Normal Responses to Restraint Stress in Mice Lacking the Gene for Neuronal Nitric Oxide Synthase

Department of Pharmacology, Israel Institute for Biological Research, Ness Ziona, Israel.
Journal of Andrology (Impact Factor: 2.47). 04/2009; 30(5):614-20. DOI: 10.2164/jandrol.108.007443
Source: PubMed

ABSTRACT The hormonal changes associated with immobilization stress (IMO) include a swift increase in corticosterone (CORT) concentration and a decrease in circulating testosterone (T) levels. There is evidence that the production of the short-lived neuromodulator nitric oxide (NO) is increased during stress in various tissues, including the brain. NO also suppresses the biosynthesis of T. Both the inducible and the neuronal isoforms of NO synthase (iNOS and nNOS, respectively) have been implicated in this suppression, but the evidence has not been conclusive. We used adult wild-type (WT) and nNOS knockout male mice (nNOS-/-) to assess the respective roles of CORT and nNOS-derived NO in stress mediated inhibition of T production. Animals were assigned to either basal control or 3-hour IMO groups. No difference in basal plasma and testicular T levels were observed between WT and nNOS-/-, although testicular weights of mutant mice were slightly lower compared to WT animals. The plasma contents of luteinizing hormone (LH) and CORT in unstressed mice of both genotypes were similar. Exposure to 3 hours of IMO increased plasma CORT and decreased T concentrations in mice of both genotypes. However, comparable levels of plasma LH and testicular nitrite and nitrate (NOx), NO stable metabolites, were detected in control and stressed WT and nNOS-/- mice. Adrenal concentrations of NOx declined after IMO, but the reduction was not statistically significant. These findings implicate CORT rather than NO generated by nNOS in the rapid stress-induced suppression of circulating T.

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Available from: Costantino Iadecola, Mar 28, 2015
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    • "It affects various physiological processes including reproductive functions. Numerous studies in human and experimental animals have shown that stress cause adverse effects in the male reproductive system: 1) erectile dysfunction (Nathan, 1986; Kennedy et al., 1999; Ernst et al., 1993), 2) decrease of sperm quality (Almeida et al., 1998; Clarke et al., 1999; Priya and Reddy, 2012; Priya et al., 2014; Rao et al., 2015; Zhang et al., 2015), 3) decrease of testosterone levels (Orr and Mann, 1990; Retana-Marquez et al., 2003; Weissman et al., 2009; Lin et al., 2014; Prabsattroo et al., 2015), and 4) damage to testicular tissue (Rai et al., 2003; 2004; Aziz et al., Journal of Zhejiang University-SCIENCE B (Biomedicine & Biotechnology) ISSN 1673-1581 (Print); ISSN 1862-1783 (Online); "
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    ABSTRACT: Objective: To investigate male reproductive parameters via changes of potentially testicular protein markers in restraint stress rats. Methods: Male Sprague-Dawley rats were divided into two groups (non-immobilized control and restraint-immobilized/stress groups, n=8 each group). The stress animals were immobilized (12 h/d) by a restraint cage for 7 consecutive days. All reproductive parameters, morphology and histology were observed and compared between groups. In addition, the expressions of steroidogenic acute regulatory (StAR) and phosphotyrosine proteins (previously localized in Sertoli and late spermatid cells) in testicular lysate were assayed by immuno-western blotting. Results: Testosterone level, sperm concentration and sperm head normality of stress rats were significantly decreased while the corticosterone level was increased as compared with the control (P<0.05). Histologically, stress rats showed low sperm mass in epididymal lumen and some atrophy of seminiferous tubules. Although the expression of testicular StAR proten was not significantly different between groups, changed patterns of the 131, 95, and 75 kDas testicular phosphorylated proteins were observed in the stress group compared to the control group. The intensity of a testicular 95 kDa phosphorylated protein was significantly decreased in stress rats. Conclusions: This study has demonstrated the alteration of testicular phosphorylated protein patterns, associated with adverse male reproductive parameters in stress rats. It could be an explanation of some infertility in stress males.
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    ABSTRACT: The role of the structural complexity of the testis and the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) signalling pathway was analysed in adult male rats exposed to acute and repeated immobilization stress (IMO). In whole testis preparations, exposure to acute and repeated IMO caused an increase in NO production. In contrast, NO production was inhibited in interstitial cell preparations after exposure to all types of stress. In purified Leydig cell preparations, NO production was inhibited only after exposure to prolonged IMO. These findings indicate that biologically active compounds released from various testicular compartments exert both stimulatory and inhibitory effects on NO production. TaqMan Low Density Array of rat phosphodiesterases revealed a decrease in the expression of cGMP-specific phosphodiesterase 5 (PDE5) in Leydig cells of animals exposed to repeated IMO. In contrast, the expression of cGMP-dependent protein kinase type I (PKG I), total and phosphorylated steroidogenic acute regulatory protein (StAR), and PKG I/StAR immunoprecipitated complex was increased during repeated exposure to IMO. The increase in both total and phosphorylated StAR formation was effectively blocked by inhibition of PKG I in vitro. Thus, increased expressions of PKG I and StAR complex, accompanied by decreased PDE5 activity, suggest that the NO-cGMP signalling pathway and consequent activation of the StAR protein regulate the adaptive response of Leydig cells to repeated IMO stress.
    International Journal of Andrology 10/2010; 33(5):717-29. DOI:10.1111/j.1365-2605.2009.01018.x · 3.70 Impact Factor
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    ABSTRACT: The molecular mechanism of stress-associated reproductive dysfunction is complex and largely unknown. This study was designed to systematically analyze molecular effects of systemic in vivo blockade of α1-adrenergic receptors (α1-ADRs) on stress-induced disturbance of cAMP/cGMP signaling in testosterone-producing Leydig cells using the following parameters (1) level of circulating stress hormones, LH & testosterone; (2) level of main molecular markers of Leydig cells functionality (testosterone, Insl3, cAMP); (3) expression of cAMP signaling (cAMP "producers"/"effectors"/"removers"); (4) expression of NO-cGMP signaling (NO-cGMP "producers"/"effectors"/"removers"). The results showed that oral administration of α1-ADRs blocker before stress increased cGMP and diminished stress-reduced cAMP production in Leydig cells. In the same cells, stress-induced effects on cAMP/cGMP signaling pathways elements were changed. Sustained in vivo α1-ADRs blockade completely abolished stress-increased transcription of most abundantly expressed phosphodiesterase that remove cAMP (Pde4b) and potentiated stress-increased expression of PRKA, the main stimulator of Leydig cells steroidogenesis. In the same Leydig cells, stress-decreased NOS3 expression was abolished, while stress-increased GUCY1 (cGMP "producer") and PRKG1 (cGMP "effector") were potentiated. It is possible that all molecules mentioned could contribute, at least in part, in recovery of Leydig cells testosterone production. Presented data provide new role of α1-ADRs in stress-triggered disturbance of cAMP/cGMP signaling, and new molecular insights into the relationship between stress and mammalian reproduction. Regardless of whether the effects of α1-blocker+stress are direct or indirect, the results are important in terms of human reproductive health and the wide use of α1-ADRs antagonists, alone or in combination, to treat posttraumatic stress disorders, hypertension, benign prostatic hyperplasia symptoms and potential drugs for prostate cancer prevention/treatment.
    Molecular Human Reproduction 07/2013; 20(1). DOI:10.1093/molehr/gat052 · 3.75 Impact Factor
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