Antifertility efficacy of twice daily oral administration of 6-chloro-6-deoxy-D-glucose (6 CDG) in male rats

A previous study had shown inability of once daily administration of 6CDG to male rats to completely suppress fertility. Twice daily administration of 12, 24 or 48 mg/kg/day, equivalent total daily doses as in the previous study, now shows dose related suppression of male fertility which is complete at the highest dose level. This dose is also correlated with a significant depression (p < 0.01) in ATP levels of retrograde-flushed epididymal sperm after 21 days of dosing. All dose levels are associated with an accelerated loss of ATP in epididymal sperm over a two-hour post-recovery incubation period relative to controls.In addition twice daily administration of 24 mg/kg shows a duration of dosing, time of incubation interaction on both motility and ATP content of epididymal sperm harvested from the treated rats. Significant effect on both motility and ATP content of these sperm is already apparent after the third dose. Three or more days of dosing results in significant suppression of ATP levels at time of harvest of epididymal sperm.It is suggested that either ATP level within epididymal sperm is a more sensitive index of action of 6CDG than is fertility or alternatively, that the antifertility action of 6CDG is mediated through more than one mechanism.     

Antifertility effects of 6-chloro-6-deoxyglucose in the male rat

Male rats were treated with daily oral doses of 12, 24, or 48 mg/kg of 6-chloro-6-deoxy-glucose (6CDG) or with 5 mg/kg of α-chlorohydrin for 28 days. Continuous fertility trials were conducted throughout the dosing period and for 3 weeks following dosing. 12 mg/kg/day of 6CDG produced partial infertility, while 24 and 48 mg produced almost complete infertility after 7 days of dosing. Although the males continued to mate with female rats after this time, only 4 to 20% of mated females became pregnant. In addition, those females which did become pregnant carried a significantly decreased number of fetuses at sacrifice one week after the breeding period. Males dosed with 5 mg/kg/day of α-chlorohydrin showed a gradual decrease in fertility over the four-week dosing period with a significant decrease in fetal numbers observed following one week of dosing. Recovery of normal fertility was achieved after one week withdrawal from all doses of 6CDG or from α-chlorohydrin. The ATP content of spermatozoa obtained from the treated rats and measured following an $\text{in vitro}$ incubation was significantly lower than controls for all groups at 4 weeks of dosing. However, 3 weeks following cessation of treatment, ATP had returned to control levels. The action of 6CDG is rapid in onset and associated with no effect on testis or accessory organ weight. These observations, together with the suppression of intracellular levels of ATP in epididymal spermatozoa, are consistent with an epididymal site of action of this compound or metabolites mediated through the glycolytic pathway.     

Dose and time related changes in LDH-X activity, epididymal carnitine levels and fertility, in gossypol-treated male rats

Gossypol acetic acid could induce total infertility in male Wistar/NIN strain rats at a dose of 30 mg per kg body weight per day, for 52 days. 20 mg for 52 days and 30 mg for 38 days produced partial infertility. Highly significant correlation between parameters of infertility like reduced cauda sperm count, and implantation sites, and reduction in LDH-X activity of cauda epididymal sperm and carnitine levels in cauda epididymal fluid were observed. Testis remained unaffected.     

Effects of multiglycosides of Tripterygium wilfordii (GTW) on rat fertility and Leydig and Sertoli cells.

Primary cultures of rat Leydig and Sertoli cells were used to evaluate the direct effects of GTW on testicular cells and to compare these to the effects of gossypol acetate. Both GTW and gossypol acetate can affect the survival of Leydig and Sertoli cells. But Sertoli cells are much more sensitive than Leydig cells, either to gossypol acetate or GTW. Leydig and Sertoli cells all died when they were exposed to gossypol acetate or GTW at a dose of 3.0 micrograms/ml or 30 micrograms/ml, respectively, for 24 hours. The cell survival-time course demonstrated that the cell numbers were decreased after 2 hours, and especially so after 8 hours. No significant changes were observed in testosterone production in Leydig cells after 24 hours of exposure to 1.0-20 micrograms/ml GTW. The forward motility of epididymal spermatozoa was completely lost and fertility of rat was significantly inhibited after the treatment of GTW in vivo. It is concluded that GTW does affect the fertility of rat and viability of cultured rat Leydig and Sertoli cells.     

