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The objective of this study was to investigate the vasoregulatory role of perivascular adipose tissue (PVAT) and its mutual interaction with endogenous and exogenous H2S in the thoracic aorta (TA) of adult normotensive Wistar rats and spontaneously hypertensive rats (SHRs). In SHRs, hypertension was associated with cardiac hypertrophy and increased contractility. Regardless of the strain, PVAT revealed an anticontractile effect; however, PVAT worsened endothelial-dependent vasorelaxation. Since H2S produced by both the vascular wall and PVAT had a pro-contractile effect in SHRs, H2S decreased the sensitivity of adrenergic receptors to noradrenaline in Wistar rats. While H2S had no contribution to endothelium-dependent relaxation in Wistar rats, in SHRs, H2S produced by the vascular wall had a pro-relaxant effect. We observed a larger vasorelaxation induced by exogenous H2S donor in SHRs than in Wistar rats. Additionally, in the presence of PVAT, this effect was potentiated. We demonstrated that PVAT of the TA aggravated endothelial function in SHRs. However, H2S produced by the TA vascular wall had a pro-relaxation effect, and PVAT revealed anti-contractile activity mediated by the release of an unknown factor and potentiated the vasorelaxation induced by exogenous H2S. All these actions could represent a form of compensatory mechanism to balance impaired vascular tone regulation.

The aim of this study was to evaluate the mutual relationship among perivascular adipose tissue (PVAT) and endogenous and exogenous H2S in vasoactive responses of isolated arteries from adult normotensive (Wistar) rats and hypertriglyceridemic (HTG) rats, which are a nonobese model of metabolic syndrome. In HTG rats, mild hypertension was associated with glucose intolerance, dyslipidemia, increased amount of retroperitoneal fat, increased arterial contractility, and endothelial dysfunction associated with arterial wall injury, which was accompanied by decreased nitric oxide (NO)-synthase activity, increased expression of H2S producing enzyme, and an altered oxidative state. In HTG, endogenous H2S participated in the inhibition of endothelium-dependent vasorelaxation regardless of PVAT presence, on the other hand, aortas with preserved PVAT revealed a stronger anticontractile effect mediated at least partially by H2S. Although we observed a higher vasorelaxation induced by exogenous H2S donor in HTG rats than in Wistar rats, intact PVAT subtilized this effect. We demonstrate that, in HTG rats, endogenous H2S could manifest a dual effect depending on the type of triggered signaling pathway. H2S within the arterial wall contributes to endothelial dysfunction. On the other hand, PVAT of HTG is endowed with compensatory vasoactive mechanisms, which include stronger anti-contractile action of H2S. Nevertheless, the possible negative impact of PVAT during hypertriglyceridemia on the activity of exogenous H2S donors needs to be taken into consideration.

Deficiency of nitric oxide (NO) and oxidative stress can be a cause, a consequence, or, more often, a potentiating factor for hypertension and hypertensive renal disease. Both NO and superoxide anions are radical molecules that interact with each other, leading to oxidative damage of such organs as the kidney. In the present study, we investigated the effect of chronic-specific (neuronal NOS inhibition) and nonspecific NOS inhibition on the oxidative state and antioxidant response and associated oxidative damage of the kidney of young normotensive and hypertensive rats. Young male normotensive Wistar rats (WRs, age 4 weeks) and spontaneously hypertensive rats (SHRs, age 4 weeks) were divided into three groups for each strain by the type of administered compounds. The first group was treated with 7-nitroindazole (WR+7-NI; SHR+7-NI), the second group was treated with N(G)-nitro-L-arginine-methyl ester (WR+L-NAME; SHR+L-NAME), and the control group was treated with pure drinking water (WR; SHR) continuously for up to 6 weeks. Systolic blood pressure increased in WR+L-NAME after the first week of administration and increased slightly in SHR+L-NAME in the third week of treatment. 7-NI had no effect on blood pressure. While total NOS activity was not affected by chronic NOS inhibition in any of the WR groups, it was attenuated in SHR+7-NI and SHR+L-NAME. Nitration of proteins (3-nitrotyrosine expression) was significantly reduced in WR+7NI but not in WR+L-NAME and increased in SHR+7-NI and SHR+L-NAME. Immunoblotting analysis of SOD isoforms showed decreased SOD2 and SOD3 expressions in both WR+7-NI and WR+L-NAME followed by increased SOD activity in WR+L-NAME. Conversely, increased expression of SOD2 and SOD3 was observed in SHR+L-NAME and SHR+7-NI, respectively. SOD1 expression and total activity of SOD did not change in the SHR groups. Our results show that the antioxidant defense system plays an important role in maintaining the oxidative state during NO deficiency. While the functioning antioxidant system seeks to balance the oxidation state in the renal cortex of normotensive WRs, the impaired antioxidant activity leads to the development of oxidative damage of proteins in the kidney induced by peroxynitrite in SHRs.

Although the role of nitric oxide (NO) in essential hypertension is still unclear, the effects of long-term NO deficiency have not yet been investigated during the critical juvenile period in spontaneously hypertensive rats (SHR). We aimed to analyze the effects of chronic NO synthase (NOS) inhibition on systolic blood pressure (sBP), vasoactivity, morphological changes and superoxide level in the thoracic aorta (TA), NOS activity in different tissues, and general biomarkers of oxidative stress in plasma of young SHR. Four-week-old SHR were treated with NG-nitro-L-arginine methyl ester (L-NAME, 50 mg/kg/day, p.o.) for 4-5 weeks. L-NAME treatment induced a transient sBP increase only, and surprisingly, slightly inhibited endothelium-dependent relaxation of TA. Hereby, the inhibition of NOS activity varied from tissue to tissue, ranging from the lowest in the TA and the kidney to the highest in the brain stem. In spite of an increased sensitivity of adrenergic receptors, the maximal adrenergic contraction of TA was unchanged, which was associated with changes in elastin arrangement and an increase in wall thickness. The production of reactive oxygen species in the TA was increased; however, the level of selected biomarkers of oxidative stress did not change. Our findings proved that the TA of young SHR responded to chronic NO deficiency by the development of adaptive mechanisms on the functional (preserved NO-derived vasorelaxation, unincreased contraction) and molecular (preserved NOS activity) level.

