[Role of cannabinoid receptors in regulation of cardiac tolerance to ischemia and reperfusion].

Coronary artery occlusion (45 min) and reperfusion (2 h) were modeled in vivo in anesthetized artificially ventilated Wistar rats. Total ischemia (45 min) and reperfusion (30 min) of the isolated rat heart were performed in vitro. The selective agonist of cannabinoid (CB) receptors HU-210 was injected intravenously at a dose of 0.1 mg/kg 15 min prior to the coronary artery ligation. The selective CB1 antagonist SR141716A and the selective CB2 antagonist SR144528 were injected intravenously 25 min prior to ischemia. In vitro, HU-210 and SR141716A were added to the perfusion solution at the final concentrations of 0.1 microM prior to total ischemia. Preliminary injection of HU-210 reduced the infarct size-to-area at risk (IS/AAR) ratio in vivo. This cardioprotective effect was completely abolished by SR141716A but remained after SR144528 injection. Both antagonists had no effect on the IS/AAR ratio. Preliminary injection of the K(ATP) channel blocker glibenclamide did not abolish the cardioprotective effect of HU-210. The addition of HU-210 prior to ischemia reduced the creatine phosphokinase (CPK) level in the coronary effluent and decreased left ventricular developed pressure. SR141716A alone had no effect on cardiac contractility and CPK levels. These results suggest that cardiac CB1 receptor activation increases cardiac tolerance to ischemia-reperfusion and has a negative effect on the cardiac pump function. Endogenous cannabinoids are not involved in the regulation of cardiac contractility and tolerance to ischemia and reperfusion. ATP-sensitive E+ channels are not involved in the mechanism of the cardioprotective effect of HU-210.

Thymol and carvacrol production from leaves of wild Palestinian Majorana syriaca.

Majorana syriaca (Zaatar in Arabic), belonging to the mint family, Labiates, is cultivated widely and grows wild in the mountains of Palestine between the months April to August. In order to determine the secondary metabolites from wild leaves of Palestinian M. syriaca, comparative analysis by static headspace (HS) and steam distillation (SD) GC-MS was used. Among the samples examined, the major constituents identified varied greatly throughout the different harvesting periods. Headspace revealed major volatiles and semi-volatiles of alpha-pinene, beta-myrecene, o-cymene, p-cymene, gamma-terpinene, thymol, and carvacrol. We found that the most abundant monoterpenes, i.e. gamma-terpinene and p-cymene were decreased in the month of May since they are the biogenetic precursors (via enzymic hydroxylation) of the phenolic terpenes, thymol and carvacrol. The harvesting time, location and the thyme type (i.e., wild) affects the yield of essential oils as reflected by normal steam distillation.

Role of cannabinoid receptors in the regulation of cardiac contractility during ischemia/reperfusion.

We studied the effect of selective ligands of cannabinoid (CB) receptors on contractility of isolated Langendorff-perfused rat heart under conditions of 45-min total ischemia and 30-min reperfusion. Perfusion with a solution containing selective CB receptor agonist HU-210 for 10 min before ischemia increased the severity of reperfusion contractile dysfunction. This drug decreased left ventricular developed pressure and maximum rates of contraction and relaxation, but had no effect on heart rate and end-diastolic pressure. The negative inotropic effect of the drug was transitory and disappeared after 5-min reperfusion. Pretreatment with selective CB1 receptor antagonist SR141716A and selective CB2 receptor antagonist SR144528 had no effect on heart rate and myocardial contractility during reperfusion. Our results indicate that stimulation of CB receptors can increase the degree of reperfusion-induced cardiac contractile dysfunction. However, endogenous cannabinoids are not involved in the development of myocardial contractile dysfunction during ischemia/reperfusion of the isolated heart.

Behavioral evidence for the interaction of oleamide with multiple neurotransmitter systems.

While the endogenous fatty acid amide oleamide has hypnotic properties, neither the breadth of its behavioral actions nor the mechanism(s) by which these behaviors may be mediated has been elucidated. Therefore, the effects of oleamide on the performance of rats in tests of motor function, analgesia, and anxiety were investigated. Oleamide reduced the distance traveled in the open field (ED50 = 14, 10-19 mg/kg, mean, 95% confidence interval), induced analgesia and hypothermia, but did not cause catalepsy. Moreover, a dose of oleamide without effect on motor function was anxiolytic in the social interaction test and elevated plus-maze. These actions of a single dose of oleamide lasted for 30 to 60 min. While rats became tolerant to oleamide following 8 days of repeated administration, oleamide is a poor inducer of physical dependence. Pretreatment with antagonists of the serotonin (5HT)1A, 5HT2C, and vanilloid receptors did not modify oleamide's effects. However, the cannabinoid receptor antagonist SR 141716A inhibited oleamide-induced analgesia in the tail-flick assay, the gamma-aminobutyric acid (GABA)A receptor antagonist bicuculline reversed the analgesia and hypothermia, and the dopamine D2 receptor antagonist L 741626 blocked oleamide's locomotor and analgesic actions. Interestingly, oleamide analogs resistant to hydrolysis by fatty acid amide hydrolase (FAAH) maintained but did not show increased behavioral potency or duration of action, whereas two FAAH inhibitors produced analogous behavioral effects. Thus, oleamide induces behaviors reminiscent of the actions of endogenous cannabinoids, but the involvement of GABAergic and dopaminergic systems, either directly or indirectly, in the actions of oleamide cannot be ruled out.

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.