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Overexpression of the calcium-binding protein regucalcin mitigates the age-associated changes in oxidative stress and semen quality

Silva, AMS1; Correia, S1; Vaz, CV1; Socorro, S1; Maia, CJ1

1: CICS-UBI – Health Sciences Research Centre, University of Beira Interior, Covilhã, Portugal

Objective: Age-related alterations, namely the augment in oxidative stress (OS) and the consequent sperm damage, result in decreased sperm quality compromising fertility. Regucalcin (RGN) is a calcium-binding protein whose expression decreases markedly with aging, including in the prostate and testis. RGN has been showing to have beneficial effects on spermatogenesis by suppressing OS and chemical/radiation-induced damage. The present work aims to evaluate whether RGN overexpression prevents the aging-associated decline of male reproductive function.

Material and Methods: Young-adult (3-month-old, 3M) and senescent (9M) transgenic rats overexpressing RGN (Tg-RGN) and their wild-type (Wt) counterparts were used for testicular and epididymal function analysis. Seminiferous tubules (SeT) of Wt and Tg-RGN were isolated, maintained in culture, and the total antioxidant activity (TAC) and lipid peroxidation were analyzed. Whole animals and testes were weighted, and the gonadosomatic index (GI) was determined. Both epididymal sperm parameters and lipid peroxidation were assessed.

Results: Higher TAC and lower lipid peroxidation levels were found in the SeT of Tg-RGN, even in the presence of oxidant stimulus. Both GI and sperm counts were reduced in the senescent Wt rats, contrarily with the observed in the Tg-RGN counterparts. Despite the age-related increase in lipid peroxidation levels in the epidydimal sperm of both Tg-RGN and Wt, senescent Tg-RGN rats presented lower lipid peroxidation relatively to the Wt. Aging did not significantly change sperm motility both in Wt and Tg-RGN animals. However, senescent Tg-RGN rats displayed higher sperm viability, higher frequency of normal sperm morphology and diminished incidence of head and neck/midpiece defects when compared with Wt rats.

Conclusions: The higher TAC and the lower lipid peroxidation found in Tg-RGN comparatively to the Wt counterparts supports the role of RGN in protecting male germ cells from OS. Moreover, aging had a lower impact on the sperm parameters of the Tg-RGN rats, which may be consequence of the lower lipid peroxidation found in the epididymal sperm of these animals. Altogether, these findings indicate that the modulation of RGN levels may alleviate the age-related decline in sperm quality.


Work supported by industry: yes, by Santander Totta (no industry support in study design or execution).

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