Anandamide elevation in cerebrospinal fluid in initial prodromal states of psychosis.

Anandamide is a bioactive lipid binding to cannabinoid receptors. A homeostatic role for anandamide has been suggested in schizophrenia. We investigated its role in initial prodromal states of psychosis. We measured the levels of anandamide and its structural analog oleoylethanolamide in cerebrospinal fluid and serum of patients in the initial prodromal state (n=27) alongside healthy volunteers (n=81) using high-performance liquid chromatograph/mass spectrometry. Cerebrospinal anandamide levels in patients were significantly elevated. Patients with lower levels showed a higher risk for transiting to psychosis earlier. This anandamidergic up-regulation in the initial prodromal course may suggest a protective role of the endocannabinoid system in early schizophrenia.

Sleep deprivation increases oleoylethanolamide in human cerebrospinal fluid.

This study investigated the role of two fatty acid ethanolamides, the endogenous cannabinoid anandamide and its structural analog oleoylethanolamide in sleep deprivation of human volunteers. Serum and cerebrospinal fluid (CSF) samples were obtained from 20 healthy volunteers before and after a night of sleep deprivation with an interval of about 12 months. We found increased levels of oleoylethanolamide in CSF (P = 0.011) but not in serum (P = 0.068) after 24 h of sleep deprivation. Oleoylethanolamide is an endogenous lipid messenger that is released after neural injury and activates peroxisome proliferator-activated receptor-alpha (PPAR-alpha) with nanomolar potency. Exogenous PPAR-alpha agonists, such as hypolipidemic fibrates and oleoylethanolamide, exert both neuroprotective and neurotrophic effects. Thus, our results suggest that oleoylethanolamide release may represent an endogenous neuroprotective signal during sleep deprivation.

Role of endocannabinoids and their analogues in obesity and eating disorders.

Fatty acids ethanolamides (FAEs) are a family of lipid mediators. A member of this family, anandamide, is an endogenous ligand for cannabinoid receptors targeted by the marijuana constituent Delta-9-tetrahydrocannabinol. Anandamide is now established as a brain endocannabinoid messenger and multiple roles for other FAEs have also been proposed. One emerging function of these lipid mediators is the regulation of feeding behavior and body weight. Anandamide causes overeating in rats because of its ability to activate cannabinoid receptors. This action is of therapeutic relevance: cannabinoid agonists are currently used to alleviate anorexia and nausea in AIDS patients, whereas the cannabinoid receptor CB1 antagonist rimonabant was recently found to be effective in the treatment of obesity. In contrast to anandamide, its monounsatured analogue, oleoylethanolamide (OEA), decreases food intake and body weight gain through a cannabinoid receptor-independent mechanism. In the rat proximal small intestine, endogenous OEA levels decrease during fasting and increase upon refeeding. These periprandial fluctuations may represent a previously undescribed signal that modulates between-meal satiety. Pharmacological studies have shown, indeed, that, as a drug, OEA produces profound anorexiant effects in rats and mice, due to selective prolongation of feeding latency and post-meal interval. The effects observed after chronic administration of OEA to different animal models of obesity, clearly indicate that inhibition of eating is not the only mechanism by which OEA can control energy metabolism. In fact, stimulation of lipolysis is responsible for the reduced fat mass and decrease of body weight gain observed in these models. Although OEA may bind to multiple receptors, several lines of evidence indicate that peripheral PPAR-alpha mediates the effects of this compound. The pathophysiological significance of OEA in the regulation of eating and body weight is further evidenced by preliminary clinical results, showing altered levels of this molecule in the cerebrospinal fluid and plasma of subjects recovered from eating disorders. These results complete previous observation on anandamide content, which resulted altered in plasma of women affected by anorexia nervosa or binge-eating disorder.

Abnormalities in the cerebrospinal fluid levels of endocannabinoids in multiple sclerosis.

OBJECTIVE: Endocannabinoids (eCBs) play a role in the modulation of neuroinflammation, and experimental findings suggest that they may be directly involved in the pathogenesis of multiple sclerosis (MS). The objective of our study was to measure eCB levels in the cerebrospinal fluid (CSF) of patients with MS. PATIENTS AND METHODS: Arachidonoylethanolamine (anandamide, AEA), palmotylethanolamide (PEA), 2-arachidonoylglycerol (2-AG) and oleoylethanolamide (OEA) levels were measured in the CSF of 50 patients with MS and 20 control subjects by isotope dilution gas-chromatography/mass-spectrometry. Patients included 35 patients with MS in the relapsing-remitting (RR) form of the disease, 20 in a stable clinical phase and 15 during a relapse, and 15 patients with MS in the secondary progressive (SP) form. RESULTS: Significantly reduced levels of all the tested eCBs were found in the CSF of patients with MS compared to control subjects, with lower values detected in the SP MS group. Higher levels of AEA and PEA, although below those of controls, were found in the CSF of RR MS patients during a relapse. Higher levels of AEA, 2-AG and OEA were found in patients with MRI gadolinium-enhancing (Gd+) lesions. DISCUSSION: The present findings suggest the presence of an impaired eCB system in MS. Increased CSF levels of AEA during relapses or in RR patients with Gd+ lesions suggest its potential role in limiting the ongoing inflammatory process with potential neuroprotective implications. These findings provide further support for the development of drugs targeting eCBs as a potential pharmacological strategy to reduce the symptoms and slow disease progression in MS.

