Efficacy of early use of remdesivir: a systematic review of subgroup analysis.

OBJECTIVE: A possible benefit has been suggested for early treatment of severe coronavirus disease 2019 (COVID-19) with remdesivir. The efficacy of this drug is controversial and could significantly influence the efficiency in healthcare systems. The objective is the methodological interpretation of subgroup analyzes according to starting of remdesivir treatment with respect to symptom onset of COVID-19. METHODS: A search in Pubmed® database was performed. Randomized clinical trials (RCTs) with subgroup analysis regarding early and late use of remdesivir were selected. All endpoints were assessed using two methodologies. First methodology considered statistical interaction, pre-specification, biological plausibility, and consistency of results. Second methodology was a validated tool with preliminary questions to discard subset analysis without relevant minimum conditions, and a checklist with recommendations for applicability. RESULTS: A total of 54 results were found and five RCTs were selected. According first methodology, consistent heterogeneity was only found in time to clinical improvement and better clinical status score at day 15 for patients with severe COVID-19 and <7 days of symptoms. About second methodology, these results about early use of remdesivir may be applied to clinical practice with caution. CONCLUSIONS: We developed a systematic search and application of an established methodology for interpretation of subgroup analysis about early use of remdesivir. Results in severe COVID-19 suggested that early use of remdesivir provides a greater benefit in <7 days of symptoms for time to clinical improvement and better clinical status score at day 15. Future studies could use 7-day cut-off of symptoms to evaluate remdesivir.

Impact of a multidisciplinary medication reconciliation program on clinical outcomes: A pre-post intervention study in surgical patients.

BACKGROUND: Previous studies have evaluated the effects of medication reconciliation (MR) and suggest that it is effective in decreasing medication discrepancies. Nevertheless, a recent overview of systematic reviews concluded that there is no clear evidence in favor of MR in patient-related outcomes and healthcare utilization, and further research about it is needed. OBJECTIVE: To evaluate the impact of a multidisciplinary MR program on clinical outcomes in patients with colorectal cancer presenting other chronic diseases, undergoing elective colorectal surgery. METHODS: We performed a pre-post study. Adult patients scheduled for elective colorectal cancer surgery were included if they presented at least one "high-risk" criteria. The MR program was developed by internists, pharmacists and surgeons, and ended with the obtention of the patient's pre-admission medication list and follow-up care until discharge. The primary outcome was the length of stay (LOS). Secondly, we evaluated mortality, preventable surgery cancellations and risk factors for complications. RESULTS: Three hundred and eight patients were enrolled. Only one patient in the pre-intervention group suffered a preventable surgery cancellation (p = 0.317). The mean LOS was 13 ± 12 vs. 11 ± 5 days in the pre-intervention and the intervention cohort, respectively (p = 0.435). A difference in favor of the intervention group in patients with cardiovascular disease (p = 0.038) and those >75 years old (p = 0.043) was observed. No difference was detected in the mortality rate (p = 0.999) neither most of the indicators of risk factors for complications. However, the management of preoperative systolic blood pressure of hypertensive patients (p = 0.004) and insulin reconciliation in patients with treated diabetes (p = 0.003) were statistically better in the intervention group. CONCLUSIONS: No statistically significant change was observed in the mean global LOS. A statistically significant positive effect on LOS was observed in vulnerable populations: patients >75 years old and those with cardiovascular disease, who presented a 5-day reduction in the mean LOS.

Dietary oleuropein and its acyl derivative ameliorate inflammatory response in peritoneal macrophages from pristane-induced SLE mice via canonical and noncanonical NLRP3 inflammasomes pathway.

Systemic lupus erythematosus (SLE) is a multifactorial autoimmune disease without an effective and safe treatment. Besides, macrophages are the major components of the innate immune system and play a critical role in the inflammation process in SLE. Secoiridoids from olive tree are phenolic compounds which have shown important pharmacological effects. Particularly, oleuropein (OL) has shown antioxidant, anti-inflammatory and immunomodulatory properties suggesting a potential application in a large number of inflammatory and reactive oxygen species (ROS)-mediated diseases. In addition, different studies have shown the importance of acyl derivatives of natural phenols due to their better hydrophilic/lipophilic balance.