Asymmetric dimethylarginine (ADMA) can elevate inhibition of NO synthesis as a risk marker of cardiovascular diseases. Reactive oxygen metabolites (ROM) inhibit elevated ADMA level and is connected with homocysteine (Hcy). In our study we focused on ADMA and Hcy level changes and ROM in plasma of young spontaneously hypertensive rats (SHR) in chronic treatment by NO-sythase inhibitors (L-NAME and 7-nitroindazole). HPLC method with fluorescence detection has been used to analyse the levels of ADMA. Detection of Hcy has been measured by UV absorbance 340 nm (Analytx, Slovakia). Reactive oxygen metabolites – dROMs assay and Total thiols levels -TTL assay and TTL vs. ROM level in plasma was detected by clinical autoanalyzer UnicelDxC 800 (Beckman-Coulter, Netherlands). ADMA level, Hcy level, ROM and TTL has not been changed in the L-NAME. In 7-NI group was observed markedly decrease the ADMA overproduction, which was correlated with Hcy level decrease and redox status of ROM in plasma. Changes among total TTL and ROM production (TTL/ROM) has been improved redox level in 7-NI group comparing to L-NAME. It has been observed that 7-NI can influence decrease of ADMA,=Hcy, ROS level and improved TTL/ROM in SHR.

Endogenous and exogenous testosterone affects several behavioural traits as shown in human and animal studies. The effects of testosterone can be mediated via androgen or oestrogen receptors, but also via rapid non-genomic effects. The aim of this study was to evaluate whether a single testosterone injection has effects, mediated via the androgen receptor, on anxiety in intact male rats. We hypothesised that administration of testosterone will have an anxiolytic effect, mediated by the androgen receptor. Intact adult male Wistar rats were divided into groups: control, flutamide, testosterone and testosterone with flutamide. Testosterone and flutamide (as an androgen receptor blocker) were applied once, intramuscularly, at a dose of 5mg/kg. Twenty four hours later, rats underwent the following behavioural tests to analyse anxiety: open field test, elevated plus maze and light-dark box. Testosterone was measured in plasma to confirm elevated levels in groups that received testosterone. The levels of testosterone were 2.5-3 fold higher amongst rats administered with testosterone compared to controls. Flutamide did not affect plasma testosterone concentrations. Testosterone administration had no effect on anxiety in the open field and elevated plus maze. In the light-dark transition task, testosterone increased the time spent in the light part of the maze by 80%, an effect which was blocked by flutamide, and which was in support of our hypothesis. Flutamide-treated rats spent more time in the central square of the open field. Using the light-dark box we have shown that a single injection of testosterone decreases anxiety in adult male rats. This effect of increased testosterone was mediated via the androgen receptor as flutamide blocked the anxiolytic effect of exogenous testosterone. Treatment with flutamide blocked the effects of endogenous testosterone and had anxiolytic effects in the open field, suggesting a non-linear relationship between genomic effects of T and anxiety.

PPARγ plays an important role in kidney physiology of cardiovascular system, contributes in hypertension and signaling pathways. In our study we focused on the effect of PPARγ agonist pioglitazone (PIO) on the RAS, redox regulation, NOS activities, redox regulation and ADMA levels in two models of young borderline hypertensive (BHR) and spontaneously hypertensive (SHR) rats. Gene expression was detected by qRT-PCR. Protein level was determined using Western blot analysis. Superoxide dismutase (SOD) and nitric oxide synthase (NOS) activities was determined spectrophotometrically and with radioactive method. ADMA levels has been analysed by HPLC method with fluorescence detection. PIO decreased (in BHR) and slowed blood pressure development (in SHR). Gene and protein expressions of NOS isoforms and total NOS activities was improved in both experimental rats and affected ADMA changes. In AT1R/NADPH - oxidase pathway the treatment was not significantly influenced, but mRNA expression in Mas, AT2R receptors and redox regulation (Nrf2 and SOD isoforms) was up-regulated. The largest effect of PPARγ has been observed in SOD1, SOD3 and Mas receptor genes in different way: SOD1 was increased in SHR and Mas receptor in BHR rats.

Dysregulation of redox- sensitive signaling plays an important role in develompment of hypertension. PPAR gamma belongs to nuclear receptors and is a potent nutritional sensor and redox regulator. In our study we focused on the role of PPAR gamma activation of RAS/ROS regulation, and antioxidant response in spontaneously hypertensive rats (SHR). Treatment was performed by gavage with PPAR gamma agonist pioglitazone (PIO - 10 mg/kg/day, 10 days). Treatment with PPAR gamma agonist PIO in influenced blood pressure, redox- sensitive responses, lipid profile and homocystein level in age- dependent manner. The improvement parameters in hypertension and redox regulation have been observed in young animals, but not in adult SHR rats. PIO treatment influenced redox regulation (gene expression of Nrf2 and SOD isoforms) correlated with SOD a CAT activity and NO bioavailibility. PPAR gamma activation has been corelated with downregulation of and AT1R - RAS axis and „up-regulation“ of AT2R and Mas receptor. This most sensitive tissue responses in RAS/ROS signaling and NO level have been found primary in kidney of young hypertensive rats.