Cimetidine (Tagamet) is a reproductive toxicant in male rats affecting peritubular cells

Biogenic amines in the testis: sources, receptors and actions

Biogenic amines are signaling molecules with multiple roles in the central nervous system and in peripheral organs, including the gonads. A series of studies indicated that these molecules, their biosynthetic enzymes and their receptors are present in the testis and that they are involved in the regulation of male reproductive physiology and/or pathology. This mini-review aims to summarize the current knowledge in this field and to pinpoint existing research gaps. We suggest that the widespread clinical use of pharmacological agonists/antagonists of these signaling molecules, calls for new investigations in this area. They are necessary to evaluate the relevance of biogenic amines for human male fertility and infertility, as well as the potential value of at least one of them as an anti-aging compound in the testis.

Testicular toxicity in mice exposed to terephthalic acid in utero and during lactation

Terephthalic acid (TPA) is a worldwide aromatic compound widely used to manufacture resins and the raw material for the polymerization reaction with ethylene glycol to produce polyethylene terephthalate, known as PET. The use of TPA extends to the synthesis of phthalates, plasticizers used in various industrialized products such as toys and cosmetics. The present study aimed to evaluate the testicular toxicity of terephthalic acid on male mice exposed in utero and during lactation to TPA in different developmental windows. The animals were treated intragastric with TPA at stock dispersal dosages corresponding to 0.0014 g/ml and 0.56 g/ml of TPA in 0.5% v/v carboxymethylcellulose as well as the control dose, composed solely of dispersion of carboxymethylcellulose (0.5% v/v). Four experimental windows were established: group I-treatment in utero, in the fetal period (gestational day-GD 10.5-18.5), with euthanasia at GD 18.5; group II-treatment in utero, in the fetal period (GD 10.5-18.5) and the lactational period (postnatal day (PND-15)), with euthanasia at 15 days; group III-treatment in utero in the fetal period (DG 10.5-18.5) with euthanasia at 70 days (age of sexual maturity, PND 70); group IV-treatment in utero, in the fetal period (GD 10.5-18.5) and the lactational period (PND-15), with euthanasia at 70 days (PND70). The results indicate that TPA changes the reproductive parameters (testicular weight, GI, penis size, and anogenital index) only at the dose of 0.56 g/ml in the fetal period. Data on the volumetric ratio of the testis elements show that the dispersion with the highest concentration of TPA significantly altered the blood vessel/capillary, lymphatic vessel, and connective tissue percentages. Only at the dose of 0.56 g/ml TPA was it effective in decreasing the Leydig and Sertoli cell numbers of the euthanized animals at GD 18.5. In group II, TPA increased the diameter and lumen of seminiferous tubules, which indicates that TPA accelerated the maturation process of Sertoli cells without changing the number and the nuclear volume of these cells. The Sertoli and Leydig cell numbers of the 70-day animals exposed to TPA in the gestational and lactational period were similar to the control. Therefore, the present study is the first in the literature to show that TPA presents a testicular toxicity during fetal (DG18.5) and postnatal life (PND15), without repercussion in adulthood (70 days).

Long-term exposure to cimetidine induced gonado-toxicity in male rats: Modulating role of Ocimum gratissimum

BACKGROUND

Available evidence suggests that cimetidine is a reproductive toxicant that induces sexual and testicular dysfunction. Ocimum gratissimum (OG) is globally consumed for medicinal and nutritional purposes. To determine the modulating role of aqueous leaf extract of Ocimum gratissimum on cimetidine-induced gonado-toxicity, sexually mature male rats were randomized into four groups of six (n=6) rats each. Group A: control given 2ml distilled water. Group B received 500mg/kg body weight (bwt) of OG extract, Group C received 50mg/kg bwt cimetidine, and group D received 50mg/kg bwt of cimetidine+500mg/kg bwt OG extract once daily for 8 weeks via gastric gavage. Parameters tested include sperm parameters, testosterone (TT), luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin, testicular alkaline phosphatase (ALP), acid phosphatase (ACP), lactate dehydrogenase (LDH), protein, cholesterol, glycogen, sexual behavioural parameters, and testicular histology.

RESULTS

There were depletions in the seminiferous epithelium, decreased sperm quality, TT, LH, and FSH, testicular enzymes, protein, cholesterol, glycogen, and sexual behaviour increase in animals treated with cimetidine only compared to control. OG restored and improved sexual behaviour and libido as evident from increased frequencies of mount, intromission, ejaculation, and ejaculatory latency. Mount latencies, intromission, post-ejaculation, and prolactin were significantly decreased. The significantly decreased testicular activities of ALP, ACP, LDH and protein, cholesterol, glycogen concentrations, TT, LH and FSH were increased by OG administration.

CONCLUSION

Ocimum gratissimum attenuated the deleterious effects of cimetidine on the testis, protected the seminiferous epithelium, restored, and boosted sexual competence, and promoted spermatogenesis.

