Remodelling and dysfunction of the sinus node in pulmonary arterial hypertension.

Patients with pulmonary arterial hypertension (PAH) have a high burden of arrhythmias, including arrhythmias arising from sinus node dysfunction, and the aim of this study was to investigate the effects of PAH on the sinus node. In the rat, PAH was induced by an injection of monocrotaline. Three weeks after injection, there was a decrease of the intrinsic heart rate (heart rate in the absence of autonomic tone) as well as the normal heart rate, evidence of sinus node dysfunction. In the sinus node of PAH rats, there was a significant downregulation of many ion channels and Ca2+-handling genes that could explain the dysfunction: HCN1 and HCN4 (responsible for pacemaker current, If), Cav1.2, Cav1.3 and Cav3.1 (responsible for L- and T-type Ca2+ currents, ICa,L and ICa,T), NCX1 (responsible for Na+-Ca2+ exchanger) and SERCA2 and RYR2 (Ca2+-handling molecules). In the sinus node of PAH rats, there was also a significant upregulation of many fibrosis genes that could also help explain the dysfunction: vimentin, collagen type 1, elastin, fibronectin and transforming growth factor ß1. In summary, in PAH, there is a remodelling of ion channel, Ca2+-handling and fibrosis genes in the sinus node that is likely to be responsible for the sinus node dysfunction. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.

Spirulina platensis and its ingredient biopterin glucoside improved insulin sensitivity in non-alcoholic steatohepatitis model.

Non-alcoholic steatohepatitis is the chronic liver disease leading to cirrhosis and cancer and its prevalence is increasing. Some agents are under clinical trials for non-alcoholic steatohepatitis treatment. We previously reported Spirulina (Arthrospira) platensis effectively prevented non-alcoholic steatohepatitis progression in our model rats. The contribution of phycocyanin, an ingredient of Spirulina (Arthrospira) platensis, was limited. We, therefore, have looked for more active components of Spirulina (Arthrospira) platensis. In this study, we pursued the effect of biopterin glucoside, another bioactive ingredient of Spirulina (Arthrospira) platensis. We found Spirulina (Arthrospira) platensis and biopterin glucoside oral administrations effectively alleviated oxidative stress, inflammation and insulin signal failure, and prevented fibroblast growth factor 21 gene overexpression in non-alcoholic steatohepatitis rat livers. We concluded biopterin glucoside is a major component of Spirulina (Arthrospira) platensis action.

Oral administration of eicosapentaenoic acid or docosahexaenoic acid modifies cardiac function and ameliorates congestive heart failure in male rats.

This study assessed the effects of eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) on normal cardiac function (part 1) and congestive heart failure (CHF) (part 2) through electrocardiogram analysis and determination of EPA, DHA, and arachidonic acid (AA) concentrations in rat hearts. In part 2, pathologic assessments were also performed. For part 1 of this study, 4-wk-old male rats were divided into a control group and 2 experimental groups. The rats daily were orally administered (1 g/kg body weight) saline, EPA-ethyl ester (EPA-Et; E group), or DHA-ethyl ester (DHA-Et; D group), respectively, for 28 d. ECGs revealed that QT intervals were significantly shorter for groups E and D compared with the control group (P ≤ 0.05). Relative to the control group, the concentration of EPA was higher in the E group and concentrations of EPA and DHA were higher in the D group, although AA concentrations were lower (P ≤ 0.05). In part 2, CHF was produced by subcutaneous injection of monocrotaline into 5-wk-old rats. At 3 d before monocrotaline injection, rats were administered either saline, EPA-Et, or DHA-Et as mentioned above and then killed at 21 d. The study groups were as follows: normal + saline (control), CHF + saline (H group), CHF + EPA-Et (HE group), and CHF + DHA-Et (HD group). QT intervals were significantly shorter (P ≤ 0.05) in the control and HD groups compared with the H and HE groups. Relative to the H group, concentrations of EPA were higher in the HE group and those of DHA were higher in the control and HD groups (P ≤ 0.05). There was less mononuclear cell infiltration in the myocytes of the HD group than in the H group (P = 0.06). The right ventricles in the H, HE, and HD groups showed significantly increased weights (P ≤ 0.05) compared with controls. The administration of EPA-Et or DHA-Et may affect cardiac function by modification of heart fatty acid composition, and the administration of DHA-Et may ameliorate CHF.

Effects of squalene/squalane on dopamine levels, antioxidant enzyme activity, and fatty acid composition in the striatum of Parkinson's disease mouse model.

