Arachidonic acid anandamide

Recently, the ethanolamide of arachidonic acid (anandamide ananda is the Sanskrit word for bliss) (Figure 3.53) has been isolated from animal brain tissue, and has been shown... 

As an example of the application of metabolomics, we will refer to the substrates of the enzyme fatty acyl amide hydrolase (FAAH) that regulates several brain lipids that have interesting pharmacological properties including effects on the control of pain. It is well known that some fatty acyl amides of ethanolamine are substrates of FAAH, such as the ethanolamide of arachidonic acid (anandamide), which is an endogenous ligand of cannabinoid receptors. 

FIGURE 12.1 Structures of arachidonic acid, anandamide, and 2-arachidonylglycerol. 

There is some evidence that in cells with low anandamide amidase activity, such as platelets and neutrophils, anandamide is inactivated by an oxidative pathway involving 12(5)-lipoxygenase (Edgemond, 1998). Metabolism of anandamide by enzymes of the arachidonic acid cascade... 

Figure 6 Anandamide metabolism NAPE, N-arachidonylphosphatidyl-ethanol-amides PLD, phospholipase D AEA, anandamide AC, anandamide carrier protein AT, anandamide transporter AEAase, anandamide amidase AA, arachidonic acid.

Anandamide amidase recognizes and hydrolyzes 2-AG (Goparaju, 1999 Di Marzo, 1999 Lang, 1999) however, there is evidence for the existence of another specific hydrolase [monoacylglycerol (MAG) lipase] that hydrolyzes 2-AG (D. Piomelli and A. Makriyannis, 2000, personal communication). In addition to this pathway, 2-AG diffuses rapidly into the cell membrane where it could be either hydrolyzed to arachidonic acid and glycerol or esterified back to phosphoglycerides (Di Marzo, 1999b). 

Anandamide is believed to be synthesized from a phospholipid precursor, /V-arachidonoyl-phosphatidylethanolamine, catalysed by phospholipase D (Di Marzo et al. 1998). The other proposed route of synthesis is from condensation of arachidonic acid and ethanolamine, although this has yet to be demonstrated in living cells. 2-AG is formed in a calcium-dependent manner, and mediated by the enzymes phospholipase C and diacylglycerol lipase (Kondo et al. 1998 Stella et al. 1997). 

Because of the small amount of natural anandamide available, we were able to record H NMR spectra only. The peaks attributed to double-bond protons (5 5.30 to 5.45, multiplet) were coupled with those of protons that have the chemical shifts of doubly allylic protons (5 2.75 to 2.90, multiplet). Such doubly allylic protons are typically found in all-af, nonconju-gated polyunsaturated fatty acids such as linoleic and arachidonic acids. Three pairs of protons were observed between 5 2.01 and 2.27, which we attributed to two allylic methylene groups and one methylene group a to a carbonyl moiety. Only one methyl group was observed (0.99, triplet). The peaks observed for two protons at 3.42 (N-CH2, triplet), two protons at 3.72 (O-CH2, triplet), and two protons at 2.20 (COCH2, triplet) were... 

A compound with the same molecular weight as anandamide, but with a shorter retention time, was identified as O-arachidonoyl ethanolamine (arachidonic acid and ethanolamine joined by an ester linkage) (EC50 = 1906 nM). Based on this opposite orientation, the molecule was named virodhamine from the Sanskrit word, virodha, which means opposition. 

Figure 2 Known second-messenger pathways that modulate capsaicin or VRs. GPCR, G protein-coupled receptors PLA2, phospholipase A2 AC, adenylate cyclase IP3, inositoltriphosphate DAC diacylglycerol LM, lipoxygenase metabolites AA, arachidonic acid ANA, anandamide PG, prostaglandins Gq/11, Gq/j, Gs, trimeric G-proteins (adapted from Premkumar, 2001)...

Anandamide can be transported inside neural cells (neurons and glia) by a carrier-mediated facilitate diffusion mechanism (Beltramo et al., 1997) and transformed through two main pathways (1) hydrolysis to arachidonic acid and ethanolamine, and (2) oxidation to various oxygenated derivatives. 

Anandamide can be hydrolyzed to arachidonic acid and ethanolamine by fatty acid amide hydrolase (FAAH) (Cravatt et al., 1996 Wei et al., 2006) (Fig. 1). FAAH is highly expressed in the brain, where it is expressed at high concentrations in neuronal cell bodies and dendrites that are juxtaposed to axon terminals containing CB receptors. This suggests that anandamide hydrolysis occurs post-synaptically (Piomelli, 2003). 

Anandamide is present in brain cells in very low concentrations [44-47]. Apparently it is released (presumably mostly when needed) through cleavage catalysed by phospholipase D from /V-arachidonoyl phosphatidyl etha-nolamide, which is formed by a calcium-dependent enzyme activity which catalyses the transfer of arachidonic acid (and other fatty acids) from various donor phospholipids to phosphatidylethanolamine (see Figure 5.4) [48, 49], In animal post mortem brains kept at room temperature, the concentration of anandamide gradually increases [44, 45], It would be of interest to find out whether anandamide concentrations also increase in vivo in brain after trauma, indicating a possible role for this fatty acid amide. Preliminary experiments by Dr. E. Shohami (unpublished) have shown that administration... 

Anandamide is rapidly hydrolysed enzymatically to arachidonic acid and ethanol-amine by a fatty acid amide hydrolase (FAAH) [50], The molecular characterization, cloning and expression of FAAH have been reported in a recent study [51]. FAAH can be blocked with either the general serine protease inhibitor phenyl methy(sulphonyl fluoride [38] or with the highly efficient methyl arachidonyl fluorophsphonate [52], The non-steroidal antiinflammatory ibuprofen in therapeutic doses, but not aspirin, sulindac or acetaminophen, also inhibits anandamide metabolism [53], This observation may have therapeutic implications. 

After the demonstration of THC binding sites in the CNS (26), a search for an endogenous ligand produced the long-chain ethanol-amine derivative (17) of arachidonic acid, known as anandamide (27). Subsequently, the glycerol ester of arachidonic acid (18), known as 2-AG, was shown to be a more abundant endogenous ligand in the brain than anandamide (28). Further development has tended... 

The discovery of cannabinoid receptors naturally stimulated a search for an endogenous ligand with which the receptors naturally interact. Such a substance was isolated from the pig brain. It was found to be chemically different from plant cannabinoids it is a derivative of the fatty acid arachidonic acid (arachidonyl ethanolamide) related to the prostaglandins. This endogenous substance was named anandamide after the Sanskrit word for bliss, ananda. It has a high affinity for CBi receptors and has most of the actions of THC. 

Arachidonic acid ethanolamide (anandamide) and similar compounds are constituents of the brain. Anandamide and certain of the compounds similar with same, bind to the cannabinoid receptor. The binding of the ananamide to the cannabinoid receptor is similar to the binding of A9-tetrahydrocannabinol. There exist in the body many mediators, which are derivatives of arachidonic acid, such as prostaglandins and leukotrienes, which are present as large families of related compounds. Certain of these do not bind to the cannabinoid receptor, and it was one of the aims of the present invention to provide and identify compounds which have pharmacological properties similar to the properties of anandamide. 

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