Proteomic Insights into Senescence of Testicular Peritubular Cells from a Nonhuman Primate Model

Age-related changes in the human testis may include morphological alterations, disturbed steroidogenesis, and impaired spermatogenesis. However, the specific impact of cell age remains poorly understood and difficult to assess. Testicular peritubular cells fulfill essential functions, including sperm transport, contributions to the spermatogonial stem cell niche, and paracrine interactions within the testis. To study their role in age-associated decline of testicular functions, we performed comprehensive proteome and secretome analyses of repeatedly passaged peritubular cells from Callithrix jacchus. This nonhuman primate model better reflects the human testicular biology than rodents and further gives access to young donors unavailable from humans. Among 5095 identified proteins, 583 were differentially abundant between samples with low and high passage numbers. The alterations indicate a reduced ability of senescent peritubular cells to contract and secrete proteins, as well as disturbances in nuclear factor (NF)-κB signaling and a reduced capacity to handle reactive oxygen species. Since this in vitro model may not exactly mirror all molecular aspects of in vivo aging, we investigated the proteomes and secretomes of testicular peritubular cells from young and old donors. Even though the age-related alterations at the protein level were less pronounced, we found evidence for impaired protein secretion, altered NF-κB signaling, and reduced contractility of these in vivo aged peritubular cells.

Essential roles of interstitial cells in testicular development and function

BACKGROUND

Testicular architecture and sperm production are supported by a complex network of communication between various cell types. These signals ensure fertility by: regulating spermatogonial stem/progenitor cells; promoting steroidogenesis; and driving male-specific differentiation of the gonad. Sertoli cells have long been assumed to be the major cellular player in testis organogenesis and spermatogenesis. However, cells in the interstitial compartment, such as Leydig, vascular, immune, and peritubular cells, also play prominent roles in the testis but are less well understood.

OBJECTIVES

Here, we aim to outline our current knowledge of the cellular and molecular mechanisms by which interstitial cell types contribute to spermatogenesis and testicular development, and how these diverse constituents of the testis play essential roles in ensuring male sexual differentiation and fertility.

METHODS

We surveyed scientific literature and summarized findings in the field that address how interstitial cells interact with other interstitial cell populations and seminiferous tubules (i.e., Sertoli and germ cells) to support spermatogenesis, male-specific differentiation, and testicular function. These studies focused on 4 major cell types: Leydig cells, vascular cells, immune cells, and peritubular cells.

RESULTS AND DISCUSSION

A growing number of studies have demonstrated that interstitial cells play a wide range of functions in the fetal and adult testis. Leydig cells, through secretion of hormones and growth factors, are responsible for steroidogenesis and progression of spermatogenesis. Vascular, immune, and peritubular cells, apart from their traditionally acknowledged physiological roles, have a broader importance than previously appreciated and are emerging as essential players in stem/progenitor cell biology.

CONCLUSION

Interstitial cells take part in complex signaling interactions with both interstitial and tubular cell populations, which are required for several biological processes, such as steroidogenesis, Sertoli cell function, spermatogenesis, and immune regulation. These various processes are essential for testicular function and demonstrate how interstitial cells are indispensable for male fertility.

Curcuma longa normalized cimetidine-induced pituitary-testicular dysfunction: Relevance in nutraceutical therapy

BACKGROUND

The increasing incidence of chemically induced infertility is both a social threat and a threat to the continuation of life itself. Treatment or management therapy is often expensive. This study investigated the effects of acetone extract of a local plant (Curcuma longa) in a Wistar rat model of cimetidine-induced pituitary-testicular dysfunction.

METHODS

Thirty-five male Wistar rats were divided into 7 groups of 5 rats. After a phytochemical screening of an acetone extract of C. Longa, cimetidine and the extract at three doses, 200, 400 and 600 mg/kg, were orally co-administered to the rats for 28 consecutive days. Comparisons were made (at P < 0.05) against a control (2 mL/kg distilled water), a standard treatment group (cimetidine + 50 mg/kg vitamin C), a toxic group (60 mg/kg cimetidine) and a group receiving extract alone.

RESULTS

Cimetidine administration was associated with deleterious alterations to sperm motility, sperm count and sperm viability, as well as derangements in the plasma levels of FSH, LH and testosterone (P < 0.05). Both brain and testicular GSH and TBARS levels were significantly altered following cimetidine administration, and distortions were seen in the pituitary and testicular histoarchitecture. These changes were significantly normalized by co-administration of graded doses of the extract, with an associated improvement of both pituitary and testicular histology.

CONCLUSION

Acetone extract of C. Longa normalized cimetidine-induced pituitary-testicular dysfunction in Wistar rats. This presents the extract as a potential nutraceutical choice against chemically induced reproductive toxicity.

Human testicular peritubular cells, mast cells and testicular inflammation

In man, the wall of seminiferous tubules forms a testicular compartment, which contains several layers of smooth muscle-like, "myoid", peritubular cells and extracellular matrix. Its architecture and its cellular composition change in male infertility associated with impaired spermatogenesis. Increased deposits of extracellular matrix, changes in the smooth muscle-like phenotype of peritubular cells and accumulation of immune cells, especially mast cells, are among the striking alterations. Taken together, the changes indicate that inflammatory events take place in particular within this compartment. This short review summarises recent studies, which pinpoint possible mechanisms of the interplay between peritubular cells and mast cells, which may contribute to sterile inflammation and impairments of testicular function. These insights are based mainly on cellular studies, for which we used isolated human testicular peritubular cells (HTPCs), and on the examination of human testicular sections. Recent data on immunological properties of peritubular cells, unexpected roles of the extracellular matrix factor, biglycan, which is secreted by peritubular cells and functions of mast cell products (chymase, tryptase and ATP) are presented. We believe that the results may foster a better understanding of peritubular cells, their roles in the human testis and specifically their involvement in infertility.

