Comparative analysis of photobiomodulation therapy and transcutaneous electrical nerve stimulation for burning mouth: a randomized clinical trial.

OBJECTIVE: To compare the effect of photobiomodulation (PBM) and transcutaneous electrical nerve stimulation (TENS) in the treatment of burning mouth. MATERIALS AND METHODS: Randomized clinical trial of 25 patients with burning mouth treated by TENS (n=12) and PBM (n=13). The patients were treated weekly for 8 weeks. Two-factor ANOVA was used to determine whether the two interventions promoted significant differences in symptoms (measured with a visual analogue scale), unstimulated salivary flow, xerostomia, and dysgeusia between T0 (baseline), T1 (after the 4th treatment session), T2 (after the 8th treatment session), and T3 (30 days after the end of treatment). RESULTS: Intragroup comparison of VAS scores for pain showed a significant difference between T0xT1, T0xT2, and T0xT3 in the TENS group and between T0xT2 and T0xT3 in the PBM group (p˂0.001). Intergroup comparison of VAS scores for pain between T2xT3 showed a better response to PBM than to TENS (p=0.003). Patients of the TENS group showed an increase in salivary flow between T1 and T2 (p=0.052). There were no expressive variations in xerostomia or dysgeusia in the two groups analyzed. CONCLUSION: TENS and PBM were effective in reducing the symptoms of burning mouth during and after treatment. The PBM group showed a better response during follow-up. TRIAL REGISTRATION: This clinical trial was registered at http://clinicaltrials.gov (Number: NCT05816200). CLINICAL RELEVANCE: TENS was found to be a safe and effective therapy for burning mouth. Trial registration number (TRN) and date of registration: This clinical trial was registered at http://clinicaltrials.gov (Number: NCT05816200; date: May 08, 2023).

Catechol-O-methyltransferase activity in individuals with substance use disorders: a case control study.

BACKGROUND: Impulsivity and substance use disorders (SUD) have been both associated with changes in dopaminergic processes. In this study, we intended to evaluate the dopaminergic function in imprisoned SUD offenders through the determination of s-COMT activity. METHODS: The study included 46 male individuals from a Portuguese penal institution. The participants were assessed through a battery of standardised instruments: Psychopathy Checklist-Revised (PCL-R), Barratt Impulsivity Scale Version 11 (BIS-11), and the European version of the Addiction Severity Index (EuropASI). In addition, s-COMT erythrocyte activity was evaluated. RESULTS: Overall, 73.9% (n = 34) of the individuals had Antisocial personality disorder (ASPD) and 58.7% (n = 27) presented SUD. We evidenced, for the first time, that, in individuals with SUD, s-COMT activity was correlated with the severity of drug dependence (EuropASI) (p = 0.009), and with BIS-11 factors self-control (p < 0.0001) and non-planning (p = 0.002). CONCLUSIONS: This study opens new perspectives regarding the pharmacological intervention on substance dependence through the interference on dopamine pathways.

Análise de alterações bucais em pacientes com covid-19 hospitalizados: um estudo de coorte retrospectivo / Analysis of oral changes in hospitalized Covid-19 patients: a retrospective cohort study

