New morpholine-containing pyrimidinones act on α-adrenoceptors.

Drugs that act on α-adrenoceptors may contain morpholine and pyrimidinone heterocycles. The aim of this study was to synthesize a series of pyrimidinones (S6a-e and S8) and characterize their α-adrenoceptor activity. Cytotoxicity assays (MTT and LDH) were performed in A7r5 and HUVECs. Concentration-effect curves to phenylephrine (Phe) were performed in rat aortic rings in the presence of compounds S6a-e and S8 or vehicle. Nitric oxide (NO) production and NO stable metabolic products, nitrite and nitrate, expressed as total nitrogen oxides (NOx) were assessed in HUVECs by confocal microscopy with the DAF-2DA probe and by the Griess reaction, respectively. Molecular docking simulations were performed using the 6a compound and α2A-adrenoceptor. In the evaluated conditions, the percentage of viable cells and the release of LDH were similar between control cells and cells exposed to the tested pyrimidinones. S6d, S6e, S8, and the positive control prazosin (but not S6a, S6b, and S6c) decreased Phe-induced contractions in endothelium-denuded aortic rings. S6a, S6b, and S6c decreased Phe-induced contractions in endothelium-intact aortic rings. The effect of S6a was abolished by L-NAME. NO production and NOx levels were inhibited in the presence of the α2 receptor antagonist yohimbine and the NOS inhibitor L-NAME. The 6a docking simulation estimated that the mean binding free energy of the compound was lower than the estimated value for yohimbine. These data suggest that S6d, S6e, and S8 may be α1-adrenoceptor antagonists while S6a acts as an agonist of α2-adrenoceptors.

RuBPY decreases intracellular calcium by decreasing influx and increasing storage.

cis-[Ru(bpy)2(py)NO2](PF6) (RuBPY) is a ruthenium complex nitric oxide (NO) donor that presents a nitrite in its moiety and has been shown to induce vasodilation in various arteries, as well as arterial pressure reduction with no changes in heart rate. Because vascular tone is highly dependent on the cytosolic calcium concentration ([Ca2+ ]c), the current study aimed to investigate the effects of RuBPY on the intracellular mobilization of calcium stores of rat aortic vascular smooth muscle cells. Vascular reactivity experiments were performed in isolated aortic rings that were contracted with a high concentration of KCl or phenylephrine (Phe). Moreover, primary cultured vascular smooth muscle cells were used to measure [Ca2+ ]c by confocal microscopy. The NO donor RuBPY decreased the [Ca2+ ]c and reduced KCl and Phe-induced contractile responses. The selective inhibitor of sarco-endoplasmic Ca-ATPase (SERCA) with thapsigargin impaired the effect of RuBPY on Phe-induced contractile response. RuBPY also reduced caffeine-induced contraction, and the contraction dependent on the capacitive Ca2+ influx. Therefore, our results suggest that NO released from RuBPY decreased [Ca2+ ]c by calcium influx blockade and activation of guanylyl-cyclase-cGMP-GK pathway. These results indicate that RuBPY increases Ca2+ storage in the sarcoplasmic reticulum by SERCA activation and also by capacitive Ca2+ influx inhibition, which is dependent on the intracellular release of nitric oxide from this compound.

Nitric Oxide as a Central Molecule in Hypertension: Focus on the Vasorelaxant Activity of New Nitric Oxide Donors.

Cardiovascular diseases include all types of disorders related to the heart or blood vessels. High blood pressure is an important risk factor for cardiac complications and pathological disorders. An increase in circulating angiotensin-II is a potent stimulus for the expression of reactive oxygen species and pro-inflammatory cytokines that activate oxidative stress, perpetuating a deleterious effect in hypertension. Studies demonstrate the capacity of NO to prevent platelet or leukocyte activation and adhesion and inhibition of proliferation, as well as to modulate inflammatory or anti-inflammatory reactions and migration of vascular smooth muscle cells. However, in conditions of low availability of NO, such as during hypertension, these processes are impaired. Currently, there is great interest in the development of compounds capable of releasing NO in a modulated and stable way. Accordingly, compounds containing metal ions coupled to NO are being investigated and are widely recognized as having great relevance in the treatment of different diseases. Therefore, the exogenous administration of NO is an attractive and pharmacological alternative in the study and treatment of hypertension. The present review summarizes the role of nitric oxide in hypertension, focusing on the role of new NO donors, particularly the metal-based drugs and their protagonist activity in vascular function.

Reversion of cardiovascular remodelling in renovascular hypertensive 2K-1C rats by renin-angiotensin system inhibitors.

