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Objective: The effect of alpha-lipoic acid on blood pressure was investigated many times in chronic studies, but there are no studies on the effect of this compound after a single administration. Alpha-lipoic acid is a drug used in diabetic neuropathy, often in obese patients, to treat hypertension. Therefore, knowledge of the potential antihypertensive effect of alpha-lipoic acid even after a single dose and possibly too much pressure reduction is interesting and useful. Methods: The mechanism of the hypotensive effect of alpha-lipoic acid was examined in normotensive rats in vivo after a single intraperitoneal administration, blood pressure in the left carotid artery of the rats was measured prior to the administration of the compounds (alphalipoic acid and/or glibenclamide) and 80 min thereafter. Results: Alpha-lipoic acid at a dosage of 50 mg/kg b.w. i.p. significantly decreased the blood pressure from the 50th min after drug administration. This cardiovascular effect of this compound was reversed by glibenclamide, a selective KATP blocker. Glibenclamide alone at this dose did not significantly affect the blood pressure. Statistical significance was evaluated using two-way ANOVA. Conclusion: This suggests that alpha-lipoic acid affects ATP-dependent potassium channels. It is possible that this is an indirect effect of hydrogen sulfide because alpha-lipoic acid can increase its concentration. The results obtained in this study are very important because the patients taking alpha-lipoic acid may be treated for co-existing hypertension. Therefore, the possibility of blood pressure lowering by alphalipoic acid should be taken into account, although it does not lead to excessive orthostatic hypotension. (Anatol Cardiol 2016; 16: 306-9)

Objective and design Histamine $H_{4}$ receptor ($H_{4}R$) offers a great potential for new therapeutic strategies for the treatment of inflammation-based diseases. The aim of this study is to present the pharmacological profile of two recently synthesized ligands of $H_{4}R$ with particular reference to their anti-inflammatory and analgesic activity. Materials and subjects We used mice and rats in the in vivo tests. We also used murine RAW 264.7 cells and isolated guinea-pig ileum in in vitro test. Treatments In the in vivo tests, animals were pre-treated with the increasing doses of investigated compounds (12.5, 25 and 50 mg/kg) and reference compounds: JNJ7777120 (25 mg/kg), indomethacin (10 mg/kg). Macrophages were pre-treated with two concentrations of tested compounds 100 and 10 $\mu$M. Methods We examined anti-inflammatory and analgesic effects of the new $H_{4}R$ antagonists in the in vivo models of inflammation induced by carrageenan or zymosan. We assessed the level of cAMP and release of cytokines, ROS and NO in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Moreover, we assessed the affinity of the investigated compounds for histamine $H_{1}$ receptor in functional studies. Results Both investigated compounds reduced paw edema, mechanical and thermal hyperalgesia in the carrageenaninduced acute inflammation. Moreover, administration of the investigated compounds resulted in decreased granulocyte influx and attenuated nociceptive reaction in the zymosan-induced peritonitis model. In the same model of inflammation, the investigated compounds reduced vascular permeability; however, this effect was observed only after the highest applied dose. Furthermore, the test compounds had no impact on cell viability in the experiments on RAW 264.7 macrophages. In these cells, stimulated with LPS, the test compounds decreased reactive oxygen species (ROS) production. They increased the cellular concentration of cAMP and attenuated the production of inflammatory cytokines such as $TNF\alpha$ and $IL-1\beta$. All results were comparable to those obtained for the reference compound JNJ7777120 with the exception of the impact on NO production. Nevertheless, this effect was similar to that obtained for the other reference compound rolipram, which is a phosphodiesterase 4 (PDE 4) inhibitor. Further experiments revealed that both of the investigated compounds possessed relatively low affinity for histamine H$_{1}$ receptor and do not inhibit the activity of the PDE 4B1 enzyme. In addition, all the effects of the investigated compounds in in vivo experiments were observed at doses that did not cause neurologic deficits in rotarod test and did not reduce spontaneous locomotor activity. Conclusions Our results demonstrate the anti-inflammatory and analgesic activity of the new aryl-1,3,5-triazine derivatives, which are primarily $H_{4}R$-dependent.

Earlier we demonstrated that 3-[4-(3-trifluoromethyl-phenyl)-piperazin-1-yl]-dihydrofuran-2-one (LPP1) elevates nociceptive thresholds in the mouse model of diabetic neuropathic pain. Since drug-induced impairments of glucose and lipid metabolism and the oxidative stress might diminish benefits from analgesia achieved by analgesic drugs used in diabetic neuropathy, the effect of LPP1 on glucose utilization, lipid accumulation and its antioxidant and cytotoxic potential were assessed in some in vitro and ex vivo tests.Total antioxidant capacity was evaluated spectrophotometrically using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical method, whereas the activities of glutathione (GSH) peroxidase and reductase were measured using methods based on the oxidation of NADPH to NADP. The spectrophotometric method for the evaluation of GSH level in mouse brain tissue homogenates involved the oxidation of GSH by the sulfhydryl reagent 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB) to form a yellow derivative, 5'-thio-2-nitrobenzoic acid (TNB), measurable at 412 nm. Cytotoxicity and glucose utilization were measured in hepatoma HepG2 cells and in 3T3-L1 adipocytes. Lipid accumulation was measured in 3T3-L1 cell lines.LPP1 had dose-dependent antioxidant properties in DPPH radical assay (14-22% versus control; p0.001). Its single administration caused an increase in GSH concentration in brain tissue homogenates of mice by 34% (versus control group; p0.05). LPP1 was not cytotoxic and it did not increase glucose utilization or lipid accumulation in cell cultures.Previously demonstrated antinociceptive properties of LPP1 are accompanied by a lack of cytotoxicity. LPP1 does not impair glucose or lipid metabolism and is an antioxidant. All these properties might be advantageous for its use in diabetic neuropathy.

The cardiovascular effects of alpha lipoic acid were evaluated in isolated rat hearts exposed to ischemia-reperfusion injury in vitro. Alpha-lipoic acid raised the level of sulfane sulfur playing an important role in the release of hydrogen sulfide. H2S was shown to prevent the post-reperfusion arrhythmias and to protect the cardiomyocytes from death caused by hypoxia. The activation of potassium ATP-sensitive channels (K(ATP) channels) is one of the most important mechanisms of action of hydrogen sulfide in the cardiovascular system. The aim of this study was to investigate whether alpha lipoic acid can prevent the occurrence of post-reperfusion arrhythmias in vitro using a Langendorff model of ischemia-reperfusion in rats affecting the K(ATP) channels. Alpha lipoic acid significantly improved post-reperfusion cardiac function (reducing incidence of arrhythmias), especially in a dose of 10(-7)M. These cardiovascular effects of this compound on the measured parameters were reversed by glibenclamide, a selective K(ATP) blocker. Alpha lipoic acid increased the level of sulfane sulfur in the hearts. This may suggest that the positive effects caused by alpha lipoic acid in the cardiovascular system are not only related to its strong antioxidant activity, and the influence on the activity of such enzymes as aldehyde dehydrogenase 2, as previously suggested, but this compound can affect K(ATP) channels. It is possible that this indirect effect of alpha lipoic acid is connected with changes in the release of sulfane sulfur and hydrogen sulfide.