Impact of medication reconciliation on health outcomes: An overview of systematic reviews.

BACKGROUND: Recent systematic reviews and meta-analyses suggest that medication reconciliation (MR) is effective in decreasing the risk of medication discrepancies. Nevertheless, the association between MR and subsequent improved healthcare outcomes is not well established. OBJECTIVES: This systematic review of reviews set out to identify published systematic reviews on the impact of MR programs on health outcomes and to describe key components of the intervention, the health outcomes assessed and any associations between MR and health outcomes. METHODS: PubMed, EMBASE, Cochrane Library, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and SCOPUS were searched from inception to May 2019. Systematic reviews of all study designs, populations, intervention providers and settings that measured patient-related outcomes or healthcare utilization were considered. Methodological quality was assessed using A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2). Two investigators performed study selection, quality assessment and data collection independently. RESULTS: Five systematic reviews met the inclusion criteria: 2 were rated as low quality and 3 as critically low quality. Reviews included primary studies in different settings (hospitals, the community and residential aged care facilities) that reported the impact of MR on mortality, length of stay, Emergency Department (ED) visits, readmissions, physician visits and healthcare utilization. Only one review reported results on mortality. However, healthcare utilization, which usually included ED visits and readmissions, was communicated in all reviews. Meta-analyses were conducted in all reviews except one. Medication reconciliation was not consistently found to be associated with improvements in health outcomes. CONCLUSIONS: Few systematic reviews support the value of MR in achieving good patient-related outcomes and healthcare utilization improvements. The quality of the systematic reviews was low and the primary studies included commonly involved additional activities related to MR. There was no clear evidence in favor of intervention in mortality, length of stay, ED visits, unplanned readmissions, physician visits and healthcare utilization.

Dietary oleuropein and its new acyl-derivate attenuate murine lupus nephritis through HO-1/Nrf2 activation and suppressing JAK/STAT, NF-κB, MAPK and NLRP3 inflammasome signaling pathways.

Systemic lupus erythemathosus (SLE) is a chronic inflammatory and autoimmune disease which can affect multiple organ systems, without an effective and safe treatment. Olive leaf extracts are of special interest for their therapeutic effects. Oleuropein (OL) is the most abundant constituents of olive leaf extract and possesses many beneficial properties. In this study, we evaluated the effects of dietary OL and its new derivate, peracetylated oleuropein (Per-OL), in a pristane-induced SLE model. Mice received an injection of pristane or saline solution and were fed with experimental diets: enriched with OL and Per-OL. The levels of proinflammatory cytokines and markers were evaluated by enzyme-linked immunosorbent assay. The protein expressions of inducible nitric oxide synthase, microsomal prostaglandin E synthase 1, heme oxygenase (HO-1), nuclear factor E2-related factor 2 (Nrf2), mitogen-activated protein kinases (MAPKs), Janus kinase/signal transducer and activator of transcription (JAK/STAT), nuclear transcription factor-kappa B (NF-κB) and inflammasome nucleotide-binding domain, leucine-rich repeats-containing family, pyrin domain-containing-3 (NLRP3) pathways activation were determined in kidneys by Western blot. OL and Per-OL significantly reduced renal damage and decreased serum matrix metalloproteinase 3 and prostaglandine E2 kidneys levels. Our findings indicate that Nrf2 and HO-1 antioxidant protein expressions were up-regulated in mice fed with OL and Per-OL diets, whereas the activation of JAK/STAT, MAPK, NF-κB and NLRP3 inflammasome pathways was significantly ameliorated. These results suggest that OL and Per-OL supplementation might provide a new alternative approach as a preventive/palliative treatment of nephritis in SLE management.

Rosiglitazone, an agonist of peroxisome proliferator-activated receptor gamma, reduces chronic colonic inflammation in rats.

