Spermatogenesis In Adult Rats Research Articles

Histological and Immunohistochemical Study on the Effect of Cyclophosphamide in Testis of Adult Albino Rats and the possible protective role of Vitamin E and Alpha Lipoic Acid

Background: cyclophosphamide is an immunosuppressive agent and anticancer drug in childhood and adult malignant tumors. The compounds that have antioxidant properties might improve the side effect of cyclophosphamide on spermatogenesis. The aim of the work: This study designed to evaluate the effect of cyclophosphamide in testis of adult albino rats and the possible protective role of vitamin E and alpha lipoic acid. Materials and Methods: Forty male adult albino rats were divided equally into five groups Group I as a control group, Group II rats were given cyclophosphamide. Group III rats were given cyclophosphamide concomitantly with vitamin E. Group IV rats were given cyclophosphamide concomitantly with alpha lipoic acid. And Group V rats were given cyclophosphamide and a combination of vitamin E plus alpha lipoic acid. The testis samples were prepared for histological examination and PCNA immunohistochemical stain. Results: cyclophosphamide induced destruction of normal testicular histological structure, increased collagen fibers deposition and significantly decreased main area percent of PCNA immune-positive germ cells indicating decreased spermatogenesis. In group III vitamin E mild prevented the pathological changes in testicular tissue and non significantly increased the main area percent of PCNA immune-positive germ cells. While in group IV alpha lipoic acid enhanced marked preservation of the lined germinal cells and significantly increased the main area percent of PCNA immune-positive germ cells compared to group II. However, in group V there was almost total prevention of side effects induced by cyclophosphamide in adult rat testis and preservation of spermatogenesis.Conclusion: Cyclophosphamide induced damage in histological structure of testis and decreased spermatogenesis of adult rats. Alpha lipoic acid comparatively preserved the normal histological structure of testis and normal spermatogenesis than vitamin E. However, administration of vitamin E and alph lipoic acid together was almost totally prevented the damaging effect of cyclophosphamide.

Protective effects of Anthocleista djalonensis A. Chev root extracts against induced testicular inflammation and impaired spermatogenesis in adult rats.

This study was designed to explore the protective effects of methanol (Meth, 200mgkg-1 body wt) and aqueous ethanol (Eth-OH, 200mgkg-1 body wt) extracts of Anthocleista djalonensis roots on testicular inflammation induced by lipopolysaccharide (LPS, 5mg/kg body wt) and depletion of tubular germ cells induced by busulfan (15mg/kg body wt) in rats after 60days of oral administration. As expected, LPS stimulation of the animals significantly increased serum and intra-testicular interleukin-6 and serum nitrite levels which were significantly inhibited in the Eth-OH + LPS and Meth + LPS animals. The increase in testicular and not serum myeloperoxidase activity that was induced by LPS treatment was synergistically increased in the Eth-OH + LPS animals, whereas it was inhibited in the Meth + LPS animals compared to LPS-treated animals. Furthermore, the administration of the Eth-OH or Meth extracts protected against busulfan-induced depletion of tubular germ cells and promotes the re-population of the seminiferous tubules with germ cells (spermatogonia, spermatocytes and round spermatids) at different stages of development. The extracts were found to contain 7'-oxaspiro [cyclopropane-1,4'-tricyclo [3.3.1.0 (6,8)] nonan-2'-one], cis,cis-7,10-hexadecadienal, hexadecanoic acid, methyl ester, hexadecanoic acid, ethyl ester, 9,12-octadecadienoic acid, methyl ester, and 9,12-octadecadienoic acid (Z,Z)-) which may partly explain the observed anti-inflammatory effects. In conclusion, Meth extracts of A. djanonesis have better anti-inflammatory effects than the Eth-OH extract for the management of impaired testicular function due to inflammation. However both extracts exhibited protective effect on the histology of the testis allowing for the recovery of spermatogenesis.

Effects of Estrogen Treatment on Aging in the Rat Epididymis.

