Low Dose of BPA Induces Liver Injury through Oxidative Stress, Inflammation and Apoptosis in Long-Evans Lactating Rats and Its Perinatal Effect on Female PND6 Offspring.

Bisphenol A (BPA) is a phenolic compound used in plastics elaboration for food protection or packaging. BPA-monomers can be released into the food chain, resulting in continuous and ubiquitous low-dose human exposure. This exposure during prenatal development is especially critical and could lead to alterations in ontogeny of tissues increasing the risk of developing diseases in adulthood. The aim was to evaluate whether BPA administration (0.036 mg/kg b.w./day and 3.42 mg/kg b.w./day) to pregnant rats could induce liver injury by generating oxidative stress, inflammation and apoptosis, and whether these effects may be observed in female postnatal day-6 (PND6) offspring. Antioxidant enzymes (CAT, SOD, GR, GPx and GST), glutathione system (GSH/GSSG) and lipid-DNA damage markers (MDA, LPO, NO, 8-OHdG) were measured using colorimetric methods. Inducers of oxidative stress (HO-1d, iNOS, eNOS), inflammation (IL-1ß) and apoptosis (AIF, BAX, Bcl-2 and BCL-XL) were measured by qRT-PCR and Western blotting in liver of lactating dams and offspring. Hepatic serum markers and histology were performed. Low dose of BPA caused liver injury in lactating dams and had a perinatal effect in female PND6 offspring by increasing oxidative stress levels, triggering an inflammatory response and apoptosis pathways in the organ responsible for detoxification of this endocrine disruptor.

Activation of NLRP3 Inflammasome in Liver of Long Evans Lactating Rats and Its Perinatal Effects in the Offspring after Bisphenol F Exposure.

The liver is the organ responsible for the metabolism and detoxification of BPF, the BPA analogue that is replacing it in plastic-based products. It is not known whether BPF can trigger inflammatory responses via the NLRP3 inflammasome, which plays a major role in the development of liver disease. The aim of this study was to evaluate nitrosative stress species (RNS) and NLRP3 inflammasome activation in the liver of lactating dams after BPF exposure. Moreover, it was studied whether this effect could also be observed in the liver of female and male offspring at postnatal day 6 (PND6). 36 Long Evans rats were randomly distributed according to oral treatment into three groups: Control, BPF-low dose (LBPF; 0.0365 mg/kg b.w./day) group and BPF-high dose (HBPF; 3.65 mg/kg b.w./day) group. The levels of nitrosative stress-inducing proteins (eNOS, iNOS, HO-1d), NLRP3 inflammasome components (NLRP3, PyCARD, CASP1) and proinflammatory cytokines (IL-1ß, IL-18, IFN-γ and TNF-α) were measured by gene and protein expression in the liver of lactating dams and in female and male PND6 offspring. Lactating dams treated with LBPF showed a significant increase in iNOS and HO-1d, activation of NLRP3 components (NLRP3, PyCARD, CASP1) and promoted the release of proinflammatory cytokines such as IL-1ß, IL-18, IFN-γ and TNF-α. Similar effects were found in female and male PND6 offspring after perinatal exposure. LBPF oral administration and perinatal exposure caused an increase of nitrosative stress markers and proinflammatory cytokines. Also, NLRP3 inflammasome activation was significantly increased in in the liver of lactating dams and PND6 offspring.

Effects of GH on the Aging Process in Several Organs: Mechanisms of Action.

In order to investigate the possible beneficial effects of GH administration on the aging process, 24-month-old rats of both sexes and 10-month-old SAMP8 mice were used. Male rats showed increased fat content and decreased lean body mass together with enhanced vasoconstriction and reduced vasodilation of their aortic rings compared to young adult animals. Chronic GH treatment for 10 weeks increased lean body mass and reduced fat weight together with inducing an enhancement of the vasodilatory response by increasing eNOS and a reduction of the constrictory responses. Old SAMP8 male mice also showed insulin resistance together with a decrease in insulin production by the endocrine pancreas and a reduced expression of differentiation parameters. GH treatment decreased plasma levels and increased pancreatic production of insulin and restored differentiation parameters in these animals. Ovariectomy plus low calcium diet in rabbits induced osteoporosis Titanium implants inserted into these rabbit tibiae showed after one month lesser bone to implant (BIC) surface and bone mineral density (BMD). Local application of GH in the surgical opening was able to increase BIC in the osteoporotic group. The hippocampus of old rats showed a reduction in the number of neurons and also in neurogenesis compared to young ones, together with an increase of caspases and a reduction of Bcl-2. GH treatment was able to enhance significantly only the total number of neurons. In conclusion, GH treatment was able to show beneficial effects in old animals on all the different organs and metabolic functions studied.

