RESUMO
The objective of the present study was to investigate a large panel of oxidative stress biomarkers in long-term trained elderly men to analyse the effects of chronic training on an aged population. We collected blood samples from two groups of male volunteers older than 65 years who maintain a measure of functional independence: one group of sedentary subjects without a history of regular physical activity and the other of subjects who have sustained training, starting during middle age (mean training time=49 ± 8 years). We studied morbidity and polypharmacy, as well as haematological parameters including red cell count, haemoglobin concentration, haematocrit, mean corpuscular volume, red cell distribution width and several oxidative biomarkers including protein carbonyl content and lipid peroxidation in plasma and erythrocytes, red blood cell H2O2-induced haemolysis test, plasma total antioxidant activity and the main antioxidant enzymes of erythrocytes: superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase. After adjusting for confounding factors, we observed an increase in all oxidative damage biomarkers in the plasma and erythrocytes of the long-term exercise group. However, we reported a decrease in the number of diseases per subject with statistical differences nearly significant (p=0.061), reduced intake of medications per subject and lower levels of red cell distribution width in the chronic exercise group. These results indicate that chronic exercise from middle age to old age increases oxidative damage; however, chronic exercise appears to be an effective strategy to attenuate the age-related decline in the elderly.
Assuntos
Antioxidantes/metabolismo , Biomarcadores/sangue , Exercício Físico/fisiologia , Estresse Oxidativo/fisiologia , Idoso , Envelhecimento/sangue , Análise de Variância , Catalase/sangue , Eritrócitos/enzimologia , Glutationa Peroxidase/sangue , Glutationa Redutase/sangue , Glutationa Transferase/sangue , Testes Hematológicos , Humanos , Peroxidação de Lipídeos , Masculino , Carbonilação Proteica , Comportamento Sedentário , Espanha , Estatísticas não Paramétricas , Superóxido Dismutase/sangueRESUMO
In the present investigation we have analyzed the association between functional dependence and inflammatory biomarkers using the Barthel Index (BI) and the Katz Index (KI). This analysis may contribute to translational medicine by incorporating the clinical and laboratory data to better understand the relationship between chronic inflammation and functional dependence in the elderly population. The ultimate goal of this study was to identify possible useful biomarkers of functional dependence in the elderly. Participants in this study consisted of 120 older subjects (90 women and 30 men; range 68-105 years) who were selected from the Santa Teresa nursing home (Oviedo, Spain). We studied functional status using the following tools to diagnose the functional dependence by clinicians: BI and KI for activities of daily living. We analyzed morbidity, sociodemographic characteristics and a panel of inflammatory and inflammatory-related markers. In linear regression models adjusted by age, sex, anti-inflammatory drug use and morbid conditions high levels of interleukin 6 (IL-6) and soluble TNF receptor-I (sTNF-RI) were associated with functional dependence as measured using BI and KI. Elevated levels of red blood cell distribution width (RDW) were also associated with functional dependence measured using the KI after adjusting for the same potential confounders. The current results suggest that high IL-6, sTNF-RI and RDW levels are associated with the functional dependence in the elderly population. The results are consistent with the presumed underlying biological mechanism, in which the up-regulation of inflammatory mediators is associated with functional dependence in elderly subjects.