Previous studies from our laboratory demonstrated that estrogen signaling in the testis contributes to maintaining spermatogenesis in adult rats, and that estrogen treatment attenuated the age-associated decline in sperm production. The purpose of this study was to determine if epididymal function is also altered with age, and what effects estrogen treatment may have on the epididymis during aging. We compared untreated rats at 3 and 15 months of age to 18-month-old vehicle-treated and estrogen treated rats. In all four groups, tubule and lumen diameter of the cauda was significantly larger than more proximal regions of the epididymis. In the 3-, 15-, and 18-month-old treated animals, the epithelial cell height of the cauda was significantly shorter than that of more proximal regions. The caput cell height was shorter at 18 months compared to 3 months but this was not seen in estrogen treated animals. Thus, estrogen appears able to prevent some age related changes in epididymal morphology. Sperm transit time through the distal cauda was significantly delayed with aging. Estrogen treatment prevented this delay, indicating that sperm transit through the epididymis is an estrogen regulated function. Differences in estradiol and testosterone concentrations were observed between 3- and 15-month-old animals, but no further differences were noted between treated or untreated animals at 18 months. Interestingly, expression of androgen receptor and estrogen receptor alpha were similar between ages and treatments. Collectively, these results suggest epididymal morphology and function are affected by aging and estrogen treatment. Anat Rec, 302:1447-1457, 2019. © 2018 Wiley Periodicals, Inc.

The impact of low‐intensity extracorporeal shock wave therapy on testicular function in adult rats

Low-intensity extracorporeal shock wave therapy (Li-ESWT) has been introduced as a treatment for penile diseases. Its impact on testicular function during treatment remains unknown. To clarify whether Li-ESWT impairs testicular function during the treatment of penile diseases by investigating the impact of Li-ESWT on testosterone synthesis and spermatogenesis in adult rats. Twenty-four male Sprague-Dawley rats were equally divided into the following three groups: control group, 1.6 BAR group, and 3.2 BAR group. Rats in the experimental groups were treated with Li-ESWT at different energy levels (300 shocks at 1.6 BAR or 3.2 BAR, 2Hz frequency) three times a week for 3weeks. The control group did not receive any treatment during the same period of time. One day after the last shock wave treatment, serum and testicular tissue testosterone concentrations were measured, and sperm quality was assayed. Histologic examination of the testes and quantitative real-time PCR were performed. Testosterone levels in both the serum and testicular tissue did not change after Li-ESWT exposure. The expression levels of steroidogenic enzymes (steroidogenic acute regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc), and 3β-hydroxysteroid dehydrogenase (3β-HSD)) were not impacted by Li-ESWT. The 3.2 BAR group showed a significantly lower sperm count and lower expression of synaptonemal complex protein 3 (SYCP3) in testicular tissue than the control group. No significant differences in sperm quality or SYCP3 expression were observed between the control group and the 1.6 BAR group. Li-ESWT exposure at 3.2 BAR inhibited spermatogenesis and decreased sperm quality, which indicated that male patients with a desire to preserve fertility should undergo low-energy Li-ESWT or other treatment modalities.

Estrogen, through estrogen receptor 1, regulates histone modifications and chromatin remodeling during spermatogenesis in adult rats

ABSTRACTEstrogen receptors (ESR1 and ESR2) play crucial roles in various processes during spermatogenesis. To elucidate individual roles of ESRs in male fertility, we developed in vivo selective ESR agonist administration models. Adult male rats treated with ESR1 and ESR2 agonist for 60 days show spermatogenic defects leading to reduced sperm counts and fertility. While studying epigenetic changes in the male germ line that could have affected fertility, we earlier observed a decrease in DNA methylation and its machinery upon ESR2 agonist treatment. Here, we explored the effects on histone modifications, which could contribute to decreased male fertility upon ESR agonist administration. ESR1 agonist treatment affected testicular levels of histone modifications associated with active and repressed chromatin states, along with heterochromatin marks. This was concomitant with deregulation of corresponding histone modifying enzymes in the testis. In addition, there was increased retention of histones along with protamine deficiency in the caudal spermatozoa after ESR1 agonist treatment. This could be due to the observed decrease in several chromatin remodeling proteins implicated in mediating histone-to-protamine exchange during spermiogenesis. The activating and repressing histone marks in spermatozoa, which play a critical role in early embryo development, were deregulated after both the ESR agonist treatments. Together, these epigenetic defects in the male germ line could affect the spermatozoa quality and lead to the observed decrease in fertility. Our results thus highlight the importance of ESRs in regulating different epigenetic processes during spermatogenesis, which are crucial for male fertility.