Active oxygen has been implicated in the pathogenesis of Parkinson's disease (PD); therefore, antioxidants have attracted attention as a potential way to prevent this disease. Squalene, a natural triterpene and an intermediate in the biosynthesis of cholesterol, is known to have active oxygen scavenging activities. Squalane, synthesized by complete hydrogenation of squalene, does not have active oxygen scavenging activities. We examined the effects of oral administration of squalene or squalane on a PD mouse model, which was developed by intracerebroventricular injection of 6-hydroxydopamine (6-OHDA). Squalene administration 7 days before and 7 days after one 6-OHDA injection prevented a reduction in striatal dopamine (DA) levels, while the same administration of squalane enhanced the levels. Neither squalene nor squalane administration for 7 days changed the levels of catalase, glutathione peroxidase, or superoxide dismutase activities in the striatum. Squalane increased thiobarbituric acid reactive substances, a marker of lipid peroxidation, in the striatum. Both squalane and squalene increased the ratio of linoleic acid/linolenic acid in the striatum. These results suggest that the administration of squalene or squalane induces similar changes in the composition of fatty acids and has no effect on the activities of active oxygen scavenging enzymes in the striatum. However, squalane increases oxidative damage in the striatum and exacerbates the toxicity of 6-OHDA, while squalene prevents it. The effects of squalene or squalane treatment in this model suggest their possible uses and risks in the treatment of PD.

Effects of zingerone [4-(4-hydroxy-3-methoxyphenyl)-2-butanone] and eugenol [2-methoxy-4-(2-propenyl)phenol] on the pathological progress in the 6-hydroxydopamine-induced Parkinson's disease mouse model.

Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic neurons in the nigrostriatal system and dopamine (DA) depletion in the striatum. The most popular therapeutic medicine for treating PD, 3-(3,4-Dihydroxyphenyl)-L-alanine (L-DOPA), has adverse effects, such as dyskinesia and disease acceleration. As superoxide (·O(2)(-)) and hydroxyl radical (·OH) have been implicated in the pathogenesis of PD, free radical scavenging and antioxidants have attracted attention as agents to prevent disease progression. Rodents injected with 6-hydroxydopamine (6-OHDA) intracerebroventricularly are considered to be a good animal model of PD. Zingerone and eugenol, essential oils extracted from ginger and cloves, are known to have free radical scavenging and antioxidant effects. Therefore, we examined the effects of zingerone and eugenol on the behavioral problems in mouse model and on the DA concentration and antioxidant activities in the striatum after 6-OHDA administration and L-DOPA treatment. Daily oral administration of eugenol/zingerone and injection of L-DOPA intraperitoneally for 4 weeks following a single 6-OHDA injection did not improve abnormal behaviors induced by L-DOPA treatment. 6-OHDA reduced the DA level in the striatum; surprisingly, zingerone and eugenol enhanced the reduction of striatal DA and its metabolites. Zingerone decreased catalase activity, and increased glutathione peroxidase activity and the oxidized L-ascorbate level in the striatum. We previously reported that pre-treatment with zingerone or eugenol prevents 6-OHDA-induced DA depression by preventing lipid peroxidation. However, the present study shows that post-treatment with these substances enhanced the DA decrease. These substances had adverse effects dependent on the time of administration relative to model PD onset. These results suggest that we should be wary of ingesting these spice elements after the onset of PD symptoms.

Effects of docosahexaenoic acid in an experimental rat model of nonalcoholic steatohepatitis.

Docosahexaenoic acid (DHA) regulates the lipid metabolism and inflammation that is closely associated with oxidative stress. The present study investigated the effects of DHA on the development of nonalcoholic steatohepatitis (NASH). To induce fatty liver, rats were fed choline-deficient high-fat diets (CDHF). The rats were then divided into 4 groups treated over the subsequent 6 weeks as follows: control, CDHF, CDHF+oxidative stress (NASH), and NASH+DHA (1.0 g/kg, p.o.). Rats of the control group were fed MF chow diet only. NASH rats showed severe steatohepatitis and liver fibrosis. Treatment with DHA significantly decreased the n-6/n-3 ratio in the livers and increased plasma SOD like activity compared with NASH rats. In addition, DHA attenuated the liver fibrosis during NASH development. Therefore, a higher DHA ratio in the liver of NASH rats might regulate the inflammatory response through a low n-6 ratio and diminished oxidative stress, effectively inhibiting liver fibrosis during NASH progression. These results suggested that DHA is a novel functional food for the prevention of NASH.

In vivo tissue uptake of intravenously injected water soluble all-trans beta-carotene used as a food colorant.