OBJECTIVES: Evaluate whether the RAS dual blockade would induce additional beneficial effects on cardiovascular remodelling when compared to monotherapy in renal hypertensive two kidneys-one clip (2K-1C) rats. METHODS: Hypertensive 2K-1C and normotensive (2K) rats were treated for 14 days with submaximal doses of losartan (LOS), enalapril (ENA), losartan plus enalapril (LOS + ENA) or vehicle (water). Blood pressure and some parameters of cardiovascular remodelling were evaluated. RESULTS: Systolic blood pressure (SBP) was higher in 2K-1C (209 ± 3 mm Hg, P < .05) than in 2K (113 ± 1 mm Hg) rats. There was an additional effect in 2K-1C treated with LOS + ENA (153 ± 9 mm Hg) on lowering SBP when compared to LOS (184 ± 12 mm Hg) or ENA (177 ± 9 mm Hg). None of the treatments had effect on SBP in 2K rats. In 2K-1C, cardiomyocyte hypertrophy was reduced by all treatments, although the cardiac hypertrophy indexes remained unchanged. 2K-1C aortas presented medial thickening that was partially reduced by the treatments. Intimal hyperplasia observed in 2K-1C (15.56 ± 0.89 µm vs 8.24 ± 0.80 µm) was reversed by ENA (9.52 ± 0.45 µm) or LOS + ENA (8.17 ± 0.53 µm). Collagen deposition was increased in 2K-1C hearts (1.77 ± 0.16 vs 1.28 ± 0.09) and aortas (8.1 ± 0.6 vs 5.2 ± 0.2). Treatment with LOS reduced (1.12 ± 0.14%) and ENA (0.81 ± 0.11%) or LOS + ENA (0.86 ± 0.11%) additionally diminished collagen only in 2K-1C hearts. CONCLUSIONS: Submaximal doses of ACEi and/or ARB have inhibitory actions on cardiac remodelling and vascular hypertrophy not entirely dependent on their effects on blood pressure normalization in renovascular hypertensive rats. Combined therapy produced additional reduction in blood pressure than monotherapy despite a similar inhibition on cardiovascular remodelling.

Consumption of a high-fat diet does not potentiate the deleterious effects on lipid and protein levels and body development in rats subjected to maternal protein restriction.

Maternal undernutrition may cause injuries in several organs of the offspring, as well as lead to diseases in adulthood. Obesity and/or the consumption of a high-fat diet may also induce metabolic and cardiorespiratory diseases. We hypothesized that the consumption of a post-weaning high-fat diet would potentiate the deleterious effects of maternal protein undernutrition. This study evaluated the effects of the association of a low-protein diet during gestation and lactation with a post-weaning high-fat diet on the biochemical and ventilatory parameters of rats. Male Wistar rats from mothers who received a low-protein (9% of protein) or normoprotein diet during pregnancy and lactation received a high-fat (32% of total kilocalories from lipids) or a normal fat diet after weaning. Mass gain and somatic growth of the offspring were monitored. Also examined were biochemical chemical parameters and respiratory frequency, tidal volume (volume of air displaced in each normal respiratory cycle when extra effort is not applied), and pulmonary ventilation. Offspring from undernourished mothers presented lower birth weight (P = .0225), which remained until the end of lactation (P < .01). The rats that consumed high-fat diet and had been submitted to maternal undernutrition presented higher tidal volume when compared to the ones that consumed control diet at the 21st day of life (P Ë‚ .05). At 30 and 90 days, no further ventilatory changes were observed. Our data show that the consumption of a high-fat diet post-weaning did not seem to potentiate the changes induced by maternal undernutrition.

The Effect of Schinus terebinthifolius Raddi (Anacardiaceae) Bark Extract on Histamine-Induced Paw Edema and Ileum Smooth Muscle Contraction.

Schinus terebinthifolius Raddi (Anacardiaceae), popularly known as red aroeira, is used in traditional medicine to treat inflammatory, gastric, and respiratory disorders. The aim of this study was to evaluate the antihistaminic activity of S. terebinthifolius (St) bark extract by using in vivo and in vitro experimental models. The effects of St were investigated on contractions induced by histamine, carbachol, and potassium chloride in isolated guinea pig ileum. St was also studied in response to hind paw edema induced by histamine in rats. Experiments revealed that although St (250, 500, and 1,000 µg/mL) reduced the histamine-induced contractions by 9.1 ± 1.8, 50.2 ± 2.0, and 68.9 ± 2.0%, respectively, it did not inhibit contractions induced by carbachol or KCl. The association of St (250 and 500 µg/mL) with hydroxyzine, an H1-antihistamine (0.125 and 0.250 µM), increased the inhibitory effect to 67.0 ± 3.2 and 85.1 ± 2.1%, respectively. Moreover, St (100, 200, and 400 mg/kg) decreased paw edema from its peak by 33.9, 48.4, and 54.8%, respectively, whereas hydroxyzine (70 mg/kg) inhibited the peak edema by 56.5%. Altogether, the results suggest that the bark extract of S. terebinthifolius has an antihistaminic effect (H1).