O surto de um novo coronavírus SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2), foi identificado em Wuhan, na China no final de 2019. O SARS-CoV-2, se propaga através de gotículas respiratórias de uma pessoa infectada e causa uma doença respiratória denominada Covid-19 (Coronavirus Disease, 2019). Seu comportamento clínico é variável e manifesta-se com sintomas leves ou moderado, podendo desenvolver uma infecção respiratória grave. A cavidade oral foi identificada como uma das portas de entrada para o SARS-CoV-2, e seu possível papel como agravante na infectividade e progressão da infecção viral têm sido controversos. Foi realizado um estudo de coorte retrospectivo com dados obtidos de 274 prontuários de pacientes com COVID-19. Foi coletado dados na admissão do paciente, com sete e quatorze dias para analisar a ocorrência de alterações bucais e relacioná-las com a severidade da infecção. Foram encontrados 154 pacientes com alteração bucal e 120 sem alteração. Dos 154 pacientes que apresentaram alteração bucal na admissão, 39 obtiveram remissão em 7 dias, 54 pacientes obtiveram remissão em 14 dias e 61 mantiveram alteração bucal até o fim do estudo. Dos 120 pacientes que não apresentavam alteração bucal na admissão, apenas 2 desenvolveram alteração bucal em 7 dias e estes foram a óbito. A alteração bucal mais frequente foi a úlcera nos três tempos de coleta ( T0: 43,8%, T1: 33,6% e T2: 21,2%). As análises dos exames complementares alteradas mais prevalentes entre os pacientes foram as hemácias, plaquetas, leucócitos, tempo de sangramento, TGP, TGO, albumina, creatinina, PCR, ureia, d-dímero e razão leucócito-linfócito. Não foram observados fatores preditores para o desenvolvimento de alterações bucais em pacientes com COVID 19. As alterações em mucosa oral foram observadas na maioria dos pacientes com COVID-19 analisados nessa pesquisa. Não foi observada associação entre as comorbidades e a presença de lesões orais nos pacientes avaliados. Os fatores de prognósticos foram avaliados pela análise multivariada de Cox que determinou que não fazer uso de medicação para o aparelho digestivo e metabolismo (HR: 2,18; IC95%: 1,13-4,22) e não apresentar hipertensão arterial sistêmica (HR: 1,78; IC95%: 1,13- 2,79) são fatores prognósticos para remissão de alteração bucal em pacientes com COVID-19 (AU).

An outbreak of a new SARS-CoV-2 coronavirus (Severe acute respiratory syndrome coronavirus 2) was identified in Wuhan, China in late 2019. SARS-CoV-2, spreads through respiratory droplets from an infected person and causes a respiratory disease called Covid-19 (Coronavirus Disease, 2019). Its clinical behavior is variable and manifests with mild or moderate symptoms, and may develop a severe respiratory infection. The oral cavity has been identified as one of the gateways for SARS-CoV-2, and its possible role as an aggravating factor in the infectivity and progression of viral infection has been controversial. A retrospective cohort study was carried out with data obtained from 274 medical records of patients with COVID-19. Data was collected on the admission of the patient, with seven and fourteen days to analyze the occurrence of oral changes and relate them to the severity of the infection. A total of 154 patients with oral alterations and 120 without alterations were found. Of the 154 patients who presented oral changes on admission, 39 achieved remission within 7 days, 54 patients achieved remission within 14 days, and 61 maintained oral changes until the end of the study. Of the 120 patients who did not present oral changes on admission, only 2 developed oral changes within 7 days and these died. The most frequent oral alteration was an ulcer in the three collection times (T0: 43.8%, T1: 33.6% and T2: 21.2%). The most prevalent abnormal exam analyses among patients were red blood cells, platelets, leukocytes, bleeding time, TGP, TGO, albumin, creatinine, CRP, urea, d-dimer, and leukocyte-lymphocyte ratio. No predictors were observed for the development of oral alterations in patients with COVID 19. Alterations in the oral mucosa were observed in most patients with COVID-19 analysed in this study. There was no association between comorbidities and the presence of oral lesions in the patients evaluated. Prognostic factors were evaluated by Cox's multivariate analysis, which determined that they did not use medication for the digestive system and for metabolism (HR: 2.18; 95%CI: 1.13- 4.22) and did not have systemic arterial hypertension (HR: 1.78; 95%CI: 1.13-2.79), these are prognostic factors for remission of oral changes in patients with COVID-19 (AU).

The role of salt-inducible kinases on the modulation of renal and intestinal Na+,K+-ATPase activity during short- and long-term high-salt intake.