Assuntos
Biomarcadores/sangue , Eritrócitos/metabolismo , Interleucina-6/sangue , Receptores do Fator de Necrose Tumoral/sangue , Atividades Cotidianas , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , MasculinoRESUMO
The Syrian hamster Harderian gland exhibits sexually dimorphic porphyrin biosynthesis, wherein the female glands display an extraordinarily high concentration of porphyrins. Damage derived from this production of porphyrins, mediated by reactive oxygen species, causes the glands to develop autophagic processes, which culminate in detachment-derived cell death; these cells normally play a central role in the secretory activity of the gland. The main aim of this study was to analyze how a change in the redox state impacts autophagy. Female Syrian hamsters were treated daily with melatonin (25 µg, subcutaneously) at ZT 10 for 1-2 months (N-acetyl-5-methoxytryptamine), an endogenous antioxidant that ameliorates the deleterious effects of free radicals via a variety of mechanisms. The length of treatment affected the redox balance, the autophagy machinery, and the activation of p53 and NF-κB. One-month treatment displaces redox balance to the antioxidant side, promotes autophagy through a p53-mediated mechanism, and increases cell detachment. Meanwhile, 2-month treatment restores redox balance to the oxidant side, activates NF-κB reducing autophagy to basal levels, increases number of type II cells, and reduces number of detached cells. Our results conclude that the redox state can modulate autophagy through redox-sensitive transcriptions factors. Additionally, these findings support a hypothesis that ascribes differences in the autophagic-lysosomal pathway to epithelial cell types, thereby restricting detachment-induced autophagic cell death to epithelial cell type I.
Assuntos
Antioxidantes/farmacologia , Autofagia/efeitos dos fármacos , Glândula de Harder/efeitos dos fármacos , Glândula de Harder/metabolismo , Melatonina/farmacologia , Animais , Caspase 3/metabolismo , Catalase/metabolismo , Catepsina B/metabolismo , Cricetinae , Feminino , Glândula de Harder/química , Glândula de Harder/citologia , Peroxidação de Lipídeos/efeitos dos fármacos , Mesocricetus , NF-kappa B/metabolismo , Antígeno Nuclear de Célula em Proliferação/metabolismo , Carbonilação Proteica/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Proteína Supressora de Tumor p53/metabolismoRESUMO
The objective of the present study was to investigate the changes in a large panel of emergent geriatric biomarkers in long-term trained elderly men to analyze the effects of long-term exercise on an aged population. We collected blood samples from two groups of male volunteers older than 65 years who maintain a measure of functional independence: one group of sedentary subjects without a history of regular physical activity and the other of subjects who have sustained training, starting during adulthood (mean training time = 49 ± 8 years). We studied morbidity, polypharmacy, cellular and serological inflammatory parameters, and endocrine mediators. After adjusting for confounding factors, we observed reduced medication intake per subject and lower number of diseases per subject with statistical differences nearly significant in the long-term exercise group. We showed that long-term training was associated with lower levels of white blood cell counts, neutrophil counts, interleukin-6, interleukin-10, interleukin-1 receptor antagonist, and soluble TNF receptor-I. Furthermore, we noted an increase in the concentrations of insulin-like growth factor-1 and dehydroepiandrosterone in the long-term training group. We concluded that long-term exercise training from adulthood to old age is clearly associated with a healthy profile of emergent geriatric biomarkers. Long-term training could improve the inflammatory-endocrine imbalance associated with disease, frailty, functional decline, and mortality in elderly men. Our results point to the benefits of prolonged exercise from adulthood to old age.
Assuntos
Envelhecimento/fisiologia , Citocinas/sangue , Exercício Físico/fisiologia , Hormônios/sangue , Inflamação/sangue , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Ensaio de Imunoadsorção Enzimática , Teste de Esforço , Seguimentos , Humanos , Masculino , Prognóstico , Valores de Referência , Fatores de TempoRESUMO
BACKGROUND: Studies of the role of oxidative stress in functional dependence among the aging population are limited. In this report, we address this situation through an analysis of a large panel of blood oxidative biomarkers in elderly population. Because the analysis of multiple biomarkers increases the complexity of data interpretation, this investigation has utilized both an analysis of single biomarkers in addition to employment of the statistical data reduction tool principal component analysis that might allow for a clearer description of redox status as compared with a single measure alone. METHODS: We studied three groups of participants older than 65 years based on their Barthel Index: an independent group (100-95), a moderately dependent group (94-60), and a severely dependent group (59-0). RESULTS: We observed a significant increase in circulating protein carbonyl levels in the severely dependent group as compared with the independent and moderately dependent groups. Using principal component analysis, we found at least three factors (an erythrocyte-related component, a protein damage-related component, and a plasma-related component) that could be used to assess the different oxidative parameters in our population. We discovered a significant association of higher levels of the protein damage-related component with the severely dependent group. CONCLUSIONS: Protein damage levels could be assessed in clinical use as a biomarker of severe dependence. Furthermore, our results support the hypothesis that functional decline could be associated in part due to oxidative stress. Finally, we show that principal component analysis could be a useful statistical tool in the analysis of age-related decline.