Protective effects of 17-ß-oestradiol and phytoestrogen on age-induced oxidative stress and inhibition of surfactant synthesis in rat type II pneumocytes.

Epidemiological data suggest protective effects of oestrogen and phytoestrogen on lung tissue. This study aimed to elucidate the role of 17-ß-oestradiol and phytoestrogen in age-related inhibition of surfactant synthesis and oxidative stress in rat type II pneumocytes. Forty male and 66 female Wistar rats were used. Female rats were randomly kept intact or ovariectomized at age 12 months. At age 22 months, ovariectomized rats received 17-ß-oestradiol, soy extract, or no treatment. Oxidative stress markers CO, NO, cGMP and lipid peroxide (LPO), antioxidant enzymes and phosphatidylcholine (PC) were measured in cultured type II pneumocytes isolated at ages 2, 14, 18, 22 and 24 months. Old, male and ovariectomized rats showed significantly higher CO, NO, cGMP and LPO and lower PC content and antioxidant enzymes. 17-ß-oestradiol and phytoestrogen significantly reversed these effects. In conclusion, aging and oestrogen deprivation decreased PC synthesis and altered the redox status in type II pneumocytes, which were partially restored by 17-ß-oestradiol or soy supplementation.

Xanthohumol exerts protective effects in liver alterations associated with aging.

BACKGROUND AND AIMS: Aging is associated with a deregulation of biological systems that lead to an increase in oxidative stress, inflammation, and apoptosis, among other effects. Xanthohumol is the main preylated chalcone present in hops (Humulus lupulus L.) whose antioxidant, anti-inflammatory and chemopreventive properties have been shown in recent years. In the present study, the possible protective effects of xanthohumol on liver alterations associated with aging were evaluated. METHODS: Male young and old senescence-accelerated prone mice (SAMP8), aged 2 and 10 months, respectively, were divided into four groups: non-treated young, non-treated old, old treated with 1 mg/kg/day xanthohumol, and old treated with 5 mg/kg/day xanthohumol. Male senescence-accelerated resistant mice (SAMR1) were used as controls. After 30 days of treatment, animals were sacrificed and livers were collected. mRNA (AIF, BAD, BAX, Bcl-2, eNOS, HO-1, IL-1ß, NF-κB2, PCNA, sirtuin 1 and TNF-α) and protein expressions (BAD, BAX, AIF, caspase-3, Blc-2, eNOS, iNOS, TNF-α, IL1ß, NF-κB2, and IL10) were measured by RT-PCR and Western blotting, respectively. Mean values were analyzed using ANOVA. RESULTS: A significant increase in mRNA and protein levels of oxidative stress, pro-inflammatory and proliferative markers, as well as pro-apoptotic parameters was shown in old non-treated SAMP8 mice compared to the young SAMP8 group and SAMR1 mice. In general, age-related oxidative stress, inflammation and apoptosis were significantly decreased (p < 0.05) after XN treatment. In most cases, this effect was dose-dependent. CONCLUSIONS: XN was shown to modulate inflammation, apoptosis, and oxidative stress in aged livers, exerting a protective effect in hepatic alterations.

Comparison of the Effect of Melatonin Treatment before and after Brain Ischemic Injury in the Inflammatory and Apoptotic Response in Aged Rats.

Aging is associated with an increase in stroke risk. Melatonin, a potent free radical scavenger and broad spectrum antioxidant, has been shown to counteract inflammation and apoptosis in brain injury. However, little is known on the possible protective effects of melatonin in aged individuals affected by brain ischemia. Also, using melatonin before or after an ischemic stroke may result in significantly different molecular outcomes. The objective of the present study was to compare the effects of pre-ischemia vs. post-ischemia melatonin administration in an ischemic lesion in the cortex and hippocampus of senescent Wistar rats. An obstruction of the middle cerebral artery (MCA) to 18-month-old animals was performed. In general, animals treated with melatonin from 24 h prior to surgery until 7 days after the surgical procedure (PrevT) experienced a significant decrease in the levels of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), glial fibrillary acidic protein (GFAP), Bcl-2-associated death promoter (BAD), and Bcl-2-associated X protein (BAX) in both cortex and hippocampus, while hippocampal levels of sirtuin 1 (SIRT1) and B-cell lymphoma 2 (Bcl-2) increased. Treatment of animals with melatonin only after surgery (AT) resulted in similar effects, but to a lesser extent than in the PrevT group. In any case, melatonin acted as a valuable therapeutic agent protecting aged animals from the harmful effects of cerebral infarction.