Reduced levels of stromal sex hormone-binding globulin and androgen receptor dysfunction in the sperm storage region of the rat epididymis

The cauda epididymidis is the major sperm storage region whose androgenic supply, essential for the sperm viability, is provided by the vasculature and is dependent upon testosterone diffusion through the stromal tissue to reach the epithelial cells. We have focused our efforts on examining the regulation of this important epididymal region by evaluating the impact of the androgen disrupter cimetidine on the epithelial–stromal androgenic microenvironment. Male rats received 100 mg/kg cimetidine (CMTG) or saline (CG) for 50 days, serum testosterone levels were measured and the epididymal cauda region was processed for light and transmission electron microscopy. In the proximal cauda region, the duct diameter was measured and birefringent collagen in the stroma was quantified. TUNEL-labeled epithelial cells were quantified, and androgen receptor (AR), karyopherin alpha (KPNA) and sex hormone-binding globulin (SHBG) levels were analyzed by immunofluorescence and Western blot. CMTG showed reduced duct diameter and high number of apoptotic epithelial cells. In the epithelium, the total AR concentration and the KPNA immunoreactivity were reduced, and a weak/absent AR nuclear immunofluorescence was observed in contrast to the enhanced AR immunolabeling observed in the cytoplasm of the epithelial cells. A significant reduction of collagen and SHBG levels in the stroma was also observed. Cimetidine treatment impairs AR nuclear import in the epithelium, causing androgenic dysfunction and subsequent epithelial cell apoptosis and duct atrophy. The connective tissue atrophy and reduction of SHBG stromal levels associated with epithelial androgenic dysfunction indicate a possible role of stromal SHBG in the androgenic supply of the sperm storage region of the epididymis.

Vitamin B12-induced spermatogenesis recovery in cimetidine-treated rats: effect on the spermatogonia number and sperm concentration

The H₂-receptor antagonist cimetidine is an antiulcer drug also used for the treatment of cancer due to its antiangiogenic effect. However, this drug has caused structural changes in the seminiferous tubules. Vitamin B₁₂ has been used as a therapeutic agent for the treatment of male infertility. The supplementation of rats with vitamin B₁₂ during cimetidine treatment has recovered the damaged seminiferous tubules, but how this vitamin restores the seminiferous epithelium has not been clarified. In this study, we evaluated whether vitamin B₁₂ improves the number of spermatogonia, spermatocytes, and sperm concentration in cimetidine-treated rats. Adult male rats were treated for 50 days as follows: cimetidine group received 100 mg kg⁻¹ b.w. of cimetidine, cimetidine-B₁₂ group received cimetidine and 3 μg of vitamin B₁₂-hydroxocobalamin, B₁₂ group received only 3 μg of vitamin, and control group received saline. Sperm concentration was calculated and historesin-embedded testes sections were used for the quantitative analyses of spermatogonia (A; In/B) and spermatocytes. TUNEL method and PCNA immunofluorescence were performed. Cimetidine caused a significant reduction in sperm concentration. TUNEL-positive spermatogonia and spermatocytes were correlated to a significant reduction in the number of these cells. In cimetidine-B₁₂ group, sperm concentration was higher than cimetidine group and a significant increase in the number of spermatogonia (stages II–VI) was correlated to a high incidence of PCNA-immunolabeled spermatogonia and spermatocytes. The results show that the supplementation of rats with vitamin B₁₂ during cimetidine treatment increases sperm concentration and exerts a potential effect in the recovery of spermatogonia and spermatocytes.

Effects of oral cimetidine on the reproductive system of male rats

Cimetidine is widely used for the treatment of digestive tract ulcers, but it induces testis injury. To explore the mechanisms underlying cimetidine-induced toxicity towards the testis, the effects of oral cimetidine on the reproductive system of male rats were assessed. Cimetidine was orally administered to male rats at 20, 40 or 120 mg/kg/day for 9 weeks. The rats were then euthanized, and serum, testis, epididymis, prostate gland, seminal vesicle, preputial gland, levator ani muscle and sphincter ani samples were collected. Sperm parameters were obtained by computer-assisted sperm analysis. Serum hormone levels were measured by ELISA. Protein expression levels were detected by immunohistochemistry. Apoptosis was assessed with the DeadEnd™ Colorimetric Apoptosis Detection System. The results indicated that the sperm average path velocity, straight line velocity and curvilinear velocity were significantly decreased in the 120 mg/kg cimetidine group compared with the control group, while luteinizing hormone and testosterone levels were significantly higher compared with the control group. Testicular lesions were observed by histopathology in the 120 mg/kg cimetidine group. The amounts of cells positive for cyclooxygenase-2 (COX-2) and nuclear factor κB (NF-κB) were increased in the 120 mg/kg cimetidine group compared with the control group. The amounts of cells positive for iNOS were increased in all cimetidine treatment groups. In addition, apoptotic cells were significantly more abundant in the 120 mg/kg cimetidine group compared with the control group, as indicated by terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling. Overall, 9 weeks of oral cimetidine induced pathological changes in the testicles and hormone secretion disorder in rats. COX-2, iNOS and NF-κB upregulation and induction of apoptosis may be associated with the reproductive toxicity caused by cimetidine.