Assuntos
Estresse Oxidativo , Análise de Componente Principal , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/metabolismo , Biomarcadores/sangue , Interpretação Estatística de Dados , Feminino , Humanos , Masculino , Carbonilação Proteica/fisiologia , Índice de Gravidade de DoençaRESUMO
The present study investigated the changes in several erythrocyte oxidative stress biomarkers in hypoxic elderly individuals to analyze the deleterious effects of low oxyhemoglobin saturation in an elderly population. We collected blood samples from one normoxic middle-aged group and two groups composed of individuals older than 75 years of age: one normoxic group and one hypoxic group. Aging appeared to provoke a defective erythrocyte antioxidant defense associated with increased oxidative damage in the elderly population. Acute hypoxia activated an insufficient antioxidant defense response as suggested by the oxidative damage observed. The oxidative imbalance presented in older participants and increased in hypoxia participants had a direct effect on glyceraldehyde-3-phosphate dehydrogenase cell distribution. Oxidative stress levels altered Band 3 protein and mediated caspase-3 activation in erythrocyte from the aged group although it was not extended to hypoxic individuals. Therefore, aged participants appeared to activate an insufficient antioxidant response against hypoxia-related oxidative stress.
Assuntos
Adaptação Fisiológica , Eritrócitos/fisiologia , Gliceraldeído-3-Fosfato Desidrogenase (NADP+)(Fosforiladora)/fisiologia , Hipóxia/fisiopatologia , Estresse Oxidativo , Idoso , Idoso de 80 Anos ou mais , Proteína 1 de Troca de Ânion do Eritrócito/fisiologia , Antioxidantes/fisiologia , Caspase 3/fisiologia , Catalase/fisiologia , Eritrócitos/enzimologia , Feminino , Glutationa Redutase/fisiologia , Humanos , Hipóxia/enzimologia , Masculino , Superóxido Dismutase/fisiologiaRESUMO
Oxidative stress has been reported to increase during aging and conditions of hypoxia. Although low oxygen saturation has a key role in the development of several age-related diseases, the underlying mechanisms are still unknown. We analyzed the relationship between aging and hypoxia by examining oxidative stress and inflammation-related cytokines. We collected blood samples from three volunteer experimental groups, consisting of one group of normoxic middle-aged people and two groups of individuals older than 75 years, which comprised a subgroup of normoxic subjects and another with oxyhemoglobin saturation lower than 95% (hypoxic). Our results showed a fall in antioxidant defenses in older people with hypoxia. TNF-alpha, the first element in the cytokine cascade, was significantly increased in the aged population, implying that aging is accompanied by a gradual increase in this inflammatory biomarker. IL-6 was not associated with aging, but it was highly elevated under hypoxia conditions in elderly subjects. Thus, these parameters could be used as biological markers of different inflammatory processes triggered by oxidative stress induced by a decrease in antioxidant defenses in the elderly population, with TNF-alpha as an indicator of chronic processes, such as aging, and IL-6 as a marker for acute responses, such as hypoxia.