Type 1 salt-inducible kinases (SIK1) has been shown to act as a mediator during the cellular adaptation to variations in intracellular sodium in a variety of cell types. Type 2 SIK (SIK2) modulates various biological functions and acts as a signal transmitter in various pathways. To evaluate the role of both SIK isoforms in renal and intestinal Na+,K+-ATPase (NKA) activity, we made use of constitutive sik1-/- (SIK1-KO), sik2-/- (SIK2-KO), double sik1-/-sik2-/- (double SIK1*2-KO) knockout and wild-type (WT) mice challenged to a standard (0.3% NaCl) or chronic high-salt (HS, 8% NaCl) diet intake for 48 h or 12 weeks. Long-term HS intake in WT was accompanied by 2-fold increase in jejunal NKA activity and slight (~30% reduction) decreases in NKA in the ileum and cecum; none of these changes was accompanied by changes in the expression of α1-NKA. The ablation of SIK1 and SIK2 prevented the marked increase in jejunal NKA activity following the long-term HS intake. The ablation of SIK1 and SIK2 in mice on a long-term HS intake impacted differently in the ileum and cecum. The most interesting finding is that in SIK2-KO mice marked reductions in NKA activity were observed in the ileum and cecum when compared to WT mice, both on normal and long-term HS intake. In summary, SIK1 or SIK2 ablation on chronic high-salt intake is accompanied by modulation of NKA along the intestinal tract, which differ from those after an acute high-salt intake, and this may represent an absorptive compensatory mechanism to keep electrolyte homeostasis.

Liver says no: the ongoing search for safe catechol O-methyltransferase inhibitors to replace tolcapone.

Catechol O-methyltransferase (COMT) inhibitors are valuable co-adjuvant drugs in the clinical management of Parkinson's disease (PD), and recent data also suggest therapeutic benefits in other neurological disorders associated with dopamine depletion. However, the relationship between tolcapone administration with fatal cases of drug-induced liver damage gave COMT inhibitors a bad reputation as hepatotoxic drugs. Thus, there is a pressing need to feed the pipeline with safe COMT inhibitors to replace tolcapone, the only currently available COMT inhibitor that effectively reaches the brain. Recent efforts led to promising phenolic and nonphenolic COMT inhibitors, which allow isoform-specific targeting and avoid the toxicological and pharmacokinetic (PK) shortcomings of classic nitrocatechols. Here, we describe advances made in this field over the past 5 years.

Effects of nepicastat upon dopamine-ß-hydroxylase activity and dopamine and norepinephrine levels in the rat left ventricle, kidney, and adrenal gland.

Background and Objective: Evaluate the activity of dopamine-ß-hydroxylase (DßH) as well as the effect of the DßH inhibitor nepicastat upon enzyme activity and levels of dopamine (DA) and norepinephrine (NE) in the rat left ventricle, kidney, and adrenal glands.Methods: DßH assay consisted of the enzymatic hydroxylation of tyramine into octopamine, and DA and NE tissues levels were quantified by HPLC-ED.Results: Nepicastat (30 mg/kg, p.o.) reduced DßH activity by 93% and 80% in the adrenals at 4 h and 8 h postdrug administration, accompanied by significant reductions in NE and epinephrine tissue levels and an increase in DA levels and of DA/NE tissue ratios, with similar findings for NE, DA and of DA/NE tissue ratios in left ventricle and kidney. DßH activity in the left ventricle and kidney showed a high degree of variability, which does not allow corroboration of the effects of nepicastat upon catecholamine tissue levels.Conclusion: The assay of DßH activity in heart and kidney lacks the necessary robustness, but DßH activity in the adrenals appears to be an appropriate marker. However, the effect size upon DA/NE tissue ratios (an indirect measure of DßH activity) as induced by nepicastat was very similar in sympathetically innervated tissues, left ventricle and kidney, and the adrenal medulla.

Acute salt loading induces sympathetic nervous system overdrive in mice lacking salt-inducible kinase 1 (SIK1).

Loss of salt-inducible kinase 1 (SIK1) triggers an increase in blood pressure (BP) upon a chronic high-salt intake in mice. Here, we further addressed the possible early mechanisms that may relate to the observed rise in BP in mice lacking SIK1. SIK1 knockout (sik1-/-) and wild-type (sik1+/+) littermate mice were challenged with either a high-salt (8% NaCl) or control (0.3% NaCl) diet for 7 days. Systolic BP was significantly increased in sik1-/- mice after 7 days of high-salt diet as compared with sik1+/+ mice and to sik1-/- counterparts on a control diet. The renin-angiotensin-aldosterone system and the sympathetic nervous system were assayed to investigate possible causes for the increase in BP in sik1-/- mice fed a 7-day high-salt diet. Although no differences in serum renin and angiotensin II levels were observed, a reduction in aldosterone serum levels was observed in mice fed a high-salt diet. Urinary L-DOPA and noradrenaline levels were significantly increased in sik1-/- mice fed a high-salt diet as compared with sik1-/- mice on a control diet. Similarly, the activity of dopamine ß-hydroxylase (DßH), the enzyme that converts dopamine to noradrenaline, was significantly increased in the adrenal glands of sik1-/- mice on a high-salt intake compared with sik1+/+ and sik1-/- mice on a control diet. Treatment with etamicastat (50 mg/kg/day), a peripheral reversible DßH inhibitor, administered prior to high-salt diet, completely prevented the systolic BP increase in sik1-/- mice. In conclusion, SIK1 activity is necessary to prevent the development of salt-induced high blood pressure and associated SNS overactivity.

