A novel inhibitor of endocannabinoid catabolic enzymes sheds light on behind the scene interplay between chronic pain, analgesic tolerance, and heroin dependence

Inhibition of Fatty Acid Amide Hydrolase (FAAH) by Macamides

The pentane extract of the Peruvian plant, Lepidium meyenii (Maca), has been demonstrated to possess neuroprotective activity in previous in vitro and in vivo studies (Pino-Figueroa et al. in Ann N Y Acad Sci 1199:77-85, 2010; Pino-Figueroa et al. in Am J Neuroprot Neuroregener 3:87-92, 2011). This extract contains a number of macamides that may act on the endocannabinoid system (Pino-Figueroa et al. in Ann N Y Acad Sci 1199:77-85, 2010; Pino-Figueroa et al., 2011; Dini et al. in Food Chem 49:347-349, 1994). The aim of this study was to characterize the inhibitory activity of four of these maccamides (N-benzylstearamide, N-benzyloleamide, N-benzyloctadeca-9Z,12Z-dienamide, and N-benzyloctadeca-9Z,12Z,15Z-trienamide) on fatty acid amide hydrolase (FAAH), an enzyme that is responsible for endocannabinoid degradation in the nervous system (Kumar et al. in Anaesthesia 56:1059-1068, 2001). The four compounds were tested at concentrations between 1 and 100 μM, utilizing an FAAH inhibitor screening assay. The results demonstrated concentration-dependent FAAH inhibitory activities for the four macamides tested. N-Benzyloctadeca-9Z,12Z-dienamide demonstrated the highest FAAH inhibitory activity whereas N-benzylstearamide had the lowest inhibitory activity. In addition, N-benzylstearamide, N-benzyloleamide, and N-benzyloctadeca-9Z,12Z-dienamide demonstrated time-dependent inhibition when tested after a pre-incubation period, indicating that the mechanism of inhibition for these compounds most likely is irreversible. Of interest, unsaturation in the fatty acid moiety resulted in greater FAAH inhibitory activity. LC/MS/MS analysis demonstrated that FAAH was able to hydrolyze N-benzyloctadeca-9Z,12Z-dienamide, suggesting that N-benzyloctadeca-9Z,12Z-dienamide is also a slow substrate for FAAH. These results provide useful information about the mechanism of action of Lepidium meyenii and may help with the development of new compounds with FAAH inhibitory or modulatory activity.

Association between alcoholism and the gene encoding the endocannabinoid synthesizing enzyme diacylglycerol lipase alpha in the Japanese population

The endocannabinoid system has been recognized to be involved in neuropsychiatric diseases. 2-arachidonoyl glycerol (2-AG) is one of the two main endocannabinoids, and their regulation could play roles in disorders under environmental influence. This study investigated the involvement of the 2-AG biosynthesizing enzyme diacylglycerol lipase alpha (DAGLA) in the pathogenesis of alcoholism. We investigated a possible association between alcoholism and single nucleotide polymorphisms (SNPs) of the human DAGLA gene in the Japanese population. To discern any environmental influences on Dagla function in an animal study, the Dagla gene expression in the brain from stressed model mice was analyzed. The SNPs, including missense polymorphism Pro899Leu in the DAGLA gene, showed associations with alcoholism in the Japanese population. Dagla expression in mice was found to be influenced by chronic mild stress and by the acquisition of alcohol preference. Our findings indicated the involvement of DAGLA in alcoholism, possibly by its genetic dysfunction and also by the influence of stress.

Effect of Aerobic Exercise on Morphine Self-administration and Pain Modulation in Rats

Background:

Exercise reverses retention deficit induced by morphine. The present study investigated the effect of aerobic exercise on tolerance to morphine usage and pain modulation.

Materials and Methods:

Male Wistar rats were divided into four groups as follows: (1) saline group (S), (2) morphine group (M), (3) saline + exercise (S + E), and (4) morphine + exercise group (M + E). The rats were initially trained to receive small pellets of food by pressing an active lever in the self-administration apparatus. The tail-flick and hot-plate tests were used for pain assessment. To perform the experiment, the jugular vein was exposed and cannulated. After recovery, the animals were placed in the self-administration apparatus and allowed to self-administer morphine in 2 h sessions over 11 consecutive days.

Results:

The morphine group was found to record a higher number of active lever pressings than did the saline one while this parameter decreased in the morphine + exercise group compared with the morphine one. Moreover, the morphine + exercise exhibited lowered pain sensitivity as evidenced to have reduced morphine use in the hot plate test.

Conclusion:

The exercise might be suggested to reduce using of morphine and modulate pain probably through the release of endogenous opioid.