Assuntos
Envelhecimento/sangue , Doença , Mediadores da Inflamação/sangue , Mediadores da Inflamação/metabolismo , Interleucina-6/sangue , Fator de Necrose Tumoral alfa/sangue , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/imunologia , Envelhecimento/metabolismo , Biomarcadores/sangue , Biomarcadores/metabolismo , Estudos de Casos e Controles , Feminino , Humanos , Inflamação/sangue , Interleucina-6/metabolismo , Masculino , Pessoa de Meia-Idade , Fator de Necrose Tumoral alfa/metabolismo , Adulto JovemRESUMO
The Syrian hamster Harderian gland (HG) has a large porphyrin metabolism with a sexual dimorphism, showing male HGs much lower porphyrin concentrations than female glands. Damage derived from this production of porphyrins, displayed by reactive oxygen species, forces the gland to develop morphological changes that must have a physiological significance. Thus, oxidative stress is present in two states: mild oxidative stress in male HGs and extreme oxidative stress in female HGs. Cathepsins data gave indirect indications about the presence of programmed cell death affecting the lysosomal pathway, especially in female HGs, which showed an accumulation of autophagic bodies. Our results showed different degrees of autophagy in Syrian hamster HGs depending on sex and probably controlled by the redox-sensitive transcription factors: NFkappaB and p53. The discovery of these sexual dimorphisms in redox signaling and in autophagy corroborates previous findings and underlines the key role of reactive oxygen species in the regulation of autophagy. In addition, in this paper we propose a physiological significance for these phenomena: male HGs develop a survival autophagy, while in female HGs, autophagy culminates in a detachment-derived cell death that plays a central role in its secretory activity, leading to a massive glandular secretion.
Assuntos
Autofagia/fisiologia , Glândula de Harder , Caracteres Sexuais , Animais , Catalase/metabolismo , Catepsinas/metabolismo , Morte Celular/fisiologia , Cricetinae , Cricetulus , Feminino , Glândula de Harder/anatomia & histologia , Glândula de Harder/metabolismo , Glândula de Harder/fisiologia , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Fígado/citologia , Fígado/metabolismo , Masculino , Mesocricetus , NF-kappa B/metabolismo , Estresse Oxidativo , Porfirinas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sirtuínas/metabolismo , Superóxido Dismutase/metabolismo , Proteína Supressora de Tumor p53/metabolismoRESUMO
The flank organ of the Syrian hamster shows a biodynamic response to androgenic stimulation and is, therefore, a suitable model for the study of androgenic effects on hair and sebaceous glands. This organ is susceptible to programmed cell death (PCD), a prominent feature associated with sexual organ adjustment. In the present report, the type of PCD (apoptosis or autophagy) exhibited by this organ was evaluated. Caspase-3 activity, indicative of apoptosis, was not detectable in flank organ homogenates. Furthermore, cytokeratins, which are normally degraded during apoptosis, remained intact. On the other hand, Western blotting of Beclin 1 and light chain 3-II, both important autophagy markers, revealed autophagic processes in the flank organ in both sexes, especially in females. Cathepsin D activity, higher in males than in females, and procathepsin D expression were also consistent with autophagy and not apoptosis. Taken together, these data indicate that macroautophagy, and not apoptosis, is the main mechanism by which the flank organ responds to androgen. This is the first direct evidence establishing the relationship between autophagy and morphological changes in androgen-dependent organs.
Assuntos
Androgênios/metabolismo , Autofagia/fisiologia , Glândulas Sebáceas/metabolismo , Glândulas Sebáceas/ultraestrutura , Caracteres Sexuais , Animais , Apoptose/fisiologia , Proteínas Reguladoras de Apoptose/metabolismo , Western Blotting , Caspase 3/metabolismo , Catepsina D/metabolismo , Cricetinae , Feminino , Queratinas/metabolismo , Masculino , Mesocricetus , Microscopia Eletrônica de TransmissãoRESUMO
We studied the effect of age and melatonin on cell death processes in brain aging. Senescence-accelerated prone mice 8 (SAMP8) and senescence-accelerated resistant mice (SAMR1) at 5 and 10 months of age were used as models of the study. Melatonin (10 mg/kg) or its vehicle (ethanol at 0.066%) was administered in the drinking water from 1 to 9 months of age. Neurodegeneration, previously shown in the aged brain of SAMP8 and SAMR1 at 10 months of age, may be due to a drop in age-related proteolytic activities (cathepsin D, calpains, and caspase-3). Likewise, lack of apoptotic and macroautophagic processes were found, without apparent modification by melatonin. However, the caspase-independent cell death, owing to high p53 and apoptosis-inducing factor (AIF) levels, might be an alternative pathway of cell death in the aged brain. The main effects of melatonin treatment were observed in the aged SAMR1 mice; in this strain we observed a marked increase in antioxidant activity (catalase and superoxide dismutase). Likewise, a key antioxidant role of apoptosis-related proteins, Bcl-2 and AIF, was suggested in the aged brain of SAM mice, which was clearly influenced by melatonin. Moreover, the age-related increase of lysosomal activity of cathepsin B and a lysosomal membrane-associated protein 2 supports the possibility of the maintenance of lysosomal viability in addition to age-related impairments of the proteolytic or macroautophagic activities. The effectiveness of melatonin against the oxidative stress-related impairments and apoptosis during the aging process is, once more, corroborated in this article.