Ameliorative effect of vitamin B12 on seminiferous epithelium of cimetidine-treated rats: a histopathological, immunohistochemical and ultrastructural study

Cimetidine is an H2 receptor antagonist that has an antiandrogenic effect. It intervenes with the conversion of testosterone into estrogen in the Sertoli cells with accompanying testicular structural changes. In the present study, the microscopic and the ultrastructural changes induced by cimetidine and the effect of vitamin B12 as a protective agent on rat testes were studied. Immunoexpression of estrogen receptor β (ERβ) in testes was evaluated. Twenty-four adult male rats were divided into four groups: control, cimetidine-treated, vitamin B12 treated, and combined cimetidine and vitamin B12 treated. The experimental rats were administered with cimetidine and/or vitamin B12 for 52 days. Group II rats showed marked atrophy of the seminiferous tubules with a significant increase in tubular diameter and decrease in the tubular luminal and epithelial areas. Ultrastructure of this group showed irregular Sertoli cells with basal cytoplasmic vacuolation and significantly thickened basement membrane. ERβ immunoexpression was similar to controls. Group III rats showed near normal seminiferous tubular structures with minimal cellular alterations and the immunoreactivity of the testicular sections was very close to normal. However, group IV rats showed markedly immunopositive detached cells, spermatids, and primary spermatocytes. Cimetidine interferes with the control of spermatogenesis as evidenced by microscopic and ultrastructural studies and affection of ERβ receptors and vitamin B12 has a protective action against this harmful effect.

The impact of drugs on male fertility: a review

Beside cytotoxic drugs, other drugs can impact men's fertility through various mechanisms. Via the modification of the hypothalamic-pituitary-gonadal axis hormones or by non-hormonal mechanisms, drugs may directly and indirectly induce sexual dysfunction and spermatogenesis impairment and alteration of epididymal maturation. This systematic literature review summarizes existing data about the negative impact and associations of pharmacological treatments on male fertility (excluding cytotoxic drugs), with a view to making these data more readily available for medical staff. In most cases, these effects on spermatogenesis/sperm maturation/sexual function are reversible after the discontinuation of the drug. When a reprotoxic treatment cannot be stopped and/or when the impact on semen parameters/sperm DNA is potentially irreversible (Sulfasalazine Azathioprine, Mycophenolate mofetil and Methotrexate), the cryopreservation of spermatozoa before treatment must be proposed. Deleterious impacts on fertility of drugs with very good or good level of evidence (Testosterone, Sulfasalazine, Anabolic steroids, Cyproterone acetate, Opioids, Tramadol, GhRH analogues and Sartan) are developed.

Gradual decrease in spermatogenesis caused by chronic stress

Chronic stress induces decreased sperm motility, viability and concentration in stressed males. Also, stress modifies oxidative status and causes apoptosis in testes, as well as a decrease in the epithelial area of seminiferous tubules. However, there are no studies that analyze the alterations caused by stress in testicular cells. Thus, in this study, alterations in the morphology of testicular germ cells caused by different days of chronic stress were assessed. Adult male rats were exposed to stress by immersion in cold water (ICW) daily for 3, 8, 20 or 50 consecutive days. Plasma testosterone and corticosterone were also assessed. Results showed that chronic stress causes loss of germ cells, and alteration of spermatogenesis. Seminiferous tubules from stressed males showed several degenerative signs, such as vacuoles in the basal epithelium, with picnotic indicia; moderate to severe exfoliation of degenerative germinal cells in the tubule lumen was also observed. These alterations were observed in all days of stress in a gradual way, from day 3-50. Testosterone levels were decreased at all those times, and corticosterone concentrations were increased on the same days. These results show that chronic stress causes severe damage to germ cells, which can account for infertility problems in males. These alterations are related to a decrease in testosterone as well as an increase in corticosterone caused by stress.

Cimetidine disrupts the renewal of testicular cells and the steroidogenesis in a hermaphrodite fish

The importance of histamine in the physiology of the testis in mammals and reptiles has been recently shown. Histamine receptors (Hrs) are well conserved in fish and are functional in several fish species. We report here for the first time that histamine and the mRNA of Hrh1, Hrh2 and Hrh3 are all present in the gonad of the hermaphrodite teleost fish gilthead seabream. Moreover, cimetidine, which acts in vitro as an agonist of Hrh1 and Hrh2 on this species, was intraperitoneally injected in one and two years old gilthead seabream males. After three and five days of cimetidine injection, we found that this compound differently modified the gonadal hrs transcript levels and affects the testicular cell renewal and the gene expression of steroidogenesis-related molecules as well as the serum steroid levels. Our data point to cimetidine as a reproductive disruptor and elucidate a role for histamine in the gonad of this hermaphrodite fish species through Hr signalling.

