Senescence and autophagy relation with the expressional status of non-canonical estrogen receptors in testes and adrenals of roe deer (Capreolus capreolus) during the pre-rut period

Abstract

The roe deer bucks represent a spontaneous model to study the synchronized testicular involution and recrudescence cycles. However, cellular processes and hormonal control of steroidogenic glands are scarcely known. For the present study testes and adrenal glands obtained from roe deer during the pre-rut season were used. We aimed to determine (i) senescence and autophagy involvement in testis atrophy (immunohistochemical analysis for tumor suppressor protein encoded by the cyclin-dependent kinase inhibitor 2A; p16 and microtubule-associated protein 1A/1B-light chain 3; LC3, respectively), (ii) the size of the adrenal cortex and medulla (morphometric analysis), (iii) G-protein coupled estrogen receptor (GPER) and estrogen-related receptors (ERRs; type α, β, and Y) distribution and expression (qRT-PCR and immunohistochemical analyses) and (iv) serum testosterone and estradiol levels (immunoassay ELISA). This study revealed pre-rut characteristics of testis structure with the presence of both senescence and autophagy-positive cells and higher involvement of senescence, especially in spermatogenic cells (P < 0.05). In the adrenal cortex, groups of cells exhibiting shrinkage were observed. The presence of ERRs in cells of the seminiferous epithelium and interstitial Leydig cells and GPER presence distinctly in Leydig cells was revealed. In adrenals, these receptors were localized in groups of normal-looking cells and those with shrinkage. Morphometric analysis showed differences in cortex width which was smaller (P < 0.05) than that of the medulla. A weak immunohistochemical signal was observed for ERRβ when compared to ERRα and ERRγ. The mRNA expression level of ERRα and ERRγ was lower (P < 0.001 and P < 0.05, respectively) while ERRβ was higher (P < 0.001) in adrenals when compared to testes. mRNA GPER expression was similar in both glands. In the pre-rut season, the testosterone level was 4.89 ng/ml while the estradiol level was 0.234 ng/ml. We postulate that: (i) senescence and autophagy may be involved in both reinitiation of testis function and/or induction of abnormal processes, (ii) hormonal modulation of testis inactivity may affect adrenal cortex causing cell shrinkage, (iii) ERRs and GPER localization in spermatogenic cells and interstitial cells, as well as cortex cells, may maintain and control the morpho-functional status of both glands, and (iv) androgens and estrogens (via ERRs and GPER) drive cellular processes in the testis and adrenal pre-rut physiology.

Keywords: Adrenals; Autophagy; Estrogen related-receptors; G-protein coupled estrogen receptor; Roe deer; Senescence; Testis.