Recent studies have shown the implication of the peroxisome proliferator-activated receptor gamma (PPARgamma) in control of inflammation, immune and apoptotic responses during early experimental colitis. However, there is little information about the effects of these agents on colonic mucosa under chronic inflammatory conditions. In this study, we have evaluated the effects of rosiglitazone, a PPAR-gamma agonist, on the chronic injury caused by intra-colonic administration of trinitrobenzensulfonic acid (TNBS) in rats. Rosiglitazone (1 and 5mg/kg p.o.) was administered by oral gavage, 24h after TNBS instillation and daily during 2 weeks before killing the rats. Colons were removed for histological and biochemical analysis. Administration of rosiglitazone corrected the disorders in morphology associated to lesions, significantly reduced the ulceration index, the rise of myeloperoxidase (MPO) and the levels of tumour necrosis factor alpha (TNF-alpha). In addition, rosiglitazone treatment increased prostaglandin (PG)E(2) production and returned PGD(2) to basal levels. Also, reduced cyclooxygenase (COX)-2 and nuclear transcription factor NF-kappa B (NF-kappaB) p65 proteins expression. Furthermore, treatment of rats with rosiglitazone caused a significant increase of TNBS-induced apoptosis. In summary, rosiglitazone exerts protective effects in chronic experimental colitis. The anti-inflammatory effects seem to be related to impairment of neutrophil function, absence of up-regulation of TNF-alpha and decrease of nuclear NF-kappaB p65 expression. Our results also suggest that the activation of the PPARgamma pathway reduces COX-2 overexpression, returns the increased PGD(2) values to basal levels and induces a significant increase of TNBS-induced apoptosis. We conclude that rosiglitazone represents a novel approach to the treatment of ulcerative colitis.

Comparative study of the neuroprotective effect of dehydroepiandrosterone and 17beta-estradiol against 1-methyl-4-phenylpyridium toxicity on rat striatum.

The effects of dehydroepiandrosterone, estradiol and testosterone on 1-methyl-4-phenylpyridium (MPP+)-induced neurotoxicity of the nigrostriatal dopaminergic system were examined in rat. They were subjected to a unilateral intrastriatal infusion of the following treatment conditions: MPP+ alone or co-injection of MPP+ plus each hormone. Four days after injection, concentrations of dopamine and their metabolites were determined from the corpus striatum. To corroborate the neurochemical data an immunohistochemical analysis of tyrosine hydroxylase-immunoreactive fibers and acetylcholinesterase histochemistry in the striatum was performed. Moreover, we performed a dose-response study of the three hormones on the high-affinity dopamine transport system in rat striatal synaptosomes. Rats co-injected within the striatum with MPP+ and either dehydroepiandrosterone or estradiol had significantly greater concentrations of dopamine and less tyrosine hydroxylase-immunoreactive fibers and acetylcholinesterase fiber density loss compared with their respective controls. In addition, 4 days after injection, the brain was fixed and cut into coronal sections, and was immunostained with major histocompatibility complex class II antigens for activated microglia, and glial fibrillary acidic protein for activated astrocytes. Dehydroepiandrosterone also attenuated microglial cell activation. In contrast, testosterone showed reductions in dopamine concentrations similar to those obtained by MPP+. The protective effect of dehydroepiandrosterone against the MPP+ neurotoxic dopaminergic system may be produced by its partial prevention of MPP+ inhibition of NADH oxidase activity, whereas the estradiol may function as a neuroprotectant by reducing the uptake of MPP+ into dopaminergic neurons. Our findings we suggest indicate that dehydroepiandrosterone and estradiol by a non-genomic effect may have an important modulatory action, capable of attenuating degeneration within the striatum, and in this way serve as neuroprotectants of the nigrostriatal dopaminergic system.

Melatonin modulates microsomal PGE synthase 1 and NF-E2-related factor-2-regulated antioxidant enzyme expression in LPS-induced murine peritoneal macrophages.

