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 estrogen status in osteocyte autophagy and its relation to osteocyte viability in alveolar process of ovariectomized rats

Estrogen maintains osteocyte viability, whereas its deficiency induces osteocyte apoptosis. As autophagy is important for osteocyte viability, we hypothesized whether the anti-apoptotic effect of estrogen is related to autophagy in osteocytes. Thirty adult female rats were sham-operated (SHAM) or ovariectomized (OVX). After three weeks, twelve rats of SHAM and OVX groups were killed before treatment (basal period), whereas the remaining rats received estrogen (OVXE) or vehicle (OVX) for 45 days. Fragments of maxilla containing alveolar process of the first molars were embedded in paraffin or Araldite. Paraffin-sections were stained with hematoxylin/eosin for histomorphometry, or subjected to the silver impregnation method for morphological analysis of osteocyte cytoplasmic processes. Autophagy was analyzed by immunohistochemical detections of beclin-1, MAP-LC3α and p62, whereas apoptosis was evaluated by immunohistochemical detections of cleaved caspase-3 and BAX, TUNEL (Terminal deoxynucleotidyl transferase dUTP nick end labeling) method and by ultrastructural analysis. Araldite-semithin sections were subjected to the Sudan-black method for detection of lipids. OVX-basal group showed high frequency of caspase-3-, TUNEL- and p62-positive osteocytes accompanied with low frequency of beclin-1- and MAP-LC3α-positive osteocytes. At 45 days, OVXE group exhibited higher number of osteocytes, higher frequency of beclin-1- and MAP-LC3α-positive osteocytes, and lower frequency of caspase-3, BAX-, TUNEL- and p62-positive osteocytes than OVX group. Significant reduction in bone area was observed in the OVX compared to OVXE and SHAM groups. The highest frequency of Sudan-Black-positive osteocytes and osteocytes with scarce cytoplasmic processes, or showing apoptotic features were mainly observed in OVX groups. Our results indicate that estrogen deficiency decreases autophagy and increases apoptosis, whereas estrogen replacement enhances osteocyte viability by inhibiting apoptosis and maintaining autophagy in alveolar process osteocytes. These results suggest that the anti-apoptotic effect of estrogen may be, at least in part, related to autophagy regulation in osteocytes.

The antineoplastic busulphan impairs peritubular and Leydig cells, and vitamin B12 stimulates spermatogonia proliferation and prevents busulphan-induced germ cell death

Busulphan (Bu), an alkylating agent used for bone marrow and spermatogonial stem cell transplantation (SSCT), impairs Sertoli (SC) cells, which are necessary for the spermatogonial stem cell (SSC) homing during transplantation. As Leydig (LC) and peritubular myoid (PMC) cells are essential for SC support and maintenance of spermatogonial niche, we evaluated the impact of Bu on the LC and PMC structural integrity. Vitamin B₁₂ (B₁₂) has demonstrated beneficial effects against drug-induced testicular changes; thus, we also examined whether this vitamin is able to stimulate spermatogonia mitotic activity and prevent Bu-induced germ cell death. Rats received 10mg/kg of Bu in the 1st and 4th days, and daily B₁₂ supplementation during Bu treatment and for 6days after the last injection of Bu (Bu-6d), totaling 10days of treatment. Other animals received the same treatment as Bu-6d, and B₁₂ supplementation (Bu+7dB₁₂) or saline (Bu+7dS) for 7 more days, totaling 17days of treatment. Serum testosterone levels were measured. In the historesin-embedded testis sections, the seminiferous tubule and epithelial areas were measured, and the number of spermatogonia and PMC was quantified. Actin and 17β-HSD6 immunofluorescence was detected, and the number of TUNEL-positive LC and germ cells was computed. In Bu-6d, PMC number reduced, and a weak actin immunoexpression and death in these cells was observed. The testosterone levels reduced, and the interstitial tissue showed a weak 17β-HSD6 immunoexpression and increased number of TUNEL-positive LC. In Bu+7dB₁₂, the number of spermatogonia was higher than in Bu-6d and Bu+7dS, and the number of TUNEL-positive germ cells was significantly lower than in Bu+7dS. Bu exerts a harmful impact on PMC and LC, reducing the testosterone levels. Vitamin B₁₂ prevents significantly Bu-induced germ cell death and stimulates spermatogonia proliferation, being a useful strategy for the enrichment of SSC in vitro and an adjuvant therapy for spermatogenesis recovery in oncologic patients.

