Chronic treatment with the cannabinoid 1 antagonist rimonabant altered vasoactive cyclo-oxygenase-derived products on arteries from obese Zucker rats.

To investigate the effect of chronic cannabinoid 1 antagonism on vascular prostanoid production, obese Zucker rats were treated with rimonabant (10 mg/kg per day) during 20 weeks and then vascular and endothelial reactivity were assessed in aortic rings by analyzing response to phenylephrine and acetylcholine. The presence of cyclo-oxygenase-1 and cyclo-oxygenase-2 selective inhibitors (SC-560 and NS-398, respectively) and the enzyme immunoassay revealed lower PGI2 production by aortic rings from obese rats with rimonabant able to restore such response toward levels found in the lean animals. The treatment also reduced TXB2 but did not alter its participation on acetylcholine-induced relaxation as the TP receptor antagonist ICI-192,605 revealed. Those effects were associated with an enhancement of cyclo-oxygenase-2 expression without affecting p38MAPK phosphorylation. Obese rats also exhibited higher nitric oxide plasma concentrations and greater inducible nitric oxide synthase participation on vascular phenylephrine-induced response without changes in inducible nitric oxide synthase protein expression. Although rimonabant reduced such alteration, the values were still higher than those found in lean rats. Finally, rimonabant was also able to reduce tumor necrosis factor-α produced by adipose tissue of obese Zucker rats. These results highlight a crosstalk among cannabinoids and cyclo-oxygenase-derived products in the vasculature of obese animals.

Argan (Argania spinosa) oil lowers blood pressure and improves endothelial dysfunction in spontaneously hypertensive rats.

Traditionally hand-pressed argan oil, obtained from Argania spinosa seeds, is eaten raw in south-west Morocco; its rich composition of tocopherols, MUFA and PUFA make a study of its actions on risk factors for CVD, such as hypertension, interesting. The effects of 7 weeks of treatment with argan oil (10 ml/kg) on the blood pressure and endothelial function of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats were investigated. Systolic blood pressure and heart rate were measured every week by the tail-cuff method and endothelial function was assessed by carbachol (10(-8) to 10(-4) M)-induced relaxations of aortic rings and small mesenteric arteries pre-contracted with phenylephrine. Argan-oil administration reduced the mean blood pressure of SHR after the fifth week of treatment (P<0.05) and increased (P<0.01) the endothelial responses of arteries from SHR. The NO synthase inhibitor, L-N-omega-nitroarginine (3 x 10(-5) M) revealed a greater participation of NO in the relaxant effect after the treatment. When cyclooxygenase (COX) was blocked with indomethacin (10(-5) M), an involvement of COX products in the endothelium-dependent response was characterized. Enzyme immunoassay of thromboxane B2 showed a significant decrease (P<0.05) in the release of thromboxane A2 in both aorta and small mesenteric artery after argan-oil treatment of SHR. Experiments in the presence of the thromboxane A2-prostaglandin H2 receptor antagonist ICI 192,605 (10(-5) M) confirmed this result. Results after incubation with the antioxidants superoxide dismutase and catalase suggested that a decreased oxidative stress might contribute to explain the beneficial effects of argan-oil treatment.