Pharmacodynamic evaluation of novel Catechol-O-methyltransferase inhibitors.

Currently, peripheral COMT inhibitors have an important role in the treatment of Parkinson's disease, and central COMT inhibitors have a potential role in the treatment of various neuropsychiatric disorders, such as attention deficit hyperactivity disorder. Adverse reactions, low bioavailability and short elimination half-lives have prompted the development of new selective COMT inhibitors. The objective of this study was to evaluate the pharmacodynamic properties of novel tight-binding COMT inhibitors (NC, NE, NDE, NCAPE, CNCAFBn, CNCAPE, NCAFBn, CNCAPA, CNCABA and CNCAHA) and compared to standard inhibitors tolcapone and entacapone. The activity of soluble (S) and membrane bound (MB) COMT from rat liver and brain was assessed in the presence of varying concentrations of each inhibitor. NE and NC behaved most potently against liver S-COMT, and CNCAPE was the most potent inhibitor against brain MB-COMT. The cytotoxicity of tolcapone and CNCAPE in human neuroblastoma SK-N-SH cells and human liver adenocarcinoma SK-HEP-1 cells was also assessed. At lower concentrations, CNCAPE did not reduce cell viability, suggesting that CNCAPE may have a potential therapeutic role as a centrally active COMT inhibitor.

Antihypertensive effect of etamicastat in dopamine D2 receptor-deficient mice.

Abnormalities of the D2R gene (DRD2) play a role in the pathogenesis of human essential hypertension; variants of the DRD2 have been reported to be associated with hypertension. Disruption of Drd2 (D2-/-) in mice increases blood pressure. The hypertension of D2-/- mice has been related, in part, to increased sympathetic activity, renal oxidative stress, and renal endothelin B receptor (ETBR) expression. We tested in D2-/- mice the effect of etamicastat, a reversible peripheral inhibitor of dopamine-ß-hydroxylase that reduces the biosynthesis of norepinephrine from dopamine and decreases sympathetic nerve activity. Blood pressure was measured in anesthetized D2-/- mice treated with etamicastat by gavage, (10 mg/kg), conscious D2-/- mice, and D2+/+ littermates, and mice with the D2R selectively silenced in the kidney, treated with etamicastat in the drinking water (10 mg/kg per day). Tissue and urinary catecholamines and renal expression of selected G protein-coupled receptors, enzymes related to the production of reactive oxygen species, and sodium transporters were also measured. Etamicastat decreased blood pressure both in anesthetized and conscious D2-/- mice and mice with renal-selective silencing of D2R to levels similar or close to those measured in D2+/+ littermates. Etamicastat decreased cardiac and renal norepinephrine and increased cardiac and urinary dopamine levels in D2-/- mice. It also normalized the increased renal protein expressions of ETBR, NADPH oxidase isoenzymes, and urinary 8-isoprostane, as well as renal NHE3 and NCC, and increased the renal expression of D1R but not D5R in D2-/- mice. In conclusion, etamicastat is effective in normalizing the increased blood pressure and some of the abnormal renal biochemical alterations of D2-/- mice.

Blood pressure decrease in spontaneously hypertensive rats folowing renal denervation or dopamine ß-hydroxylase inhibition with etamicastat.

