Probiotic Microbes Sustain Youthful Serum Testosterone Levels and Testicular Size in Aging Mice

The decline of circulating testosterone levels in aging men is associated with adverse health effects. During studies of probiotic bacteria and obesity, we discovered that male mice routinely consuming purified lactic acid bacteria originally isolated from human milk had larger testicles and increased serum testosterone levels compared to their age-matched controls. Further investigation using microscopy-assisted histomorphometry of testicular tissue showed that mice consuming Lactobacillus reuteri in their drinking water had significantly increased seminiferous tubule cross-sectional profiles and increased spermatogenesis and Leydig cell numbers per testis when compared with matched diet counterparts This showed that criteria of gonadal aging were reduced after routinely consuming a purified microbe such as L. reuteri. We tested whether these features typical of sustained reproductive fitness may be due to anti-inflammatory properties of L. reuteri, and found that testicular mass and other indicators typical of old age were similarly restored to youthful levels using systemic administration of antibodies blocking pro-inflammatory cytokine interleukin-17A. This indicated that uncontrolled host inflammatory responses contributed to the testicular atrophy phenotype in aged mice. Reduced circulating testosterone levels have been implicated in many adverse effects; dietary L. reuteri or other probiotic supplementation may provide a viable natural approach to prevention of male hypogonadism, absent the controversy and side-effects of traditional therapies, and yield practical options for management of disorders typically associated with normal aging. These novel findings suggest a potential high impact for microbe therapy in public health by imparting hormonal and gonad features of reproductive fitness typical of much younger healthy individuals.     

Rôle du peptide vasoactif intestinal (VIP) dans la stéroïdogenèse et le vieillissement testiculaire

VIP (vasoactive intestinal peptide) neuropeptide has long been considered to be putative regulator of testicular functions.In vitro evidence suggests that VIP could play an important role in testosterone biosynthesis. However, the endogenous role of VIP on testicular functions remained to be demonstrated. In C57BL/6 mice exhibiting complete disruption of the VIP gene, the authors observed that male fertility remained intact but serum testosterone levels were lower than those of WT littermates. At the age of 4 months, this phenotype was accompanied by reduced steroidogenesis due to inhibition of the expression of StAR (steroidogenic acute regulatory protein) and 3ßHSD (3ß-hydroxysteroid dehydrogenase) in the testis. In addition, serum levels of FSH (Follicle-stimulating hormone) but not LH (Luteinizing hormone) were reduced in young KO males. Testicular anatomy also revealed a subtle but significantly higher percentage of degenerated seminiferous tubules in 4-month-old VIP-/-animals compared to WT. In aging animals (15 months old), control males showed typical testicular aging including severe degeneration of seminiferous tubules, a dramatic decrease in serum testosterone levels and a reduction in StAR and 3ß-HSD gene expression. In age-matched VIP-/-males, serum levels of testosterone and steroidogenic enzymes were still very low. Interestingly, in contrast with young mice, testicular degeneration at 15 months was significantly less severe marked in VIP-/-mice than in WT mice. Altogether, these results suggest that: 1) VIP is an important factor for regulating testosterone biosynthesis and FSH secretion and 2) VIP regulates testicular aging.     

Sphk2−/− mice are protected from obesity and insulin resistance

Sphingosine kinases phosphorylate sphingosine to sphingosine 1?phosphate (S1P), which functions as a signaling molecule. We have previously shown that sphingosine kinase 2 (Sphk2) is important for insulin secretion. To obtain a better understanding of the role of Sphk2 in glucose and lipid metabolism, we have characterized 20- and 52-week old Sphk2^?/? mice using glucose and insulin tolerance tests and by analyzing metabolic gene expression in adipose tissue. A detailed metabolic characterization of these mice revealed that aging Sphk2^?/? mice are protected from metabolic decline and obesity compared to WT mice. Specifically, we found that 52-week old male Sphk2^?/? mice had decreased weight and fat mass, and increased glucose tolerance and insulin sensitivity compared to control mice. Indirect calorimetry studies demonstrated an increased energy expenditure and food intake in 52-week old male Sphk2^?/? versus control mice. Furthermore, expression of adiponectin gene in adipose tissue was increased and the plasma levels of adiponectin elevated in aged Sphk2^?/? mice compared to WT. Analysis of lipid metabolic gene expression in adipose tissue showed increased expression of the Atgl gene, which was associated with increased Atgl protein levels. Atgl encodes for the adipocyte triglyceride lipase, which catalyzes the rate-limiting step of lipolysis. In summary, these data suggest that mice lacking the Sphk2 gene are protected from obesity and insulin resistance during aging. The beneficial metabolic effects observed in aged Sphk2^?/? mice may be in part due to enhanced lipolysis by Atgl and increased levels of adiponectin, which has lipid- and glucose-lowering effects.     

