Atorvastatin-induced endothelial nitric oxide synthase expression in endothelial cells is mediated by endoglin.

Endoglin, a transforming growth factor ß (TGF-ß) receptor type III, is co-expressed with endothelial nitric oxide synthase (eNOS) in aortic endothelium in atherosclerotic plaques of mice. Interestingly, atorvastatin (ATV) is able to increase both endoglin and eNOS expression and reduce plaque size beyond its lipid lowering effects but by unknown mechanisms. We hypothesized whether inflammation modulates ATV-dependent induction of endoglin and eNOS expression in vitro in endothelial cells and whether ATV-induced eNOS expression is regulated via endoglin. After treatment of human umbilical vein endothelial cells (HUVECs) with TNF-α, endoglin and eNOS protein expression was reduced, concomitantly with increased levels of cell surface VCAM-1 and soluble endoglin, as determined by flow cytometry, Western blot and ELISA analyses. By contrast, ATV treatment increased endoglin and eNOS protein expression, while preventing TNF-α-mediated downregulation of endoglin and eNOS protein levels. Moreover, suppression of endoglin using small interfering RNA (siRNA), but not inhibition of TGF-ß signaling with SB431542, abrogated ATV-induced eNOS expression. These results suggest that ATV treatment prevents inflammation-reduced endoglin and eNOS expression in endothelial cells and that ATV-induced eNOS expression strongly depends on the proper expression of endoglin in HUVECs. Possible implications of these findings might be reflected in pathological conditions characterized by reduced expression of endoglin and eNOS as for example in hereditary hemorrhagic telangiectasia or in other endothelial dysfunctions.

Antioxidants and vitamins in clinical conditions.

Various reactive oxygen species (ROS) may be produced from normal biochemical, essential metabolic processes or from external sources as exposure to a variety of agents presented in the environment. Lipids, proteins, carbohydrates and DNA are all capable of reacting with ROS and can be implicated in etiology of various human disorders (rheumatoid arthritis, reperfusion injury, atherosclerosis, lung diseases etc.). In the organism damage by ROS is counteracted with natural antioxidants (glutathione peroxidases, superoxide dismutases, catalase, glutathione, ubiquinol, uric acid, and essential minerals) and nutritional antioxidants from diet (i.e. vitamins E, C, carotenoids). Possible mechanisms of nutritional depletion and side effects of high intake are in the article described.

Anticonvulsant effects of bretazenil (Ro 16-6028) during ontogenesis.

Anticonvulsant action of a new benzodiazepine, bretazenil (Ro 16-6028), was studied in 240 rats in five age groups: age 7, 12, 18, 25 and 90 days. Motor seizures induced by metrazol (pentamethylenetetrazol, PTZ, 100 mg/kg subcutaneously (s.c.) except for 18-day-old rats which received a dose of 90 mg/kg) served as a model. Animals were pretreated with Ro 16-6028 in doses of 0.001-0.1 mg/kg intraperitoneally (i.p.) 10 min before metrazol. Both types of metrazol-induced seizures, minimal (mMS, predominantly clonic with preserved righting ability) and major (MMS, generalized tonic-clonic), were suppressed by Ro 16-6028 in a dose-dependent manner. Major seizures were always more sensitive to Ro 16-6028 than were minimal seizures. The youngest rats exhibited maximal effects of Ro 16-6028 against major seizures. On the other hand, this drug increased the incidence of minimal seizures in 7- and 12-day-old rats, i.e., in age groups in which this type of seizure is rare under control conditions.

Anticonvulsant activity of flumazenil in rats during ontogenetic development.

The influence of flumazenil on seizures induced by pentylenetetrazol (PTZ) was studied in rats aged 7, 12, 18, 25, and 90 days. Flumazenil in doses of 25, 37.5, and 50 mg/kg IP injected 10 min before PTZ exhibited a dose-dependent anticonvulsant action in all age groups studied. It was more effective against generalized tonic-clonic than against minimal clonic seizures at all developmental stages studied. In the two youngest groups, minimal seizures were elicited only rarely under control conditions. Pretreatment with the two lower doses of flumazenil resulted in an increased incidence of this type of seizure for these two groups. The anticonvulsant activity found in all age groups is in agreement with data from other benzodiazepines and speaks against a pure benzodiazepine-antagonistic action of flumazenil.