Overactivity of the sympathetic nervous system has an important role in the development and progression of arterial hypertension. Catheter-based renal nerve ablation for the treatment of drug-resistant hypertension has recently been developed. An alternative strategy for the modulation of sympathetic nerve function is to reduce the biosynthesis of noradrenaline (NA) by inhibiting dopamine ß-hydroxylase (DßH), the enzyme that catalyzes the conversion of dopamine (DA) to NA in the sympathetic nerves. Renal denervation (RDN) surgery was performed in spontaneously hypertensive rats (SHR) to evaluate the effect of RDN on the DA and NA levels and on blood pressure over a 28-day period. The selective peripheral DßH inhibitor etamicastat (30 mg kg (-1)day(-1)) was administered to another cohort of SHR. RDN and etamicastat treatment had no effect on the renal function, as assessed by measuring the water balance response, renal function and urinary electrolyte levels. RDN significantly decreased the systolic blood pressure (SBP) and the diastolic blood pressure (DBP). A gradual return of the SBP and the DBP to the high baseline levels was observed over time. Conversely, treatment with etamicastat resulted in a significant decrease in the SBP and the DBP at all time points. On the last day of the assessment, NA levels in renal tissue were significantly decreased in both RDN and etamicastat-treated groups. In contrast, the NA levels in the left ventricle were decreased only in the etamicastat-treated group. Thus, RDN produces transitory decreases in blood pressure, whereas prolonged downregulation of sympathetic drive with the DßH inhibitor etamicastat results in a sustained decrease in the SBP and the DBP.

Renalase regulates peripheral and central dopaminergic activities.

Renalase is a recently identified FAD/NADH-dependent amine oxidase mainly expressed in kidney that is secreted into blood and urine where it was suggested to metabolize catecholamines. The present study evaluated central and peripheral dopaminergic activities in the renalase knockout (KO) mouse model and examined the changes induced by recombinant renalase (RR) administration on plasma and urine catecholamine levels. Compared with wild-type (WT) mice, KO mice presented increased plasma levels of epinephrine (Epi), norepinephrine (NE), and dopamine (DA) that were accompanied by increases in the urinary excretion of Epi, NE, DA. In addition, the KO mice presented an increase in urinary DA-to-l-3,4-dihydroxyphenylalanine (l-DOPA) ratios without changes in renal tubular aromatic-l-amino acid decarboxylase (AADC) activity. By contrast, the in vivo administration of RR (1.5 mg/kg sc) to KO mice was accompanied by significant decreases in plasma levels of Epi, DA, and l-DOPA as well as in urinary excretion of Epi, DA, and DA-to-l-DOPA ratios notwithstanding the accompanied increase in renal AADC activity. In addition, the increase in renal DA output observed in renalase KO mice was accompanied by an increase in the expression of the L-type amino acid transporter like (LAT) 1 that is reversed by the administration of RR in these animals. These results suggest that the overexpression of LAT1 in the renal cortex of the renalase KO mice might contribute to the enhanced l-DOPA availability/uptake and consequently to the activation of the renal dopaminergic system in the presence of renalase deficiency.

Catechol-O-methyltransferase activity in psoriasis patients treated with psoralen plus ultraviolet A therapy.

BACKGROUND: Catechol-O-methyltransferase (COMT) activity is increased in patients with mild/moderate psoriasis. Narrowband ultraviolet B (nbUVB) phototherapy decreases COMT activity. However, the effect of psoralen plus ultraviolet A (PUVA) on this enzyme activity is unknown, and it remains to be clarified if the nbUVB-induced effect in COMT activity is related to clinical response. The aim of this study is to evaluate COMT activity in moderate/severe psoriasis and assess whether PUVA therapy modifies this activity. METHODS: An observational study was conducted on 18 patients with moderate/severe psoriasis and 13 matched controls. Patients were treated with PUVA twice weekly during 6 weeks, and they were evaluated for Psoriasis Area and Severity Index (PASI) and COMT activity before photochemotherapy, at the end of it and 4 weeks after stopping. RESULTS: Before PUVA therapy, S(soluble)-COMT activity was significantly (P < 0.05) higher in psoriasis patients than in controls. After photochemotherapy, no significant differences were found in S-COMT activity at all end points. Photochemotherapy significantly decreased PASI but COMT activity values remained higher than those of control population. CONCLUSION: Psoriasis patients with moderate/severe disease present higher S-COMT activity than controls. Although a good clinical response was observed, PUVA therapy does not change S-COMT activity. This differential COMT effect of PUVA and nbUVB suggests a wavelength-specific regulation.