Ecotoxicological assessment of cimetidine and determination of its potential for endocrine disruption using three test organisms: Daphnia magna, Moina macrocopa, and Danio rerio

Cimetidine is a histamine H2-receptor antagonist used for treatment of gastrointestinal disorders. It is often detected in aquatic environments, but its ecotoxicological effects have not been well studied. Thus, ecotoxicity of cimetidine was evaluated using Daphnia magna and Moina macrocopa, and zebrafish (Danio rerio), and a predicted no effect concentration (PNEC) was derived. In D. magna, 48 h immobilization EC50 was determined at 394.9 mg L(-1). However, reproduction damages in D. magna were not found even at the maximum exposure level (30 mg L(-1)). For M. macrocopa, 48 h EC50 was found at 175.8 mg L(-1) and the 7 d reproduction no observed effect concentration (NOEC) was 1.1 mg L(-1). For D. rerio, 40 d growth NOEC was determined at 100 mg L(-1), the highest experimental concentration. The PNEC of cimetidine was estimated at 0.1 mg L(-1) based on M. macrocopa 7d reproduction NOEC. In 14 d adult zebrafish exposure, endocrine disruption potentials of cimetidine were observed. In male, decrease in plasma 17β-estradiol and testosterone levels, up-regulation of gonadal cyp17, and down-regulation of hepatic erα were observed at 300 mg L(-1). In female, increase in plasma E2 level and down-regulation of hepatic cyp1a were noted at 3 mg L(-1). Endocrine disruption effects were also observed in early life stage exposure. Up-regulation of erβ at 17d, and cyp19a and vtg at 40 d post fertilization were detected at 100 mg L(-1), and co-occurrence of ovary and putative testis was observed at as low as 1.1 mg L(-1). The results indicate that there is little evidence for cimetidine to cause direct ecological impact at the current ambient levels in the aquatic environment. However potential consequences of endocrine disruption following long-term exposure in aquatic environment deserves further investigation.

Morphologic manifestations of testicular and epididymal toxicity

Histopathologic examination of the testis is the most sensitive means to detect effects on spermatogenesis; however, the complexity of testicular histology, interrelatedness of cell types within the testis, and long duration of spermatogenesis can make assessment of a testicular toxicant challenging. A thorough understanding of the histology and morphologic manifestations of response to injury is critical to successfully identify a testicular effect and to begin to understand the underlying mechanism of action. The basic patterns of response to xenobiotic-induced injury to the testis and epididymis are detailed and discussed.

The regulation of spermatogenesis by androgens

Testosterone is essential for maintaining spermatogenesis and male fertility. However, the molecular mechanisms by which testosterone acts have not begun to be revealed until recently. With the advances obtained from the use of transgenic mice lacking or overexpressing the androgen receptor, the cell specific targets of testosterone action as well as the genes and signaling pathways that are regulated by testosterone are being identified. In this review, the critical steps of spermatogenesis that are regulated by testosterone are discussed as well as the intracellular signaling pathways by which testosterone acts. We also review the functional information that has been obtained from the knock out of the androgen receptor from specific cell types in the testis and the genes found to be regulated after altering testosterone levels or androgen receptor expression.

NF-kB overexpression and decreased immunoexpression of AR in the muscular layer is related to structural damages and apoptosis in cimetidine-treated rat vas deferens

BACKGROUND

Cimetidine, histamine H2 receptors antagonist, has caused adverse effects on the male hormones and reproductive tract due to its antiandrogenic effect. In the testes, peritubular myoid cells and muscle vascular cells death has been associated to seminiferous tubules and testicular microvascularization damages, respectively. Either androgen or histamine H2 receptors have been detected in the mucosa and smooth muscular layer of vas deferens. Thus, the effect of cimetidine on this androgen and histamine-dependent muscular duct was morphologically evaluated.

METHODS

The animals from cimetidine group (CMTG; n=5) received intraperitoneal injections of 100 mg/kg b.w. of cimetidine for 50 days; the control group (CG) received saline solution. The distal portions of vas deferens were fixed in formaldehyde and embedded in paraffin. Masson´s trichrome-stained sections were subjected to morphological and the following morphometrical analyzes: epithelial perimeter and area of the smooth muscular layer. TUNEL (Terminal deoxynucleotidyl-transferase mediated dUTP Nick End Labeling) method, NF-kB (nuclear factor kappa B) and AR (androgen receptors) immunohistochemical detection were also carried out. The birefringent collagen of the muscular layer was quantified in picrosirius red-stained sections under polarized light. The muscular layer was also evaluated under Transmission Electron Microscopy (TEM).

RESULTS

In CMTG, the mucosa of vas deferens was intensely folded; the epithelial cells showed numerous pyknotic nuclei and the epithelial perimeter and the area of the muscular layer decreased significantly. Numerous TUNEL-labeled nuclei were found either in the epithelial cells, mainly basal cells, or in the smooth muscle cells which also showed typical features of apoptosis under TEM. While an enhanced NF-kB immunoexpression was found in the cytoplasm of muscle cells, a weak AR immunolabeling was detected in these cells. In CMTG, no significant difference was observed in the birefringent collagen content of the muscular layer in comparison to CG.