Intercellular communication between Sertoli cells and Leydig cells in the absence of follicle-stimulating hormone-receptor signaling

Effective interactions among the various compartments of the testis are necessary to sustain efficiency of the spermatogenic process. To study the intercellular communication between the Sertoli and Leydig cells in the complete absence of FSH receptor signaling, we have examined several indices of Leydig cell function in FSH receptor knockout (FORKO) mice. The serum testosterone levels were reduced in the 3- to 4-mo-old adult FORKO males compared to wild-type mice despite no significant alteration in circulating LH levels. Treatment with ovine LH resulted in a dose-dependent increase in serum testosterone levels in all three genotypes (+/+, +/-, and -/-). However, the response in FORKO males was significantly reduced. Similarly, the total intratesticular testosterone per testis was also lower, but the intratesticular testosterone per milligram of testis was significantly elevated in the FORKO males. Western blot analysis revealed an apparent higher expression of the enzyme 3beta-hydroxysteroid dehydrogenase (3beta-HSD) as well as LH-receptor density in the testis of FORKO males. Immunohistochemistry also showed an increase in the intensity of 3beta-HSD staining in the testicular sections of FORKO males. Although LH receptor binding increased per unit weight in FORKO mice, the total LH binding remained the same in all genotypes. Taken together, the results of the present study suggest that, in the absence of FSH receptor signaling, the testicular milieu is altered to affect Leydig cell response to LH such that circulating testosterone is reduced in the adult mutant. Studies are currently under way to understand the mechanisms underlying this phenomenon.     

Dehydroepiandrosterone prevents age-associated alterations, increasing insulin sensitivity

The age decline in DHEA levels has been associated with the appearance of age-related disorders such as obesity and insulin resistance. The aim of this study was to analyse the effect of chronic administration (13 weeks) of DHEA (5 g/kg diet) to old female rats fed on a high-fat diet on body weight and adiposity, and concretely on the expression of the adipokines related to obesity and insulin resistance, such as leptin, adiponectin and resistin. DHEA treatment induced a decrease in body weight, adipose tissue mass and serum insulin, adiponectin and leptin levels. Adiponectin mRNA expression in visceral fat depots decreased with aging, but this reduction was attenuated by DHEA treatment. DHEA treatment also stimulated resistin gene expression in the ovaric and renal adipose depots, which is associated with an increase in its circulating levels. In conclusion, DHEA treatment decreases body weight and adiposity in old female rats fed a high-fat diet, leading to an improvement of the HOMA index for insulin sensitivity, with decreasing circulating insulin levels, and preventing the age-associated decline of visceral-adipose adiponectin expression.     

Morphological and functional variations of Leydig cells in testis of the domestic pig during the different biological stages of development

The relationship of morphometrical and androgen receptor evaluations of the main testicular interstitium cellular element (Leydig cells) in the domestic pig provided interesting numerical and morphological features during the different aging stages. As early as 25 days (a period in which the pig is sexually immature) there was a low number of Leydig cells (1.46 x 10(8)) with respect to a 78% and 35% increase in the adult (2.48 x 108) and aged (1.78 x 10(8)) animal, respectively. Interestingly, when the volume density of Leydig cells was considered, the average volume of these cells seemed to be high (75%) in the aged pig with respect to the young immature animal whereas a lower increase (27%) was observed for the adult animal. Moreover, the evaluation of testosterone receptor binding sites in the testis at the various stages of development also displayed a differentiated pattern since elevated testosterone receptor binding levels of the high dissociation affinity type were obtained for the adult pig. Thus, from the combined morphological variations of Leydig cells and testosterone receptor binding activity, it appears that this androgenic receptor component exerts distinct autocrine effects on the different functional features of some testicular tissue constituents at the different aging stages of the domestic pig.     