Catechol-O-methyltransferase activity is higher in psoriasis patients and is down-regulated by narrowband ultraviolet B treatment.

BACKGROUND: Narrowband ultraviolet B (nbUVB) phototherapy is widely used in psoriasis treatment. UVB irradiation decreases catechol-O-methyltransferase (COMT) activity in human keratinocytes and melanoma cells. COMT activity is higher in psoriatic lesions than in normal skin but the effect of nbUVB on COMT activity in psoriasis patients is unknown. OBJECTIVES: To evaluate COMT activity in patients with psoriasis and determine whether nbUVB modifies this activity. METHODS: An open observational study was conducted with 20 psoriasis patients and 15 healthy volunteers. Patients were treated with nbUVB thrice weekly during six weeks and evaluated at baseline, three and six weeks after phototherapy and four weeks after stopping. In each evaluation body mass index (BMI), Psoriasis Area and Severity Index (PASI) and Dermatology Life Quality Index (DLQI) were calculated and blood samples for erythrocytes soluble (S-) COMT activity assessment were taken. RESULTS: Before phototherapy (baseline), using a single concentration of substrate adreneline (1,000 µM), S-COMT activity levels (pmol/mg protein/h) were significantly higher in psoriasis patients than in controls. After nbUVB treatment, S-COMT activity significantly decreased. This decrease correlated positively with baseline activity. Four weeks after stopping phototherapy, S-COMT activity returned to baseline levels. After phototherapy, PASI score improved significantly but no correlation to baseline S-COMT values or decrease in S-COMT activity was found. CONCLUSIONS: This study shows that baseline S-COMT activity is higher in psoriasis patients than in controls and that this activity is significantly decreased by nbUVB treatment for psoriasis. This decrease is more evident in patients with higher baseline S-COMT activity.

α2C-Adrenoceptors modulate L-DOPA uptake in opossum kidney cells and in the mouse kidney.

Targeted deletion or selective pharmacological inhibition of α(2C)-adrenoceptors in mice results in increased brain tissue levels of dopamine and its precursor l-3,4-dihydroxyphenylalanine (l-DOPA), without significant changes in l-DOPA synthesis. l-DOPA uptake is considered the rate-limiting step in dopamine synthesis in the kidney. Since α(2C)-adrenoceptors may influence the transport of l-DOPA, we investigated the effect of α(2C)-adrenoceptor activation on l-DOPA uptake in a kidney cell line (opossum kidney cells). l-DOPA and dopamine kidney tissue levels in α(2C)-adrenoceptor knockout (α(2C)KO) mice and in mice treated with the selective α(2C)-adrenoceptor antagonist JP-1302 were also evaluated. The α(2)-adrenoceptor agonist medetomidine (0.1-1,000 nM) produced a concentration-dependent decrease in l-DOPA uptake in opossum kidney cells (IC(50): 2.5 ± 0.5 nM and maximal effect: 28 ± 5% of inhibition). This effect was abolished by a preincubation with JP-1302 (300 nM). Furthermore, the effect of medetomidine (100 nM) was abolished by a preincubation with U-0126 (10 µM), a MEK1/2 inhibitor. Kidney tissue levels of l-DOPA were significantly higher in α(2C)KO mice compared with wild-type mice (wild-type mice: 58 ± 2 pmol/g tissue and α(2C)KO mice: 81 ± 15 pmol/g tissue, P < 0.05) and in mice treated with JP-1302 (3 µmol/kg body wt) compared with control mice (control mice: 62 ± 2 pmol/g tissue and JP-1302-treated mice: 75 ± 1 pmol/g tissue, P < 0.05), both without significant changes in dopamine kidney tissue levels. However, mice treated with JP-1302 on a high-salt diet presented significantly higher dopamine levels in the kidney and urine compared with control animals on a high-salt diet. In conclusion, in a kidney cell line, α(2C)-adrenoceptor activation inhibits l-DOPA uptake, and in mice, deletion or blockade of α(2C)-adrenoceptors increases l-DOPA kidney tissue levels.

Long-term food restriction attenuates age-related changes in the expression of renal aldosterone-sensitive sodium transporters in Wistar-Kyoto rats: a comparison with SHR.