Assuntos
Senilidade Prematura/tratamento farmacológico , Encéfalo/efeitos dos fármacos , Encéfalo/fisiologia , Melatonina/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Senilidade Prematura/metabolismo , Animais , Western Blotting , Encéfalo/metabolismo , Caspase 3/metabolismo , Catalase/metabolismo , Catepsina D/metabolismo , Morte Celular/efeitos dos fármacos , Glutationa Redutase/metabolismo , Proteína 2 de Membrana Associada ao Lisossomo/metabolismo , Camundongos , Camundongos Transgênicos , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Estatísticas não Paramétricas , Superóxido Dismutase/metabolismo , Proteína X Associada a bcl-2/metabolismoRESUMO
Senescence-accelerated mice (SAMP8) and senescence-accelerated resistant mice (SAMR1) were studied at 5 and 10 months of age, respectively. In the animals, neurodegenerative processes and how they were influenced by melatonin were examined. Melatonin (10 mg/kg) or vehicle (ethanol at 0.066%) treatments were administrated from the age of 1 to 9 months in the drinking water. Differences in the neurodegenerative markers examined were found between the two strains with a more damaged protein, phosphorylated Tau at Ser392, increased neurofibrillary tangles (NT) and higher alpha-synuclein expression in SAMP8 versus SAMR1 mice overall, when the mice were 10 months of age. Changes in density of receptors and oxidative stress-related signaling with age were found in the brains of SAM strains at 10 months as shown by a marked decrease in the level of MT-1 melatonin receptor and retinoic acid receptor-related orphan receptor (ROR)-alpha1. This diminution was earlier and more pronounced in SAMP8 mice. Likewise, the levels of nuclear factor-kappa B (NF-kB) transcriptional factor were higher in SAMP8 mice compared with SAMR1 mice regardless of age confirming the direct role of oxidative stress in the aging process. Treatment with melatonin in SAMP8 and SAMR1 mice reduced the neurodegenerative changes with an increase of ROR-alpha1 levels without an apparent influence in the levels of MT-1 receptor. However, different melatonin effects on NF-kB signaling were observed suggesting that NF-kB could trigger inflammatory processes in a different way, being SAM strain-dependent and associated with age-related oxidative stress levels. The effectiveness of melatonin in improving age-related neural impairments is corroborated.