Chemokine Involvement in Lung Injury Secondary to Ischaemia/Reperfusion.

INTRODUCTION: During transplant surgeries, the lung experiences an ischaemia-reperfusion (I/R)-induced damage identified as a significant cause of morbidity and mortality. However, the mechanisms by which I/R induces leucocyte accumulation and subsequent tissue damage in lung surgeries remain unknown. Therefore, the present study aims to assess the role of monocyte chemotactic protein 1 (MCP-1) and macrophage inflammatory protein 2 (MIP-2) in leucocyte chemotaxis related to lung injury secondary to I/R. METHODS: Six pigs were subjected to an orthotopic left caudal lobe lung transplantation with a subsequent 60-min graft reperfusion (Transplant group). In addition, six animals underwent to sham surgery (Sham Group). Plasma samples and lung biopsies were collected before the beginning of pneumonectomy, before starting the reperfusion, and 30 min and 60 min after the beginning of the reperfusion. Plasma levels of intercellular adhesion molecule 1 (ICAM-1) and lung expressions of MCP-1, MIP-2, myeloperoxidase (MPO), and lung oedema were measured. RESULTS: Lung I/R caused substantial damage observed as pulmonary oedema. The oedema was evident after the ischemic insult and increased after reperfusion. After reperfusion, increased levels of MPO were observed which suggests an activation and infiltration of neutrophils into the lung tissue. After 30 min of reperfusion, MCP-1, MIP-2, and ICAM-1 levels were significantly increased compared to prepneumonectomy levels (p < 0.05) and a further increase was observed after 60 min of reperfusion (p < 0.05). CONCLUSION: The present study demonstrates that activated neutrophils, as well as MCP-1, MIP-2, and ICAM-1, are involved in inflammatory response induced by ischaemia-reperfusion-induced lung injury.

Self-perception of the acquisition of transferable competencies by the participants in a research congress for undergraduate students: A cross-sectional study.

Context: Several curricular initiatives have been developed to improve the acquisition of research competencies by Health Science students. Objectives: To know how students self-perceived of whether their participation in the XIV National Research Congress for Undergraduate Students of Health Sciences had helped them in the acquisition of 36 research-related transferable competencies (TCs) common to Health Science degrees. Methods: A survey design (Cronbach's alpha = 0.924), using a self-administered questionnaire, was conducted among undergraduate students who voluntarily participated in the Congress. Data analysis was performed using SPSS 25 and Statgraphics 19. Statistical significance was considered for P < 0.05. Results: Eighty-one students from 12 Health Science degree programs responded. Key findings are presented in a structured manner, using a Likert-5 scale. Twenty-five of the competencies surveyed obtained an average ≥ 4 highlighting: "Critically evaluate and know how to use sources of clinical and biomedical information to obtain, organize, interpret, and communicate scientific and health information"; "To be able to formulate hypotheses, collect and critically evaluate information for problem solving, following the scientific method", "Critical analysis and research" and "Communicate effectively and clearly, orally and in writing with other professionals". Significance was found in 15 competencies. The development of the competencies "Teamwork", "Critical reasoning" and "Analysis and synthesis abilities" was considered to be of greater "personal utility" by the respondents. Conclusion: Participation in this event contributed to the development of research-related TCs, critical analysis and information management and communication, especially in relation to learning the sources of clinical and biomedical information, to know, following the scientific method, how to formulate hypotheses that allow students to solve problems in their professional activity. The experience was significantly influenced by the respondents' year, the type of participation in the event and the gender of the students. Limitations and suggestions regarding future research are discussed to encourage further exploration of the topic.

Anti-inflammatory effects of melatonin in a rat model of caerulein-induced acute pancreatitis.