Effects of chronic bhang (cannabis) administration on the reproductive system of male mice

BACKGROUND: The purpose of this study was to investigate the effect of chronic uptake of bhang, prepared from the Cannabis sativa, on male reproductive physiology in adult male Parkes strain (P) mice. An attempt was also made to investigate the presence of cannabinoid 1 (CB1) and cannabinoid 2 (CB2) receptors, and fatty acid amide hydrolase (FAAH) in the testis and to evaluate any changes in it resulting from chronic intake of bhang in mice. METHODS AND RESULTS: Adult male mice were given bhang (3 or 6 mg/kg body weight/day) orally for 36 consecutive days. Chronic intake of bhang caused regressive changes in the testes and suppressed sperm count, viability and motility. Bhang intake also caused significant decline in circulating testosterone level due to decline in testicular 3β HSD enzyme activity. An immunohistochemical study demonstrated the presence of CB1, CB2 and FAAH in the testis of mice. The present study also showed significant variation in the CB1 and CB2 receptors and FAAH protein levels in testes of mice exposed to bhang. These suppressive effects may be due to inhibitory effect of bhang on pituitary expression of gonadotrophin releasing hormone (GnRH) I receptor protein. Treatment of testes with bhang in vitro significantly decreased testicular luteinizing hormone receptor (LHR) and FAAH expression suggesting direct action of bhang on testicular activity. CONCLUSIONS: The findings of this study thus suggest that bhang may impair fertility in male mice through alteration in the testicular endocannabinoid system and that chronic bhang exposure in humans would be predicted to alter male fertility. Birth Defects Res (Part B) 92:195–205, 2011. © 2011 Wiley‐Liss, Inc.     

Over-expression of IL-18, ICE and IL-18 R in testicular tissue from sexually immature as compared to mature mice

In this study we examined the cellular origin and the expression levels of interleukin-18 (IL-18), IL-18 receptor (IL-18R) and IL-1beta-converting enzyme (ICE), which activates pro-IL-18, during normal maturation of murine testis. The levels of IL-18, IL-18R and ICE were significantly higher in testicular tissues and homogenates (but not in the spleen or liver) from sexually immature than mature mice. Immunohistochemical staining of testicular tissues from sexually immature and mature mice shows that testicular germ cells and Leydig cells/interstitial cells express higher levels of IL-18, as compared to other testicular cells. Peritubular cells of sexually immature and mature mice also expressed IL-18. Our results demonstrate, for the first time, over-expression of the IL-18 family in testicular tissues of sexually immature mice, as compared to mature mice, as well as the expression of IL-18 in the different stages of differentiation of testicular germ cells. Thus, our results may indicate involvement of the endocrine system (gonadotropins and testosterone) in the regulation of the testicular IL-18 family, which could be involved in the regulation of testicular functions, development and spermatogenesis under physiological conditions.     

Bisphenol S induces oxidative stress-mediated impairment of testosterone synthesis by inhibiting the Nrf2/HO-1 signaling pathway