BACKGROUND AND PURPOSE: Increasing evidence demonstrates that melatonin regulates inflammatory and immune processes acting as both an activator and inhibitor of these responses. Nevertheless, the molecular mechanisms of its anti-inflammatory action remain unclear. Here we have characterized the cellular mechanisms underlying the redox modulation of LPS-stimulated inflammatory responses in murine peritoneal macrophages by melatonin to provide insight into its anti-inflammatory effects. EXPERIMENTAL APPROACH: Murine peritoneal macrophages were isolated and treated with melatonin in the presence or absence of LPS (5 µg·mL(-1) ) for 18 h. Cell viability was determined using sulforhodamine B assay and NO production was measured using the Griess reaction. Pro-inflammatory enzymes and transcription factors were detected by Western blotting. KEY RESULTS: Without affecting cell viability, melatonin (12.5, 25, 50 and 100 µM) reduced the level of nitrites, inducible NOS (iNOS), COX-2 and microsomal PGE synthase-1 (mPGES1) protein, and p38 MAPK phosphorylation, and prevented NF-κB translocation. Furthermore, melatonin treatment significantly increased NF-E2-related factor 2 (Nrf2) and haem oxygenase 1 (HO1) protein levels in murine macrophages exposed to LPS. CONCLUSIONS AND IMPLICATIONS: Melatonin reduced pro-inflammatory mediators and enhanced the expression of HO1 via NF-κB, p38 MAPK and Nrf2 cascade signalling pathways in murine macrophages. Thus, melatonin might be a promising target for diseases associated with overactivation of macrophages.

Extra virgin olive oil polyphenolic extracts downregulate inflammatory responses in LPS-activated murine peritoneal macrophages suppressing NFκB and MAPK signalling pathways.

Extra virgin olive oil (EVOO) is obtained from the fruit of the olive tree Olea europaea L. Phenolic compounds present in EVOO have recognized anti-oxidant and anti-inflammatory properties. However, the activity of the total phenolic fraction extracted from EVOO and the action mechanisms involved are not well defined. The present study was designed to evaluate the potential anti-inflammatory mechanisms of the polyphenolic extract (PE) from EVOO on LPS-stimulated peritoneal murine macrophages. Nitric oxide (NO) production was analyzed by the Griess method and intracellular reactive oxygen species (ROS) by fluorescence analysis. Moreover, changes in the protein expression of the pro-inflammatory enzymes, inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2 and microsomal prostaglandin E synthase-1 (mPGES-1), as well as the role of nuclear transcription factor kappa B (NFκB) and mitogen-activated protein kinase (MAPK) signalling pathways, were analyzed by Western blot. PE from EVOO reduced LPS-induced oxidative stress and inflammatory responses through decreasing NO and ROS generation. In addition, PE induced a significant down-regulation of iNOS, COX-2 and mPGES-1 protein expressions, reduced MAPK phosphorylation and prevented the nuclear NFκB translocation. This study establishes that PE from EVOO possesses anti-inflammatory activities on LPS-stimulated murine macrophages.

The unsaponifiable fraction of extra virgin olive oil promotes apoptosis and attenuates activation and homing properties of T cells from patients with inflammatory bowel disease.

The unsaponifiable fraction (UF) of extra virgin olive oil (EVOO) possesses anti-inflammatory properties and exerts preventative effects in murine models of inflammatory bowel disease (IBD). The present study was designed to determine the in vitro effects of UF on blood and intestinal T cells from IBD patients and healthy subjects. The T cell phenotype was investigated by flow cytometry and cytokine secretion was determined by ELISA. The presence of UF of EVOO promoted apoptosis and attenuated activation of intestinal and blood T cells isolated from IBD patients, decreasing the frequency of CD69(+) and CD25(+) T cells and, also, the secretion of IFN-γ. Moreover, UF reduced the expression of the gut homing receptor integrin ß7 on blood T cells from IBD patients. In conclusion, UF modulates the activity and the gut homing capacity of T cells, and might therefore be considered as a dietary complement with an anti-inflammatory role in IBD patients.

An up-date of olive oil phenols in inflammation and cancer: molecular mechanisms and clinical implications.