Estrogen signaling, through estrogen receptor β, regulates DNA methylation and its machinery in male germ line in adult rats

ABSTRACTEstrogen, through its receptors, regulates various aspects of spermatogenesis and male fertility. To understand the roles of estrogen receptors (ERα and ERβ) in male fertility, we have developed in vivo selective ER agonist administration models. Treatment of adult male rats with ERα or ERβ agonist for 60 d decreases fertility and litter size mainly due to increased pre- and post-implantation embryo loss. Since epigenetic mechanisms like DNA methylation play a crucial role in male fertility, we investigated the effects of the ER agonists on DNA methylation in spermatozoa. Treatment with ERβ agonist causes a significant decrease in DNA methylation both at the global level and at the H19 differentially methylated region (DMR). This could be due to decrease in DNA methyltransferases in the testis upon ERβ agonist treatment. The hypomethylation observed at the H19 DMR corroborates with aberrant expression of Igf2 and H19 imprinted genes in the resorbed embryos sired by ERβ agonist-treated males. Thus, our study demonstrates that ERβ regulates DNA methylation and methylating enzymes during adult rat spermatogenesis. Activation of estrogen signaling through ERβ could therefore cause DNA methylation defects leading to impaired male fertility. These results define a role for estrogen in epigenetic regulation of male germ line, suggesting that epigenetic insults by exposure to environmental estrogens could potentially affect male fertility.

Efficacy of Crocus sativus L. on reduction of cadmium-induced toxicity on spermatogenesis in adult rats.

Cadmium is a toxic heavy metal element, which probably cause infertility by impairment in spermatogenesis. The present work aimed (i) to study the toxic effect of cadmium on spermatogenesis in rat, as well as (ii) the protective effect of Crocus sativus L. on cadmium-intoxicated rats. Cadmium chloride was administered intraperitoneally during 16days at intervals of 48h between subsequent treatments. Crocus sativus L. was pre-treated in both of control and cadmium-injected rats. Animals were sacrificed on day 17 after the first treatment. The left cauda epididymis was removed and immediately immersed into Hank's balanced salt solution for the evaluation of sperm count and viability, and left testis was fixed in 10% formalin for histological evaluation. Following contamination with cadmium, a decrease was observed in the number and viability of cauda epididymis sperm, which were increased by Crocus sativus L. pre-treatment (P<0.05). In addition, cadmium decreased both cell proliferation and Johnsen Scores in the seminiferous tubules, which were reversed by Crocus sativus pre-treatment (P<0.05). Furthermore, cadmium-induced decrease in the amount of free serum testosterone as well as an increase in lipid peroxidation activity in the testicular tissue was reversed by Crocus sativus L. (P<0.05). These findings may support the concept that Crocus sativus L. can improve the cadmium toxicity on spermatogenesis.

Actin related protein complex subunit 1b controls sperm release, barrier integrity and cell division during adult rat spermatogenesis

Actin remodeling is a vital process for signaling, movement and survival in all cells. In the testes, extensive actin reorganization occurs at spermatid–Sertoli cell junctions during sperm release (spermiation) and at inter Sertoli cell junctions during restructuring of the blood testis barrier (BTB). During spermiation, tubulobulbar complexes (TBCs), rich in branched actin networks, ensure recycling of spermatid–Sertoli cell junctional molecules. Similar recycling occurs during BTB restructuring around the same time as spermiation occurs. Actin related protein 2/3 complex is an essential actin nucleation and branching protein. One of its subunits, Arpc1b, was earlier found to be down-regulated in an estrogen-induced rat model of spermiation failure. Also, Arpc1b was found to be estrogen responsive through estrogen receptor beta in seminiferous tubule culture. Here, knockdown of Arpc1b by siRNA in adult rat testis led to defects in spermiation caused by failure in TBC formation. Knockdown also compromised BTB integrity and caused polarity defects of mature spermatids. Apart from these effects pertaining to Sertoli cells, Arpc1b reduction perturbed ability of germ cells to enter G2/M phase thus hindering cell division. In summary, Arpc1b, an estrogen responsive gene, is a regulator of spermiation, mature spermatid polarity, BTB integrity and cell division during adult spermatogenesis.

