The Anti-Reproductive Effects of Long Term Oral Administration of Cadmium on the Adult Male Rat

The toxic effects of prolonged oral administration of cadmium on gametogenic and endocrine function of testes of adult rats were investigated. The experimental animals received daily, for 3, 6, 12 or 15 months, pellets containing 8.8 mg or 88 mg of cadmium chloride per kg body weight.
The rats treated with the higher doses of cadmium for 12 and 15 months showed a marked reduction in absolute weight of testes accompanied by histological signs of impairment of seminiferous tubules. There were no necrotic changes but a number of cross-sections of seminiferous tubules were deprived of spermatocytes and spermatids, reaching about 50 per cent of the tubules in the rats treated with higher doses of cadmium. The appearance of histological changes in rats treated for 12 and 15 months correlated with cumulation step of cadmium in testes and with alterations in serum concentration of LH but not of testosterone. Therefore, we suppose that under these experimental conditions the impairment of seminiferous tubules was induced by the direct influence of cadmium on germinal epithelium beginning the moment when cadmium reaches an effectively toxic concentration in testis.     

Androgen Dependence of Testicular and Epididymal Angiotensin Converting Enzyme

Treatment with cadmium chloride (CdCl2) and cyproterone acetate (CA) depressed angiotensin converting enzyme (ACE) activity significantly in testes and epididymal regions of the adult rats compared to the corresponding untreated controls. Exogenous testosterone to CA-treated rats significantly increased the enzyme activity both in the testes and epididymis, the effect in the latter being very significant comparable to CA-treated and untreated controls. Testosterone failed to induce ACE activity in the testes and caput epididymis of 30 day-old immature rats, but the enzyme activity was detected in corpus and cauda epididymis. Our findings indicate that ACE activity in the testicular complex is possibly linked with androgen and is concerned with spermatogenesis and sperm maturation.     

Thymoquinone therapy abrogates toxic effect of cadmium on rat testes

The protective effect of thymoquinone was investigated against cadmium‐induced testicular toxicity in rats. Testicular toxicity was induced by a single intraperitoneal (i.p.) injection of cadmium chloride (2 mg kg^?1). Thymoquinone treatment (10 mg kg^?1 day^?1, i.p.) was applied for five consecutive days, starting 3 days before cadmium administration. Thymoquinone significantly attenuated the cadmium‐induced decreases in serum testosterone, and testicular reduced glutathione and superoxide dismutase activity and significantly decreased the elevations of testicular malondialdehyde, nitric oxide and cadmium ion levels resulted from cadmium chloride administration. Also, thymoquinone ameliorated the cadmium‐induced testicular tissue injury observed by histopathological examination. In addition, thymoquinone significantly decreased the cadmium‐induced expression of inducible nitric oxide synthase, tumour necrosis factor‐α, cyclooxygenase‐2, nuclear factor‐κB and caspase‐3 in testicular tissue. It was concluded that thymoquinone, through its antioxidant and anti‐inflammatory activities, may represent a potential candidate to protect the testes against the detrimental effect of cadmium exposure.     

The time-response and magnitude of HCG-induced vascular changes are different in scrotal and abdominal testes

Adult unilaterally cryptorchid rats were injected with 50 IU human chorionic gonadotrophin (hCG). At 4, 8, 24 and 72 h after treatment, testicular vascular permeability was studied by injecting colloidal carbon intravenously. The number of blood vessel profiles labelled with carbon was increased by hCG in both types of testes, but the response was more sustained in abdominal than in scrotal testes. The number of polymorphonuclear leucocytes (PMNs) accumulating in testicular blood vessels and migrating into the interstitial space in response to hCG treatment was also measured. The volume density of intravascular and interstitial PMNs was increased in both types of testes but the peak response was larger in scrotal than in abdominal testes. PMN accumulation and vascular leakage were apparently correlated in the scrotal but not in the abdominal testes.
Testicular interstitial fluid (IF) was collected from intact and unilaterally cryptorchid adult rats. The IF was diluted with sterile buffer and injected intracutaneously in test animals. The vascular permeability response was assessed by measuring the leakage of Evans blue into the injection sites. IF from scrotal and abdominal testes increased vascular permeability in the skin. The response was rapid and transient. IF collected from rats given hCG 24 h earlier did not increase vascular permeability. The vascular permeability response to IF was reduced slightly in neutrophil-depleted animals. The inflammation mediator present in IF cannot explain the kinetics and magnitude of the hCG-induced changes in vascular premeability in intact or unilaterally cryptorchid rats.     

