Localization of cyclooxygenase-2 in mice testis and assessment of its possible role through suppressing its expression using nimesulide: a preferential cyclooxygenase-2 inhibitor

Cyclooxygenases of ovoviviparous black rockfish (Sebastes schlegelii): Cloning, tissue distribution and potential role in mating and parturition

Prostaglandins are a series of unsaturated fatty acids that play critical roles in regulating reproductive events. The prostaglandins endoperoxide H synthases-1/2 (PGHS-1/2; also named cyclooxygenases-1/2, COX-1/2) catalyse the commitment step in prostaglandin synthesis. However, the of the cox genes in teleosts, especially ovoviviparous teleosts, is still unclear. The aim of the present study was to determine the potential role of cox genes in mating and parturition behaviour using black rockfish (Sebastes schlegelii) as a model species. Two transcripts, cox1 and cox2, were cloned. The phylogenetic analysis results revealed that both cox genes were closely related to mammalian coxs. qPCR analyses of their tissue distribution showed that cox1 was mainly expressed in the heart in both sexes, while cox2 was mainly expressed in the testis and ovary. Detection of cox expression in samples from reproductive-related stages further showed that both cox genes may play important roles in mating and parturition processes. In situ hybridization further detected positive cox mRNA signals in the testis and ovary, where they are known to be involved in mating and parturition behaviour. These data suggest that cox1 and cox2 are crucial in inducing mating, gonad regeneration and parturition behaviour.

Different Chemical Structures and Physiological/Pathological Roles of Cyclooxygenases

This review describes cyclooxygenase (COX), which synthesizes prostanoids that play an important role in living things. The authors conducted a national and international literature review on the subject. The COX enzyme uses arachidonic acid to form prostanoids, which play a role in several physiological and pathological conditions. This enzyme has different isoforms, mainly COX-1 and COX-2. The constitutive isoform is COX-1, while COX-2 is the inducible isoform. Both are expressed in different tissues and at different levels, but they may also coexist within the same tissue. Both isoforms show essentially the same mode of action, but their substrates and inhibitors may differ. The COX-1 isoform, which plays a role in the continuation of physiological events, has an increased expression level in various carcinomas, and the COX-2 isoform, which is increased in inflammatory conditions, is typically expressed at low physiological levels in some tissues such as the brain, kidney, and uterus. In addition to investigating the efficacies of the COX-1 and COX-2 isoforms, the discovery of potential new COX enzymes and their effect continues. This review also looks at the roles of the COX enzyme in certain physiological and pathological conditions.

Non Concurrent Multimodal Stress Decreases Sperm Quality and Motor Activity in Male Wister Albino Rats

Every human being is exposed to the stress in one or the other form in the day to day life. Most of the existing studies on the impact of stress on the male reproduction were assessed by using single stressor, which may lead habituation to that stressor. The present study intends to estimate the consequence of stress on motor activity, sperm quality and histopathology of the testis in stress-induced male rats using multimodal stress one per day. Four weeks old Wister albino rats were randomly split into 4 groups and induced multimodal stress at different ages of life span. After induction of stress serum corticosterone levels, muscle strength and coordination, quality of sperm and histopathology of testes were estimated. Elevated serum corticosterone levels and body weight, reduced muscle strength, coordination. Sperm concentration and motility was significantly reduced and increased morphologically abnormal sperm in stress induced animals but sperm viability was not altered much. Histopathology of testes in stress received animals showed decreased tubular diameter and increased intertubular space. Multimodal stress caused elevated serum corticosterone and body weight, decreased motor activity, sperm quality and degenerative changes in the testis

Cyclooxygenase-2 is acutely induced by CCAAT/enhancer-binding protein β to produce prostaglandin E 2 and F 2α following gonadotropin stimulation in Leydig cells

Cyclooxygenase 2 (COX-2) is an inducible rate-limiting enzyme for prostanoid production. Because COX-2 represents one of the inducible genes in mouse mesenchymal stem cells upon differentiation into Leydig cells, we investigated COX-2 expression and production of prostaglandin (PG) in Leydig cells. Although COX-2 was undetectable in mouse testis, it was transiently induced in Leydig cells by human chorionic gonadotropin (hCG) administration. Consistent with the finding that Leydig cells expressed aldo-keto reductase 1B7 (PGF synthase) and PGE synthase 2, induction of COX-2 by hCG caused a marked increase in testicular PGF _2α and PGE ₂ levels. Using mouse Leydig cell tumor-derived MA-10 cells as a model, it was indicated by reporter assays and electron mobility shift assays that transcription of the COX-2 gene was activated by CCAAT/enhancer-binding protein β (C/EBPβ) with cAMP-stimulation. C/EBPβ expression was induced by cAMP-stimulation, whereas expression of C/EBP homolog protein (CHOP) was robustly downregulated. Transfection of CHOP expression plasmid inhibited cAMP-induced COX-2 promoter activity. In addition, CHOP reduced constitutive COX-2 expression in other mouse Leydig cell tumor-derived TM3 cells. These results indicate that COX-2 is induced in Leydig cells by activation of C/EBPβ via reduction of CHOP expression upon gonadotropin-stimulation to produce PGF _2α and PGE ₂ .