A new orally active male antifertility agent

CL 88,236 (1-1-amino-3-chloro-2-propanol HC1) was tested orally for antifertility in male rats, mice and hamsters. It was given orally in propylene glycol either daily for 14 days with mating on Days 7-14, (or for 7 days with mating on Days 2, 4, and 6, or for 7 days every other week for 3 weeks in withdrawal tests. In male rats, 5 mg per kg for 14 days reduced number of pregnant females 50%, and at 10-80 mg per kg males were completely sterile. Libido, coitus, and ejaculation were normal, but fragmented sperm, spermatogenic arrest, and granuloma-like epididymal lesions appeared at 40 and 80 mg per kg. Serial matings showed that sterility developed within 6 days and lasted for 1 week after withdrawal. Sterility was maintained by treating rats with CL 88,236 on alternating weeks. Male mice and hamsters were sterilized by 300 mg per kg per day for 14 days, without toxicity. Sterility was apparently mediated by affecting epididymal and vas sperm stores.     

Effects of monothioglycerol,alpha-chlorohydrin and 5-thio-D-glucose on the fertility of male hamster

Male hamsters were treated with monothioglycerol, alphachlorohydrin and 5-thio-D-glucose and their fertility was tested by mating and after artificial insemination with epididymal spermatozoa.Monothioglycerol at a dose of 25 mg/kg body weight twice daily for 5 weeks deprived 4 out of 5 males of their fertility. The epididymal spermatozoa of two of the infertile males could effect fertilization when deposited in the uterus artificially. Thus, the infertility of these two males appeared to be due to a sperm toxic action of the accessory gland secretions rather than the lack of fertilizing capacity of the spermatozoa. Oral administration of alpha-chlorohydrin at a dose of 100 mg/kg body weight daily for 1 week induced sterility in all of the 8 males treated. This sterility appeared to be due to adverse effects on both the spermatozoa and the male accessory glands. 5-thio-D-glucose administered in silastic capsules had only a marginal effect even after 5 weeks of treatment and only 1 out of 6 animals became sterile.     

The effect of ketoconazole on fertility of male rats

The effect of ketoconazole on the fertility of male rats was evaluated. Three days of oral dosing with ketoconazole at 200 mg/kg reduced fertility compared to controls. A complete loss of fertility was observed after doses of 400 mg/kg. There was no change in the testicular weight, epididymal sperm concentration or epididymal weight between the control and treatment groups. Motility was reduced in the high-dose group and forward progression was reduced in both dosing groups compared to control. These data support previous observations in the dog and primate that orally administered ketoconazole alters sperm viability. Although ketoconazole is too toxic for contraceptive application, its derivatives may be useful for this purpose.     

Antispermatogenic effect of embelin, a plant benzoquinone, on male albino rats in vivo and in vitro

Embelin, the active principle of the seeds of Embelia ribes Burm, has been isolated and the purity established. Daily subcutaneous administration of the compound at a dose of 20 mg/kg body weight to male albino rats for 15 or 30 days revealed an inhibition of: a) epididymal motile sperm count, b) fertility parameters such as pregnancy attainment and litter size, and c) the activities of the enzymes of glycolysis and energy metabolism. These changes were reversible, as seen after 15 and 30 days of recovery. Addition of embelin to epididymal sperm suspensions caused a dose- and duration-dependent inhibition of spermatozoal motility and the activities of the enzymes of carbohydrate metabolism. Light and scanning electron microscopy showed that both in vivo and in vitro treatment with the drug causes profound morphological changes in spermatozoa such as: a) decapitation of the spermatozoal head, b) discontinuity of the outer membranous sheath in the mid-piece and the tail region, and c) alteration in the shape of the cytoplasmic droplet in the tail.     

