Coenzyme Q10 evaluation in pituitary-adrenal axis disease: preliminary data

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.

The Modulation of Ubiquinone, a Lipid Antioxidant, on Neuronal Voltage-Gated Sodium Current

Ubiquinone, composed of a 1,4-benzoquinone and naturally produced in the body, actively participates in the mitochondrial redox reaction and functions as an endogenous lipid antioxidant, protecting against peroxidation in the pituitary-dependent hormonal system. However, the questions of if and how ubiquinone directly affects neuronal ionic currents remain largely unsettled. We investigated its effects on ionic currents in pituitary neurons (GH3 and MMQ cells) with the aid of patch-clamp technology. Ubiquinone decreased the peak amplitude of the voltage-gated Na+ current (INa) with a slowing of the inactivation rate. Neither menadione nor superoxide dismutase modified the ubiquinone-induced INa inhibition. In response to an isosceles-triangular ramp pulse, the persistent INa (INa(P)) at high- and low- threshold potentials occurred concurrently with a figure-eight hysteresis loop. With ubiquinone, the INa(P) increased with no change in the intersection voltage, and the magnitude of the voltage-dependent hysteresis of the current was enhanced. Ubiquinone was ineffective in modifying the gating of hyperpolarization-activated cation currents. In MMQ lactotrophs, ubiquinone effectively decreased the amplitude of the INa and the current inactivation rate. In sum, the effects of ubiquinone demonstrated herein occur upstream of its effects on mitochondrial redox processes, involved in its modulation of sodium channels and neuronal excitability.

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.

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.

Efficacy of coenzyme Q10 on semen parameters, sperm function and reproductive hormones in infertile men

PURPOSE

We determined the efficacy of coenzyme Q10 supplementation on semen parameters, sperm function and reproductive hormone profiles in infertile men.

MATERIALS AND METHODS

A total of 212 infertile men with idiopathic oligoasthenoteratospermia were randomly assigned to receive 300 mg coenzyme Q10 (Kaneka, Osaka, Japan) orally daily (106 in group 1) or a similar placebo regimen (106 in group 2) during a 26-week period, followed by a 30-week treatment-free phase. Two semen analyses, acrosome reaction test, immunobead test for antisperm antibody, and determination of resting levels of luteinizing hormone, follicle-stimulating hormone, prolactin, testosterone and inhibin B were done in all participants. Blood and seminal plasma total coenzyme Q10 was also assessed.

RESULTS

Significant improvement in sperm density and motility was evident with coenzyme Q10 therapy (each p = 0.01). Using the Kruger classification sperm morphology evaluation revealed an increase in the percent of normal forms in the coenzyme Q10 group (p = 0.07). A positive correlation was found between treatment duration with coenzyme Q10 and sperm count (r = 0.46, p = 0.03) as well as with sperm motility (r = 0.45, p = 0.04) and sperm morphology (r = 0.34, p = 0.04). The coenzyme Q10 group had a significant decrease in serum follicle-stimulating hormone and luteinizing hormone at the 26-week treatment phase (each p = 0.03). By the end of the treatment phase the mean +/- SD acrosome reaction had increased from 14% +/- 8% and 15% +/- 8% to 31% +/- 11% and 16% +/- 10% in the coenzyme Q10 and placebo groups, respectively (p = 0.01).

CONCLUSIONS

Coenzyme Q10 supplementation resulted in a statistically significant improvement in certain semen parameters. However, further studies are needed to draw a final conclusion and evaluate the effect of coenzyme Q10 supplementation on the pregnancy rate.

Evaluation of antioxidant systems (coenzyme Q10 and total antioxidant capacity) in morbid obesity before and after biliopancreatic diversion

Biliopancreatic diversion (BPD) is a surgical procedure performed in patients with untreatable obesity and insulin resistance. The demonstrated metabolic and hormonal results of this procedure include the reversal of insulin resistance; an increase in diet-induced thermogenesis; and modifications of gut hormones, such as gastrin, enteroglucagon, neurotensin, and cholecystokinin. On the other hand, obesity is a condition of increased oxidative stress; however, few studies have investigated antioxidant systems in obese persons with BPD. To evaluate the metabolic status and antioxidant systems in such patients, we studied a group of 11 morbidly obese patients, aged 28 to 62 years, with a mean body mass index (BMI) of 54.71 +/- 2.52 kg/m(2), before and after successful BPD (mean post-BPD BMI, 44.68 +/- 1.51 kg/m(2)). A control group composed of 10 slightly overweight women, with a mean BMI of 28.5 +/- 0.72 kg/m(2), was also studied. Coenzyme Q(10) (CoQ(10)) levels (also normalized for cholesterol levels) and total antioxidant capacity in blood plasma were assessed in these populations. The most striking datum was the extremely low level of CoQ(10) in postoperative period (0.34 +/- 0.16 vs 0.66 +/- 0.09 mug/mL, P = .04); also, the data corrected for cholesterol levels presented the same pattern, with a more marked significance (152.46 +/- 11.13 vs 186.4 +/- 17.98 nmol/mmol, P = .001). This could be due to lipid malabsorption after surgery. In fact, the pre-BPD data present all the metabolic and hormonal characteristics of severe obesity; and after BPD, there was a net improvement in the metabolic parameters. The first pathophysiologic phenomenon seems to be lipid malabsorption that has been argued to be the cause of insulin resistance reversion. This metabolic interpretation is also confirmed by the absence of significant variations of total antioxidant capacity (57.5 +/- 5.3 vs 66 +/- 5.3). The mechanisms of these phenomena remain to be established. These data suggest the importance of correcting postsurgical metabolic complications, in these clinical populations, with CoQ(10) supplementation.