Water soluble beta-carotene (WS-BC) is a carotenoid form that has been developed as a food colorant. WS-BC is known to contain 10% of all-trans beta-carotene (AT-BC). The aim of the present study was to investigate in vivo tissue uptake of AT-BC after the administration of WS-BC into rats. Seven-week-old male rats were administered 20 mg of WS-BC dissolved in saline by intravenous injection into the tail vein. At 0, 6, 24, 72, 120 and 168 hours (n = 7/time), blood was drawn and liver, lungs, adrenal glands, kidneys and testes were dissected. The levels of AT-BC in the plasma and dissected tissues were quantified with HPLC. After intravenous administration, AT-BC level in plasma first increased up to 6 h and returned to normal at 72 h. In the testes, the AT-BC level first increased up to 24 h and then did not decrease but was retained up to 168 h. In the other tissues, the level first increased up to 6 h and then decreased from 6 to 120 or 168 h but did not return to normal. The accumulation of WS-BC in testes but not in the other 5 tissues examined may suggest that AT-BC was excreted or metabolized in these tissues but not in testes. Although WS-BC is commonly used as a food colorant, its effects on body tissues are still not clarified. Results of the present study suggest that further investigations are required to elucidate effects of WS-BC on various body tissues.

Docosahexaenoic acid ethyl ester enhances 6-hydroxydopamine-induced neuronal damage by induction of lipid peroxidation in mouse striatum.

Superoxide and hydroxyl radicals are implicated in the pathogenesis of Parkinson disease, and induction of lipid peroxidation is an important factor in progression of this disease. Docosahexaenoic acid (DHA) is a key component of the cell membrane, and its peroxidation is inducible due to the double-bond chemical structure. However, DHA has neuroprotective effects. In this study, we examined the effects of intraperitoneal injection (ipi) of DHA ethyl ester (DHA-Et) on 6-hydroxydopamine (6-OHDA)-induced dopamine (DA) reduction in the mouse striatum. DHA-Et ipi for 7 days before and 7 days after a single intracerebroventricular injection of 6-OHDA enhanced 6-OHDA-induced reduction of striatal DA level. On the other hand, ipi of DHA-Et for 7 days increased its concentration in the striatum. Co-injection of DHA-Et and 6-OHDA increased the levels of thiobarbituric acid-reactive substances (a marker of lipid peroxidation) in the striatum. Our results suggest that DHA-Et enhances 6-OHDA-induced DA depression by increasing lipid peroxidation, and that excessive use of DHA-Et may increase the susceptibility of Parkinson disease in animal model.

Eugenol [2-methoxy-4-(2-propenyl)phenol] prevents 6-hydroxydopamine-induced dopamine depression and lipid peroxidation inductivity in mouse striatum.

As superoxide (.O2-) and hydroxyl radical (.OH) have been implicated in the pathogenesis of Parkinson disease, free radical scavenging and antioxidants have attracted attention as way to prevent progression of this disease. We examined the effects of eugenol, an essential oil extracted from cloves, on 6-hydroxydopamine (6-OHDA)-induced dopamine (DA) reduction in the mouse striatum. Eugenol administration 3 d before and 7 more days following one intracerebroventricular 6-OHDA injection prevented the reduction of striatal DA and its metabolites. Eugenol administration for 3 d reduced the increase of thiobarbituric acid-reactive substances (an indicator of lipid peroxidation) induced by ferric ion and increased glutathione (GSH) and L-ascorbate (Asc) in the striatum. Eugenol did not change the levels of catalase, glutathione peroxidase, or superoxide dismutase-like activities. Eugenol is known to have .O2- and .OH scavenging activities in vitro. These results suggest that eugenol prevents 6-OHDA-induced DA depression by preventing lipid peroxidation directly and indirectly (via stimulation of GSH and Asc generating systems). Furthermore, increased GSH may protect cell death by conjugating with p-quinone produced in 6-OHDA auto-oxidation. The effects of eugenol treatment in this model suggest its possible usefulness for the treatment of Parkinson disease.

Zingerone [4-(4-hydroxy-3-methoxyphenyl)-2-butanone] prevents 6-hydroxydopamine-induced dopamine depression in mouse striatum and increases superoxide scavenging activity in serum.