Olive oil (OO), the main fatty component of the Mediterranean diet, exhibits numerous biological functions which are beneficial for the state of health. In addition to monounsaturated fatty acid (MUFA) evidences have accumulated on the favorable properties of its minor though highly bioactive components, particularly the phenolic compounds, which have shown a broad spectrum of bioactive properties, including antioxidant and anti-inflammatory effects both associated with the origin of the main chronic diseases. Additional studies have demonstrated that the health effects of olive oil polyphenols have been also associated with their, neuroprotective, antiaging and antiatherogenic effects. On the other hand, because of their ability to modulate cell death, olive polyphenols have been proposed as chemopreventive and therapeutic agents. Thus, the purpose of this article is to review the chemistry, bioavailability and pharmacokinetic characteristics of OO polyphenols, in addition to provide the reader an up-date of their putative antioxidant, anti-inflammatory and anti-cancer activities as well as the plausible action mechanisms involved.

Dietary unsaponifiable fraction from extra virgin olive oil supplementation attenuates acute ulcerative colitis in mice.

Extra virgin olive oil (EVOO) has demonstrated immunomodulatory and antiinflammatory properties in murine experimental ulcerative colitis (UC). In addition to its high monounsaturated fatty acid content, evidences have accumulated on the favorable properties of minor, although highly bioactive, components present in the unsaponifiable fraction (UF). The present study was designed to evaluate the effects of dietary EVOO's UF supplementation on acute UC. C57BL/6 mice were fed from weaning with sunflower oil (SD), EVOO diet and UF-enriched SD at 5% oil (SD+UF). After 30 days, mice were exposed to 3% dextran sulfate sodium (DSS) for 5 days developing acute colitis. After 4 days of DSS removal, animals were sacrificed and colons were histological and biochemically processed. Disease activity index and microscopic damage score were significantly improved in EVOO and SD+UF dietary groups versus SD group. In addition, both dietary treatments significantly induced decreases in MCP-1 and TNF-α levels, iNOS and COX-2 overexpression and p38 MAPKs activation in colon mucosa. Moreover, an upregulation of IκB expression was also observed after feeding the animals with both diets. However, no statistically differences between data from mice fed with EVOO or UF+SD diets were observed. Dietary enrichment with EVOO's UF reduces the damage in acute colitis model, alleviating the oxidative events and returning proinflammatory proteins expression to basal levels probably through p38 MAPK and NFκB signalling pathways. EVOO's UF diet might provide a basis for developing a new strategy in dietary supplementation for the prevention of UC.

Sirtuin modulators: mechanisms and potential clinical implications.

In the last years, studies about longevity have highlighted that caloric restriction can be linked with a less normal agingassociated damage, and in the same way, with the activity of the Silent Information Regulator 2 (SIR2) gene. Sir2-like genes, known as sirtuins (SIRTs), have been found in organisms ranging from bacteria to mammals promoting health and survival. At the moment, it has been identified seven classes of SIRTs in mammalian and the understanding of many of them remains still rudimentary. However, they are in the spotlight by their potential protection against aging-associated diseases and have emerged as key mediators of longevity in evolutionarily distant organisms models. SIRTs are proteins found in numerous compartments within the cell, which are NAD(+)-dependent protein deacetylases and adenosine diphosphate (ADP)-ribosyltransferases. They catalyse a reaction in which NAD(+) and an acetylated substrate are converted into a deacetylated substrate, nicotinamide and a novel metabolite O-acetyl ADP ribose. Therefore, its enzymatic activity requires NAD(+), which is a crucial molecule intermediary of many metabolic reactions in cells. Basically, SIRTs are mediators of aging process, they have the potential of ameliorating and taking part in important cellular processes associated, such as metabolic homeostasis, tumorigenesis and cancer cell proliferation, inflammatory disorders, cardiovascular diseases and neurodegeneration. This background opens up new lines of investigation into the modulation of SIRTs activity in order to develop novel therapeutic targets to these age-related diseases. Current experiments using molecule activators or inhibitors and genetically engineered animals have facilitated new insights into the role of these enzymes and contributed to highlight some of the potentially relevant targets. This review is intended to provide an appreciation of the possible protection against aging-associated diseases by these enzymes, summarize novel underlying mechanisms and evaluate potential clinical applications.

Melatonin, a natural programmed cell death inducer in cancer.