Assuntos
Senilidade Prematura/tratamento farmacológico , Envelhecimento/efeitos dos fármacos , Antioxidantes/uso terapêutico , Melatonina/uso terapêutico , Degeneração Neural/tratamento farmacológico , Estresse Oxidativo/efeitos dos fármacos , Senilidade Prematura/metabolismo , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/patologia , Corpos de Lewy , Camundongos , Subunidade p50 de NF-kappa B/metabolismo , Degeneração Neural/metabolismo , Emaranhados Neurofibrilares/efeitos dos fármacos , Membro 1 do Grupo F da Subfamília 1 de Receptores Nucleares , Carbonilação Proteica/efeitos dos fármacos , Receptor MT1 de Melatonina/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Transdução de Sinais , Transativadores/metabolismo , alfa-Sinucleína/metabolismo , Proteínas tau/metabolismoRESUMO
The prevalence of liver diseases emphasizes the need of animal models to research on the mechanism of disease pathogenesis. Furthermore, most of the liver pathologies have the oxidative stress as an important component. The senescence-accelerated mouse strain SAMP8 was proposed as a valuable animal model for the study of liver diseases. To gain a better understanding of the mechanisms underlying degenerative processes in SAMP8 mice livers, we studied the oxidative-induced damage in 5-month-old SAMP8 mice and SAMR1, senescence-accelerated-resistant mice. We found profound differences in the antioxidant response to aging between sexes, with males displaying lowest levels of main antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR) in SAMP8; whereas females had no difference in their activities, except for GR, when compared with their SAMR1 controls. The results obtained show the binomial SOD/CAT as an important factor for counteracting reactive oxygen species-dependent damage. There were not pathological differences at the morphological level between both strains, although the decay in protection against free radicals had an immediate response by increasing lipid and protein oxidative damage in SAMP8 mice liver. At 5 months, both male and female SAMP8 mice confront the oxidative stress challenge to different extents. Indeed, proteins seem to be the most vulnerable biomolecule in SAMP8 male mice.
Assuntos
Envelhecimento/metabolismo , Fígado/metabolismo , Estresse Oxidativo/genética , Caracteres Sexuais , Envelhecimento/genética , Animais , Feminino , Peroxidação de Lipídeos/genética , Fígado/patologia , Hepatopatias/genética , Hepatopatias/metabolismo , Hepatopatias/patologia , Masculino , Camundongos , Camundongos MutantesRESUMO
The blind subterranean mole rat Spalax ehrenbergi superspecies has evolved adaptive strategies to cope with underground stress. Hypoxia is known to stimulate reactive oxygen species generation; however, mechanisms by which Spalax counteracts oxidative damage have not been investigated before. We studied in Spalax the oxidative status of the Harderian gland (HG), an organ which is particularly vulnerable to oxidative stress in many rodents. With regard to the sexual dimorphism found in this gland, differences between males and females were determined and compared to the surface-dwelling Syrian hamster. Our results show, for the first time, that Spalax exhibits remarkably low biomolecular damage, which implies the existence of physiological strategies to avoid oxidative damage under fluctuating O(2) and CO(2) levels existing in the mole rat's subterranean niche. Correspondingly, main antioxidant enzymes, such as superoxide dismutase (SOD), catalase, and glutathione reductase (GR), exhibited high activities in both genders; in particular, remarkably high levels were measured in SOD. SOD and GR activities showed statistically significant differences between sexes. Melatonin, an important circadian agent is also a very important antioxidant molecule and is synthesized in the Harderian glands (HGs) of Spalax. Therefore, the possible interaction between antioxidant enzymes and melatonin is suggested.
Assuntos
Aclimatação/fisiologia , Antioxidantes/metabolismo , Glândula de Harder/enzimologia , Estresse Oxidativo/fisiologia , Análise de Variância , Animais , Catalase/metabolismo , Cricetinae , Feminino , Glutationa Redutase/metabolismo , Hipóxia/enzimologia , Hipóxia/fisiopatologia , Peroxidação de Lipídeos/fisiologia , Masculino , Mesocricetus , Ratos-Toupeira , Carbonilação Proteica/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Fatores Sexuais , Especificidade da Espécie , Superóxido Dismutase/metabolismoRESUMO
The Syrian hamster Harderian gland has as the remarkable feature of an extraordinary rate of porphyrin production, even higher than the liver. The low activity of the last enzyme of the route gives rise to the accumulation of the uncomplex porphyrins in the female glands. Moreover, due to the localization of the Harderian gland, porphyrins exposed to light produce reactive oxygen species and, thus, the gland presents a physiological oxidative stress, with a great number of sings of degeneration, but without compromising the gland integrity. The appearance of abnormal features in this gland was largely described in the past, but the significance is interpreted for the first time in this study. We have found that autophagic processes are the first result of an elevated porphyrin metabolism, as it is observed in both sexes. This mechanism is considered, in this case, as a constant renovation system that allows the normal gland activity to be sustained. Furthermore, there is a second procedure, invasive processes toward connective tissue, which even occasionally reach blood vessels with intravasation of damaged gland components into the bloodstream. This effect is a consequence of a strong oxidative stress environment that is mainly observed in the female gland, resembling to tumoral progression. Both mechanisms, autophagy and invasive processes, have to be implied in the maintenance of the gland integrity.
