Proliferative and Apoptotic Pathways in the Testis of Quail Coturnix coturnix during the Seasonal Reproductive Cycle

Abstract

The quail Coturnix coturnix is a seasonal breeding species, with the annual reproductive cycle of its testes comprising an activation phase and a regression phase. Our previous results have proven that the testicular levels of both 17β-estradiol (E2) and androgens are higher during the reproductive period compared to the non-reproductive period, which led us to hypothesize that estrogens and androgens may act synergistically to initiate spermatogenesis. The present study was, therefore, aimed to investigate the estrogen responsive system in quail testis in relation to the reproduction seasonality, with a focus on the molecular pathways elicited in both active and regressive quail testes. Western blotting and immunohistochemistry analysis revealed that the expression of ERα, which is the predominant form of estrogen receptors in quail testis, was correlated with E2 concentration, suggesting that increased levels of E2-induced ERα could play a key role in the resumption of spermatogenesis during the reproductive period, when both PCNA and SYCP3, the mitotic and meiotic markers, respectively, were also increased. In the reproductive period we also found the activation of the ERK1/2 and Akt-1 kinase pathways and an increase in second messengers cAMP and cGMP levels. In the non-reproductive phase, when the E2/ERα levels were low, the inactivation of ERK1/2 and Akt-1 pathways favored apoptotic events due to an increase in the levels of Bax and cytochrome C, with a consequent regression of the gonad.

Effects of a high‐fat diet on rat epididymis

“…We speculated that the promotion of apoptosis might be a strategy to eliminate dysfunctional cells arising as a result of HFD‐induced oxidative stress. However, apoptosis might also be induced by the inhibition of the Akt signaling pathway (Falvo et al, 2021; Kang et al, 2020; Wu et al, 2020). Our findings showed that pAkt levels were lower in the corpus of the epididymis of HFD rats.…”

“…Several studies have shown that PCNA is regulated by the Akt signaling pathways in the testis. Specifically, the inhibition of the Akt pathway downregulates the expression of PCNA (Falvo et al, 2021; Lim et al, 2019). The increase in apoptosis and decrease in proliferation in HFD rat epididymis were supported by the reduction in epididymal tissue weight observed in this group.…”

Cocaine Effects on Reproductive Behavior and Fertility: An Overview

“…The levels of these two hormones are strongly correlated since 17-β estradiol is produced via the aromatization of testosterone of the key enzyme P450 aromatase [ 47 , 48 ]. In rats, a daily subcutaneously administration of cocaine hydrochloride (30 or 15 mg/Kg) for a minimum of 72 days induced a decrease in the levels of estrogens (E2), which in males are key hormones in cell differentiation processes, such as spermiohistogenesis [ 49 , 50 , 51 , 52 , 53 ], and at high dose induced an increase in the percentage of spermatozoa having heads separated from the tail [ 54 ]. It was assumed that the reduction in E2 levels was due to decreased body weight rather than a direct drug-related effect.…”