The opposite roles of glucocorticoid and α₁-adrenergic receptors in stress triggered apoptosis of rat Leydig cells

Abstract

The stress-induced initiation of proapoptotic signaling in Leydig cells is relatively well defined, but the duration of this signaling and the mechanism(s) involved in opposing the stress responses have not been addressed. In this study, immobilization stress (IMO) was applied for 2 h daily, and animals were euthanized immediately after the first (IMO1), second (IMO2), and 10th (IMO10) sessions. In IMO1 and IMO2 rats, serum corticosterone and adrenaline were elevated, whereas serum androgens and mRNA transcription of insulin-like factor-3 in Leydig cells were inhibited. Reduced oxygen consumption and the mitochondrial membrane potential coupled with a leak of cytochrome c from mitochondria and increased caspase-9 expression, caspase-3 activity, and number of apoptotic Leydig cells was also observed. Corticosterone and adrenaline were also elevated in IMO10 rats but were accompanied with a partial recovery of androgen secretion and normalization of insulin-like factor-3 transcription coupled with increased cytochrome c expression, abolition of proapoptotic signaling, and normalization of the apoptotic events. Blockade of intratesticular glucocorticoid receptors diminished proapoptotic effects without affecting antiapoptotic effects, whereas blockade of intratesticular ␣1-adrenergic receptors diminished the antiapoptotic effects without affecting proapoptotic effects. These results confirmed a critical role of glucocorticoids in mitochondria-dependent apoptosis and showed for the first time the relevance of stress-induced upregulation of ␣ 1-adrenergic receptor expression in cell apoptotic resistance to repetitive IMOs. The opposite role of two hormones in control of the apoptotic rate in Leydig cells also provides a rationale for a partial recovery of androgen production in chronically stressed animals. Leydig cells; immobilization stress; corticosterone; adrenaline; testis; apoptosis THE LEVELS OF TESTOSTERONE (T) in circulation reflect the steroidogenic capacity of individual testicular Leydig cells and the total number of these cells per testes (2,3,10,16). Because Leydig cells from adult animals are fully differentiated and rarely proliferate or die under normal physiological conditions, their steroidogenic capacity is controlled predominantly by the status of the hypothalamo-pituitary-gonadal axis via GnRH-LH secretory pathway (10, 23). The sustained stress lowers circulating LH and androgen levels (13,40,42), and acute stress also lowers T levels without changing circulating LH levels (35, 42). Furthermore, the reciprocal changes in plasma corticosterone (CORT) and T in stressed rats (45) and increase in steroidogenic capacity of Leydig cells induced by suppression of CORT levels (19) suggested that this stress hormone directly inhibits T biosynthesis.Several hypotheses have also been introduced to explain the mechanism by which glucocorticoids directly inhibit androgenesis. The CORT-induced decline in steroidogenic capacity could reflect inhibition of the expression (48) and activity (47) of T-biosynthetic...

Interactive Effect of Corticosterone and Lactate on Regulation of Testosterone Production in Rat Leydig Cells

“…A). Since glucocorticoid treatment has been shown to trigger the apoptosis in rat Leydig cells (Andric et al, ), we measured the viability of Leydig cells upon exposure to CORT for 1 h. Result showed that CORT at the doses from 10 −9 to 10 −4 M did not cause any adverse effects on survival of Leydig cells (Fig. B).…”

Sustained in vivo blockade of α1-adrenergic receptors prevented some of stress-triggered effects on steroidogenic machinery in Leydig cells

“…Rats were handled daily during a 3-wk period of acclimation before experiments. Immobilization stress (IMO) was performed in the morning (from 0800 to 1000) by the method of Kvetnansky (39) described previously (5,36,37,72). Briefly, IMO rats were bound in the supine position by fixing the ras' limbs by thread to a wooden board, but head motion was not limited.…”

“…Primary cultures of purified Leydig cells were obtained from all experimental groups as described previously (5,72,73). The proportion of Leydig cells present in culture was 95.3 Ϯ 1.7% as determined by staining for HSD3B activity.…”

“…reproductive function is well documented (5,21,23,24,36,37,49,55,70,72). A sharp decline of serum testosterone is one of the first signs of IMO.…”

“…IMO was chosen as a typical and frequently used model of psychophysiological stress (5,36,37,39,49,72). The IMO sessions, established and justified previously (5,36,37,39,72), include the acute (1ϫIMO) and repeated stress without (2ϫIMO) or with (10ϫIMO) partial recovery of circulating T levels. The focus in our study was on the role of ␣ 1 -ADRs in stress-induced disturbance and/or recovery of Leydig cell steroidogenic machinery.…”