Differential roles of estrogen receptors, ESR1 and ESR2, in adult rat spermatogenesis

Estrogens, through their receptors, play an important role in regulation of spermatogenesis. However, the precise role of the estrogen receptors (ESR1 and ESR2) has been difficult to determine as in vivo estradiol treatment would signal through both the ESRs. Hence we had developed in vivo selective ESR agonist administration models in adult male rats to decipher the individual roles of the ESRs. Treatment with both ESR1 and ESR2 agonists decreased sperm counts after 60 days of treatment. The present study aimed to delineate the precise causes of decreased sperm counts following treatment with the two ESR agonists. Treatment with ESR1 agonist causes an arrest in differentiation of round spermatids into elongated spermatids, mainly due to down-regulation of genes involved in spermiogenesis. ESR2 agonist administration reduces sperm counts due to spermiation failure and spermatocyte apoptosis. Spermiation failure observed is due to defects in tubulobulbar complex formation because of decrease in expression of genes involved in actin remodelling. The increase in spermatocyte apoptosis could be due to increase in oxidative stress and decrease in transcripts of anti-apoptotic genes. Our results suggest that the two ESRs regulate distinct aspects of spermatogenesis. ESR1 is mainly involved with regulation of spermiogenesis, while ESR2 regulates spermatocyte apoptosis and spermiation. Activation of estrogen signaling through either of the receptors can affect their respective processes during spermatogenesis and lead to low sperm output. Since many environmental estrogens can bind to the two ESRs with different affinities, these observations can be useful in understanding their potential effects on spermatogenesis.

Dibutyl phthalate induces oxidative stress and impairs spermatogenesis in adult rats.

Phthalates are abundantly produced plasticizers, and dibutyl phthalate (DBP) is the most widely used derivative in various consumer products and medical devices. This study was conducted to further explore the potential testicular toxicity of DBP in adult rats and to elucidate the underlying mechanisms. Adult male albino rats were treated orally with DBP at doses of 0, 200, 400, or 600 mg/kg/day for 15 consecutive days. Testicular weight, sperm count, and motility were significantly decreased. Treatment with DBP decreased serum follicle-stimulating hormone and testosterone levels and testicular lactate dehydrogenase activity. DBP treatment also decreased serum total antioxidant capacity and the activities of the testicular antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione reductase. Further, DBP treatment provoked degeneration with absence of spermatogenesis and sperms and necrosis in some of seminiferous tubules. These results indicated that oxidative stress and subsequent decrease in testosterone secretion were the potential underlying mechanism of DBP-induced testicular toxicity.

Protective Effects of Morus Alba (M.alba) Extract on the Alteration of Testicular Tissue and Spermatogenesis in Adult Rats Treated with Monosodium Glutamate

Various studies have confirmed toxic effects of monosodium glutamate in different organs. The review of literatures about influence of MSG on the male reproductive system shows the variety of tissue damages. Most of these changes mainly manifested by increased oxidative stress and cytotoxicity. The present study was aimed to investigate the possible protective effects of herbal antioxidants (Morus Alba) on the tissue damages related to monosodium glutamate cytotoxicity. Forty-eight adult Wistar rats were divided into two control and experimental groups. Each group divided into short (14 days) and long term (28 days) group. Experimental group was subdivided into four subgroups. The experimental group was injected with MSG (4 mg/kg BW, i.p.). Morus Alba extract (100 mg/kg BW) was administrated to two MSG treated experimental subgroups. At the end of study, the right testis was processed for histological evaluation and the left one was processed for sperm analysis and morphometric studies. Decrease of spermatogenic indices was accompanied with the changes in histomorphology of seminiferous tubules in MSG treated groups. Moreover, the sperm analysis indices were decreased in MSG treated rats. These changes were more obvious in long term treatments. The administration of Morus Alba extract led to improvement in histologic and spermatogenic indices. The most observable improvement in tissue changes was obtained by long term treatment with Morus Alba extract. The present study suggests that the administration of Morus Alba extract can preserve the positive effects in reduction of testicular tissue alterations in Monosodium glutamate tissue toxicity.