Melatonin, an indolamine derived from the amino-acid tryptophan, participates in diverse physiological functions and has great functional versatility related to the regulation of circadian rhythms and seasonal behaviour, sexual development, retinal physiology, tumour inhibition, as an antioxidant, immunomodulatory and anti-aging properties. In relation to its oncostatic properties, there is evidence that tumor initiation, promotion or progression may be restrained by the night-time physiological surge of melatonin in the blood or extracellular fluid. In addition, depressed nocturnal melatonin concentrations or nocturnal excretion of the main melatonin metabolite, 6-sulfatoxymelatonin, were found in individuals with various tumor types. In the majority of studies, melatonin was shown to inhibit development and/or growth of various experimental animal tumors and some human cell lines in vitro. Many tumors do not respond to drug treatment due to their resistance to undergo apoptosis thereby contributing to the development of cancer. Thus, given the importance of the apoptotic program in cancer treatment, the role of melatonin in influencing apoptosis in tumor cells attracted attention because it seems that it actually promotes apoptosis in most tumor cells, in contrast to the obvious inhibition of apoptotic processes in normal cells. Thus, this paper is also intended to provide to the reader an up-date of all the researches that have been carried out to date, which investigate the proapoptotic effects of melatonin in experimental preclinical models of cancer (in vitro and in vivo) and the underlying proposed action mechanism of this effects. If melatonin uniformly induces apoptosis in cancer cells, the findings could have important clinical implications to improve the quality of live while preventing the appearance of cancer.

Protective effect of ellagic acid, a natural polyphenolic compound, in a murine model of Crohn's disease.

Current epidemiological and experimental studies support a beneficial role of dietary polyphenols in several gastrointestinal diseases, including inflammatory bowel disease. The aim of this study was to gain a better understanding of the effects of a naturally occurring polyphenol, ellagic acid, present in some fruits such as pomegranate, raspberries and nuts among others, in an experimental murine model of Crohn's disease by intra-colonic administration of TNBS in rats. Analysis of the lesions were carried out by macroscopic and histological technics. Inflammation response was assessed by histology and myeloperoxidase activity. iNOS and COX-2 are upregulated by MAPKs and NF-κB nuclear transcription factor in intestinal epithelial cells thus, we determined the expression of iNOS, COX-2 and the involvement of the p38, JNK, ERK1/2 MAPKs and NF-κB signalling in the protective effect of EA by western blotting. Oral administration of EA (10-20 mg/kg) diminished the severity and extension of the intestinal injuries induced by TNBS although there was no observed a significant dose-response. In addition, EA increased mucus production in goblet cells in colon mucosa, decreased neutrophil infiltration and pro-inflammatory proteins COX-2 and iNOS overexpression. Also EA was capable of reducing the activation of p38, JNK and ERK1/2 MAPKs, preventing the inhibitory protein IκB-degradation and inducing an inhibition of the nuclear translocation level of p65 in colonic mucosa. In conclusion, EA reduces the damage in a rat model of Crohn's disease, alleviates the oxidative events and returns pro-inflammatory proteins expression to basal levels probably through MAPKs and NF-κB signalling pathways.

Extra-virgin olive oil-enriched diet modulates DSS-colitis-associated colon carcinogenesis in mice.

BACKGROUND & AIMS: Patients with inflammatory bowel disease (IBD) are at increased risk for developing ulcerative colitis (UC)-associated colorectal cancer (CRC). Several studies have shown that extra virgin olive oil (EVOO) might possess anti-inflammatory, antiproliferative and antiapoptotic effects. We have evaluated EVOO diet effects on the severity of repeated colitis-associated CRC. METHODS: Six-week-old C57BL/6 mice were randomized into two dietary groups: sunflower oil (SFO) and EVOO diets, both at 10%. Mice were exposed to 15 cycles of 0.7% dextran sodium sulphate (DSS) for 1 week followed by distilled water for 10 days. After, the rats were sacrificed and colonic damage was both histologically and biochemically assessed. RESULTS: Disease activity index (DAI) was significantly higher on SFO vs. EVOO diet at the end of the experimental period. EVOO-fed mice showed less incidence and multiplicity of tumors than in those SFO-fed mice. ß-catenin immunostaining was limited to cell membranes in control groups, whereas translocation from the cell membrane to the cytoplasm and/or nucleus was showed in DSS-treated groups and its expression was higher in SFO-fed animals. Cytokine production was significantly enhanced in SFO-fed mice, while this increase was not significant in EVOO-fed mice. Conversely, cyclooxygenase-2 (COX-2) and inducible nitric oxidase synthase (iNOS) expression were significantly lower in the animal group fed with EVOO than in the SFO group. CONCLUSIONS: These results confirm that EVOO diet has protective/preventive effect in the UC-associated CRC. This beneficial effect was correlated with a better DAI, a minor number of dysplastic lesions, a lower ß-catenin immunoreactivity, a proinflammatory cytokine levels reduction, a non modification of p53 expression and, COX-2 and iNOS reduction in the colonic tissue.