The effect of selective destruction and regeneration of rat Leydig cells on the intratesticular distribution of testosterone and morphology of the seminiferous epithelium

This study was designed to explore the relationship between the intratesticular distribution of testosterone and spermatogenesis by completely destroying the Leydig cells of mature male rats with injection of a single i.p. dose of ethane dimethanesulphonate. After such treatment, testosterone levels in serum, testicular interstitial fluid, seminiferous tubules, and whole testis declined significantly 6 to 24 hours after injection and fell below assay detection limits between 3 and 7 days. At 3 and 7 days, serum LH and FSH levels rose significantly and remained elevated up to 4 and 6 weeks, respectively, in comparison with vehicle-treated controls. Leydig cells disappeared from the interstitium by day 3, but between 2 and 4 weeks postinjection a new generation of fetal-like Leydig cells repopulated the testicular interstitium and, during weeks 6 to 10, were transformed into, or replaced by, Leydig cells with an adult type of morphology. Histologic examination of the seminiferous tubules showed progressive disruption of spermatogenesis between 3 and 14 days post-ethane dimethanesulphonate. The first histologic sign of spermatogenic damage was noted at day 3, with the occurrence of stage-specific degenerating pachytene primary spermatocytes at stages VII to VIII of the spermatogenic cycle. On day 7, these cells and degenerating round, or step 19, spermatids often were observed during stages VII to XI, although qualitatively normal spermatogenesis also was seen in these and all other stages of the cycle. Maximum impairment of spermatogenesis occurred 2 weeks post-ethane dimethane sulphonate, at which time the tubules commonly lacked one or more germ cell generations or, alternatively, showed accumulation of lipid inclusions, extracellular spaces, and variable numbers of degenerating germ cells. Following repopulation of the testis by Leydig cells during weeks 3 and 4, spermatogenesis recovered. By 10 weeks after treatment, qualitatively normal spermatogenesis was seen in the great majority of seminiferous tubules, although a few tubules still remained in which the germ cell complement was severely reduced, and contained only Sertoli cells and spermatogonia.(ABSTRACT TRUNCATED AT 400 WORDS)     

The effects of ethylene glycol monomethyl ether on testicular histology in F344 rats

Ethylene glycol monomethyl ether (EGME) has been found to produce testicular atrophy in experimental rodents. The studies that follow were designed to determine the testicular cell type(s) most susceptible to EGME administration. For histologic studies, F344 rats were gavaged with 150 mg/kg/day of EGME 5 days per week, and serially sacrificed. In sections from perfusion-fixed tissue, necrotic changes were observed in some meiotic and premeiotic spermatocytes 24 hours after a single dose. Also, nuclear condensation was seen in occasional early pachytene spermatocytes. These effects were magnified after two doses; there were more necrotic pachytene and meiotic spermatocytes than necrotic stage I pachytene spermatocytes. By day 4, testes from all treated animals were affected; there was a pronounced maturation-depletion effect, seen as the absence of round spermatids from tubules in stages I to III. These effects continued to develop at days 7 and 10, leaving only Sertoli cells, spermatogonia, and late stage spermatids populating the epithelium. Other animals were treated similarly, but subject to efferent duct ligation 16 hours prior to sacrifice. Fluid production, as judged by weight gain in the testes after efferent duct ligation, was unaffected by EGME treatment. Analysis of the fluid collected at the rete testis indicated that there was no treatment-related change in the relative amounts of androgen binding protein. The data indicate that the spermatocyte is the primary target cell for the histologic effects of EGME in the testis of F344 rats.     