Osteoporosis and autophagy: What is the relationship?

Autophagy is a survival pathway wherein non-functional proteins and organelles are degraded in lysosomes for recycling and energy production. Therefore, autophagy is fundamental for the maintenance of cell viability, acting as a quality control process that prevents the accumulation of unnecessary structures and oxidative stress. Increasing evidence has shown that autophagy dysfunction is related to several pathologies including neurodegenerative diseases and cancer. Moreover, recent studies have shown that autophagy plays an important role for the maintenance of bone homeostasis. For instance, in vitro and animal and human studies indicate that autophagy dysfunction in bone cells is associated with the onset of bone diseases such as osteoporosis. This review had the purpose of discussing the issue to confirm whether a relationship between autophagy dysfunction and osteoporosis exits.

Cimetidine Reduces Interleukin-6, Matrix Metalloproteinases-1 and -9 Immunoexpression in the Gingival Mucosa of Rat Molars With Induced Periodontal Disease

BACKGROUND

Histamine seems to act, via H₂ receptor, on inflammatory processes by stimulating interleukin (IL)-6 and matrix metalloproteinase (MMP) release. As cimetidine is an H₂ receptor antagonist, the authors hypothesize that this antiulcer drug reduces IL-6, MMP-1, and MMP-9 immunoexpression in gingiva with induced periodontal disease (PD). To confirm a possible modulatory role of IL-6 on MMPs, the relationship between IL-6/MMP-1 and IL-6/MMP-9 immunoexpression was evaluated.

METHODS

Forty-six male rats were distributed into the cimetidine group (CimG: received daily intraperitoneal injections of 100 mg/kg of body weight of cimetidine) or the saline group (SG). PD was induced by cotton ligature around the maxillary left first molars (PDSG and PDCimG). The right molars were used as controls (SG and CimG). After 7, 15, 30, and 50 days, maxillary fragments were processed for paraffin embedding or for transmission electron microscopy. Tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in the alveolar process surface and number of IL-6, MMP-1, and MMP-9-immunolabeled cells in the gingival mucosa were quantified. Statistical analyses were performed (P ≤0.05).

RESULTS

In PDSG and PDCimG, gingival mucosa exhibited few collagen fibers among numerous inflammatory cells. In PDCimG, the number of TRAP-positive osteoclasts and IL-6, MMP-1, and MMP-9-immunolabeled cells was significantly lower than in PDSG at all periods. A positive correlation between IL-6/MMP-1 and IL-6/MMP-9 was detected in PDSG and PDCimG.

CONCLUSION

Cimetidine decreases bone loss through reduction of osteoclast number and induces reduction of IL-6, MMP-1, and MMP-9 immunoexpression, reinforcing the idea that the beneficial effect of cimetidine in PD may be due to reduction of IL-6 immunolabeling in the inflamed gingival mucosa.

Seminiferous epithelium damage after short period of busulphan treatment in adult rats and vitamin B12 efficacy in the recovery of spermatogonial germ cells

Several different strategies have been adopted in attempt to recover from chemotherapy-damaged spermatogenesis that is often seen in oncologic patients. In this study, we have evaluated the impact of short period of exposure to busulphan on the haemogram and seminiferous epithelium of adult rats, focusing on spermatogonial depletion and Sertoli cell (SC) integrity. We then examined whether vitamin B₁₂ supplementation improves the haematological parameters and spermatogonia number. The animals received 10 mg/kg of busulphan (BuG) or busulfan+vitamin B₁₂ (Bu/B₁₂ G) on the first and fourth days of treatment. In H.E.-stained testicular sections, the areas of the seminiferous tubule (ST) and seminiferous epithelium were measured. The number of spermatogonia in H.E-stained and PCNA-immunolabelled testicular sections was quantified. The frequency of tubules with abnormal SC nuclei or TUNEL-positive SC was evaluated. Vimentin immunofluorescence in ST was also evaluated. In BuG and Bu/B₁₂ G, the animals showed leukopenia and thrombocytopenia, but the body weight reduced only in BuG. The areas of ST and seminiferous epithelium decreased in Bu/B₁₂ G and BuG. In BuG, the number of H.E.-stained and PCNA-immunolabelled spermatogonia reduced significantly. The frequency of tubules containing abnormal SC nuclei and TUNEL-positive SC increased and the vimentin immunoexpression pattern changed. In Bu/B₁₂ G, the number of H.E.-stained or PCNA-immunolabelled spermatogonia increased fourfold in comparison with BuG. The structural changes in ST after 6 days of busulphan exposure may be associated with the potential effect of this anti-neoplastic agent on SC. The increased number of spermatogonia in the busulphan-treated animals receiving vitamin B₁₂ indicates that this vitamin can be an adjuvant therapy to improve the fertility in male cancer patients.