Bisphenol S (BPS) is an environmental endocrine disruptor widely used in industrial production. BPS induces oxidative stress and exhibits male reproductive toxicity in mice, but the mechanisms by which BPS impairs steroid hormone synthesis are not fully understood. Nuclear factor erythroid 2-related factor 2(Nrf2)/HO-1 signaling is a key pathway in improving cellular antioxidant defense capacities. Therefore, this study explored the effects of exposure to BPS on testosterone synthesis in adult male mice and its mechanisms with regard to the Nrf2/HO-1 signaling pathway. Adult male C57BL/6 mice were orally exposed to BPS (2, 20, and 200 mg/kg BW) with sesame oil as a vehicle (0.1 ml/10 g BW) per day for 28 consecutive days. The results showed that compared with the control group, serum testosterone levels were substantially reduced in the 20 and 200 mg/kg BPS treatment groups, and testicular testosterone levels were reduced in all BPS treatment groups. These changes were accompanied by a prominent decrease in the expression levels of testosterone synthesis-related enzymes (STAR, CYP11A1, CYP17A1, HSD3B1, and HSD17B3) in the mouse testis. In addition, BPS induced oxidative stress in the testis by upregulating the messenger RNA and protein levels of Keap1 and downregulating the levels of Nrf2, HO-1, and downstream antioxidant enzymes (CAT, SOD1, and Gpx4). In summary, our results indicate that exposure of adult male mice to BPS can inhibit Nrf2/HO-1 signaling and antioxidant enzyme activity, which induces oxidative stress and thereby may impair testosterone synthesis in testicular tissues, leading to reproductive damage.     

Globular adiponectin protected ob/ob mice from diabetes and ApoE-deficient mice from atherosclerosis

The adipocyte-derived hormone adiponectin has been shown to play important roles in the regulation of energy homeostasis and insulin sensitivity. In this study, we analyzed globular domain adiponectin (gAd) transgenic (Tg) mice crossed with leptin-deficient ob/ob or apoE-deficient mice. Interestingly, despite an unexpected similar body weight, gAd Tg ob/ob mice showed amelioration of insulin resistance and beta-cell degranulation as well as diabetes, indicating that globular adiponectin and leptin appeared to have both distinct and overlapping functions. Amelioration of diabetes and insulin resistance was associated with increased expression of molecules involved in fatty acid oxidation such as acyl-CoA oxidase, and molecules involved in energy dissipation such as uncoupling proteins 2 and 3 and increased fatty acid oxidation in skeletal muscle of gAd Tg ob/ob mice. Moreover, despite similar plasma glucose and lipid levels on an apoE-deficient background, gAd Tg apoE-deficient mice showed amelioration of atherosclerosis, which was associated with decreased expression of class A scavenger receptor and tumor necrosis factor alpha. This is the first demonstration that globular adiponectin can protect against atherosclerosis in vivo. In conclusion, replenishment of globular adiponectin may provide a novel treatment modality for both type 2 diabetes and atherosclerosis.     

Interleukin-6 expression during normal maturation of the mouse testis

In this study, we examined the cellular origin and the expression levels of interleukin-6 (IL-6) during normal maturation of mouse testis. The levels of IL-6 (protein and mRNA) were higher in testicular homogenates of sexually immature than mature mice. Immunohistochemical staining of testicular tissues of sexually immature and adult mice show that testicular germ cells, at different stages of differentiation, Leydig cells/interstitial cells and peritubular cells express IL-6. Our results demonstrate, for the first time, overexpression of IL-6 in testicular tissues of immature mice, as compared to mature mice, as well as the expression of IL-6 in germ cells of testicular tissues of adult and sexually immature mice. Thus, our results may indicate the involvement of the endocrine system (gonadotropins and testosterone) in the regulation of IL-6, which is involved in the regulation of testicular development, functions and spermatogenesis.     

Effects of IGF‐1 isoforms on muscle growth and sarcopenia

The decline in skeletal muscle mass and strength occurring in aging, referred as sarcopenia, is the result of many factors including an imbalance between protein synthesis and degradation, changes in metabolic/hormonal status, and in circulating levels of inflammatory mediators. Thus, factors that increase muscle mass and promote anabolic pathways might be of therapeutic benefit to counteract sarcopenia. Among these, the insulin‐like growth factor‐1 (IGF‐1) has been implicated in many anabolic pathways in skeletal muscle. IGF‐1 exists in different isoforms that might exert different role in skeletal muscle. Here we study the effects of two full propeptides IGF‐1Ea and IGF‐1Eb in skeletal muscle, with the aim to define whether and through which mechanisms their overexpression impacts muscle aging. We report that only IGF‐1Ea expression promotes a pronounced hypertrophic phenotype in young mice, which is maintained in aged mice. Nevertheless, examination of aged transgenic mice revealed that the local expression of either IGF‐1Ea or IGF‐1Eb transgenes was protective against age‐related loss of muscle mass and force. At molecular level, both isoforms activate the autophagy/lysosome system, normally altered during aging, and increase PGC1‐α expression, modulating mitochondrial function, ROS detoxification, and the basal inflammatory state occurring at old age. Moreover, morphological integrity of neuromuscular junctions was maintained and preserved in both MLC/IGF‐1Ea and MLC/IGF‐1Eb mice during aging. These data suggest that IGF‐1 is a promising therapeutic agent in staving off advancing muscle weakness.     