Age-related changes in melatonin synthesis in rat extrapineal tissues.

In the search of new therapeutic targets improving the quality of life of elderly, melatonin, "the chemical expression of darkness", seems to play a remarkable role in aging process possibly due to its antioxidant, immunoenhancer and anti-aging properties. The present study was designed to elucidate effects of aging in melatonin extrapineal synthesis and investigate evident age-related alterations in the action mechanisms involved. The presence of the two key enzymes involved in melatonin synthesis, arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT) was analyzed in thymus, spleen, liver, kidney and heart of 3- and 12month-old rats using real time PCR as well as its functionality by enzymatic activity assays. In addition, extrapineal melatonin content was measured by a competitive enzyme immunoassay (ELISA). The results of this study reveal that all rat tissues studied including thymus, and for the first time, spleen, liver, kidney and heart have the necessary machinery to synthesize melatonin. Moreover, we report an age-related decline in rat extrapineal melatonin synthesis with a consequent HIOMT functionality decrease in spleen, liver and heart during physiological aging. On the contrary, NAT enzymatic activity maintains unchanged without evident alterations with advancing age. Moreover, diminished melatonin concentrations were measured in these tissues cited above during aging except in the thymus, where, surprisingly, melatonin content, NAT/HIOMT expression, and enzymatic functionality assays revealed no significant alterations with age. As a conclusion, we report evident age-related changes in melatonin synthesis in some rat peripheral organs. We suggest that thymus may develop compensatory mechanisms to counteract the loss of immune activity and consequently, the loss of this potent antioxidant, during physiological aging.

Melatonin inhibits fatty acid-induced triglyceride accumulation in ROS17/2.8 cells: implications for osteoblast differentiation and osteoporosis.

Melatonin is produced not only by the pineal gland but by cells of the bone marrow. Moreover, melatonin is known to promote osteogenic differentiation in several cell line models and in multipotential bone marrow mesenchymal stem cells. Fatty acids have been independently shown to direct such cells to acquire the phenotype and molecular characteristics of adipocytes. To examine the effect of melatonin on intracellular triglyceride accumulation, an indicator of adipogenic differentiation in the rat osteoblast-like ROS17/2.8 cell line, cells were incubated with added oleic acid (100 muM), fixed and stained with Oil Red O. Cellular lipid accumulation was quantitated by an Oil Red O method highly specific for triglycerides and expressed as a triglyceride accumulation index (TGAI, triglyceride per cell). Melatonin in nanomolar concentrations inhibited oleic acid-induced triglyceride accumulation. To identify the mechanism by which melatonin reduces triglyceride accumulation, cells were incubated with the two melatonin receptor antagonists, luzindole and S20928, or forskolin, a stimulator of adenylyl cyclase and cAMP production. These compounds prevented the inhibitory effect of melatonin on triglyceride accumulation, indicating that melatonin acts through known melatonin receptor-mediated mechanisms. In view of the previously demonstrated positive effects of melatonin in promoting osteoblastic differentiation in ROS17/2.8 cells and their reciprocal adipocytic differentiation induced by fatty acids, our observations may serve to relate the known age-related decreases of melatonin production, the shift in the bone marrow toward an adipocytic line of cell development, and the development of osteoporosis during aging.