Apoptosis and reduced microvascular density of the lamina propria during tooth eruption in rats

During tooth eruption, structural and functional changes must occur in the lamina propria to establish the eruptive pathway. In this study, we evaluate the structural changes that occur during lamina propria degradation and focus these efforts on apoptosis and microvascular density. Fragments of maxilla containing the first molars from 9-, 11-, 13- and 16-day-old rats were fixed, decalcified and embedded in paraffin. The immunohistochemical detection of vascular endothelial growth factor (VEGF), caspase-3 and MAC387 (macrophage marker), and the TUNEL method were applied to the histological molar sections. The numerical density of TUNEL-positive cells and VEGF-positive blood vessel profiles were also obtained. Data were statistically evaluated using a one-way anova with the post-hoc Kruskal-Wallis or Tukey test and a significance level of P ≤ 0.05. Fragments of maxilla were embedded in Araldite for analysis under transmission electron microscopy (TEM). TUNEL-positive structures, fibroblasts with strongly basophilic nuclei and macrophages were observed in the lamina propria at all ages. Using TEM, we identified processes of fibroblasts or macrophages surrounding partially apoptotic cells. We found a high number of apoptotic cells in 11-, 13- and 16-day-old rats. We observed VEGF-positive blood vessel profiles at all ages, but a significant decrease in the numerical density was found in 13- and 16-day-old rats compared with 9-day-old rats. Therefore, the establishment of the eruptive pathway during the mucosal penetration stage depends on cell death by apoptosis, the phagocytic activity of fibroblasts and macrophages, and a decrease in the microvasculature due to vascular cell death. These data point to the importance of vascular rearrangement and vascular neoformation during tooth eruption and the development of oral mucosa.

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.

Immunoexpression of aromatase and estrogen receptors β in stem spermatogonia of bullfrogs indicates a role of estrogen in the seasonal spermatogonial mitotic activity

Bullfrog stem spermatogonia, also named primordial germ cells (PGCs), show strong testosterone immunolabeling in winter, but no or weak testosterone immunoexpression in summer. Thus, the role of testosterone in these cells needs to be clarified. In this study, we proposed to evaluate whether PGCs express aromatase and estrogen receptors, and verify a possible role of estrogen in PGCs seasonal proliferation. Testes of male adult bullfrogs, collected in winter (WG) and summer (SG), were fixed and embedded in historesin, for quantitative analysis, or paraffin for immunohistochemistry (IHC). The number of haematoxylin/eosin stained PGCs/lobular area was obtained. Proliferating cell nuclear antigen (PCNA), aromatase, estrogen receptor β (ERβ) and PCNA/ERβ double immunolabeling were detected by IHC. The number of PCNA-positive PGCs and the histological score (HSCORE) of aromatase and ERβ immunolabeled PGCs were obtained. Although the number of PGCs increased significantly in WG, a high number of PCNA-positive PGCs was observed in summer. Moreover, aromatase and ERβ HSCORE was higher in SG than WG. The results indicate that PGCs express a seasonal proliferative activity; the low mitotic activity in winter is related to the maximal limit of germ cells which can be supported in the large lobules. In SG, the increased ERβ and aromatase HSCORE suggests that testosterone is converted into estrogen from winter to summer. Moreover, the parallelism between the high PGCs mitotic activity and ERβ immunoexpression suggest a participation of estrogen in the control of the PGCs seasonal proliferative activity which guarantee the formation of new germ cysts from summer to next autumn.