CONCLUSIONS

Cimetidine induces significant damages in the epithelium; a possible antiandrogenic effect on the basal cells turnover should be considered. The cimetidine-induced muscle cells apoptosis confirms the susceptibility of these cells to this drug. The parallelism between enhanced cytoplasmic NF-kB immunolabeling in the damaged muscular tissue and muscle cell apoptosis suggests that this drug may avoid the translocation of NF-kB to the nucleus and interfere in the control of NF-kB-mediated smooth muscle cell apoptosis. The decreased immunoexpression of ARs verified in the damaged muscular tissue reinforces this possibility.

Stereological analysis of age-related changes of testicular peritubular cells in men

This work aimed to analyze quantitative changes of peritubular cells in testes of aged men. Testicular tissues were obtained from 42 aged men with advanced prostate cancer and 16 young men with biopsy, quantitatively investigated with stereological techniques with quadrate mask grid, measured the parameters volume density (V(V)), numerical density on area (N(A)), and numerical density (N(V)) with grid test points. No significant differences were found in cell ratio, peritubular cell number per tubule, diameter of seminiferous tubules between young and old men (p>0.05). Aged men had higher pathologic assignment score than that of young men, which demonstrated more severe pathologic changes (p<0.05). Peritubular cell V(V) and pachytene germ cell V(V) increased significantly in old men compared to young men (p<0.05). Sertoli cell (SC) number per tubule in two-dimensional was significantly less in aged men than that of young men, p<0.01. Peritubular cell N(A), N(V) decreased significantly in aged men compared to young one, p<0.05. It is concluded that the stereological data of peritubular cells from three-dimensional level in testes of aged men suggest a significant decrease when compared with young men, indicating age-related changes.

Immunosuppressant prograf® (tacrolimus) induces histopathological disorders in the peritubular tissue of rat testes

Treatment with tacrolimus (FK-506) has been shown to induce a significant decrease in the number of spermatocytes, spermatids, and Sertoli cells. Regarding the importance of the peritubular tissue for the maintenance of Sertoli cells, the integrity of the cellular and extracellular components of the peritubular tissue was evaluated in adult rats that were treated with 1 mg/kg/day of FK-506 for 30 and 60 days. Testicular sections were used for a quantitative analysis of the peritubular cells (PCs) and were submitted to the PAS method. Paraffin sections were submitted to the TUNEL method and to immunohistochemistry for the detection of caspase-3. Several testicular fragments were analyzed under a transmission electron microscope (TEM). A weak PAS reaction was noted in the peritubular tissue of the tacrolimus-treated animals. Next to the damaged peritubular tissue, the Sertoli cell nuclei were absent or dislocated from the basement membrane. In the treated animals, the number of PCs decreased significantly compared to the control animals, and these cells showed apoptotic features, were TUNEL positive, and were caspase-3 immunolabeled. Using the TEM, apoptosis was confirmed in myoid cells; moreover, the thickness and undulation of the basal laminae and an enlargement of the collagen I layer adjacent to the myoid cells was observed. Long-term treatment with the immunosuppressor induced peritubular myoid cell death by apoptosis and disarrangement of the peritubular extracellular layers. Future studies are necessary to confirm whether the structural alterations in the seminiferous epithelium are related to the effect of FK-506 on peritubular tissue.

Androgen action via testicular peritubular myoid cells is essential for male fertility

Androgens are essential for normal spermatogenesis and male fertility, but how androgens exert this effect remains uncertain. Androgen receptors (ARs) are expressed in several testicular cell types, but continuing uncertainty exists over which cell type mediates androgen control of spermatogenesis. Androgen signaling via Sertoli cells (SCs) is essential for complete spermatogenesis, but the role for androgen signaling via peritubular myoid (PTM) cells is contentious. To address this controversy, we generated PTM-specific AR-knockout (PTM-ARKO) mice in which gross reproductive development was normal, but all PTM-ARKO males were azoospermic and infertile. Testis weight was reduced beyond puberty, and in adulthood there was an 86% reduction in germ cells, compared with wild-type littermates. These changes were not explained by any deficits in testosterone, luteinizing hormone, or follicle-stimulating hormone concentrations. SC function was impaired in PTM-ARKO males, indicated by reduced seminiferous tubule fluid production and reduced expression of some androgen-dependent SC genes. Androgen action via PTM cells is therefore essential for normal testis function, spermatogenesis, and fertility in males. This study also provides the first direct evidence for the importance of androgen-driven stromal-epithelial interactions underpinning the regulation of spermatogenesis; PTM-ARKO mice will enable identification of the new molecular pathways involved.

Enhanced ERbeta immunoexpression and apoptosis in the germ cells of cimetidine-treated rats

BACKGROUND

Cimetidine, refereed as antiandrogenic drug, causes hormonal changes in male patients such as increased testosterone and FSH levels. In the rat testis, structural alterations in the seminiferous tubules have been related to germ cell loss and Sertoli cell death by apoptosis. Regarding the important role of Sertoli cells in the conversion of testosterone into estrogen, via aromatase, the immunoexpression of estrogen receptors-beta (ERbeta) was evaluated in the germ cells of untreated and treated rats with cimetidine. A relationship between ERbeta immunoreactivity and apoptosis was also investigated in the germ cells of damaged tubules.

