Evaluation of antioxidant systems in pituitary-adrenal axis diseases

The Double-Edged Sword of Total Antioxidant Capacity: Clinical Significance and Personal Experience

Oxidative stress (OS) could be a condition underlying several human diseases, despite the physiological role of reactive oxygen species (oxidative eustress). Therefore, antioxidant compounds could represent a modulatory mechanism for maintaining a proper redox balance and redox signaling. When antioxidants are insufficient or overwhelmed, OS ensues, causing multiple damages at molecular, tissue, and cellular levels. This study focuses on the role of total antioxidant capacity (TAC) as a biomarker to be interpreted according to several clinical scenarios. After a brief description of various assay methods to elucidate terminology and physiopathological roles, we focus on the hormonal influence on TAC in blood plasma and other biological fluids, as different endocrine systems can modulate the antioxidant response. Furthermore, OS characterizes several endocrinopathies through different mechanisms: an inadequate antioxidant response to an increase in reducing equivalents (reductive distress) or a marked consumption of antioxidants (oxidative distress), which leads to low TAC values. An increased TAC could instead represent an adaptive mechanism, suggesting a situation of OS. Hence, the clinical context is fundamental for a correct interpretation of TAC. This review aims to provide the reader with a general overview of oxidative stress in several clinical examples of endocrine relevance, such as metabolic syndrome, non-thyroid illness syndrome, hypopituitarism, and infertility. Finally, the impact of dietary and surgical interventions on TAC in the model of metabolic syndrome is highlighted, along with personal experience.

Harnessing the power of nutritional antioxidants against adrenal hormone imbalance-associated oxidative stress

Oxidative stress, resulting from dysregulation in the secretion of adrenal hormones, represents a major concern in human health. The present review comprehensively examines various categories of endocrine dysregulation within the adrenal glands, encompassing glucocorticoids, mineralocorticoids, and androgens. Additionally, a comprehensive account of adrenal hormone disorders, including adrenal insufficiency, Cushing's syndrome, and adrenal tumors, is presented, with particular emphasis on their intricate association with oxidative stress. The review also delves into an examination of various nutritional antioxidants, namely vitamin C, vitamin E, carotenoids, selenium, zinc, polyphenols, coenzyme Q10, and probiotics, and elucidates their role in mitigating the adverse effects of oxidative stress arising from imbalances in adrenal hormone levels. In conclusion, harnessing the power of nutritional antioxidants has the potential to help with oxidative stress caused by an imbalance in adrenal hormones. This could lead to new research and therapeutic interventions.

Coenzyme Q10 and Endocrine Disorders: An Overview

Mitochondrial dysfunction and oxidative stress have been implicated in the pathogenesis of a number of endocrine disorders; this, in turn, suggests a potential role for the vitamin-like substance coenzyme Q10 (CoQ10) in the pathogenesis and treatment of these disorders, on the basis of its key roles in mitochondrial function, and as an antioxidant. In this article we have therefore reviewed the role of CoQ10 deficiency and supplementation in disorders of the thyroid, pancreas, gonads, pituitary and adrenals, with a particular focus on hyperthyroidism, type II diabetes, male infertility and polycystic ovary syndrome.

Oxidative Stress in Metabolic and Endocrine Diseases: Basic and Translational Aspects

The aim of this Special Issue is to highlight oxidative stress (OS) as a mechanism underlying a major risk factor for several human diseases [...]

Age-Related Loss in Bone Mineral Density of Rats Fed Lifelong on a Fish Oil-Based Diet Is Avoided by Coenzyme Q10 Addition

During aging, bone mass declines increasing osteoporosis and fracture risks. Oxidative stress has been related to this bone loss, making dietary compounds with antioxidant properties a promising weapon. Male Wistar rats were maintained for 6 or 24 months on diets with fish oil as unique fat source, supplemented or not with coenzyme Q10 (CoQ10), to evaluate the potential of adding this molecule to the n-3 polyunsaturated fatty acid (n-3 PUFA)-based diet for bone mineral density (BMD) preservation. BMD was evaluated in the femur. Serum osteocalcin, osteopontin, receptor activator of nuclear factor-κB ligand, ostroprotegerin, parathyroid hormone, urinary F₂-isoprostanes, and lymphocytes DNA strand breaks were also measured. BMD was lower in aged rats fed a diet without CoQ10 respect than their younger counterparts, whereas older animals receiving CoQ10 showed the highest BMD. F₂-isoprostanes and DNA strand breaks showed that oxidative stress was higher during aging. Supplementation with CoQ10 prevented oxidative damage to lipid and DNA, in young and old animals, respectively. Reduced oxidative stress associated to CoQ10 supplementation of this n-3 PUFA-rich diet might explain the higher BMD found in aged rats in this group of animals.

Thyroid Hormones, Oxidative Stress, and Inflammation

Inflammation and oxidative stress (OS) are closely related processes, as well exemplified in obesity and cardiovascular diseases. OS is also related to hormonal derangement in a reciprocal way. Among the various hormonal influences that operate on the antioxidant balance, thyroid hormones play particularly important roles, since both hyperthyroidism and hypothyroidism have been shown to be associated with OS in animals and humans. In this context, the nonthyroidal illness syndrome (NTIS) that typically manifests as reduced conversion of thyroxine (T₄) to triiodothyronine (T₃) in different acute and chronic systemic conditions is still a debated topic. The pathophysiological mechanisms of this syndrome are reviewed, together with the roles of deiodinases, the enzymes responsible for the conversion of T₄ to T₃, in both physiological and pathological situations. The presence of OS indexes in NTIS supports the hypothesis that it represents a condition of hypothyroidism at the tissue level and not only an adaptive mechanism to diseases.