Aristolochic acid impedes endocytosis and induces DNA adducts in proximal tubule cells

BACKGROUND: Aristolochic acid (AA), present in Aristolochia plants, appears to be the toxin responsible for Chinese herbs nephropathy (CHN), a rapidly progressive tubulointerstitial nephritis. One of the earliest sign of CHN is the urinary excretion of low-molecular-weight proteins (LMWP), suggesting that AA is toxic to proximal tubules (PT). METHODS: The effects of AA on PT functions including reabsorption of LMWP were investigated on the well-established opossum kidney (OK) cell line, a model for PT, and compared with those of the classical PT toxin cadmium chloride (CdCl2). RESULTS: OK cell monolayers internalized albumin and beta2-microglobulin by receptor-mediated endocytosis, both proteins apparently competing for the same receptor, a complex of megalin and cubulin. The process was significantly impaired by 24-hour preincubation with AA (10 or 20 micromol/L) or CdCl2 (15 micromol/L). Furthermore, 24-hour exposure to AA followed by its removal during one to six days led to a persistent inhibition of the uptake of albumin, in contrast to the substantial recovery observed after CdCl2 removal. Neither AA nor CdCl2 affected cell viability, Na+-glucose cotransport or total rate of protein synthesis. AA significantly decreased megalin expression and formed specific DNA adducts in OK cells, similar to those found in kidneys from CHN patients. CONCLUSIONS: The present data support the involvement of AA in the early PT dysfunction found in CHN; furthermore, they suggest a causal relationship between DNA adduct formation, decreased megalin expression, and inhibition of receptor-mediated endocytosis of LMWP.     

Alpha-L-fucosidase in rat testis during sexual maturity

alpha-L-fucosidase (EC 3.2.1.51) activity, concentration of testosterone (T), and its metabolite dihydrotestosterone (DHT) were tested in rat testis during the onset of puberty. This study was also carried out in testes of rats treated with 17-beta-N,N-diethylcarbamoyl-4-methyl-4-aza-5-alpha-androstane-3-one (DMAA), an inhibitor of the 5-alpha-reductase-mediated conversion of T into DHT. alpha-L-fucosidase activity in seminiferous tubules of control and DMAA-treated rats was found to be relatively high on the 25th day after birth (approximately 24 units) but decreased and remained relatively constant the following days (approximately 10 units). In contrast, alpha-L-fucosidase activity was nearly undetectable in the immature interstitium of the control rats but sharply increased the following days. A maximum was reached at the 55th day, followed by a rapid decrease. alpha-L-fucosidase activity evolved in parallel with an increase and decrease of DHT concentration. In DMAA-treated rats with DHT levels and an alpha-L-fucosidase activity significantly lower than in the control rats between the 55th and the 65th days, this parallelism existed as well.     

Effect of prolonged cryptorchidism on germ cell apoptosis and testicular sperm count

Aim:To evaluate the long term effect of experimental cryptorchidism on germ cell apoptotic rate and testicular sperm content in adult rats.Methods:Bilateral cryptorchidism was created in 40 adult male Sprague-Dawley rats by surgically manipulating the testes into the abdominal cavity and closing the internal inguinal ring.The rats were sacrificed and the testes removed 6 hours and 2,4,7,21,28 and 56 days after cryptorchidism.Germ cell apoptosis was quantified by means of TUNEL assay and apoptosis was confirmed using transmission electron microscopy.Results:The rate of apoptosis peaked at 4 days of cryptorchidism and then progressively declined to a nadir at 14 days of cryptorchidism.At 56 days of cryptorchidism,the germinal epithelium was largely depleted by the apoptotic process and only a few mature sperm were seen within the testis.At this point,a few tubules were seen to be repopulating with primary spermatocytes and the level of germ cell apoptosis began to increase marginally.Testicular sperm count (TSC) began to decline rapidly at day 7 of cryptorchidism.Only a few mature sperm were found in the testes of rats following 56 days of cryptorchidism.Multinucleated giant cells (MGC) were most numerous within the seminiferous tubules at day 4.At day 7,35% of MGCs were TUNEL positive.At all subsequent time points,however,MGCs fail to stain positive for apoptosis.This resumption of increased apoptosis coincided with the appearance of a population of primary spermatocytes in some seminiferous tubules.Moreover,there was not a corresponding increase in the number of mature sperm after 56 days of cryptorchidism.Conclusion:The decline in germ cell apoptosis after 4 days of cryptorchidism can be attributed to be the result of an overall depletion of germ cells.It appears that after a prolonged cryptorchidism (56 days),there is a limited resumption of spermatogenesis presumably as a result of a decrease in the maturing germ cells undergoing programmed cell death.(Asian JAndrol2004 Mar;6:47-51)     