Alterations in the estrogen environment of the testis contribute to declining sperm production in aging rats

Testicular function, specifically, production of testosterone by Leydig cells, diminishes during aging. Estradiol is also produced by the testis and potentially acts in an autocrine or paracrine manner to help regulate spermatogenesis. However, changes in estradiol concentration or receptor expression within the testis during aging remain unclear. This study was designed to test the hypothesis that the estrogen environment of the testis is altered during aging and that these changes are associated with declining sperm production. Sprague Dawley rats were examined at three, 15, 18, and 21 months of age to detail changes in sperm production and testicular concentration of testosterone and estradiol; five rats were used at three and 21 months and three rats were used at 15 and 18 months. Daily sperm production declined 49% from 15 to 21 months of age. Testicular concentrations of estradiol declined 53% from 15 to 21 months of age; testosterone concentrations were not significantly different. These results suggest that declines in intra-testicular estradiol may contribute to declining sperm production. We further tested our hypothesis by treating rats once every third day with a subcutaneous injection of estradiol valerate (1 µg/kg) from 15 to 18 months of age. Estradiol was increased 54% in treated animals while testosterone was unaffected. Estrogen receptor alpha (ESR1) expression was significantly reduced from 15 to 18 months and expression in estrogen-treated animals was significantly higher than age-matched controls. Additionally, ESR1 expression in 18 month treated animals was not different from 15 months of age. Importantly, daily sperm production in 18 month treated animals was 22% higher than age-matched controls; thus, treatment prevented approximately half of the decline observed in control animals. Collectively, our results suggest that estrogen is involved in maintaining optimum spermatogenesis in adult rats and that estrogen treatment may attenuate the age-associated loss in sperm production.

Correction: Cytochrome P450 3A1 Mediates 2,2′,4,4′-Tetrabromodiphenyl Ether-Induced Reduction of Spermatogenesis in Adult Rats

Correction: Cytochrome P450 3A1 Mediates 2,2′,4,4′-Tetrabromodiphenyl Ether-Induced Reduction of Spermatogenesis in Adult Rats

Testis evaluation of adult Wistar rats after neonatal treatment with fluoxetine

In current assay the serotoninergic system in newly-born Wistar rats underwent pharmacological modification by fluoxetine, a selective serotonin reuptake inhibitor (SSRI), to investigate its repercussion on testicular parameters in adult animals. Thirty animals were distributed according to treatment: control animals (n = 6), animals treated with 1 mg kg -1 (n = 6), 5 mg kg -1 (n = 6), 10 mg kg -1 (n = 6) and 20 mg kg -1 (n = 6) of fluoxetine (IP). When 150 days old, the animals were anesthetized and perfused intra-cardiacally with fixative solution. Testes were routinely processed for inclusion in plastic resin (methacrylate glycol). Further, 4 µm-thick histological sections were stained with toluidine blue/sodium borate 1% and analyzed histometrically. Pharmacological intervention on the serotoninergic system during the postnatal period of the testes development in Wistar rats with fluoxetine chlorohydrate reduced parameters, such as testicular weight, testis liquid weight and seminiferous tubules diameter. However, testicular parameters, such as daily sperm production (DSP), spermatogenesis efficiency (DSP/g/testis) and cell population in stage VII of adult animals, were not influenced by fluoxetine chlorohydrate usage during neonatal period. Results show that administration of fluoxetine during 21 days after birth may induce adverse changes in the spermatogenesis of adult rats.

