Showing papers by "Branca M. Silva published in 2014"

White tea as a promising antioxidant medium additive for sperm storage at room temperature: a comparative study with green tea.

Abstract: Storage of sperm under refrigeration reduces its viability, due to oxidative unbalance. Unfermented teas present high levels of catechin derivatives, known to reduce oxidative stress. This study investigated the effect of white tea (WTEA) on epididymal spermatozoa survival at room temperature (RT), using green tea (GTEA) for comparative purposes. The chemical profiles of WTEA and GTEA aqueous extracts were evaluated by 1H NMR. (−)-Epigallocatechin-3-gallate was the most abundant catechin, being twice as abundant in WTEA extract. The antioxidant power of storage media was evaluated. Spermatozoa antioxidant potential, lipid peroxidation, and viability were assessed. The media antioxidant potential increased the most with WTEA supplementation, which was concomitant with the highest increase in sperm antioxidant potential and lipid peroxidation decrease. WTEA supplementation restored spermatozoa viability to values similar to those obtained at collection time. These findings provide evidence that WTEA extract...

Melatonin alters the glycolytic profile of Sertoli cells: implications for male fertility

Abstract: Melatonin co-operates with insulin in the regulation of glucose homeostasis. Within the testis, glucose metabolism in the somatic Sertoli cells (SCs) is pivotal for spermatogenesis. Since the effects of melatonin on male reproductive physiology remain largely unknown, we hypothesized that melatonin may affect spermatogenesis by modulating SC metabolism, interacting with insulin. To test our hypothesis, rat SCs were maintained in culture for 24 h in the presence of insulin, melatonin or both and metabolite production/consumption was determined by proton nuclear magnetic resonance ( 1 H-NMR). Protein levels of glucose transporters (GLUT1 and GLUT3), phosphofructokinase 1, lactate dehydrogenase (LDH) and monocarboxylate transporter 4 were determined by western blot. LDH activity was also assessed. SCs treated with melatonin showed an increase in glucose consumption via modulation of GLUT1 levels, but decreased LDH protein expression and activity, which resulted in lower lactate production. Moreover, SCs exposed to melatonin produced and accumulated less acetate than insulin-exposed cells. The combined treatment (insulin plus melatonin) increased acetate production by SCs, but intracellular acetate content remained lower than in insulin exposed cells. Finally, the intracellular redox state, as reflected by intracellular lactate/alanine ratio, was maintained at control levels in SCs by melatonin exposure (i.e. melatonin, alone or with insulin, increased the lactate/alanine ratio versus cells treated with insulin). Furthermore, SCs exposed to insulin plus melatonin produced more lactate and maintained the protein levels of some glycolysis-related enzymes and trans- porters at control levels. These findings illustrate that melatonin regulates SCs metabolism, and thus may affect spermatogenesis. Since lactate produced by SCs provides nutritional support and has an anti-apoptotic effect in developing germ cells, melatonin supplementation may be an effective therapy for diabetic male individuals facing subfertility/infertility.

Effect of white tea (Camellia sinensis (L.)) extract in the glycolytic profile of Sertoli cell.

Abstract: Purpose Many health benefits have been attributed to tea (Camellia sinensis (L.)), and tea infusions are used as dietary agent and included in food supplements. Herein, we report the effect of a white tea (WTEA) extract in Sertoli cell (SC) metabolism. The SC is responsible for the nutritional support of the developing germ cells.

Tea (Camellia sinensis (L.)): a putative anticancer agent in bladder carcinoma?

Abstract: The leaves of Camellia sinensis (L.) are the source of tea, the second most consumed beverage worldwide. Tea contains several chemical compounds such as polyphenols (mainly catechins), caffeine, theophylline, L-theanine, among many others. Polyphenolic compounds are mainly responsible for its significant antioxidant properties and anticarcinogenic potential. Bladder cancer is one of the most common types of cancer, and its progression and onset are thought to be controlled by dietary and lifestyle factors. Epidemiological studies showed that the regular consumption of tea can be a preventive factor for this type of cancer, and several in vivo and in vitro studies reported that tea and its components may interfere in the cancer cells' signaling, preventing the bladder tumor progression. The mechanisms responsible for this protection include deregulation of cell cycle, induction of apoptosis while protecting the surrounding healthy bladder cells, inhibition of metastization processes, among others. Herein, we discuss the potential beneficial effects of tea and tea components in bladder cancer prevention and/or treatment, and how they can be helpful in finding new therapeutic strategies to treat this type of cancer.

Nutritional Factors and Male Reproduction

Abstract: Alterations in nutrition and lifestyle patterns along the years have been associated with a decline in sperm quality and pregnancy rates. One of the main factors for this situation is the increasing prevalence of many diet-related health conditions and diseases with a negative impact on male reproductive potential, especially due to the generation of oxidative stress. In this chapter, we will discuss the impact of several nutritional factors in male reproduction and the possible use of antioxidant therapies to counteract the oxidative-induced damages.

Pineal Gland and Melatonin Biosynthesis

Abstract: The anatomical features of the pineal gland show that it has a central role in the individual's health. The most remarkable function of this gland is melatonin biosynthesis, which is a very complex process. Melatonin carries the information concerning photoperiod that is then differently used by the cells, tissues and even has a species-dependent action. Herein we discuss pineal gland physiology and the process of melatonin biosynthesis, with emphasis on how it mediates the several known biological actions for melatonin.

Pineal Gland and Regulatory Function

Abstract: The pineal gland controls the biological rhythms dependent of the light/dark cycle mainly through the levels of melatonin released into the blood during that cycle. This multitasking molecule has a key role in reproduction and reproductive processes of males and females and interacts with hypothalamic–pituitary–ovarian and the hypothalamic–pituitary–testis axes. Thus, pineal gland has emerged as a relevant regulatory organ of several physiological functions. Herein we discuss the pineal gland regulatory functions, with emphasis on reproductive events.

Energetics of the Male Reproduction

Abstract: Spermatogenesis is a highly regulated process that depends of specific metabolic alterations during each step of germ cell differentiation and sperm production. The somatic Sertoli cell, also known as “nurse cell”, provides the germ line with the different metabolic substrates needed for its maintenance and differentiation, which led to the concept of a permanent metabolic cooperation established between Sertoli and developing germ cells. The former are under a permanent control by endocrine, paracrine, but also environmental factors and metabolic cues. Any changes in testicular cells metabolism may compromise spermatogenesis and thus male fertility. In this chapter we present a brief overview of testicular and spermatozoa metabolism, as well as some of the mechanisms that control those processes. The energetics of male reproduction will be discussed.