Hypotensive effect and vascular relaxation in different arteries induced by the nitric oxide donor RuBPY.

NO donors are compounds that release NO that can be used when the endogenous NO bioavailability is impaired. The compound cis-[Ru(bpy)2(py)(NO2)](PF6) (RuBPY) is a nitrite-ruthenium, since it has a NO2 in its molecule. The aim of the present study was to evaluate the effect of RuBPY on arterial pressure, as well as on the vascular relaxation of different vascular arteries in renal hypertensive (2K-1C) and normotensive (2K) rats. We have evaluated the arterial pressure and heart rate changes as well as the RuBPY and SNP-induced relaxation (thoracic aorta, mesenteric resistance, coronary and basilar arteries). The administration of RuBPY in awake rats evoked a smaller but long lasting hypotensive effect when compared to SNP, with no increase in heart rate. The relaxation induced by RuBPY was similar between 2K-1C and 2K rats in thoracic aorta, mesenteric resistance and coronary arteries. However, the relaxation induced by RuBPY was smaller in basilar arteries from 2K-1C than in 2K. Taken together, our results show that RuBPY presents several advantages over SNP, since it does not induce hypotensive effect in normotensive animals, the hypotensive effect is slower, with no reflex tachycardia, and it is long lasting. In addition, RuBPY induces coronary artery relaxation (useful for angina) and presented only a small effect on basilar artery (may not induce headache).

Repeated-doses and reproductive toxicity studies of the monoterpene 1,8-cineole (eucalyptol) in Wistar rats.

1,8-cineole (eucalyptol) is widely used as an excipient in the pharmaceutical industry and as a food flavoring agent, thus providing significant potential for human exposure to the compound. We investigated the preclinical toxicity and reproductive toxicity of 1,8-cineole (CIN). In the repeated-doses toxicity study for 50 days, CIN (100, 500 or 1000 mg/kg) did not produce any signs of toxicity or deaths, but affected body weight gain during the first week of treatment. The hematological and biochemical profiles did not show significant differences except for increase in the MCV, platelet and urea levels or reduction in MCHC, MPV and alkaline phosphatase. Histopathological analysis showed weak changes in the lungs, liver, kidneys and uterus. In the reproductive toxicity, CIN (250, 500 or 1000 mg/kg) produced a reduction in body weight in pregnant rats treated during the pre-implantation or organogenesis periods. The highest doses induced a reduction in the mass of fetuses (pre-implantation) and dead fetuses (both periods) of pregnant rats. The results indicate that the treatment by repeated-doses showed occasional alterations in rats of both sexes. However, provide evidence that possibly 1,8-cineole presents maternal and fetal toxicity. This requires more detailed investigation to better characterize the toxic effects of this compound.

Gastroprotective Mechanisms of the Monoterpene 1,8-Cineole (Eucalyptol).

Recently, our research group identified and reported 1,8-cineole (CIN), a monoterpene that naturally occur in many aromatic plants, as one of the major constituent of the essential oil from leaves of Hyptis martiusii (EOHM), as well as characterized the gastroprotective action of this oil. The aim of this study was to investigate the mechanisms of action involved in the antiulcer and healing activity of CIN, in order to confirm its correlation with the gastroprotective effect of EOHM. Wistar rats were exposed to different protocols (acute ulceration, gastrointestinal motility and antisecretory activity). In addition, were determinated the involvement of nitric oxide and sulphydryl groups; the levels of gastric mucus, lipid peroxidation, sulphydryl groups and myeloperoxidase activity. The healing ability was evaluated by acetic acid-induced chronic ulcer and histological and immunohistochemical analysis (PCNA, Ki-67 and BrdU). The treatment with CIN inhibited ethanol-, ethanol/HCl- and indomethacin-induced gastric lesions. The highest doses of CIN inhibited gastric emptying, but did not affect intestinal transit. CIN (100 mg/kg) reduced the volume of basal but not stimulated acid secretion. CIN increased levels of mucus (89.3%), prevented depletion of -SH groups (62.6%) and reduced the level of lipid peroxidation (55.3%) and myeloperoxidase activity (59.4%) in the gastric mucosa. In chronic ulcer model, CIN reduced in 43.1% the gastric area lesion, promoted significant regeneration and restoration of the levels of mucus in glandular cells as confirmed by histological analysis; and promoted increase in cell proliferation as evidenced by reactivity for PCNA, Ki-67 and BrdU. This findings demonstrate the role of 1,8-cineole as an important ulcer healing agent and indicate the involvement of antioxidant and cytoprotective mechanisms in the gastroprotective effect of compound. This study also provides evidence that 1,8-cineole is related to the gastroprotective effect of the essential oil of Hyptis martiusii.