Expression of PTGS2, PGFS and PTGFR during downregulation and restart of spermatogenesis following GnRH agonist treatment in the dog

Prostaglandins (PGs) and prostaglandin endoperoxide synthase (PTGS) are considered to be relevant for spermatogenesis and steroidogenesis. PTGS2, prostaglandin F synthase (PGFS) and PGF receptor (PTGFR) are investigated in the adult male dog using the model of the GnRH-agonist implant downregulated canine testis and its subsequent restart of spermatogenesis following abolition of treatment (3, 6, 9, 12 weeks after implant removal). On the mRNA level (ratio), PTGS2, PGFS and PTGFR expression did not differ between downregulation, different stages of recovery of spermatogenesis and untreated adult controls (CG). On the protein level, Sertoli and Leydig cells in all samples and some peritubular cells stained immunopositive for PTGS2. In the tubular compartment, the percentage of the PTGS2-immunopositive area (PIA) and the mean PTGS2-staining intensity (gray scale, GS) did not differ between groups but in the interstitial compartment, the PIA (p = 0.0494) and the GS (p < 0.0001) were significantly upregulated during early recrudescence (week 3/6). Comparing downregulation by two GnRH-agonist implants with juvenile controls (JG) and CG, the mRNA expression (ratio) did not differ. In the tubular compartment, the GS (p = 0.0321) was significantly higher at downregulation compared to CG and in the interstitial compartment, the PIA (p = 0.0073) and the GS (p = 0.0097) were significantly higher in JG compared to downregulation/CG. PTGS2, PGFS and PTGFR mRNA and PTGS2 protein are regularly expressed in the adult, juvenile and downregulated canine testis and downregulation and subsequent recrudescence affect PTGS2 protein expression mainly in Leydig cells. PTGS2 expression in the downregulated testis resembles the one in seasonal Syrian hamster but not juvenile canine testis.

Cyclooxygenase and prostaglandins in somatic cell populations of the testis

Prostaglandins (PGs) are synthesized through the action of the rate-limiting enzyme cyclooxygenase (COX) and further specific enzymes. The development ofCox-deficient mice in the 1990s gave insights into the reproductive roles of PGs. FemaleCox-knockout mice were subfertile or infertile. Interestingly, fertility was not affected in male mice deficient inCox, suggesting that PGs may not be critical for the functioning of the testis. However, this conclusion has recently been challenged by observations of important roles for PGs in both physiological and pathological processes in the testis. The two key somatic cell types in the testis, Leydig and Sertoli cells, express the inducible isoenzyme COX2 and produce PGs. Testicular COX2 expression in these somatic cells is regulated by hormonal input (FSH, prolactin (PRL), and testosterone) as well as by IL1β. PGs modulate steroidogenesis in Leydig cells and glucose uptake in Sertoli cells. Hence, the COX2/PG system in Leydig and Sertoli cells acts as a local modulator of testicular activity, and consequently may regulate spermatogenic efficiency. In addition to its expression in Leydig and Sertoli cells, COX2 has been detected in the seminiferous tubule wall, and in testicular macrophages and mast cells of infertile patients. These observations highlight the possible relevance of PGs in testicular inflammation associated with idiopathic infertility. Collectively, these data indicate that the COX2/PG system plays crucial roles not only in testicular physiology (i.e., development, steroidogenesis, and spermatogenesis), but more importantly in the pathogenesis or maintenance of infertility status in the male gonad. Further studies of these actions could lead to new therapeutic approaches to idiopathic male infertility.

Free German abstract

A German translation of this abstract is freely available athttp://www.reproduction-online.org/content/149/4/R169/suppl/DC1.

Free Spanish abstract

A Spanish translation of this abstract is freely available athttp://www.reproduction-online.org/content/149/4/R169/suppl/DC2.