In the present study we hypothesized that age-associated changes in the renal aldosterone/mineralocorticoid receptor (MR) system may differ between normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). In WKY, body mass index significantly increased with age. Fat mass may operate as a confounding factor; therefore, WKY (WKY-FR) was pair-fed with SHR. Pair-feeding resulted in a 14% body weight reduction at the age of 52 weeks in WKY-FR. Renal oxidative stress was increased in aged WKY and SHR. Aged WKY and SHR had increased MR functionality, which correlated positively with increased plasma aldosterone levels, nuclear MR content and abundance of aldosterone effectors in the renal medulla. In contrast, decreases in nuclear MR content were observed in the renal cortex of both strains with aging. When compared to aged SHR, aged WKY-FR had decreased plasma aldosterone levels and decreased activation of the aldosterone/MR system in the renal medulla. Increases in renal oxidative stress and plasma aldosterone in aged WKY, to levels observed in SHR, were not sufficient to result in sustained increases in blood pressure. In conclusion, activation of the aldosterone/MR system is intensified by aging in SHR, whereas increases in body fat mass in WKY associate with hyperaldosteronism and oxidative stress.

Ultraviolet B radiation differentially modifies catechol-O-methyltransferase activity in keratinocytes and melanoma cells.

BACKGROUND: Catechol-O-methyltransferase (COMT) is a ubiquitous enzyme inactivating catecholic compounds. COMT is expressed also in human skin samples, and in melanoma cells it may be cytoprotective. A role of COMT in keratinocytes (HaCat) is unknown. OBJECTIVE: The objective of this study is: to investigate whether ultraviolet-B (UVB) radiation modifies COMT activity in melanocytes and HaCat and whether COMT inhibition plays a role in UVB-induced cell death. METHODS: Human cell lines of melanotic melanoma (SK-mel-1) and HaCat were used. COMT activity was evaluated under basal conditions and after UVB irradiation (311 nm) at a low (8 mJ/cm(2)) and a high dose (60 mJ/cm(2)). Tolcapone 1 µM was used to inhibit COMT. RESULTS: Both SK-mel-1 and Ha-Cat cells express COMT activity. In SK-mel-1, COMT activity is reduced nearly 50% both 24 h and 48 h after a high dose UVB. In Ha-Cat cells, COMT activity increased 24 h after a high dose UVB but decreased at 48 h. Tolcapone increases significantly the cytotoxic effect of high dose UVB irradiation only in HaCat. High concentrations of tolcapone reduced melanin levels in melanoma cells parallel to reduced cell numbers. CONCLUSIONS: Ultraviolet radiation differentially modifies COMT activity in melanoma cells and HaCat. Furthermore, tolcapone increased death of HaCat after irradiation but did not affect melanoma cells.

Adrenal α2-adrenergic receptors in the aging normotensive and spontaneously hypertensive rat.

This study investigates α(2)-adrenergic receptor (α(2)AR) mediated feedback inhibition of catecholamine release from the adrenal medulla of adult (52 weeks) and old (98 weeks) spontaneously hypertensive rats (SHR) and normotensive controls Wistar Kyoto (WKY) rats. Adrenal epinephrine content as well as the spontaneous and the nicotinic-evoked release of epinephrine were similar between adult SHR and WKY rats. Aging produced a significant reduction in epinephrine synthesis in WKY rats. In contrast, in SHR aging produced a significant increase in epinephrine release without significant changes in epinephrine synthesis. The α(2)AR agonist medetomidine abolished (80-90% inhibition) the nicotinic-evoked release of epinephrine in adult SHR and WKY rats. With aging, this effect was unaltered in WKY rats but was significantly decreased in SHR (30% inhibition). Adrenal α(2A)AR mRNA levels were significantly reduced in old SHR compared with age matched WKY rats. In conclusion, in aging the α(2)AR mediated feedback inhibition of epinephrine release from the adrenal medulla is preserved in WKY rats but compromised in SHR, resulting in increased epinephrine release.

Influence of dietary supplementation with dextrin or oligofructose on the hepatic redox balance in rats.