Assuntos
Glândula de Harder/metabolismo , Estresse Oxidativo , Animais , Apoptose , Autofagia , Western Blotting , Caspase 3 , Caspases/metabolismo , Catepsina B/biossíntese , Catepsina D/biossíntese , Catepsina H , Catepsinas/biossíntese , Catepsinas/metabolismo , Cricetinae , Cisteína Endopeptidases/biossíntese , Progressão da Doença , Feminino , Glândula de Harder/patologia , Glândula de Harder/ultraestrutura , Imuno-Histoquímica , Masculino , Mesocricetus , Modelos Biológicos , Modelos Estatísticos , Porfirinas/metabolismo , Espécies Reativas de Oxigênio , Fatores SexuaisRESUMO
Melatonin binding sites were characterized in the nuclei of mouse mammary glands. The specific binding of 2-125I-iodomelatonin by homogenates of purified mammary gland cell nuclei was found to be rapid, reversible and saturable. Binding of 125I-melatonin exhibited day-night variations with the highest binding affinity observed during the dark period and the lowest affinity at midday. However, when the animals were maintained under continuous light exposure, binding of 125I-melatonin to cell nuclei showed a higher affinity than the daytime values found in animals maintained in normal photoperiod. Scatchard analysis of the binding data revealed the existence of a significant night-day variation in the binding kinetics, compatible with the existence of two classes of binding sites: a high-affinity binding site expressed during the night, with KD = 185 +/- 36 pm and a binding capacity of 6.24 +/- 0.4 fmol/mg protein, and a low-affinity site with KD = 562 +/- 57 nm and Bmax = 7.56 +/- 0.49 pmol/mg protein during the day. Interestingly, after 2 wk of continuous exposure to light, the animals killed at an equivalent midday time showed a significant increase in binding affinity, with KD = 1.43 +/- 0.2 nm and Bmax = 24.75 +/- 3.5 fmol/mg protein. Displacement experiments show an IC50 value compatible with the affinity constants obtained in the saturation experiments. These results indicate that the low-affinity binding site may be saturated by the high levels of melatonin found in the mouse mammary gland, and sustain the hypothesis of a circadian regulation of these melatonin binding sites by the photoperiod.
Assuntos
Núcleo Celular/metabolismo , Glândulas Mamárias Animais/metabolismo , Melatonina/metabolismo , Fotoperíodo , Animais , Ligação Competitiva , Feminino , Radioisótopos do Iodo , Glândulas Mamárias Animais/citologia , CamundongosRESUMO
The Syrian hamster Harderian gland (HG), an organ present in the male two secretory cell types (type-I and type-II cells), is physiologically exposed to high oxidative stress because of high concentrations of porphyrins and their precursor, 5-aminolevulinic acid. Because of its juxtaorbital location, the HG is accessible to light, and subject to phototoxic effects of these substances. After having previously demonstrated circadian rhythms in antioxidant enzymes, porphyric enzymes and oxidative damage of proteins and lipids, as well as influences of melatonin on these parameters, we have now studied the effects of continuous light (LL), which suppresses melatonin secretion by the pineal gland. Measurements were performed in two different circadian phases, in order to detect the presence or absence of day/night differences. In LL, no differences between circadian phases of subjective day and subjective night were demonstrable for 5-aminolevulinate synthase, 5-aminolevulinate dehydratase, porphobilinogen deaminase, or superoxide dismutase; temporal differences in glutathione reductase and catalase were markedly diminished, whereas all these parameters showed marked day/night differences in the rats exposed to a light/dark cycle of 14:10. In LL, oxidative damage to lipids was minimally effected, while protein damage was enhanced. LL also caused a reduction in the percentage of type-II cells. Therefore, cell differentiation in the HG does not seem to be controlled only by the androgen, but, unexpectedly, also by melatonin.