As superoxide (*O(2)-) and hydroxyl radical (*OH) have been implicated in pathogenesis of Parkinson's disease, free radical scavenging, antioxidant, and neuroprotective agents have attracted attention as ways to prevent progression. We examined effects of zingerone, an alkaloid extracted from ginger root, on 6-hydroxydopamine (6-OHDA)-induced dopamine (DA) reduction in mouse striatum. Zingerone administration 1 h before and for 6 more days following one intracerebroventricular 6-OHDA injection prevented reductions of striatal DA and its metabolites, and increased serum *O(2)- scavenging activity. Zingerone did not change activities of catalase or glutathione peroxidase in striatum or serum, or *O(2)- scavenging activity in striatum. Treatment with diethyldithiocarbamate, SOD inhibitor, abolished the protective effect of zingerone against 6-OHDA-induced DA reduction. In vitro, zingerone scavenged *O(2)- and *OH and suppressed lipid peroxidation only weakly. Thus, direct antioxidant effects may be a minor component of its putative neuroprotective effect; instead, zingerone acted mainly by increasing systemic superoxide dismutase activity. Effects of zingerone treatment in this model suggest possible value in treatment of Parkinson's disease.

Exposure to bisphenol A during embryonic/fetal life and infancy increases oxidative injury and causes underdevelopment of the brain and testis in mice.

We investigated the modifications in endogenous antioxidant capacity and oxidative damage in the brain, liver, kidney and testis in mice exposed to bisphenol A (BPA), an environmental endocrine disrupter. Mice were exposed to BPA throughout embryonic/fetal life and during lactation by feeding their pregnant/lactating mothers BPA at 5 or 10 microg per milliliter of drinking water. At the age of four weeks, male mice were sacrificed. Exposure to BPA increased the activity of catalase and glutathione peroxidase in the liver and kidney, respectively. It also increased thiobarbituric acid-reactive substances in the brain, kidney and testis, and decreased the wet weight of the brain, kidney and testis. Our results suggest that exposure to BPA throughout embryonic/fetal life and during infancy induces tissue oxidative stress and peroxidation, ultimately leading to underdevelopment of the brain, kidney and testis.

alpha-Tocopheryl-L-ascorbate-2-O-phosphate diester, a hydroxyl radical scavenger, prevents the occurrence of epileptic foci in a rat model of post-traumatic epilepsy.

Intracortical injection of iron ions has been used to model post-traumatic epilepsy. The results obtained using these models suggest that oxidation of neural membranes by active oxygen free radicals may be involved in the etiology of post-traumatic epilepsy. This is a study of the effects of alpha-tocopheryl-L-ascorbate-2-O-phosphate diester potassium salt (EPC-K1), known as a hydroxyl radical scavenger, on the peroxidation of neural membranes by FeCl(3) in vitro and on the occurrence of epileptic discharges in the FeCl(3) injected post-traumatic epilepsy model rats. EPC-K1 dose-dependently inhibited the production of thiobarbituric acid reactive substances (TBARS) and protein carbonyl (P-Carb), both indices of biogenic macromolecular peroxidation. In vivo studies, sporadic spike discharges and/or epileptiform activities were observed in electrocorticograms (ECoG) of male Sprague-Dawley rat 15-90 min after 500 nmol of FeCl(3) was injected into the motor cortex. On the other hand, when 200 mg/kg of EPC-K1 was injected intraperitoneally 60 min prior to the injection of FeCl(3), the occurrence of epileptic discharges was prevented or delayed. When EPC-K1 (2.5-5 nmol) was injected along with the ferric ions, the occurrence of epileptiform activities was also prevented or delayed. EPC-K1 prevented the induction of early convulsion, the major risk factor of post-traumatic epilepsy. Rats in the Fe+EPC group were injected with 500 nmol of FeCl(3) into the left motor cortex and were given an EPC-K1-diet (CE-2 chow contained 0.2% of EPC-K1, and daily EPC-K1 intake was about 80 mg/kg/day). In the Fe+EPC group rats, the percent induction of epileptic discharges in ECoGs was significantly lower than that in the Fe+CE group rats, which were fed CE-2 after FeCl(3) injection. In the homotropic contra lateral cortex, TBARS and P-Carb content did not show any changes. However, the relative TBARS content in the focal area significantly increased in the Fe+CE and Fe+EPC group rats 3 h after the injection. It became normal 3 days after in the Fe+EPC group. The relative P-Carb content in the focal area significantly increased in the Fe+CE and Fe+EPC group rats 3 h after the injection. However, it became normal after 3 days. In the present study, EPC-K1, which consists of vitamins E and C connected by a phosphate, protected the oxidation of neural membranes and prevented the occurrence of ferric ion-induced epileptic discharges by its radical scavenger activity. These data suggest that EPC-K1 may be clinically useful in not only preventing the focus formation of post-traumatic epilepsy, but also in treating and attenuating the progression of free radical-induced degenerative disorders.