Déficit Androgénique Lié à l’Age

In contrast with the abrupt cessation of ovarian function at menopause in women, alteration of testicular functions in aging males is partial and progressive. Several cross-sectional studies have demonstrated an age-related decrease of testosterone levels in men. This decrease has also been observed when only men in good health are included in such studies. This age-related decline of testosterone levels has been recently confirmed by a longitudinal study including a large number of subjects. The progressive decline begins early, from the late thirties, and continues at a constant rate throughout the subject’s lifetime. Since SHBG increases with age, free testosterone and non-SHBG-bound testosterone (referred to as bioavailable testosterone) decrease more markedly than total testosterone. As variations of SHBG levels (mainly a decrease in obese and/or insulin-resistant subjects) are often encountered in clinical practice and as it is difficult to reliably measure free testosterone, bioavailable testosterone appears to be the better index to diagnose androgen deficiency in the aging male. Elevation of basal LH levels, decrease of hCG-induced testosterone levels and reduction of Leydig cell number demonstrate the testicular origin of hypogonadism. However, gonadotropic function is also relatively altered with aging. As a result of this alteration of gonadotropic function, LH level is not a reliable index of hypogonadism in the aging male. None of the androgen-dependent functions that are altered with aging, i.e. libido, erectile function, sense of well-being, muscle mass, muscle strength, fat mass, bone mass, etc., are exclusively controlled by androgens. In clinical practice, the indication for androgen replacement therapy must therefore be based on a combination of clinical symptoms and a reduction of bioavailable testosterone below a certain cut-off value, indicating “significant” hypogonadism.     

Multiple roles of the nuclear receptors for oxysterols liver X receptor to maintain male fertility

Oxysterol nuclear receptors liver X receptor (LXR)alpha and LXRbeta are known to regulate lipid homeostasis in cells exposed to high amounts of cholesterol and/or fatty acids. In order to elucidate the specific and redundant roles of the LXRs in the testis, we explored the reproductive phenotypes of mice deficient of LXRalpha, LXRbeta, and both, of which only the lxralpha;beta-/- mice are infertile by 5 months of age. We demonstrate that LXRalpha-deficient mice had lower levels of testicular testosterone that correlated with a higher apoptotic rate of the germ cells. LXRbeta-deficient mice showed increased lipid accumulation in the Sertoli cells and a lower proliferation rate of the germ cells. In lxralpha;beta-/- mice, fatty acid metabolism was affected through a decrease of srebp1c and increase in scd1 mRNA expression. The retinoid acid signaling pathway was also altered in lxralpha;beta-/- mice, with a higher accumulation of all-trans retinoid receptor alpha, all-trans retinoid receptor beta, and retinoic aldehyde dehydrogenase-2 mRNA. Combination of these alterations might explain the deleterious phenotype of infertility observed only in lxralpha;beta-/- mice, even though lipid homeostasis seemed to be first altered. Wild-type mice treated with a specific LXR agonist showed an increase of testosterone production involving both LXR isoforms. Altogether, these data identify new roles of each LXR, collaborating to maintain both integrity and functions of the testis.     