Assuntos
Catalase/efeitos da radiação , Glutationa Redutase/efeitos da radiação , Glândula de Harder/fisiologia , Luz , Porfirinas/biossíntese , Superóxido Dismutase/efeitos da radiação , Animais , Ritmo Circadiano/fisiologia , Ritmo Circadiano/efeitos da radiação , Cricetinae , Heme/biossíntese , MasculinoRESUMO
Effects of delta-aminolevulinic acid (ALA) and melatonin were investigated in the female Syrian hamster Harderian gland. This is an organ physiologically exposed to strong oxidative stress due to the highest porphyrinogenic rates known in nature. Enzyme activities of porphyrin biosynthesis and of antioxidative protection, oxidative protein modification, and histological integrity were studied. In the porphyrin biosynthetic pathway, ALA and melatonin acted synergistically by downregulating ALA synthase (ALA-S) and stimulating product formation from ALA; the combination of ALA and melatonin suppressed ALA-S activity, down to about 1% of that in controls. While ALA effects on porphyrinogenesis can be interpreted in terms of homeostasis, melatonin's actions may be seen in relation to seasonality and/or reduction of oxidative stress. Among antioxidant enzymes, superoxide dismutase (SOD) and glutathione reductase (GR) activities were diminished by ALA, presumably due to the vulnerability of their active centers to free radicals, whereas melatonin moderately increased SOD. Both ALA and melatonin strongly stimulated catalase (CAT), thereby counteracting the oxidative stress induced by ALA and its metabolites. Nevertheless, exogenous ALA caused a strong net rise in protein carbonyl and considerable damage of tissue. When given together with ALA, melatonin antagonized these effects and largely protected the integrity of glandular structures.
Assuntos
Ácido Aminolevulínico/farmacologia , Antioxidantes/farmacologia , Sequestradores de Radicais Livres/farmacologia , Glândula de Harder/efeitos dos fármacos , Melatonina/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Animais , Catalase/metabolismo , Cricetinae , Feminino , Glutationa Redutase/metabolismo , Glândula de Harder/enzimologia , Hidroximetilbilano Sintase/metabolismo , Mesocricetus , Oxirredução , Sintase do Porfobilinogênio/metabolismo , Superóxido Dismutase/metabolismoRESUMO
Effects of the prooxidant delta-aminolevulinic acid (ALA) and the antioxidant melatonin (MEL) were investigated in the male Syrian hamster Harderian gland (HG). Rodent Harderian glands are highly porphyrogenic organs, which may be used as model systems for studying damage by delta-aminolevulinic acid and its metabolites, as occurring in porphyrias. Chronic administration of delta-aminolevulinic acid (2 weeks) markedly decreased activities of the porphyrogenic enzymes delta-aminolevulinate synthase (ALA-S) and delta-aminolevulinate dehydratase (ALA-D) and of the antioxidant enzymes superoxide dismutase (SOD), glutathione reductase (GR) and catalase (CAT), whereas porphobilinogen deaminase (PBG-D) remained unaffected. This treatment led to increased lipid peroxidation (LPO) and oxidatively modified protein (protein carbonyl) as well as to morphologically apparent tissue damage. Melatonin also caused decreases in delta-aminolevulinate synthase, delta-aminolevulinate dehydratase, superoxide dismutase, glutathione reductase and catalase. Despite lower activities of antioxidant enzymes, lipid peroxidation and protein carbonyl were markedly diminished. The combination of delta-aminolevulinic acid and melatonin led to approximately normal levels of delta-aminolevulinate dehydratase, glutathione reductase, catalase and protein carbonyl, and to rises in superoxide dismutase and porphobilinogen deaminase activities; lipid peroxidation remained even lower than in controls and the appearance of the tissue revealed a protective influence of melatonin. These results suggest that melatonin may have profound effects on the oxidant status of the Harderian gland.