METHODS

Immunohistochemistry for detection of ERbeta and TUNEL method were performed in testicular sections of adult male rats treated with 50 mg/Kg of cimetidine (CmG) or saline solution (CG) for 52 days.

RESULTS

In CG, a cytoplasmic immunoexpression for ERbeta was observed in spermatogonia, primary spermatocytes and spermatids. An evident ERbeta immunoreactivity was always observed in the flagellum and residual bodies of late spermatids. In CmG, the cytoplasm or cytoplasm and nuclei of germ cells of the damaged tubules by cimetidine showed enhanced ERbeta immunostaining. TUNEL-labeling was usually observed in the same germ cell types exhibiting enhanced ERbeta immunoreactivity.

CONCLUSION

The presence of ERbeta immunolabeling in the flagellum and residual bodies of spermatids reinforces the role of estrogen in spermiogenesis. The overexpression of ERbeta in the germ cells of CmG could be related to a possible interference of cimetidine on tubular androgenization and/or on the intratubular aromatase due to Sertoli cell damage. The parallelism between ERbeta overexpression and apoptosis indicates a participation of ERbeta on germ cell death.

Morphological evidences indicate that the interference of cimetidine on the peritubular components is responsible for detachment and apoptosis of Sertoli cells

Cimetidine, referred as antiandrogenic agent, has caused alterations in the seminiferous tubules, including alterations in the peritubular tissue and death of myoid cells by apoptosis. Regarding the structural and functional importance of the peritubular tissue for the maintenance of Sertoli cells (SC), we purpose to investigate the SC-basement membrane interface, focusing the morphological features of SC and their interaction with the basement membrane in the affected tubules by cimetidine. Ten animals were distributed into two groups, control (CG) and cimetidine (CmG) which received saline solution and 50 mg of cimetidine per kg of body weight, respectively, for 52 days. The testes were fixed, dehydrated and embedded for analyses under light and transmission electron microscopy. Paraffin sections were submitted to the TUNEL method; sections of testes embedded in glycol methacrylate were submitted to PAS method and stained by H&E for morphological and quantitative analyses of Sertoli Cells. In the CmG, the SC nuclei were positive to the TUNEL method and showed typical morphological alterations of cell death by apoptosis (from early to advanced stages). A significant reduction in the number of Sertoli Cells was probably due to death of these cells by apoptosis. A close relationship between SC nuclear alterations (including a high frequency of dislocated nuclei from the basal portion) and damage in the peritubular tissue was observed. The ultrastructural analysis showed a parallelism between the gradual advancement of apoptotic process in SC and detachment of the anchoring sites (hemidesmosomes) of SC plasma membrane from the lamina densa. The presence of portions of lamina densa underlying the detached hemidesmosomes indicates a continuous deposition of lamina densa, resulting in the thickening of the basal lamina. The results indicate a possible disarrangement of the SC cytoskeleton, including the focal adhesion structure. These alterations are related to SC apoptosis and probably result from disturbs induced by cimetidine on the peritubular tissue.

Apoptosis during the seasonal spermatogenic cycle of Rana catesbeiana

In the bullfrog Rana catesbeiana, testicular weight is constant throughout the year, but the volume densities of germinative and interstitial compartments undergo inverse changes from winter (non-breeding) to summer (breeding). The occurrence of apoptosis in the seminiferous lobules of bullfrogs was investigated in these two periods using sections stained with haematoxylin and eosin (H&E), the TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling) method and transmission electron microscopy. TUNEL-positive cells were observed in the seminiferous lobules, and ultrastructural morphological details confirmed the occurrence of cell death by apoptosis. In summer, the occurrence of several spermatogenic processes (in addition to spermiogenesis and spermiation), and then the overconsumption of Sertoli cell-derived pro-survival factors, could be responsible for the increased density of apoptotic cells. Alternatively, the low apoptotic frequency in winter could be related to the constant homeostasis in the germinative compartment given that most lobules are filled with primary spermatocytes. As volume densities of interstitial and germinative compartments undergo inverse seasonal variations through the year, the incidence of apoptosis (in summer) could play a part in controlling the spermatogenic process, maintaining the lobular size when interstitial tissue is maximally developed. In winter, the low apoptotic cell density leads to spermatogenic recrudescence and, thereby, the production of an adequate quantity of spermatozoa for the next breeding period. Thus, apoptosis may participate not only in the maintenance of spermatogenic homeostasis, but also in the cyclical control of the different spermatogenic processes according to seasonal changes of the testicular compartments as a whole.