Alteration in expression of estrogen receptor isoforms alpha and beta, and aromatase in the testis and its relation with changes in nitric oxide during aging in mice

The aim of present study was to investigate the changes in the testicular expression of aromatase, ER alpha, ER beta and iNOS protein and correlate these with serum testosterone and nitric oxide levels, to elucidate the role of estrogen and nitric oxide in the testis during aging. This study showed localization of aromatase and ER alpha mainly in the Leydig cell and showed close correlation of testicular aromatase level with circulating testosterone level suggesting that estrogen may be modulating testicular steroidogenesis. Localization ER alpha mainly in the mitotically active germ cell suggest possible role of estrogen in germ cell proliferation. This study showed basal level of nitric oxide during reproductively active period, whereas increased serum nitric oxide coincides with decreased testicular activity in old age. This study showed inverse correlation between aromatase and NO level. Treatment with either SNP or L-NAME on testicular steroidogenic factor (3-beta HSD/ StAR) or germ cell survival factor (Bcl2) showed that increased NO causes decreased steroidogenesis and increased germ cell apoptosis. In conclusion this study suggest that estrogen modulate steroidogenesis and germ cell survival in reproductively active period whereas in old age decreased estrogen concentration causes increased nitric oxide which in turn decreases testicular steroidogenesis and germ cell apoptosis.     

Testicular apoptosis is down-regulated during spontaneous recrudescence in white-footed mice (Peromyscus leucopus).

Among individuals of many nontropical species, seasonal breeding is timed by tracking changes in the daily photoperiod. Transfer of rodents to short (< 12 h of light/day) day lengths for 6 to 14 weeks can induce regression of the testes mediated by apoptosis. After 16 to 20 weeks of short day exposure, reproductive function is "spontaneously" initiated, and testicular recrudescence is observed. The gonadal mechanisms that underlie testicular recrudescence are not fully understood. If the onset of testicular regrowth that occurs during spontaneous recrudescence reflects a down-regulation of apoptotic signals, then a decline in apoptosis should be noted concurrent with increased testis mass. This experiment sought to assess the role of apoptosis in the restoration of reproductive capacity to photoperiod-inhibited white-footed mice. Males were assigned to long (16:8 LD) or short (8:16 LD) photoperiods for 0, 14, 18, 22, 26, or 30 weeks. At each of these time points, testis mass and testosterone concentrations were assessed. In addition, apoptotic activity was measured using both in situ terminal deoxynucleotidyl transferase dNTP end labeling (TUNEL) and DNA laddering. Short photoperiod exposure induced maximal decreases in testicular parameters after 14 weeks (p < 0.05). After 26 weeks of short days, testis mass was no longer different between males housed in long days and those housed in short days. In contrast, the high incidence of apoptotic TUNEL labeling and DNA laddering observed at 14 weeks was reduced to long day values after 22 weeks of short day exposure. Together, our results establish that a decrease in testicular apoptosis coincides with testicular recrudescence in white-footed mice. The current study demonstrates a decline in the incidence of testicular cell death concomitant with changes in testis mass or length, elucidating a timeline of changes at the cellular level related to the onset of recrudescence.     

Stress contributes to the development of central insulin resistance during aging: Implications for Alzheimer’s disease

It is becoming evident that chronic exposure to stress not only might result in insulin resistance or cognitive deficits, but may also be considered a risk factor for pathologies such as depression or Alzheimer's disease (AD). There is great interest in determining the molecular mechanisms underlying interactions between stress, aging, memory and Alzheimer's disease (AD). We have used the chronic mild stress (CMS) model to study the effects of chronic stress on the aging process and the development of central insulin resistance and AD pathology. CMS aged mice showed cognitive impairments in the novel object recognition test. In addition, CMS aged mice displayed both peripheral insulin resistance, as shown by HOMA index, and decreased hippocampal levels of pIRS and downstream intracellular signaling (pAKT, pGSK and pERK1/2). Interestingly, there was a significant increase in both C99:C83 ratio and BACE1 levels in the hippocampus of CMS aged mice. Increased expression of the AD marker pTau was also found in stressed aged mice. Increased expression of the stress-activated protein kinase JNK was found in CMS aged mice, accompanied by significant decreases in glucocorticoid receptor (GR) expression and increases in mineralocorticoid receptor (MR) expression. It is suggested that the interaction of stress with aging should be considered when studying determinants of the onset and progression of AD.     