Cadmium-induced alterations in the Siberian hamster epididymis

The epididymis of sexually mature Siberian hamsters was found to consist of eight histologically distinct zones that were similar, in most respects, to those reported for other species. The notable exception to this is the presence of two types of tubules in zone 6; the typical major tubules predominate but are accompanied by smaller, contiguous, minor tubules. Following a single parenteral injection of cadmium chloride, the testes became necrotic and exhibited generalized sloughing of the seminiferous epithelium. The epididymis, on the other hand, retained their integrity following cadmium administration, although foci of degenerating cells were observed in the more proximal portions of the organ--i.e., zones 1-3. Vacular compromise is believed to be responsible for these necroses because of the severe edematous changes observed in the interstitial spaces. Evidence is presented for the localized degradation and elimination of necrotic cells from the testes as well as the epididymis.     

Pulmonary and systemic fluid filtration after continuous versus bolus interleukin-2 infusion

Interleukin-2 has been widely investigated as adjuvant therapy for advanced cancer and is administered by either bolus or continuous infusion. We compared the effects of bolus and continuous interleukin-2 infusion on pulmonary (QL) and systemic microvascular fluid filtration in 11 adult sheep prepared with chronic lung and soft-tissue lymph fistulas. Interleukin-2 was administered as a bolus infusion (100,000 units/kg) every 8 hours for 3 days or as a continuous infusion at the same dose for 3 days. No significant changes in pulmonary hydrostatic pressures or pulmonary vascular resistance were noted after either bolus or continuous interleukin-2 infusion. However, significantly decreased (p less than or equal to 0.05) systemic vascular resistances were observed in both groups. QL increased steadily throughout the infusion period in both groups, peaking at three times baseline on the third infusion day. The plasma/interstitial protein clearance (QL X lymph/plasma protein ratio) rose similarly in both groups, indicating increased barrier permeability. Increased lymphocyte clearance into lung lymph occurred by day 3 but was not associated with lymphocytic sequestration in the lung interstitium. We conclude that pulmonary and systemic microvascular fluid and protein flux exhibit similar changes after bolus or continuous interleukin-2 infusion. These changes are associated with increased clearance of lymphocytes into lung lymph that are not sequestered in the pulmonary interstitium after infusions of shorter duration.     

Short-Term Effects of an LHRH-Agonist alone or in Combination with Testosterone Propionate or Indomethacin on Rat Testes

The treatment of adult male Wistar rats with a LHRH-agonist (lutrelin Wyeth/WY 40972) resulted in severe damage of the seminiferous tubules as well as in remarkable changes of the blood vessels within 24 hours. First striking signs of alterations within the blood vessels were already found 6 hours after the injection of lutrelin: the blood vessels were almost totally filled with leucocytes. Neither the effects on the germinal epithelium nor the effects on the blood vessels were prevented by the simultaneous treatment with 3 mg testosterone propionate (TP). The treatment with indomethacin, however, clearly antagonized both events. The complete inefficiency of TP to overcome the inhibitory effects of lutrelin on the testes does argue against an androgen deficiency as the primary cause. The results obtained with indomethacin strengthen the hypothesis, that the early deleterious effects of LHRH-agonists on the germinal epithelium of the rat are primarily caused by circulatory disturbances in the testes and that prostaglandins may act as mediators.     

Morphological and Histochemical Observations on the Prenatal and Postnatal Testes of the Field Rat (Millardia meltada)

The foetal testis of the field rat (Millardia meltada) shows seminiferous tubules and interstitium consisting of mesenchymal cells and differentiated Leydig cells associated with blood vessels. The tubules during the prenatal period show gonocytes and Sertoli cells. After birth, their diameter decreases but again increases progressively after postnatal days 9 and 10. Spermatogonia appear among the gonocytes on postnatal day 1 and primary spermatocytes on day 8. Secondary spermatocytes and spermatids are not seen up-to-day 23. Several hypertrophied Leydig cells are seen in the foetal testis on day 17 but are greatly increased in number on days 18 and 19. A few hours after birth the Leydig cells show a rapid decrease in their number. These fluctuations in the Leydig cells of prenatal and neonatal testes have been correlated to the rise and fall in testosterone production during these periods. The Leydig cells show the histochemical characteristics of actively steroid-secreting cells, which consist of the presence of diffuse lipoproteins and a few lipid granules consisting of phospholipids; no cholesterol and/or its esters could be demonstrated. Such lipids are not present in the cytoplasm of undifferentiated mesenchymal cells. The seminiferous tubules do not show any appreciable development of lipid changes.     