We assessed the impact of oligofructose (OFS) and dextrin (DEX) as diet supplements on hepatic redox state. Rats were fed either a 10% OFS or a 10% DEX supplemented diet for 9 wk. In the DEX diet group, the levels of hepatic protein carbonylation were decreased by 63%. Total glutathione and reduced glutathione (GSH) contents were reduced in the OFS and DEX diet groups by around 20%. DEX supplementation significantly reduced oxidized glutathione (GSSG) levels resulting in a 33% increase in the GSH/GSSG ratio. The activity of the hepatic antioxidant enzymes was not changed by either OFS or DEX supplementation. OFS supplementation caused a decrease in serum levels of triglycerides (36%), cholesterol (24%), HDL (16%) and LDL (17%). DEX supplementation only reduced triglycerides (32%) and urea (22%). Both diets increased serum levels of acetate by fivefold and propionate by twofold, but DEX diet decreased butyrate levels by 75%. Due to their different composition/structure these two dietary fibers affected metabolism in different ways. Diet supplementation with 10% DEX can potentially improve host health, by protecting the liver from protein carbonylation and by improving GSH/GSSG ratio and diet supplementation with 10% OFS can improve the lipid profile.

Age-related changes in the renal dopaminergic system and expression of renal amino acid transporters in WKY and SHR rats.

This study examined age-related changes in renal dopaminergic activity and expression of amino acid transporters potentially involved in renal tubular uptake of l-DOPA in Wistar Kyoto (WKY) and spontaneously hypertensive rats. Aging (from 13 to 91 weeks) was accompanied by increases in systolic blood pressure (SBP) in both WKY and SHR. The sum of urinary dopamine and DOPAC and the urinary dopamine/l-DOPA ratio were increased in aged SHR but not in aged WKY. The urinary dopamine/renal delivery of l-DOPA ratio was increased in both rat strains with aging. LAT2 abundance was increased in aged WKY and SHR. The expression of 4F2hc was markedly elevated in aged SHR but not in aged WKY. ASCT2 was upregulated in both aged WKY and SHR. Plasma aldosterone levels and urinary noradrenaline levels were increased in aged WKY and SHR though levels of both entities were more elevated in aged SHR. Activation of the renal dopaminergic system is more pronounced in aged SHR than in aged WKY and is associated with an upregulation of renal cortical ASCT2 in WKY and of LAT2/4F2hc and ASCT2 in SHR. This activation may be the consequence of a counter-regulatory mechanism for stimuli leading to sodium reabsorption.

α2-Adrenoceptor-mediated inhibition of catecholamine release from the adrenal medulla of spontaneously hypertensive rats is preserved in the early stages of hypertension.

In this study, we evaluated the effect of α(2) -adrenoceptor activation on catecholamine release from the adrenal medulla of pre-hypertensive (6-week-old) and hypertensive (16-week-old) spontaneously hypertensive rats (SHR) and of age-matched normotensive control Wistar Kyoto (WKY) rats. Catecholamine overflow from isolated adrenal medullae was evoked by the nicotinic receptor agonist 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP) in the absence and presence of the α(2) -adrenoceptor agonist medetomidine (MED). The spontaneous outflow of adrenaline was similar between age-matched SHR and WKY rats. However, the spontaneous outflow of noradrenaline was significantly lower in SHR compared with age-matched WKY rats. DMPP (0.1-3 mM) increased the outflow of noradrenaline and adrenaline in a concentration-dependent manner. The E(max) values for adrenaline overflow were similar between strains, but the E(max) values for noradrenaline overflow were significantly lower in SHR. The EC(50) values for noradrenaline and adrenaline overflow were significantly higher in SHR compared with age-matched WKY rats. MED (0.1-300 nM) reduced the DMPP-evoked overflow (DMPP 500 µM) of noradrenaline and adrenaline in a concentration-dependent manner and was capable of totally inhibiting this effect. The inhibitory action of MED was similar between age-matched SHR and WKY rats. In the adrenals, the α(2A)- and α(2B)-adrenoceptor subtypes had the highest mRNA expression levels; the α(2C)-adrenoceptor subtype had the lowest mRNA expression levels. The mRNA levels for the three subtypes were similar between strains. In conclusion, in SHR during the development of hypertension, adrenal α(2) -adrenoceptor inhibitory function is conserved, accompanied by reduced noradrenaline release and unchanged adrenaline release.