Evaluation of the reproductive toxicity of naproxen sodium and meloxicam in male rats

Nonsteroidal anti-inflammatory drugs that are cyclooxygenase (COX) enzyme inhibitors have generally been used in short-term pain management and also to treat inflammation chronically. It is known that COX enzyme and prostaglandins play important roles in the regulation of reproductive functions in females. However, there are relatively few studies for the male reproductive system, and the results of these studies are contradictory. In this study, sperm count and motility, COX-1, COX-2, prostaglandin E1 (PGE1), prostaglandin E2 (PGE2), and prostaglandin F2α (PGF2α) levels in testis tissue, plasma follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone levels, and histopathological examination of testis tissue were evaluated after naproxen sodium and meloxicam administration in male rats. Also, testis superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and glutathione (GSH) levels were measured to investigate the oxidation status. According to our results, sperm count and motility were significantly decreased in treatment groups. Plasma hormone levels did not show any statistical differences between the groups. COX-1, PGE2, and PGF2α levels were significantly decreased, while the decreases in COX-2 and PGE1 levels did not show any significance statistically. Testis SOD, catalase, GPx, and GSH levels were decreased significantly. According to the results of histopathological examination, damage in seminiferous tubules, where spermatogenesis developed, was observed. In conclusion, naproxen sodium and meloxicam decreased the sperm count and motility and also induced the damage of seminiferous tubules as a direct effect without affecting plasma hormone levels in our study. The mechanism of the reproductive toxicity induced by these agents may be based on the inhibition of prostaglandin synthesis and the induction of oxidative stress can be emphasized as a secondary factor.

Immunopresence and enzymatic activity of nitric oxide synthases, cyclooxygenases and PGE2-9-ketoreductase and in vitro production of PGF2α, PGE2 and testosterone in the testis of adult and prepubertal alpaca (Lama pacos)

This study presents the first evidence for differences in COXs, PGE2-9-ketoreductase and NOSs immunopresence and enzyme activity, and prostaglandin and testosterone production between the testes of adult and prepubertal alpacas. The prepubertal testis immunohistochemical data revealed that COX1 was expressed in spermatogonia and endothelial cells whereas COX2 was present only in the stromal cells. In adult animals, COX2 immunosignals were evidenced in germ cells, as well as both COX1 and -2 in Leydig and Sertoli cells. In adult testes, the spermatogonia, spermatocytes and round spermatids had expression of e- and n-NOS only, whereas elongated spermatids exhibited immunopositivity for i- and e-NOS and Sertoli cells expressed only n-NOS. In prepubertal alpacas, i-NOS was localized in spermatogonia, e-NOS in Sertoli cells and all three NOS isoforms in Leydig cells. PGE2-9-ketoreductase immunopresence was observed in spermatogonia nuclei and cytoplasm of prepubertal testis whereas they were localized in spermatid acrosomal vesicle of adult. The enzymatic data indicated that COX1 activity was higher than COX2 in adult alpaca testis whereas the activity of COX2 was greater than that of COX1 in prepubertal animals. Total NOS and PGE2-9-ketoreductase activities were more extensive in adult alpacas. In vitro hormone production results showed that prepubertal testes released lower amounts of testosterone and PGF2α while PGE2 synthesis was six times more elevated than in in vitro incubated adult testes. Taken together, the data on COX2, i-NOS and PGE2 led us to hypothesize that development in prepubertal male reproductive tissues utilizes a mechanism similar to that of inflammation.

In vitro effects of gonadotropin-releasing hormone (GnRH) on Leydig cells of adult alpaca (Lama pacos) testis: GnRH receptor immunolocalization, testosterone and prostaglandin synthesis, and cyclooxygenase activities

The main objective of this study was to examine the modulatory in vitro effects of gonadotropin-releasing hormone (GnRH) on isolated Leydig cells of adult alpaca (Lama pacos) testis. We first evaluated the presence of GnRH receptor (GnRHR) and cyclooxygenase (COX) 1 and COX2 in alpaca testis. We then studied the in vitro effects of buserelin (GnRH analogue), antide (GnRH antagonist), and buserelin plus antide or inhibitor of phospholipase C (compound 48/80) and COXs (acetylsalicylic acid) on the production of testosterone, PGE(2), and PGF(2α) and on the enzymatic activities of COX1 and COX2. Immunoreactivity for GnRHR was detected in the cytoplasm of Leydig cells and in the acrosomal region of spermatids. COX1 and COX2 immunosignals were noted in the cytoplasm of spermatogonia, spermatocytes, spermatids, Leydig cells, and Sertoli cells. Western blot analysis confirmed the GnRHR and COX1 presence in alpaca testis. The in vitro experiments showed that buserelin alone increased (P < 0.01) and antide and buserelin plus acetylsalicylic acid decreased (P < 0.01) testosterone and PGF(2α) production and COX1 activity, whereas antide and compound 48/80 counteracted buserelin effects. Prostaglandin E(2) production and COX2 activity were not affected by buserelin or antide. These data suggest that GnRH directly up-regulates testosterone production in Leydig cells of adult alpaca testis with a postreceptorial mechanism that involves PLC, COX1, and PGF(2α).