Anti-inflammatory drugs in the vascular response to burn injury

Within 24 hours after a full-thickness burn injury, predictable alterations occur in the dermal vasculature. At the immediate site of injury, vessels lose patency. In the periphery, vasodilation and increased permeability become widespread. A variety of interventions were employed to prevent these vascular sequelae. While systemic treatment, immediately after burn trauma, with hydrocortisone or the non-steroidal anti-inflammatory compound indomethacin, was ineffective in preventing vascular alteration, treatments with other NSAI agents such as ibuprofen and imidazole were effective in preventing microvascular occlusion. In addition, utilizing standard radioimmunoassay techniques, the concentrations of the metabolites of two potent eicosanoids, thromboxane and prostacyclin, were measured from fluid collected in the implanted wound chambers. Following full-thickness burns, the synthesis and release of thromboxane were inhibited by indomethacin, imidazole, and ibuprofen. Furthermore, indomethacin and ibuprofen, but not imidazole, blocked the synthesis and release of prostacyclin into wound fluid. Significantly, ibuprofen was effective in preserving the dermal vasculature, even when administration was delayed as long as 6 hours after burn trauma. Pharmacologic actions not associated with the production of thromboxane or prostacyclin appear responsible for the protective effects of ibuprofen during burn injury. Such findings do not support an important role for either thromboxane or prostacyclin in the development of vascular alterations following burn injury.     

Acute cerebral vascular injury after subarachnoid hemorrhage and its prevention by administration of a nitric oxide donor

OBJECT: Structural changes in brain parenchymal vessels occur within minutes after subarachnoid hemorrhage (SAH). These changes include platelet aggregation, activation of vascular collagenases, and destruction of perivascular collagen IV. Because collagen IV is an important component of the basal lamina, the authors attempted to further define changes in vascular structure (length and luminal diameter) and their relationship to vascular permeability immediately after SAH. In addition, the authors explored whether such alterations were attenuated by administration of a nitric oxide (NO) donor. METHODS: Endovascular perforation was used to induce SAH in rats. Two sets of experiments were performed. The first established changes in vascular structure and permeability (collagen IV and endothelial barrier antigen [EBA] dual immunofluorescence) during the first 24 hours after SAH. In the second, the investigators examined the effects of an NO donor on vascular structure, permeability, and collagenase activity (in situ zymography). In this second study, animals received intravenous infusion of the NO donor S-nitrosoglutathione (GSNO, 1 microM/8 microl/min) 15 minutes after induction of SAH and were killed 3 hours after SAH onset. Controls were naive unoperated animals for the first study and saline-infused SAH animals for the second. The authors found a time-dependent decrease in area fraction, length, and luminal diameter of collagen IV- and EBA-immunofluorescent vessels after SAH. The greatest change occurred at 3 hours after onset of SAH. Administration of GSNO was associated with striking preservation of collagen IV and EBA immunofluorescence compared with saline treatment. Zymography indicated decreased collagenase activity in GSNO-treated SAH animals compared with saline-treated SAH animals. CONCLUSIONS: These results demonstrate changes in the structure and permeability of brain parenchymal microvessels after SAH and their reversal by treatment with an NO donor.     