Thyroid hormones and antioxidant systems: focus on oxidative stress in cardiovascular and pulmonary diseases

In previous works we demonstrated an inverse correlation between plasma Coenzyme Q₁₀ (CoQ₁₀) and thyroid hormones; in fact, CoQ₁₀ levels in hyperthyroid patients were found among the lowest detected in human diseases. On the contrary, CoQ₁₀ is elevated in hypothyroid subjects, also in subclinical conditions, suggesting the usefulness of this index in assessing metabolic status in thyroid disorders. A Low-T3 syndrome is a condition observed in several chronic diseases: it is considered an adaptation mechanism, where there is a reduction in pro-hormone T4 conversion. Low T3-Syndrome is not usually considered to be corrected with replacement therapy. We review the role of thyroid hormones in regulation of antioxidant systems, also presenting data on total antioxidant capacity and Coenzyme Q₁₀. Published studies suggest that oxidative stress could be involved in the clinical course of different heart diseases; our data could support the rationale of replacement therapy in low-T3 conditions.

Measurement of oxidized and reduced coenzyme Q in biological fluids, cells, and tissues: an HPLC-EC method

Direct measure of coenzyme Q (CoQ) in biological specimens may provide important advantages. Precise and selective high-performance liquid chromatography (HPLC) methods with electrochemical (EC) detection have been developed for the measurement of reduced (ubiquinol) and oxidized (ubiquinone) CoQ in biological fluids, cells, and tissues. EC detection is preferred for measurement of CoQ because of its high sensitivity. Reduced and oxidized CoQ are first extracted from biological specimens using 1-propanol. After centrifugation, the 1-propanol supernatant is directly injected into HPLC and monitored at a dual-electrode. The EC reactions occur at the electrode surface. The first electrode transforms ubiquinone into ubiquinol, and the second electrode measures the current produced by the oxidation of the hydroquinone group of ubiquinol. The methods described provide rapid, precise, and simple procedures for determination of reduced and oxidized CoQ in biological fluids, cells, and tissues. The methods have been successfully adapted to meet regulatory requirements for clinical laboratories, and have been proven reliable for analysis of clinical and research samples for clinical trials and animal studies involving large numbers of specimens.

Hormonal influence on coenzyme Q(10) levels in blood plasma

Coenzyme Q₁₀ (CoQ₁₀), also known as ubiquinone for its presence in all body cells, is an essential part of the cell energy-producing system. However, it is also a powerful lipophilic antioxidant protecting lipoproteins and cell membranes. Due to these two actions, CoQ₁₀ is commonly used in clinical practice in chronic heart failure, male infertility, and neurodegenerative disease. However, it is also taken as an anti-aging substance by healthy people aiming for long-term neuroprotection and by sportsmen to improve endurance. Many hormones are known to be involved in body energy regulation, in terms of production, consumption and dissipation, and their influence on CoQ₁₀ body content or blood values may represent an important pathophysiological mechanism. We summarize the main findings of the literature about the link between hormonal systems and circulating CoQ₁₀ levels. In particular the role of thyroid hormones, directly involved in the regulation of energy homeostasis, is discussed. There is also a link with gonadal and adrenal hormones, partially due to the common biosynthetic pathway with CoQ₁₀, but also to the increased oxidative stress found in hypogonadism and hypoadrenalism.

Coenzyme Q(10) in male infertility: physiopathology and therapy

Both the bioenergetic and the antioxidant role of CoQ(10) suggest a possible involvement in sperm biochemistry and male infertility. CoQ(10) can be quantified in seminal fluid, where its concentration correlates with sperm count and motility. It was found that distribution of CoQ(10) between sperm cells and seminal plasma was altered in varicocele patients, who also presented a higher level of oxidative stress and lower total antioxidant capacity. The effect of vericocelectomy on partially reversing these biochemical abnormalities is discussed. The redox status of coenzyme Q(10) in seminal fluid was also determined: an inverse correlation was found between ubiquinol/ubiquinone ratio and hydroperoxide levels and between this ratio and the percentage of abnormal sperm forms. After the first in vitro observations CoQ(10) was administered to infertile patients affected by idiopathic asthenozoospermia, originally in an open label study and then in three randomized placebo-controlled trials; doses were around 200-300 mg/day and treatment lasted 6 months. A significant increase in the concentration of CoQ(10) was found, both in seminal plasma and sperm cells. Treatment also led to a certain improvement in sperm motility. In one of the studies there was also a decrease in plasma levels of follicle stimulating horhone (FSH) and luteinizine horhone (LH). Administration of CoQ(10) may play a positive role in the treatment of asthenozoospermia, possibly related to not only to its function in the mitochondrial respiratory chain but also to its antioxidant properties. Further studies are needed in order to determine whether there is also an effect on fertility rate.

Hormones and antioxidant systems: role of pituitary and pituitary-dependent axes

Oxidative stress, a condition defined as unbalancing between production of free radicals and antioxidant defenses, is an important pathogenetic mechanism in different diseases. Despite the abundant literature, many aspects of hormone role in regulating antioxidant synthesis and activity still remain obscure. Therefore, we reviewed experimental data, in vivo and in vitro, about the effects of the different pituitary- dependent axes on antioxidant levels, trying to give a broad view from hormones which also have antioxidant properties to the classic antioxidants, from the lipophilic antioxidant Coenzyme Q10, strictly related to thyroid function, to total antioxidant capacity, a measure of non-protein non-enzymatic antioxidants in serum and other biological fluids. Taken together, these data underline the importance of oxidative stress in various pituitary-dependent disorders, suggesting a possible clinical usefulness of antioxidant molecules.