Immunology of the Testis and Male Reproductive Tract

A large body of evidence points to the existence of a close, dynamic relationship between the immune system and the male reproductive tract, which has important implications for our understanding of both systems. The testis and the male reproductive tract provide an environment that protects the otherwise highly immunogenic spermatogenic cells and sperm from immunological attack. At the same time, secretions of the testis, including androgens, influence the development and mature functions of the immune system. Activation of the immune system has negative effects on both androgen and sperm production, so that systemic or local infection and inflammation compromise male fertility. The mechanisms underlying these interactions have begun to receive the attention from reproductive biologists and immunologists that they deserve, but many crucial details remain to be uncovered. A complete picture of male reproductive tract function and its response to toxic agents is contingent upon continued exploration of these interactions and the mechanisms involved.

Testosterone induction of prostaglandin-endoperoxide synthase 2 expression and prostaglandin F(2alpha) production in hamster Leydig cells

We have previously observed expression of prostaglandin-endoperoxide synthase 2 (PTGS2), the key enzyme in the biosynthesis of prostaglandins (PGs), in reproductively active Syrian hamster Leydig cells, and reported an inhibitory role of PGF(2alpha) on hamster testicular steroidogenesis. In this study, we further investigated PTGS2 expression in hamster Leydig cells during sexual development and photoperiodic gonadal regression. Since PTGS2 is mostly expressed in pubertal and reproductively active adult hamsters with high circulating levels of LH and androgens, we studied the role of these hormones in the regulation/maintenance of testicular PTGS2/PGF(2alpha). In active hamster Leydig cells, LH/hCG and testosterone induced PTGS2 and PGF(2alpha) production, and their actions were abolished by the antiandrogen bicalutamide (Bi). These results indicate that LH does not exert a direct effect on PG synthesis. Testosterone also stimulated phosphorylation of the mitogen-activated protein kinase isoforms 3/1 (MAPK3/1) within minutes and hours, but the testosterone metabolite dihydrotestosterone had no effect on PTGS2 and MAPK3/1. Because Bi and U0126, an inhibitor of the MAP kinase kinases 1 and 2 (MAP2K1/2), abolished testosterone actions on MAPK3/1 and PTGS2, our studies suggest that testosterone directly induces PTGS2/PGF(2alpha) in hamster Leydig cells via androgen receptors and a non-classical mechanism that involves MAPK3/1 activation. Since PGF(2alpha) inhibits testosterone production, it might imply the existence of a regulatory loop that is setting a brake on steroidogenesis. Thus, the androgen environment might be crucial for the regulation of testicular PG production at least during sexual development and photoperiodic variations in hamsters.

Effects of chronic celecoxib on testicular function in normal and lipopolysaccharide-treated rats

Celecoxib (Celebrex), an inhibitor of cyclooxygenase-2 (COX-2; prostaglandin-endoperoxide synthase 2; EC 1.14.99.1), is widely used in the treatment of chronic inflammation and pain. COX-2 is constitutively expressed in the testis, where it is responsible for prostaglandin production, so inhibition of this enzyme should have effects on testicular function. The effects of administering celecoxib (oral with feed, 0.15% w/w) for 5 weeks on normal testis function and the response to low dose (0.1 mg/kg body weight) or high dose (5.0 mg/kg) lipopolysaccharide (LPS) were examined in adult male rats. Celecoxib caused a 60% reduction in testicular interstitial fluid (IF) prostaglandin E(2) (PGE(2)) concentrations, accompanied by a compensatory increase in COX-2 mRNA expression. Celecoxib increased IF volume by 30%, but had no effect on testis weight, testis morphology or serum testosterone levels. In the celecoxib-fed rats, the dose-dependent inhibitory effects of LPS on testis weight, IF volume and serum testosterone levels were significantly diminished. However, celecoxib had no effect on COX-2 protein levels or LPS-induced expression of the inflammatory mediators interleukin-1beta, tumour necrosis factor-alpha or inducible nitric-oxide synthase. A similar lack of inhibition of LPS-induced cytokine expression by another COX-2 inhibitor, NS-398, was observed in vitro. These data indicate that celecoxib reduces intratesticular activity of COX-2 (as indicated by PGE(2) levels) and inhibits IF formation in the testis, but has no appreciable effect on steroidogenesis or spermatogenesis, at least in the short term. Celecoxib does not appear to alter the ability of the testis to mount an inflammatory response but opposes the deleterious effects of inflammation on IF formation and testosterone production. These results indicate significant roles for products of the COX-2 pathway in testicular vascular control and steroidogenesis, which may have implications for men with marginal fertility taking celecoxib for extended periods, but also highlight the potential of this drug to ameliorate testicular damage caused by systemic or local inflammation.