Diurnal variation of arachidonoylethanolamine, palmitoylethanolamide and oleoylethanolamide in the brain of the rat.

The diurnal variations of the endocannabinoid arachidonoylethanolamine (anandamide, ANA) as well as palmitoylethanolamide (PEA) and oleoylethanolamide (OEA) were detected and quantified in cerebrospinal fluid (CSF), pons, hippocampus, and hypothalamus in the rat over 24 h using HPLC/MS. In CSF, the 3 compounds presented an increase in their concentration during the lights-on period and a remarkable decrease in their values during the lights-off period. In the pons, ANA, PEA and OEA showed the maximum values during the dark phase. On the other hand, we found that in the hippocampus, ANA increased its concentration during the lights-off period and PEA showed the highest peak at the beginning of the same period. OEA concentration showed no diurnal variations in the hippocampus. Finally, in the hypothalamus, ANA rose during the lights-on period whereas PEA and OEA presented the highest concentration at the end of the lights-off period. We postulate that all compounds are likely to be accumulated in parenchyma during the lights-off period (when animal is awake) and then, released into the CSF in order to reach target regions in turn to modulate diverse behaviors, such as feeding and sleep.

Free fatty acids in human cerebrospinal fluid following subarachnoid hemorrhage and their potential role in vasospasm: a preliminary observation.

OBJECT: The mechanisms leading to vasospasm following subarachnoid hemorrhage (SAH) remain unclear. Accumulation in cerebrospinal fluid (CSF) of free fatty acids (FFAs) may play a role in the development of vasospasm; however, in no previous study have concentrations of FFAs in CSF been examined after SAH. METHODS: We collected samples of CSF from 20 patients with SAH (18 cases of aneurysmal SAH and two cases of spontaneous cryptogenic SAH) and used a high-performance liquid chromatography assay to determine the FFA concentrations in these samples. We then compared these findings with FFA concentrations in the CSF of control patients. All FFA concentrations measured 24 hours after SAH were significantly greater than control concentrations (p < 0.01 for palmitic acid and < 0.001 for all other FFAs). All measured FFAs remained elevated for the first 48 hours after SAH (p < 0.05 for linoleic acid, p < 0.01 for palmitic acid, and p < 0.001 for the other FFAs). After 7 days, a second elevation in all FFAs was observed (p < 0.05 for linoleic acid, p < 0.01 for palmitic acid, and p < 0.001 for the other FFAs). Samples of CSF collected within 48 hours after SAH from patients in whom angiography and clinical examination confirmed the development of vasospasm after SAH were found to have significantly higher concentrations of arachidonic, linoleic, and palmitic acids than samples collected from patients in whom vasospasm did not develop (p < 0.05). CONCLUSIONS: Following SAH, all FFAs are initially elevated. A secondary elevation occurs between 8 and 10 days after SAH. This study provides preliminary evidence of FFA elevation following SAH and of a potential role for FFAs in SAH-induced vasospasm. A prospective study is warranted to determine if CSF concentrations of FFAs are predictive of vasospasm.

Fatty acid amide hydrolase expression in rat choroid plexus: possible role in regulation of the sleep-inducing action of oleamide.

The enzyme fatty acid amide hydrolase (FAAH) catalyses hydrolysis of oleamide, a sleep-inducing lipid whose concentration in the cerebrospinal fluid (CSF) is elevated in sleep-deprived mammals. Previous studies have reported expression of FAAH by distinct populations of neurons in the rat brain. Here we demonstrate using immunocytochemical methods that FAAH is also expressed by non-neuronal epithelial cells of the rat choroid plexus. The choroid plexus is formed by invaginations of the pia mater into the ventricle cavities of the brain and an important function of the choroidal epithelium is to regulate production and composition of CSF. Therefore, the role of FAAH in epithelial cells of the choroid plexus may be to control the concentration of oleamide in the CSF and as such FAAH may exert an important regulatory role in shaping the duration and magnitude of the sleep-inducing effect of endogenously or exogenously derived oleamide.