Risk assessment of chemicals potentially affecting male fertility

Male reproductive toxicity involves a broad range of targets and mechanisms such as direct effects on the seminiferous epithelium and/or on Leydig and Sertoli cells supporting spermatogenesis, epididymal sperm maturation as well as endocrine disruption. Direct effects on spermatogenesis may be adequately revealed through both reproduction and repeated-dose toxicity studies; however, more research is needed on early markers of effect and on long-term sequelae of short-term exposures. Endocrine-related mechanisms are particularly relevant to subtle, but persistent effects on reproductive development due to altered early programming; the two-generation study is the test of choice, whereas targeted studies on the prepubertal phase are also desirable. Studies using in vitro methods as well as toxicogenomics are increasing; although gaps exist and much validation work is needed, in perspective, such approaches may be important in order to select compound, understand mechanisms, as well identify biomarkers of potential use also in human studies.

Dual role of histamine in modulation of Leydig cell steroidogenesis via HRH1 and HRH2 receptor subtypes

Although several reports indicate effects of histamine (HA) on female reproductive functions, scant literature exists to suggest a physiological role of HA in the male gonad. In the present study, we report a dual concentration-dependent effect of HA on steroidogenesis in MA-10 murine Leydig cells and purified rat Leydig cells. Although 1 nM HA can stimulate steroid production and significantly increase the response to LH/hCG in these cells, 10 microM HA exerts an inhibitory effect. We also provide confirming evidence for the existence of functional HRH1 and HRH2 receptors in both experimental models. The use of HRH1 and HRH2 selective agonists and antagonists led us to suggest that HRH2 activation would be largely responsible for stimulation of steroidogenesis, while HRH1 activation is required for inhibition of steroid synthesis. Our results regarding signal transduction pathways associated with these receptors indicate the coupling of HRH2 to the adenylate cyclase system through direct interaction with a Gs protein. Moreover, we show HRH1 activation mediates increases in inositol phosphate production, possibly due to coupling of this receptor to Gq protein and phospholipase C activation. The data compiled in this report clearly indicate that HA can modulate Leydig cell steroidogenesis in the testis and suggest a possible new physiological site of action for HA. Given that many drugs binding to HRH1, HRH2, or both, are widely prescribed for the treatment of diverse HA-related pathologies, it seems necessary to increase the knowledge regarding histaminergic regulation of testicular functions, to avoid possible unexpected side effects of such substances in the testis.

Evidence for a histaminergic system in the human testis

The complete lack of information about mast cells as a source of histamine and potential target cells for histamine in human testes prompted us to investigate these issues in testes of fertile and infertile patients using a combination of laser microdissection, reverse transcription-polymerase chain reaction (RT-PCR), and immunohistochemistry. We show for the first time the expression of the rate-limiting enzyme in histamine synthesis-histidine decarboxylase-by human testicular mast cells and the expression of the histamine (H) receptors 1 (H1) and 2 (H2) by germinal, interstitial, and peritubular cells in the testes of fertile and infertile patients.

The effect of sustained and local administration of epidermal growth factor on improving bilateral testicular tissue after torsion

Epidermal growth factor (EGF) modulates Leydig cell proliferation, steroidogenesis, spermiogenesis, and Sertoli cell activity. It plays an important role in repairing ischemia-reperfusion injury in different tissues. The aim of this study was to evaluate the effects of sustained and local administration of EGF on improving bilateral testicular tissue after torsion. A total of 57 Wistar albino rats were used. For the EGF transport system, 1x2 cm gelatin films containing 2 microg EGF were used. Torsion was created by rotating the right testis 720 degrees in a clockwise direction for 4 h in all groups except the control group. Then, in the torsion group, bilateral orchiectomy was performed. After returning the torsioned ipsilateral testes to their normal state, the bilateral testes were wrapped by 1x2 cm unloaded gelatin films in the gelatin (G7 and G21) groups and, by 2 microg EGF loaded gelatin films in the EGF 7 and EGF 21 groups. The testes were removed on the seventh and 21st days, respectively, for biochemical and histological examination. Histologically, Johnsen's spermatogenesis criteria and mean seminiferous tubule diameter (MSTD) measurements were used. The EGF7 group did not show significant loss of Sertoli cells, while in the G7 group the number of these cells decreased. The ipsilateral ischemic testis of the EGF21 group showed Leydig cell hyperplasia, and the contralateral non-ischemic testes in this group were similar to the control group. In the G21 group, the bilateral testes showed Sertoli cell only syndrome in some sections, and most of the cells were undergoing apoptosis. The mean spermatogenesis scores and MSTD in the EGF7 and EGF21 groups were higher than in the G7 and G21 groups ( P<0.05). Malondialdehyde levels were significantly lower in the EGF groups than in the G groups ( P<0.05). Glutathione peroxidase (GSH-Px) levels in the G21 group were significantly higher than in the EGF21 group. Our study shows that local and sustained EGF release after testicular torsion improves bilateral testicular injury. EGF administration may be a new treatment choice for bilaterally injured testis after detorsion without removing the twisted testis.

Physiological and pathological cell deaths in the reproductive organs

Apoptosis of testicular germ cells and oocytes and their supporting cells in the gonads occurs at physiological and normal conditions or after exposure to pathological stimuli. Cell-death regulators, including Bcl-2 family members, caspases, Fas and p53 are thought to be involved in these processes. This article reviews the details of the apoptotic machinery in the reproductive organs by describing briefly the abnormal phenotypes observed in transgenic and gene-ablated mice.