Effects of exposure to extremely low frequency magnetic fields on spermatogenesis in adult rats

The constant exposure of modern society to extremely low frequency magnetic fields (ELF-MF) has raised considerable concerns about the potential risks to male reproduction. However, the epidemiological and experimental data remain contradictory and inconclusive. In the present study, we investigated the effects of 50 Hz ELF-MF of 500 µT applied 4 h/day, 7 days/week for 4 and 8 weeks on male reproduction, focusing on changes in spermatogenesis. Several biological endpoints related to testicular function and spermatogenesis were measured, including the following: body mass, masses of testes and epididymis, sperm count and abnormal sperm ratio in the caudal epididymis, serum testosterone level, testicular histology, frequency of 14 stages of the cycle of the seminiferous epithelium and of four stages of meiosis I, germ cell apoptosis and testicular oxidative status. No significant differences were found in the biological endpoints between the sham control and the exposed rats in either the 4- or 8-week exposure period. These negative results may result from the lack of change in serum testosterone. In conclusion, our study indicates that exposure to low intensity ELF-MF may have no adverse effects on spermatogenesis.

Cytochrome P450 3A1 Mediates 2,2′,4,4′-Tetrabromodiphenyl Ether-Induced Reduction of Spermatogenesis in Adult Rats

Background2,2′,4,4′-tetrabromodiphenyl ether (BDE47) is the dominant PBDE congener in humans, wildlife, and the environment. It has been reported to be metabolized by cytochrome P450 (CYP) enzymes. Still, the effects of BDE47 on spermatogenesis failure are attracting an increasing amount of attention. However, it is unclear whether CYP-mediated metabolism contributes to BDE47-induced reproductive toxicity.Methodology and Principal FindingsThe role of cytochrome P450 3A1 (CYP3A1) in the formation of oxidative metabolites of BDE47 and its induced spermatogenesis failure was investigated in SD rats. BDE47 significantly increased the expression and activity of CYP3A1 in rat liver, and 3-OH-BDE47, the major oxidative metabolite of BDE47, dose-dependently increased in rat liver, serum, and testis, which was aggravated by dexamethasone (DEX), an inducer of CYP3A1. Additionally, testicular 3-OH-BDE47 and reactive oxygen species (ROS) in seminiferous tubules increased especially when BDE47 was administered in combination with DEX, which was confirmed in GC-1 and GC-2 cells that 3-OH-BDE47 induced more ROS production and cell apoptosis via the upregulation of FAS/FASL, p-p53 and caspase 3. As a result, daily sperm production dose-dependently decreased, consistent with histological observations in giant cells and vacuolar spaces and increase in TUNEL-positive apoptotic germ cells.ConclusionCYP3A1-mediated metabolic activation of BDE47 and the active metabolite 3-OH-BDE47 and consequent ROS played an important role in reduction of spermatogenesis by germ cell apoptosis. Our study helps provide new insights into the mechanism of reproductive toxicity of environmental chemicals.

Exposure to bisphenol A disrupts meiotic progression during spermatogenesis in adult rats through estrogen-like activity.

The effect of bisphenol A (BPA) on the reproductive system is highly debated but has been associated with meiotic abnormalities. However, evidence is lacking with regard to the mechanisms involved. In order to explore the underlying mechanisms of BPA-induced meiotic abnormalities in adult male rats, we exposed 9-week-old male Wistar rats to BPA by gavage at 0, 2, 20 or 200 μg/kg body weight (bw)/day for 60 consecutive days. 17β-Estradiol (E2) was administered at 10 μg/kg bw/day as the estrogenic positive control. Treatments with 200 μg/kg bw/day of BPA and E2 significantly decreased sperm counts and inhibited spermiation, characterized by an increase in stage VII and decrease in stage VIII in the seminiferous epithelium. This was concomitant with a disruption in the progression of meiosis I and the persistence of meiotic DNA strand breaks in pachytene spermatocytes,and the ataxia–telangiectasia-mutated and checkpoint kinase 2 signal pathway was also activated; Eventually, germ cell apoptosis was triggered as evaluated by terminal dUTP nick-end labeling assay and western blot for caspase 3. Using the estrogen receptor (ER) antagonist ICI 182780, we determined that ER signaling mediated BPA-induced meiotic disruption and reproductive impairment. Our results suggest that ER signaling-mediated meiotic disruption may be a major contributor to the molecular events leading to BPA-related male reproductive disorders. These rodent data support the growing association between BPA exposure and the rapid increase in the incidence of male reproductive disorders.