The purpose of our study was to evaluate the protective effect of melatonin in a rat model of caerulein-induced acute pancreatitis. For the induction of experimental acute pancreatitis, four subcutaneous injections of caerulein (20 mgkg­1 body weight) were given to Wistar rats at 2-h intervals. Melatonin was injected intraperitoneally (25 mg kg­1 body weight) 30 min before each caerulein injection. After 12 h, rats were sacrificed by decapitation. Blood and pancreas samples were collected and processed for serological and histopathological studies,respectively. Lipase, a-amylase, corticosterone, total antioxidant power and cytokines interleukin (IL)-1b, IL-4 and tumour necrosis factor(TNF)-a were determined using commercial kits. ANOVA and Tukey tests (P<0.05) were performed for the statistical analysis of the results.Results showed that the administration of melatonin reduced histological damage induced by caerulein treatment as well as the hyperamylasemia and hyperlipidemia. Corticosterone and antioxidant total power were also reverted to basal activities. Furthermore, melatonin pre-treatment reduced pro-inflammatory cytokines IL-1b and TNF-a and increased the serum levels of anti-inflammatory cytokine IL-4. In conclusion,the findings suggest that the protective effect of melatonin in caerulein-induced acute pancreatitis is mediated by the anti-inflammatory ability of this indolamine. Thus, melatonin may have a protective effect against acute pancreatitis.

Protective Actions of Cannabidiol on Aging-Related Inflammation, Oxidative Stress and Apoptosis Alterations in Liver and Lung of Long Evans Rats.

BACKGROUND: Aging is characterised by the progressive accumulation of oxidative damage which leads to inflammation and apoptosis in cells. This affects all tissues in the body causing the deterioration of several organs. Previous studies observed that cannabidiol (CBD) could extend lifespan and health span by its antioxidant, anti-inflammatory and autophagy properties. However, research on the anti-aging effect of CBD is still in the beginning stages. This study aimed to investigate the role of cannabidiol (CBD) in the prevention of age-related alterations in liver and lung using a murine model. METHODS: 15-month-old Long Evans rats were treated with 10 mg/kg b.w./day of CBD for 10 weeks and compared to animals of the same age as old control and 2-month-old animals as young control. Gene and/or protein expressions, by RT-qPCR and Western blotting, respectively, were assessed in terms of molecules related to oxidative stress (GST, GPx, GR and HO-1d), inflammation (NFκB, IL-1ß and TNF-α) and apoptosis (BAX, Bcl-2, AIF, and CASP-1). In addition, MDA and MPO levels were measured by colorimetric assay. Results were analysed by ANOVA followed by Tukey-Kramer test, considering statistically significant a p < 0.05. RESULTS: GST, GPx and GR expressions were significantly reduced (p < 0.01) in liver samples from old animals compared to young ones and CBD treatment was able to revert it. A significant increase was observed in old animals compared to young ones in relation to oxidative stress markers (MDA and HO-1d), proinflammatory molecules (NFκB, IL-1ß and TNF-α), MPO levels and proapoptotic molecules (BAX, AIF and CASP-1), while no significant alterations were observed in the antiapoptotic molecules (Bcl-2). All these changes were more noticeable in the liver, while the lung seemed to be less affected. In almost all the measured parameters, CBD treatment was able to revert the alterations caused by age restoring the levels to those observed in the group of young animals. CONCLUSIONS: Chronic treatment with CBD in 15-month-old rats showed beneficial effects in lung and more significantly in liver by reducing the levels of inflammatory, oxidative and apoptotic mediators, and hence the cell damage associated with these three processes inherent to aging.

Oxidative stress increases in liver of lactating rats after BPF-low-dose exposure: perinatal effects in the offspring.

Bisphenol F (BPF) is replacing Bisphenol A (BPA) in the manufacture of products due to endocrine-disrupting effects. BPF monomers can also be released into the environment and enter the food chain, resulting in human exposure to low doses. Since bisphenols are primarily metabolized by the liver, this organ is more vulnerable to lower doses of bisphenols than others. Exposure during prenatal development may increase the risk of diseases in adulthood. The aim was to evaluate whether BPF administration could generate oxidative stress in liver of lactating rats, and whether these effects may be also observed in female and male postnatal day 6 (PND6) offspring. Long Evans rats received oral treatment: Control, BPF-low-dose (LBPF) 0.0365 mg/kg b.w./day, and BPF-high-dose (HBPF) 3.65 mg/kg b.w./day. The levels of antioxidant enzymes (CAT, SOD, GR, GPx and GST), glutathione system (GSH, GSSG) and lipid damage markers (MDA, LPO) were measured using colorimetric methods in liver of both lactating dams and in PND6 offspring. Mean values were analyzed using Prism-7. LBPF affected liver defense mechanisms (antioxidant enzymes and glutathione system), increasing ROS levels and producing lipid peroxidation in lactating dams. Similar effects were found in female and male PND6 offspring as a consequence of perinatal exposure.