A gas chromatographic-mass spectral assay for the quantitative determination of oleamide in biological fluids.

Oleamide is a putative endogenous sleep-inducing lipid which potently enhances currents mediated by GABAA and serotonin receptors. While a quantitative assay would aid in determining the role of oleamide in physiological processes, most of the available assays are lacking in sensitivity. We now describe a quantitative assay for measuring low nanogram amounts of oleamide in biological fluids using GC/MS in the selective ion-monitoring mode. The internal standard (13C18 oleamide) was added to known concentrations of oleamide, which were converted to the N-trimethylsilyl or N-tert-butyldimethylsilyl derivatives before analysis by GC/MS, yielding linear calibration curves over the range of 1-25 ng of oleamide when monitoring the m/z 338/356 fragments. Using this technique, oleamide levels were determined following solvent extraction of normal rat cerebrospinal fluid and plasma to be 44 and 9.9 ng/ml, respectively. This technique constitutes a sensitive and reliable method for determining low nanogram quantities of oleamide in biological fluids.

Characterization of the hypnotic properties of oleamide.

While preliminary studies associated oleamide with sleep regulation, we now characterize the involvement of oleamide in sleep using a number of techniques. Peripheral administration of oleamide to rats dose dependently suppressed motor activity in the open field, with an ED50 of 17+/-1.5mg/kg for the decrease in distance traveled. Moreover, endogenous oleamide concentrations increased 3- to 4-fold in the cerebrospinal fluid of rats sleep-deprived for 6 h or longer. Oleamide also decreased sleep latency to 44-64% of control values without altering other sleep parameters. Unlike many putative endogenous sleep-inducing agents, oleamide potently induces behavioral and electroencephalographic manifestations of sleep. Moreover, its endogenous concentrations and temporal associations are consistent with previous reports of its enhancement of serotonergic and GABAergic neurotransmission, which may be involved in sleep induction.

Oleamide-induced modulation of 5-hydroxytryptamine receptor-mediated signaling.

We investigated the effects of oleamide, a fatty acid amide isolated from the cerebrospinal fluid of sleep-deprived cats, on serotonin receptor-mediated signaling in cultured mammalian cells. Oleamide demonstrated opposing effects on 5-HT2A and 5-HT7 receptors, in rat pituitary cells and transfected HeLa cells, respectively. Oleamide caused a potentiation of 5-HT-elicited inositol phosphate formation mediated by the 5-HT2A receptor, but inhibited the effects of 5-HT on cAMP production mediated by the 5-HT7 receptor. In addition, oleamide alone caused a significant increase in cAMP accumulation that was dependent on the presence of the 5-HT7 receptor, but was not blocked by clozapine. These results demonstrate that oleamide can have diverse effects on 5-HT-mediated signal transduction at different subtypes of mammalian 5-HT receptors. Additionally, our data suggest that oleamide may act at an allosteric site on the 5-HT7 receptor and can elicit functional responses via activation of this site.

Oleamide: an endogenous sleep-inducing lipid and prototypical member of a new class of biological signaling molecules.

Oleamide is an endogenous fatty acid primary amide that accumulates in the cerebrospinal fluid under conditions of sleep deprivation and induces physiological sleep in animals. A review covering its discovery, its implications, and the emerging biology surrounding its discovery is presented. Consistent with its role as a prototypical member of a new class of biological signaling molecules, enzymatic regulation of endogenous concentrations of oleamide have been characterized or proposed. Fatty acid amide hydrolase (FAAH) is an integral membrane protein that degrades oleamide and potent inhibitors with physiological sleep-inducing properties have been disclosed. The characterization, cloning, and neuronal distribution of FAAH have been detailed and the enzyme was found to possess the ability to hydrolyze a range of fatty acid amides including anandamide which serves as the endogenous ligand for the cannabinoid receptor. An additional endogenous substance with REM sleep-inducing properties, 2-octyl gamma-bromoacetoacetate, was characterized as a potent FAAH inhibitor. Oleamide has been shown to modulate serotonergic neurotransmission and inhibit intercellular gap junction communication and detailed studies of its well defined and selective structural features required for activity have been disclosed.

Chemical characterization of a family of brain lipids that induce sleep.

A molecule isolated from the cerebrospinal fluid of sleep-deprived cats has been chemically characterized and identified as cis-9,10-octadecenoamide. Other fatty acid primary amides in addition to cis-9,10-octadecenoamide were identified as natural constituents of the cerebrospinal fluid of cat, rat, and human, indicating that these compounds compose a distinct family of brain lipids. Synthetic cis-9,10-octadecenoamide induced physiological sleep when injected into rats. Together, these results suggest that fatty acid primary amides may represent a previously unrecognized class of biological signaling molecules.