocyte mitochondrial dysfunction, resulting in excessive ROS production and adipose tissue inflammation. This inflammation is transmitted systemically, leading to metabolic disorders that also impact the central nervous system, where pro-inflammatory cytokines impair mitochondrial and cellular functions in different areas of the brain, leading to neurodegenerative diseases. To date, several bioactive compounds are able to prevent and/or slow down neurogenerative processes by acting on mitochondrial functions. Among these, some molecules present in the Mediterranean diet, such as polyphenols, carotenoids, and omega-3 PUFAs, exert a protective action due to their antioxidant and anti-inflammatory ability. The aim of this review is to provide an overview of the involvement of adipose tissue dysfunction in the development of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and multiple sclerosis, emphasizing the central role played by mitochondria, the main actors in the cross-talk between adipose tissue and the central nervous system.

Oleic acid-derived oleoylethanolamide: A nutritional science perspective

The fatty acid ethanolamide oleoylethanolamide (OEA) is an endogenous lipid mediator derived from the monounsaturated fatty acid, oleic acid. OEA is synthesized from membrane glycerophospholipids and is a high-affinity agonist of the nuclear transcription factor peroxisome proliferator-activated receptor α (PPAR-α). Dietary intake of oleic acid elevates circulating levels of OEA in humans by increasing substrate availability for OEA biosynthesis. Numerous clinical studies demonstrate a beneficial relationship between high-oleic acid diets and body composition, with emerging evidence to suggest OEA may mediate this response through modulation of lipid metabolism and energy intake. OEA exposure has been shown to stimulate fatty acid uptake, lipolysis, and β-oxidation, and also promote food intake control. Future research on high-oleic acid diets and body composition is warranted to confirm these outcomes and elucidate the underlying mechanisms by which oleic acid exerts its biological effects. These findings have significant practical implications, as the oleic acid-derived OEA molecule may be a promising therapeutic agent for weight management and obesity treatment.

Arylboronic acids as dual-action FAAH and TRPV1 ligands

A series of 31 arylboronic acids designed on the basis of the pharmacophore model for a variety of TRPV1 antagonists was prepared and tested on FAAH and TRPV1 channel. Four of them, that is, compounds 3c, 4a, 5a,b acted as dual FAAH/TRPV1 blockers with IC50 values between 0.56 and 8.11μM whereas ten others (compounds 1c,f-i, 2c-f, 4b) inhibited FAAH and activated/desensitized TRPV1.

Preclinical Characterization of the FAAH Inhibitor JNJ-42165279

The pre-clinical characterization of the aryl piperazinyl urea inhibitor of fatty acid amide hydrolase (FAAH) JNJ-42165279 is described. JNJ-42165279 covalently inactivates the FAAH enzyme, but is highly selective with regard to other enzymes, ion channels, transporters, and receptors. JNJ-42165279 exhibited excellent ADME and pharmacodynamic properties as evidenced by its ability to block FAAH in the brain and periphery of rats and thereby cause an elevation of the concentrations of anandamide (AEA), oleoyl ethanolamide (OEA), and palmitoyl ethanolamide (PEA). The compound was also efficacious in the spinal nerve ligation (SNL) model of neuropathic pain. The combination of good physical, ADME, and PD properties of JNJ-42165279 supported it entering the clinical portfolio.

Modulation of plasma N-acylethanolamine levels and physiological parameters by dietary fatty acid composition in humans

N-Acylethanolamines (NAEs) are endogenous lipid-signaling molecules involved in satiety and energetics; however, how diet impacts circulating NAE concentrations and their downstream metabolic actions in humans remains unknown. Objectives were to examine effects of diets enriched with high-oleic canola oil (HOCO) or HOCO blended with flaxseed oil (FXCO), compared with a Western diet (WD), on plasma NAE levels and the association with energy expenditure and substrate oxidation. Using a randomized controlled crossover design, 36 hypercholesterolemic participants consumed three isoenergetic diets for 28 days, each containing 36% energy from fat, of which 70% was HOCO, FXCO, or WD. Ultra-performance liquid chromatography-MS/MS was used to measure plasma NAE levels and indirect calorimetry to assess energy expenditure and substrate oxidation. After 28 days, compared with WD, plasma oleoylethanolamide (OEA) and alpha-linolenoyl ethanolamide (ALEA) levels were significantly increased in response to HOCO and FXCO (P = 0.002, P < 0.001), respectively. Correlation analysis demonstrated an inverse association between plasma OEA levels and percent body fat (r = -0.21, P = 0.04), and a positive association was observed between the plasma arachidonoyl ethanolamide (AEA)/OEA ratio and android:gynoid fat (r = 0.23, P = 0.02), respectively. Results suggest that plasma NAE levels are upregulated via their dietary lipid substrates and may modulate regional and total fat mass through lipid-signaling mechanisms.

Aryl Piperazinyl Ureas as Inhibitors of Fatty Acid Amide Hydrolase (FAAH) in Rat, Dog, and Primate

A series of aryl piperazinyl ureas that act as covalent inhibitors of fatty acid amide hydrolase (FAAH) is described. A potent and selective (does not inhibit FAAH-2) member of this class, JNJ-40355003, was found to elevate the plasma levels of three fatty acid amides: anandamide, oleoyl ethanolamide, and palmitoyl ethanolamide, in the rat, dog, and cynomolgous monkey. The elevation of the levels of these lipids in the plasma of monkeys suggests that FAAH-2 may not play a significant role in regulating plasma levels of fatty acid ethanolamides in primates.

Oleoylethanolamide-based lyotropic liquid crystals as vehicles for delivery of amino acids in aqueous environment

We have investigated the phase behavior of self-assembled lyotropic liquid crystals (LC) formed by ternary mixtures of oleoylethanolamide (OEA), water and arginine. OEA, a natural analog of the endogenous cannabinoid anandamide involved in the peripheral regulation of feeding, was selected as a main component due to its capacity to induce efficient decreases in food intake and gains in body mass. Arginine was selected as representative hydrophilic amino acid and added to the OEA-water mixture at different concentrations. The phase diagrams were determined by combining cross-polarized optical microscopy and small angle x-ray scattering. First, the phase diagram for the OEA-water system was determined. It was shown that these two compounds give rise to reverse Ia3d double gyroid and reverse Pn3m double diamond cubic phases existing in bulk over a large window of temperature and composition, and that for water content beyond 25% Pn3m coexisted with excess water. Successively, the influence of arginine as guest molecule in the water channels of the reverse LC was investigated. For the sake of comparison, results for the OEA-water-arginine system were compared with analog series of OEA-water-glucose. The results showed that, at a fixed water content and temperature, the phase behavior of the liquid crystalline phases is strongly dependent on arginine concentration. In more detail, arginine could be encapsulated in the bulk OEA-water LC up to 2.0% wt, whereas transitions from Ia3d to Pn3m cubic phase were observed with increasing arginine concentration. Interestingly, upon an increase of water concentration beyond 20-25%, Pn3m phase started to coexist with excess water releasing the arginine in external water solution. Quantitative measurements of arginine content inside the LC water channels and in the excess external water solution revealed a complete release of the amino acid, demonstrating that the investigated lyotropic liquid crystalline systems can be used as ideal vehicles for the delivery of functional hydrophilic active molecules in aqueous environment.

Thiadiazolopiperazinyl ureas as inhibitors of fatty acid amide hydrolase

A series of thiadiazolopiperazinyl aryl urea fatty acid amide hydrolase (FAAH) inhibitors is described. The molecules were found to inhibit the enzyme by acting as mechanism-based substrates, forming a covalent bond with Ser241. SAR and PK properties are presented.