S-Adenosylmethionine Decreases Bacterial Translocation, Proinflammatory Cytokines, Oxidative Stress and Apoptosis Markers in Hepatic Ischemia-Reperfusion Injury in Wistar Rats.

Hepatic ischemia/reperfusion injury (IRI) can seriously impair liver function. It is initiated by oxidative stress, resulting in inflammation and apoptosis-induced cellular damage. Glutathione (GSH) prevents oxidative stress. S-Adenosylmethionine (SAMet) is a GSH synthesis precursor that avoids the deficit in SAMet-synthetase activity and contributes to intracellular ATP repletion. It also acts as a methyl group donor, stabilizing hepatocyte membranes, among other functions. This study investigated the effect of SAMet on bacterial translocation and levels of proinflammatory cytokines, oxidative stress and apoptosis markers in male Wistar rats subjected to hepatic IRI. Animals were randomly divided into six groups: (1) sham operation, (3) animals undergoing 60 min of ischemia of the right lateral lobe for temporary occlusion of the portal vein and hepatic artery plus 10 min of reperfusion, and (5) the same as (3) but with a reperfusion period of 120 min. Groups 2, 4 and 6, respectively, are the same as (1), (3) and (5), except that animals received SAMet (20 mg/kg) 15 min before ischemia. GSH, ATP, lipid peroxidation (LPO), TNF-α, IL-1ß, IL-6, total caspase-1 and caspase-9, total and cleaved caspase-3, and phosphatidylcholine were determined in the liver. Endotoxin, TNF-α, IL-1ß, IL-6, IL-10 and LPO in vena cava and portal vein blood samples were also measured. Endotoxin and LPO levels as well as proinflammatory cytokines and apoptotic markers increased significantly in animals undergoing IRI, both after 10 and 120 min of reperfusion. IRI produced a significant decrease in GSH, ATP, portal IL-10 and phosphatidylcholine. SAMet treatment prevented these effects significantly and increased survival rate. The study suggests that SAMet exerts protective effects in hepatic IRI.

Reducing oxidative/nitrosative stress: a newly-discovered genre for melatonin.

The discovery of melatonin and its derivatives as antioxidants has stimulated a very large number of studies which have, virtually uniformly, documented the ability of these molecules to detoxify harmful reactants and reduce molecular damage. These observations have clear clinical implications given that numerous age-related diseases in humans have an important free radical component. Moreover, a major theory to explain the processes of aging invokes radicals and their derivatives as causative agents. These conditions, coupled with the loss of melatonin as organisms age, suggest that some diseases and some aspects of aging may be aggravated by the diminished melatonin levels in advanced age. Another corollary of this is that the administration of melatonin, which has an uncommonly low toxicity profile, could theoretically defer the progression of some diseases and possibly forestall signs of aging. Certainly, research in the next decade will help to define the role of melatonin in age-related diseases and in determining successful aging. While increasing life span will not necessarily be a goal of these investigative efforts, improving health and the quality of life in the aged should be an aim of this research.

Melatonin enhances hydrogen peroxide-induced apoptosis in human promyelocytic leukaemia HL-60 cells.

Melatonin is an indoleamine secreted by the pineal gland that shows multiple tasks. This ubiquitously acting free radical scavenger has recently been shown to stimulate the production of reactive oxygen species (ROS) in tumour cells, making them undergo apoptosis, whilst it prevents apoptosis in healthy cells. The mechanisms by which melatonin exerts these dual actions are, however, not yet clearly understood. Thus, the aim of this study was to further investigate how melatonin can enhance oxidative stress-induced apoptosis in a leukaemia cell line. The results show that melatonin increased the apoptotic effects of H(2)O(2) in human myeloid HL-60 cells as assessed by cellular viability, mitochondrial permeability transition induction, mitochondrial membrane depolarization, ROS generation, caspases 3, 8 and 9 activity, phosphatidylserine externalization, and DNA fragmentation techniques. When healthy leucocytes were exposed to H(2)O(2), melatonin increased the viability of the cells. Taken together, the findings indicate that melatonin is a potential physiological tool capable of protecting healthy cells from chemotherapy-induced ROS production as well as inducing tumour cell death. Because cancer cells manifest increased oxidative stress as a result of their elevated metabolism, the use of melatonin may be useful in impairing their ROS buffering capacity.