Cimetidine-induced vascular cell apoptosis impairs testicular microvasculature in adult rats

Cimetidine, an H₂ receptor antagonist used for treatment of gastric ulcers, exerts antiandrogenic and antiangiogenic effects. In the testes cimetidine impairs spermatogenesis, Sertoli cells and peritubular tissue, inducing apoptosis in the myoid cells. Regarding the importance of histamine and androgens for vascular maintenance, the effect of cimetidine on the structural integrity of the testicular vasculature was evaluated. Adult male rats received cimetidine (CMTG) and saline (CG) for 50 days. The testes were fixed in buffered 4% formaldehyde and embedded in historesin and paraffin. In the PAS-stained sections, the microvascular density (MVD) and the vascular luminal area (VLA) were obtained. TUNEL method was performed for detection of cell death. Testicular fragments embedded in Araldite were analyzed under transmission electron microscopy. A significant decrease in the MVD and VLA and a high number of collapsed blood vessel profiles were observed in CMTG. Endothelial cells and vascular muscle cells were TUNEL-positive and showed ultrastructural features of apoptosis. These results indicate that cimetidine induces apoptosis in vascular cells, leading to testicular vascular atrophy. A possible antagonist effect of cimetidine on the H₂ receptors and/or androgen receptors in the vascular cells may be responsible for the impairment of the testicular microvasculature.

Increased apoptosis in osteoclasts and decreased RANKL immunoexpression in periodontium of cimetidine-treated rats

It has been demonstrated that histamine interferes with the recruitment, formation and activity of osteoclasts via H(1)- and H(2)-receptors. Cimetidine is a H(2)-receptor antagonist used for treatment of gastric ulcers that seems to prevent bone resorption. In this study, a possible cimetidine interference was investigated in the number of alveolar bone osteoclasts. The incidence of osteoclast apoptosis and immunoexpression of RANKL (receptor activator of nuclear factor κB ligand) was also evaluated. Adult male rats were treated with 100 mg kg(-1) of cimetidine for 50 days (CimG); the sham group (SG) received saline. Maxillary fragments containing the first molars and alveolar bone were fixed, decalcified and embedded in paraffin. The sections were stained by H&E or submitted to tartrate-resistant acid phosphatase (TRAP) method. TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) method and immunohistochemical reactions for detecting caspase-3 and RANKL were performed. The number of TRAP-positive osteoclasts, the frequency of apoptotic osteoclasts and the numerical density of RANKL-positive cells were obtained. Osteoclast death by apoptosis was confirmed by transmission electron microscopy (TEM). In CimG, TRAP-positive osteoclasts with TUNEL-positive nuclei and caspase-3-immunolabeled osteoclasts were found. A significant reduction in the number of TRAP-positive osteoclasts and a high frequency of apoptotic osteoclasts were observed in CimG. Under TEM, detached osteoclasts from the bone surface showed typical features of apoptosis. Moreover, a significant reduction in the numerical density of RANKL-positive cells was observed in CimG. The significant reduction in the number of osteoclasts may be due to cimetidine-induced osteoclast apoptosis. However, RANKL immunoexpression reduction also suggests a possible interference of cimetidine treatment in the osteoclastogenesis.

Late morfofunctional alterations of the Sertoli cell caused by doxorubicin administered to prepubertal rats

BACKGROUND

Doxorubicin is a potent chemotherapeutic drug used against a variety of cancers. It acts through interaction with polymerases and topoisomerase II and free radical production. Doxorubicin activity is not specific to cancer cells and can also damage healthy cells, especially those undergoing rapid proliferation, such as spermatogonia. In previous studies our group showed that etoposide, another topoisomarese II poison, causes irreversible damage to Sertoli cells. Thus, the aim of this study was to address the effects of doxorubicin on Sertoli cell morphology and function and on the seminiferous epithelium cycle when administered to prepubertal rats.

METHODS

Prepubertal rats received the dose of 5 mg/Kg of doxorubicin, which was fractioned in two doses: 3 mg/Kg at 15dpp and 2 mg/Kg at 22 dpp. The testes were collected at 40, 64 and 127 dpp, fixed in Bouin's liquid and submitted to transferrin immunolabeling for Sertoli cell function analysis. Sertoli cell morphology and the frequency of the stages of the seminiferous epithelium cycle were analyzed in PAS + H-stained sections.

