Basic nutritional investigationDietary lipids modify redox homeostasis and steroidogenic status in rat testis
Introduction
During previous decades great interest was focused on the relation between lipid metabolism and the atherogenic condition as a cause of different vascular-related diseases [1]. However, much less attention was given to the role played by lipid metabolism in other human pathologies, especially those involved in reproductive function. Disorders associated with male infertility have exhibited an increased incidence during the past few years, due to many concomitant factors not fully understood or even recognized [2].
It is well known that testicular lipids strongly influence the histology and physiology of this tissue [3], [4], [5]. Essential fatty acid deficiency [6], [7] or alterations in fatty acid metabolism in diabetic patients [7] have been associated with testicular malfunction. Moreover, it was previously demonstrated that polyunsaturated fatty acid (PUFA) supplementation to diets produced significant changes in testicular lipid composition, modifying the metabolism of C20–22 fatty acids with a strong impact on the physiology of germinal and steroidogenic cells [3], [5]. In addition, lipids have been closely associated with intracellular generation of reactive oxygen species [8] as substrates for oxidative attack and a source for free radical generation and/or chain propagator reactions. This “two-face” characteristic of lipids depends on multiple factors; one of them is the quantity and quality of the fatty acyl chains acylated to complex cellular lipids [8], [9], [10]. Several reports demonstrated that under oxidative stress conditions testes are especially susceptible to develop damage derived from the redox imbalance [11], [12], [13], [14], [15], [16], [17]. This fact is considered one of the most important features in the etiology of human reproductive illnesses of high incidence such as varicocele [2], [18].
However, strong differences in the lipid composition of diets across the world have been poorly studied from the point of view of their influence on the relation between free radical generation and testicular steroidogenesis. Thus, the lipid composition of testes (modifiable by the diet), the regulation of reactive oxygen species (and other reactive species), and the testicular integrity and function are closely related factors.
In this study we investigated the effect of diet-induced modification of testicular lipids on the generation of reactive oxygen species and the activity of the main steroidogenic enzymes (3β- and 17β-hydroxysteroid dehydrogenases [3β-HSD and 17β-HSD]). Results obtained may contribute to the understanding of the role played by dietary lipid sources on testicular function and its relation to redox homeostasis.
Section snippets
Chemicals
Solvents (high-performance liquid chromatographic grade) were provided by Carlo Erba (Milano, Italy). Other chemicals were from Sigma Chemical Co. and Fluka Chemie AG (Buenos Aires, Argentina).
Lipids used as standards were from Serdary Research Laboratory (London, ON, Canada) or Nu-Check-Prep (Elysian, MN, USA). Commercial oils added to diets were from Molinos Río de La Plata SAIC and Platafarm SA (La Plata, Argentina).
Diets and animal treatment
Female Wistar rats weighing 180 ± 10 g were bred and maintained on a control
Influence of diet on growth parameters
Feeding parameters associated to diets are listed in Table 3. Animals fed the different diets showed almost identical water consumption (approximately 15 mL/d) and food intake (approximately 15 g/d). Initial body weight was similar in all groups. However, final body weight, rate of body weight gain, and food efficiency ratio were significantly elevated in the C group compared with the others. Absolute and relative testicular weights were significantly increased in the O group compared with the
Discussion
In this study we examined the relation among testicular antioxidant status, steroidogenic function, and lipid composition of the diet. The oils selected are widely used all over the world. The S and G oils were characterized by a high content of linoleic acid. However, in both diets the ω-6/ω-3 fatty acid ratio was markedly different. Soybean and fish oils showed similar high levels of ω-3 acids, but the former is more advantageous due to the lack of cholesterol. Therefore the S and G groups
Conclusion
The present results indicate that there is a close relation among the source of dietary oil, the antioxidant defense system status, and the steroidogenic function of the testis. According to our results the consumption of an appropriate mixture of olive and soybean oils could be a healthy eating recommendation.
Acknowledgments
The authors are grateful to Eva Illara de Bozzolo for excellent technical assistance and Norma Tedesco for language revision.
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This study was supported in part by grants from CIC and CONICET, Argentina.