Gastroprotective and ulcer healing effects of essential oil of Hyptis martiusii Benth. (Lamiaceae).

Hyptis martiusii Benth. is an aromatic plant found in abundance in northeastern Brazil that is used in ethnomedicine to treat gastric disorders. The aim of this study was to elucidate the mechanisms of action involved in the gastroprotection of the essential oil of Hyptis martiusii (EOHM) and to evaluate its healing capacity. Wistar rats were exposed to different protocols and subsequently were treated with 1% Tween-80 aqueous solution (negative control), pantoprazole, carbenoxolone, N-acetylcysteine (depending on the specificity of each model) or EOHM. The antisecretory activity (basal or stimulated) was determined using the pyloric ligature method. The gastroprotective action of nitric oxide and sulphydryl groups (-SH groups), as well as the quantification of adherent mucus and the levels of malondialdehyde and -SH groups in gastric mucosa, were evaluated using ethanol-induced gastric ulcer model. The healing ability was evaluated using the acetic acid-induced gastric ulcer model and histological and immunohistochemical analysis (HE, PAS and PCNA). EOHM (400 mg/kg) reduced the volume and acidity of gastric secretion stimulated by histamine and pentagastrin. The gastroprotective effect of EOHM involves the participation of endogenous sulfhydryl groups. EOHM increased mucus production (54.8%), reduced levels of MDA (72.5%) and prevented the depletion of -SH groups (73.8%) in the gastric mucosa. The treatment with EOHM reduced in 70.3% the gastric lesion area, promoting significant regeneration of the gastric mucosa, as confirmed by histological analysis and analysis of proliferating cell nuclear antigen. The results show that gastroprotective effect of EOHM is mediated by cytoprotective and antioxidant mechanisms and by their antisecretory activity, and suggest that the essential oil of Hyptis martiusii is a promising candidate for the treatment of gastric ulcers.

Repeated-Doses Toxicity Study of the Essential Oil of Hyptis martiusii Benth. (Lamiaceae) in Swiss Mice.

Hyptis martiusii Benth. (Lamiaceae) is found in abundance in Northeastern Brazil where it is used in traditional medicine to treat gastric disorders. Since there are no studies reporting the toxicity and safety profile of this species, we investigated repeated-doses toxicity of the essential oil of Hyptis martiusii (EOHM). Swiss mice of both sexes were orally treated with EOHM (100 and 500 mg/kg) for 30 days, and biochemical, hematological, and morphological parameters were determined. No toxicity signs or deaths were recorded during the treatment with EOHM. The body weight gain was not affected, but there was an occasional variation in water and food consumption among mice of both sexes treated with both doses. The hematological and biochemical profiles did not show significant differences except for a decrease in the MCV and an increase in albumin, but these variations are within the limits described for the species. The microscopic analysis showed changes in liver, kidneys, lungs, and spleen; however, these changes do not have clinical relevance since they varied among the groups, including the control group. The results indicate that the treatment of repeated-doses with the essential oil of Hyptis martiusii showed low toxicity in mice.

Sodium nitroprusside activates potassium channels in the vena cava in normotensive but not in hypertensive rats.

Despite the importance of the venous system in the regulation of blood pressure, there are few studies that evaluate venous function in health and disease, and the effects of drugs on venous function. Blood pressure depends directly on the peripheral resistance and cardiac output. Unlike the peripheral resistance, in which the contractile activity of the arteries is the key factor, cardiac output depends primarily on the venomotor tone. An increase in cardiac blood pressure can be caused by an increase in blood volume, structural changes in the walls of the veins, leading to a reduced compliance thereof, or an increase in the contractile activity of venous smooth muscle. This study examined the effect of sodium nitroprusside (SNP), a classical nitric oxide donor, on vascular relaxation in the vena cava from normotensive (2K) and renal hypertensive (2K-1C) rats. We studied the effect of this compound in vena cava rings from normotensive and renal hypertensive rats. We showed for the first time that the vascular relaxation induced by SNP is impaired in vena cavas from hypertensive rats because of an impaired functional activity of potassium channels. Another relevant finding of this study is that the sarcoplasmic reticulum Ca(2+) ATPase is not involved in the venorelaxation induced by SNP.