Protective effect of melatonin against human leukocyte apoptosis induced by intracellular calcium overload: relation with its antioxidant actions.

Apoptosis or programmed cell death plays a critical role in both inflammatory and immune responses. Recent evidence demonstrates that control of leukocyte apoptosis is one of the most striking immune system-related roles of melatonin. For this reason, this study evaluated the protective effects of melatonin on human leukocyte apoptosis induced by sustained cytosolic calcium increases. Such protective effects are likely mediated by melatonin's free-radical scavenging actions. Treatments with the specific inhibitor of cytosolic calcium re-uptake, thapsigargin (TG), and/or the calcium-mobilizing agonist, N-formyl-methionyl-leucyl-phenylalanine (FMLP), induced intracellular reactive oxygen species (ROS) production, caspase activation as well as DNA fragmentation in human leukocytes. Also, TG- and/or FMLP-induced apoptosis was dependent on both cytosolic calcium increases and calcium uptake into mitochondria, because when cells were preincubated with the cytosolic calcium chelator, dimethyl BAPTA, and the inhibitor of mitochondrial calcium uptake, Ru360, TG- and FMLP-induced apoptosis was largely inhibited. Importantly, melatonin treatment substantially prevented intracellular ROS production, reversed caspase activation, and forestalled DNA fragmentation induced by TG and FMLP. Similar results were obtained by preincubating the cells with another well-known antioxidant, i.e., N-acetyl-L-cysteine. To sum up, depletion of intracellular calcium stores induced by TG and/or FMLP triggers different apoptotic events in human leukocytes that are dependent on calcium signaling. The protective effects resulting from melatonin administration on leukocyte apoptosis likely depend on melatonin's antioxidant action because we proved that this protection is melatonin receptor independent. These findings help to understand how melatonin controls apoptosis in cells of immune/inflammatory relevance.

Actions of melatonin mixed with collagenized porcine bone versus porcine bone only on osteointegration of dental implants.

This study evaluated the effect of the topical application of melatonin mixed with collagenized porcine bone on the osteointegration on the rough discrete calcium deposit (DCD) surface implants in Beagle dogs 3 months after their insertion. In preparation for subsequent insertion of dental implants, lower molars were extracted from 12 Beagle dogs. Each mandible received two parallel wall expanded platform implants with a DCD surface of 4 mm in diameter and 10 mm in length. The implants were randomly assigned to the distal sites on each mandible in the molar area and the gaps were filled with 5 mg lyophilized powdered melatonin and porcine bone and collagenized porcine bone alone. Ten histological sections per implant were obtained for histomorphometric studies. After a 4-wk treatment period, melatonin plus porcine bone significantly increased the perimeter of bone that was in direct contact with the treated implants (P < 0.0001), bone density (P < 0.0001), and new bone formation (P < 0.0001) in comparison with porcine bone alone around the implants. Melatonin plus collagenized porcine bone on DCD surface may act as a biomimetic agent in the placement of endo-osseous dental implants and enhance the osteointegration. Melatonin combined with porcine bone on DCD implants reveals more bone in implant contact at 12 wk (84.5 +/- 1.5%) compared with porcine bone alone treated area (67.17 +/- 1.2%).

Melatonin and reproduction revisited.