RESULTS

The rats treated with doxorubicin showed reduction of transferrin labeling in the seminiferous epithelium at 40 and 64 dpp, suggesting that Sertoli cell function is altered in these rats. All doxorubicin-treated rats showed sloughing and morphological alterations of Sertoli cells. The frequency of the stages of the seminiferous epithelium cycle was also affected in all doxorubicin-treated rats.

CONCLUSIONS AND DISCUSSION

These data show that doxorubicin administration during prepuberty causes functional and morphological late damage to Sertoli cells; such damage is secondary to the germ cell primary injury and contributed to enhance the spermatogenic harm caused by this drug. However, additional studies are required to clarify if there is also a direct effect of doxorubicin on Sertoli cells producing a primary damage on these cells.

Primordial germ cells (spermatogonial stem cells) of bullfrogs express sex hormone-binding globulin and steroid receptors during seasonal spermatogenesis

In vertebrate species, testosterone seems to inhibit spermatogonial differentiation and proliferation. However, this androgen can also be converted, via aromatase, into estrogen which stimulates spermatogonial differentiation and mitotic activity. During seasonal spermatogenesis of adult bullfrogs Lithobates catesbeianus, primordial germ cells (PGCs) show enhanced testosterone cytoplasm immunoexpression in winter; however, in summer, weak or no testosterone immunolabelling was observed. The aim of this study was to confirm if PGCs express stem cell markers - alkaline phosphatase (AP) activity and GFRα1 (glial-cell-line-derived neurotrophic factor) - and verify whether testosterone is maintained in these cells by androgen receptors (ARs) and/or sex hormone-binding globulin (SHBG) in winter. Furthermore, regarding the possibility that testosterone is converted into estrogen by PGCs in summer, the immunoexpression of estrogen receptor (ER)β was investigated. Bullfrog testes were collected in winter and in summer and were embedded in glycol methacrylate for morphological analyses or in paraffin for the histochemical detection of AP activity. GFRα1, AR, SHBG and ERβ expression were detected by Western blot and immunohistochemical analyses. The expression of AP activity and GFRα1 in the PGCs suggest that these cells are spermatogonial stem cells. In winter, the cytoplasmic immunoexpression of ARs and SHBG in the PGCs indicates that testosterone is maintained by these proteins in these cells. The cytoplasmic immunoexpression of ERβ, in summer, also points to an ER-mediated action of estrogen in PGCs. The results indicate a participation of testosterone and estrogen in the control of the primordial spermatogonia during the seasonal spermatogenesis of L. catesbeianus.

Structural and functional changes in the alveolar bone osteoclasts of estrogen-treated rats

This study investigated structural and functional features of apoptotic alveolar bone osteoclasts in estrogen-treated rats. For this purpose, 15 female rats 22 days old were divided into three groups: Estrogen (EG), Sham (SG) and Control (CG). The rats of EG received daily intramuscular injection of estrogen for 7 days. The SG received only the oil vehicle. Maxillary fragments containing alveolar bone were removed and processed for light and transmission electron microscopy. Area (OcA) and number of nuclei (OcN) and bone resorption surface per TRAP-positive osteoclasts (BS/OC) were obtained. Vimentin, caspase-3 and MMP-9 immunoreactions, TUNEL/TRAP and MMP-9/TUNEL combined reactions were performed. In EG, the OcA, OcN and BS/Oc were reduced. Moreover, osteoclasts showed cytoplasm immunolabelled by caspase-3 and a different pattern of vimentin expression in comparison with CG and SG. MMP-9 expression was not affected by estrogen and the TUNEL-positive osteoclasts were MMP-9-immunolabelled. In EG, ultrastructural images showed that apoptotic osteoclasts did not exhibit ruffled borders or clear zones and were shedding mononucleated portions. TRAP-positive structures containing irregular and dense chromatin were partially surrounded by fibroblast-like cells. In conclusion, the reduction in the BS/Oc may be due to reduction in OcA and OcN; these effects seem to be related to vimentin disarrangement rather than to an interference of estrogen with osteoclast MMP-9 expression. Osteoclast apoptosis involves caspase-3 activity and vimentin degradation; these cells release portions containing one apoptotic nucleus and, subsequently, undergo fragmentation, giving rise to apoptotic bodies.

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.