The effects of gap junction modulators on the rhythmic contractions in aortas isolated from rats subjected with sinoaortic denervation.

Following sinoaortic denervation (SAD) rats present intense arterial pressure lability without sustained hypertension. This study aimed to verify the effects of heptanol (a putative gap-junction blocker) and tetraethylammonium (TEA, a putative gap-junction activator) on rhythmic contractions (RCs) and vascular reactivity in the aortas isolated from SAD and Sham-operated (SO) rats. Rhythmic contractions were observed with phenylephrine in endothelium-removed aortic rings from SAD rats. We evaluated the effects of the gap-junction modulators heptanol or TEA on the frequency and amplitude of these oscillations. Additionally, concentration-response curves were constructed to TEA and KCl and in pre-contracted arteries (with phenylephrine or KCl) to heptanol in order to verify the effects of those gap-junction modulators. Comparatively, rhythmic contractions were observed in 10/10 SAD rat aortas vs. 2/10 controls. Heptanol decreased the frequency of oscillations in a concentration-dependent manner. TEA increased the amplitude and frequency of RCs. In the experiments of concentration-response curves to TEA, the maximal contractile effect was similar in both groups, although the potency was lower in SAD than in SO rat aortas. The relaxation to heptanol was different between the groups only after pre-contraction induced by phenylephrine. Heptanol showed higher potency in SAD as compared to SO rat aortas. In conclusion, arterial pressure lability occurs only in SAD rats, and their isolated aortas exhibit intense RCs. These RCs seem to be dependent of the gap-junction communication, since these oscillations are intensified by TEA and inhibited by heptanol. After SAD, aortas are more sensitive to heptanol and less sensitive to TEA.

Avaliação do extrato hidroalcoólico de Mentha crispa sobre a performance reprodutiva em ratos Wistar / Evaluation of the hydroalcoholic extract of Mentha crispa on the reproductive performance in Wistar rats

A Mentha crispa (Lamiaceae) é conhecida popularmente como hortelã-da-folha-miúda. O extrato hidroalcoólico (EHA) de Mentha crispa, obtido do caule e da folha, possui atividade amebicida (Entamoeba histolytica) e giardicida (Giardia lamblia) e é explorado comercialmente na produção do fitoterápico Giamebil plus®. Os efeitos da administração oral subcrônica do EHA de Mentha crispa foram investigados sobre a performance reprodutiva em ratos Wistar adultos. Três grupos de ratos machos (n=6-12/grupo) foram tratados durante 30 dias consecutivos com EHA por via oral nas doses de 0,5 e 1,0 g/kg de peso ou água destilada (grupo controle). Em seguida, foram determinados os índices reprodutivos, massa dos órgãos e análise morfológica do testículo, epidídimo e ducto deferente. Os resultados mostram que, durante o período de tratamento, não se observaram sinais de toxicidade ou morte dos animais. Os índices reprodutivos, assim como a massa e as morfologias macro e microscópica dos órgãos não foram modificados pela administração subcrônica do EHA. Dessa forma, conclui-se que a administração subcrônica do extrato hidroalcoólico de Mentha crispa (Giamebil plus®) não possui atividade contraceptiva sobre o sistema reprodutor de ratos Wistar.

Mentha crispa (Lamiaceae) is commonly known as "hortelã-da-folha-miúda". The hydroalcoholic extract (HAE) from the leaves and stem of Mentha crispa possesses amebicidal (Entamoeba histolytica) and giardicidal (Giardia lamblia) activity and it is commercially used in the production of the phytoterapic Giamebil plus®. The effects of the subchronic administration of the HAE of Mentha crispa were investigated on reproductive performance in adult Wistar rats. Three groups of male rats (n=6-12/group) were orally treated daily for 30 consecutive days with the HAE at doses of 0.5 and 1.0 g/kg or distilled water (control group). Then, the reproductive indices, the organ weight and the morphologic analysis of testicle, epididymis and vas deferens were determined. There were no signs of toxicity or deaths during the period of treatment. Furthermore, the reproductive indices, the organ weight and the macroscopic and microscopic morphologic analysis of the organs were not altered by subchronic administration of the HAE of Mentha crispa. It shows that the subchronic administration of the HAE of Mentha crispa (Giamebil plus®) did not possess contraceptive activity on the reproductive system of Wistar rats.