Methoxychlor induced biochemical alterations and disruption of spermatogenesis in adult rats

Adult male albino rats were treated orally with methoxychlor at doses of 0, 50, 100 or 200mg/kg/day for 15 consecutive days. Testicular weight, sperm count and motility were significantly decreased. Methoxychlor at doses of 100 and 200mg/kg significantly inhibited α-glucosidase activity, while plasma testosterone was significantly decrease by the three dose levels in a dose-related pattern. Testicular activities of 3β-HSD, 17β-HSD, SDH were significantly decreased, while ACP, ALP (except for 50mg/kg), and LDH were significantly increased. H2O2 production and LPO were significantly increased while the enzymic (SOD, CAT and GPx) and non-enzymic antioxidants (thiol content) were significantly decreased. Caspase-3 activity was significantly increased in a dose related manner. The findings of this study indicate that methoxychlor induces oxidative stress associated with impairment of spermatogenesis, in addition to apoptosis. These data provide insight into the mode of action of methoxychlor-induced toxicity in the rat testis.

Functional role of progestin and the progesterone receptor in the suppression of spermatogenesis in rodents

Synthetic progestins such as levonorgestrel (LNG) are used in combination with testosterone (T) in male contraceptive clinical trials to suppress gonadotropins secretion, but whether progestins have additional direct effects on the testis are not known. This study aimed to examine the effect of a potent progestin, (LNG), alone or in combination with testosterone (T) on spermatogenesis in adult rats, and to evaluate the functional role of the progesterone receptors (PRs) in the testis. In comparison with a low dose of LNG treatment in adult rats for 4 weeks, T and T + LNG treatment decreased testicular sperm count to 64.1 and 40.2% of control levels respectively. LNG induced germ cell apoptosis at stages I-IV and XII-XIV; T increased apoptosis at stages VII-VIII; LNG + T treatment induced greater germ cell apoptosis at a wider range of seminiferous epithelial stages. RT-PCR and Western Blots showed that PR was present in testes and up-regulated during suppression of spermatogenesis induced by testicular hormonal deprivation. PR knockout (PRKO) mice had larger testes, greater sperm production, increased numbers of Sertoli and Leydig cells. Suppression of gonadotropin and intratesticular T by GnRH-antagonist treatment induced PR promoter driven LacZ expression in Leydig cells of PRKO mice. This suggests that GnRH-antagonist treatment while inducing germ cell apoptosis also up-regulates PR. We conclude that (i) LNG + T induced greater suppression of spermatogenesis through increase in germ cell apoptosis involving a wider range of seminiferous epithelial stages than either treatment alone, (ii) up-regulation of PR was associated with inhibition of spermatogenesis, (iii) PR knockout mice showed increased sperm production suggesting that testicular PR activated events play a physiological and pharmacological inhibitory role in the testis. These data support the hypothesis that in addition to its known suppressive effects on gonadotropins, progestins may have direct inhibitory actions on the testis.

Differences in Testicular Development Between 5α-Reductase 2 Deficiency and Isolated Bilateral Cryptorchidism

We demonstrated that infertility develops in most patients with steroid 5alpha-reductase 2 deficiency. We compared the testicular histopathology of boys with steroid 5alpha-reductase 2 deficiency to that of boys with isolated bilateral cryptorchidism. Testes with steroid 5alpha-reductase 2 deficiency lacked spermatocytes but had Ad spermatogonia and a normal germ cell count. In contrast, bilateral cryptorchid testes had severe germ cell depletion and the majority lacked Ad spermatogonia. In patients with steroid 5alpha-reductase 2 deficiency the impaired second step of germ cell maturation results in defective transformation of spermatogonia into spermatocytes. The position of the undescended testis appears to have no major pathological impact on the development of germ cells in patients with steroid 5alpha-reductase 2 deficiency.