大鼠睾丸扭转复位后附睾唾液酸含量变化及意义

目的 :探讨大鼠睾丸扭转 2h和 4h复位后 2 4h附睾唾液酸含量的变化和意义。　方法 :用 2 4只雄性SD大鼠建立左侧睾丸扭转复位模型 ,分为对照组、扭转 2h组和 4h组 ,每组 8只。 5 甲基苯二酚法检测扭转侧附睾唾液酸的含量。　结果 :睾丸扭转 2h复位后 2 4h扭转侧附睾唾液酸含量 [(2 3.385± 9.2 2 0 )mg/mgprot]改变不明显 ;睾丸扭转 4h复位后 2 4h附睾唾液酸含量 [(13.72 5± 7.80 1)mg/mgprot]下降明显 (P <0 .0 5 )。　结论 :睾丸扭转 2h复位后 2 4h附睾分泌唾液酸功能不受影响 ,扭转 4h复位后 2 4h附睾分泌唾液酸功能下降 ;附睾耐受缺血再灌注损伤的时间可能较长。     

Protective effects of kolaviron and quercetin on cadmium-induced testicular damage and endocrine pathology in rats

This study evaluated the effects of kolaviron, a biflavonoid from Garcinia kola seed, and quercetin on cadmium-induced reproductive toxicity in rats. Adult male rats were administered with either cadmium (15 mg kg(-1)) alone or in combination with kolaviron (200 mg kg(-1)) or quercetin (10 mg kg(-1)) daily for 5 days. Cadmium-treated rats showed (P < 0.05) decrease in the body weight gain, testis and epididymis weights. However, upon co-administration of kolaviron or quercetin, these changes were significantly reversed in cadmium-treated rats. Also, administration of kolaviron or quercetin significantly prevented cadmium-mediated decrease in sperm motility and epididymal sperm concentration and reversed the increased level of sperm abnormality to near control. In testes and sperm, cadmium treatment resulted in significant decrease in the activities of superoxide dismutase, catalase and glutathione peroxidase, whereas it increased glutathione S-transferase activity as well as hydrogen peroxide and malondialdehyde levels. While plasma levels of triiodothyronine and tetraiodothyronine remained unaffected, the levels of testosterone, luteinising hormone and follicle stimulating hormone were decreased in cadmium-treated rats. Cadmium treatment caused mild congestion of interstitial vessels and oedema in the testes. Taken together, kolaviron and quercetin inhibited the adverse effects of cadmium on the antioxidant enzymes, markers of oxidative stress, endocrine and testicular structure in rats.     

Sensitivity of locally regenerated testicular vessels to cadmium

The conditions under which capillaries and venules within the testes of most scrotum-bearing mammals become sensitive and/or resistant to cadmium are not clearly elucidated. Localized heat lesions were produced within the testes of rats to allow regrowth from surrounding Cd-sensitive vessels into the damaged areas. After 2, 4, or 8 weeks rats were given a subcutaneous injection of CdCl2 in saline (5 mg/kg) and were sacrificed 6 h later. Tissue samples were examined by both light and electron microscopy. No evidence of Cd sensitivity in regenerated vessels was present after 2 weeks, but the surrounding normal tissue did show typical Cd-related damage. By 8 weeks, vessels within the lesioned areas responded to Cd in a manner similar to those in the surrounding tissue. Newly grown testicular vessels do not demonstrate Cd sensitivity, but they develop it between 4 and 8 weeks.     

Oxidative stress and vascular permeability in steroid-induced osteonecrosis model

We focused on the role of oxidative stress in the pathogenesis of steroid-induced osteonecrosis (ON) and the possibility of preventing this condition by antioxidant administration. Methylprednisolone 4mg/kg was injected only once into Japanese white rabbits. The involvement of oxidative stress and the presence/absence of bone circulatory impairment were investigated in groups of 10 rabbits killed at 3, 5, and 14 days each and in 10 rabbits administered the antioxidant glutathione. Reduced blood glutathione and lipid peroxide levels were determined biochemically, and the presence/absence of advanced glycation end-product expression was determined immunohistochemically. Vascular permeability in bone was confirmed by finding albumin leakage into the stroma. These blood biochemical and immunohistochemical studies clarified that the oxidative stress in this model developed 3–5 days after steroid administration. Elevated vascular permeability was observed in the 5- and 14-day groups. Hence, circulatory disturbance in bone was noted 5 days after steroid administration, coinciding with the onset of oxidative stress. The rate of ON development, which was 70% in the steroid-alone 14-day group, was significantly reduced to 0% in the steroid + antioxidant group. These results suggest the involvement of oxidative stress and vascular permeability in this steroid-induced ON model and the possibility of its prevention by suppression of oxidative stress.