This brief review summarizes new findings related to the reported beneficial effects of melatonin on reproductive physiology beyond its now well-known role in determining the sexual status in both long-day and short-day seasonally breeding mammals. Of particular note are those reproductive processes that have been shown to benefit from the ability of melatonin to function in the reduction of oxidative stress. In the few species that have been tested, brightly colored secondary sexual characteristics that serve as a sexual attractant reportedly are enhanced by melatonin administration. This is of potential importance inasmuch as the brightness of ornamental pigmentation is also associated with animals that are of the highest genetic quality. Free radical damage is commonplace during pregnancy and has negative effects on the mother, placenta, and fetus. Because of its ability to readily pass through the placenta, melatonin easily protects the fetus from oxidative damage, as well as the maternal tissues and placenta. Examples of conditions in which oxidative and nitrosative stress can be extensive during pregnancy include preeclampsia and damage resulting from anoxia or hypoxia that is followed by reflow of oxygenated blood into the tissue. Given the uncommonly low toxicity of melatonin, clinical trials are warranted to document the protection by melatonin against pathophysiological states of the reproductive system in which free radical damage is known to occur. Finally, the beneficial effects of melatonin in improving the outcomes of in vitro fertilization and embryo transfer should be further tested and exploited. The information in this article has applicability to human and veterinary medicine.

Phytomelatonin: a review.

Melatonin (N-acetyl-5-methoxytryptamine) has been detected in a number of plant species. Indeed, there exists evidence that this classically-considered animal indole is actually both synthesized in and taken up by plants. Among the actions that melatonin may carry out in plant tissues, its role as an antioxidant or growth promoter is most strongly supported by the experimental evidence. Other suggested functional implications include the co-ordination of photoperiodic responses and regulation of plant reproductive physiology, defence of plant cells against apoptosis induced by harsh environmental conditions, its participation as a free radical scavenging agent and/or up-regulator of certain protective enzymes in the senescent process. This review presents a detailed summary of the investigations that have been performed to date in the plant melatonin (phytomelatonin) field. The purpose of this summary is to bring the reader up to date on what is known about melatonin in plants and to encourage plant scientists to investigate this novel research topic; this would certainly assist in solving the numerous questions that still remain regarding the role of melatonin in plants.

Melatonin, as an adjuvant-like agent, enhances platelet responsiveness.

Melatonin exerts immunomodulatory actions that enhance the magnitude and quality of immune responses specific for certain antigens; this has raised the possibility of using melatonin to design novel vaccine adjuvant systems. The present study investigated the effect of subcutaneous slow-release melatonin implants and subcutaneous melatonin injections on the responsiveness of circulating platelets in sheep after vaccination against Dichelobacter nodosus (A1 and C serotypes), the bacterium that causes ovine footrot, a major cause of lameness in sheep. The experiments were carried out in sheep from a farm located in an area of Mediterranean-type ecosystem. Plasma melatonin levels were determined by radioimmunoassay, sheep platelet aggregation was monitored using an aggregometer and Ca2+ mobilization was determined by spectrofluorimetry using fura-2. Administration of melatonin either by implants or subcutaneous injections increased plasma melatonin concentrations, an effect that was found to be greater and more sustained when melatonin was administered via implants. Vaccination per se, as well as melatonin, increased the percentage and rate of platelet aggregation and reduced the lag-time in response to the physiological agonist thrombin, an effect that was found to be significantly greater when melatonin was administered to vaccinated animals. Melatonin enhanced thrombin-evoked Ca2+ release and entry and further increased Ca2+ mobilization observed in platelets from vaccinated sheep. These observations suggest that the use of melatonin, as a novel adjuvant, induces beneficial effects on platelet function and haemostasis, and opens new perspectives for therapeutic manipulation of immune responses to vaccination.

Melatonin induces mitochondrial-mediated apoptosis in human myeloid HL-60 cells.

The role of melatonin in the mediation of apoptotic events has recently gained attention, especially after recent studies have reported that melatonin exerts antiapoptotic actions in normal cells but may activate proapoptotic pathways in some tumor cells. Here, we have evaluated the effect of melatonin on apoptosis in the human leukemia cell line HL-60. Melatonin treatment (1 mm) induced a significant increase in caspase-3 and -9 activities. The effect of melatonin on the activation of caspases was time dependent, reaching a maximum after 12 hr of stimulation, and then decreasing to a minimum after 72 hr. Treatment with melatonin also evoked mitochondrial membrane depolarization and permeability transition pore induction, which caused loss of mitochondrial staining by calcein, and increased cell death by apoptosis/necrosis as demonstrated by propidium iodide positive-staining of cells after 72 hr of stimulation. In addition, the exposure of cells to melatonin resulted in an activation and association of the proapoptotic proteins Bax and Bid, as well as promoting detectable increases in the expression of both proteins. We conclude that melatonin has proapoptotic and/or oncostatic effects in the human myeloid cell line HL-60.