Nandrolone decanoate interferes with testosterone biosynthesis altering blood–testis barrier components

The aim of this study was to investigate whether nandrolone decanoate (ND) use affects testosterone production and testicular morphology in a model of trained and sedentary mice. A group of mice underwent endurance training while another set led a sedentary lifestyle and were freely mobile within cages. All experimental groups were treated with either ND or peanut oil at different doses for 6 weeks. Testosterone serum levels were measured via liquid chromatography–mass spectrometry. Western blot analysis and quantitative real‐time PCR were utilized to determine gene and protein expression levels of the primary enzymes implicated in testosterone biosynthesis and gene expression levels of the blood–testis barrier (BTB) components. Immunohistochemistry and immunofluorescence were conducted for testicular morphological evaluation. The study demonstrated that moderate to high doses of ND induced a diminished serum testosterone level and altered the expression level of the key steroidogenic enzymes involved in testosterone biosynthesis. At the morphological level, ND induced degradation of the BTB by targeting the tight junction protein‐1 (TJP1). ND stimulation deregulated metalloproteinase‐9, metalloproteinase‐2 (MMP‐2) and the tissue inhibitor of MMP‐2. Moreover, ND administration resulted in a mislocalization of mucin‐1. In conclusion, ND abuse induces a decline in testosterone production that is unable to regulate the internalization and redistribution of TJP1 and may induce the deregulation of other BTB constituents via the inhibition of MMP‐2. ND may well be considered as both a potential inducer of male infertility and a potential risk factor to a low endogenous bioavailable testosterone.     

Assessment of Testicular Corticosterone Biosynthesis in Adult Male Rats

Corticosterone is synthesized in the adrenal glands and is circulated throughout the body to perform regulatory functions in various tissues. The testis is known to synthesize and secrete testosterone and other androgens. We developed an accurate method to measure steroid content using liquid chromatography-mass spectrometry analysis. In the present study, significant levels of the precursor compounds of testosterone and corticosterone synthesis could be detected in rat testis using this method. After adrenalectomy, corticosterone remained in the blood and testicular tissue at approximately 1% of the amount present in the control testis. When the excised testicular tissue was washed and incubated with NADH, NADPH and progesterone, not only testosterone and its precursors but also 11-deoxycorticosterone and corticosterone were produced; the levels of 11-deoxycorticosterone and corticosterone increased with incubation time. The production rate of 11-deoxycorticosterone from progesterone was estimated to be approximately 1/20 that of 17-hydroxyprogesterone, and the corticosterone level was approximately 1/10 that of testosterone. These ratios coincided with those in the testicular tissue of the adrenalectomized rats, indicating that corticosterone was synthesized in the testis and not in the blood. A primary finding of this study was that corticosterone and testosterone were synthesized in a 1/10-20 ratio in the testis. It is concluded that corticosterone, which has various functions, such as the regulation of glycolysis and mediating spermatogenesis, is produced locally in the testis and that this the local production is convenient and functional to respond to local needs.     

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

Present generation non-steroidal anti-inflammatory drugs (NSAID) are potent inhibitors of the enzyme cyclooxygenase-2 (COX-2). Even though they exhibit reduced incidence of gastrotoxicity, severe nephrotoxicity and other side effects have been widely reported with respect to usage of these drugs. Since COX-2 levels are not only upregulated by inflammation but also by other stimuli such as cytokines, growth factors, mitogens and steroid hormones, we investigated the localization of COX-2 and activity of both COX-1 and COX-2 in mice testis. To correlate the localization of COX-2 with its function we suppressed COX-2 expression with the aid of nimesulide a preferential COX-2 inhibitor. We found COX-2 was constitutively expressed in the Leydig cells of mice testis suggesting a role on testosterone synthesis. Suppression of COX-2 resulted in increased concentration of most of polyunsaturated fatty acids especially arachidonic acid (AA). Prostaglandin (PG) levels which showed an initial decline during nimesulide treatment had a reversible effect during prolonged treatment. These findings state that cyclooxygenase is constitutively expressed in mice testis and continuous inhibition of COX-2 interferes in maturation of sperm.