米非司酮抗着床作用的实验研究

抗孕激素米非司酮皮下注射给药,对大白鼠抗着床作用随剂量增加而增强,妊娠第一天单次给药半数有效量DE_(50)为5mg/kg,完全抗着床剂量为10mg/kg,同一剂量分次给药其抗着床效果优于单次给药。     

Antifertility effect of sulfasalazine in the male rat

Sulfasalazine, which has been used for treatment of ulcerative colitis in man, caused a dose-dependent and reversible reduction in fertility of the male rat. By five weeks after forced feeding with sulfasalazine in corn oil at daily doses of 300, 450 and 600 mg/kg, the fertility decreased to 60.9, 35.5 and 26.8% of the control rats, respectively. Besides, the number of cohabited female being successfully inseminated was significantly reduced especially at high dose. However, complete recoveries of the mating behavior and fertility were evident by three weeks after drug withdrawal. Number of spermatozoa in the caput, the corpus and the cauda epididymides were not changed, but motility of spermatozoa collected from the cauda epididymides was significantly decreased. The body weight and the weights of testes, epididymides, seminal vesicles, prostate glands and coagulating glands as well as the concentration of plasma testosterone were not altered by five weeks after drug treatment at a dose of 450 mg/kg. This study shows that sulfasalazine also has an antifertility action in the male rat without affecting the blood androgens as previously reported in male patients.     

The reversible antifertility effect of Piper betle Linn. on Swiss albino male mice

To study the antifertility effect of an extract (alcoholic) of the leaf-stalk of Piper betle Linn., one set of experiments with two different doses in Swiss male albino mice were evaluated. Initially, 500 mg of the leaf-stalk extractive for 30 days and then 1000 mg for next 30 days/animal/day/kg body weight were administered orally. The extract reduced fertility to 0% within 60 days. Suppression of cauda epididymal sperm count and motility (p <0.05) was observed. Biochemical parameters did not show any marked alterations in testosterone content in serum nor 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activity in testes although fructose content in seminal vesicles was reduced as are the weights of reproductive organs. The cholesterol content in testes increased, although not appreciably. After cessation of drug (plant extract) treatment, the altered parameters recovered. Results suggest that the contraceptive effect of the extract of leaf-stalk of Piper betle Linn. is mainly on the maturation process of spermatozoa in epididymides without influencing hystemic hormonal profiles. Withdrawal of the extract restored all altered parameters including organ weights and fertility after 60 days.     

Evaluation of STS-557 as an oral contraceptive in male rat

To examine the nature and site of post-testicular antifertility action of STS-557 (17 alpha-cyanomethyl-17 beta-hydroxy-estra-4,9-dien-3-one), male rats were given the steroid orally daily for 60 days. In doses of 1 and 5 mg per animal per day it had no effect on fertility at the end of 3 weeks of treatment. When the treatment was extended for 60 days, spermatogenic arrest and loss of libido were evident in animals treated with 5 mg dose; animals receiving 1 mg dose of steroid showed no decrease of spermatogenesis or sexual activity and their fertility remained unaffected. In 35-day-old growing rats the steroid produced inconsistent effects on spermatogenesis after a 15-day treatment period at 1 and 5 mg doses. Both in adult and in growing rats the steroid caused a significant reduction in the weights and secretory function of the epididymis and other accessory sex organs; a dose-dependent response was seen in all the sex organs. Evaluation in castrated rat model revealed that STS-557 is a weak anti-androgen. Although this steroid is a potent inhibitor of spermatogenesis, its inhibitory effect on Leydig cell function is a contraindication for its use as a male oral contraceptive.     

Could zinc prevent reproductive alterations caused by cigarette smoke in male rats?

The aim of the present study was to evaluate the effects of zinc on fertility through semen parameters, testosterone level and oxidative DNA damage to spermatozoa of rats exposed to cigarette smoke. Male Wistar rats (60 days old) were divided into four groups (n = 10 per group): control, cigarette-smoking (20 cigarettes per day), zinc (zinc chloride 20 mg kg?1 day?1) and zinc plus cigarette-smoking (zinc chloride 20 mg kg?1 day?1; 20 cigarettes per day). The treatment was applied for nine weeks and the following parameters were analysed: bodyweight, wet weights of the reproductive organs and the adrenal gland, plasma testosterone concentration, testicular function (seminal analysis and daily sperm production) and sperm DNA oxidative damage. The exposure to cigarette smoke decreased testosterone concentration, the percentage of normal morphology and the motility of spermatozoa. In addition, this exposure increased sperm DNA oxidative damage. Zinc treatment protected against the toxic damage that smoking caused to spermatozoa. This study showed a correlation between smoking and possible male infertility and subfertility, and also that the majority of smoking-induced changes in spermatozoa were prevented by zinc treatment. In conclusion, zinc, an antioxidant and stimulant of cell division, can be indicated as a promising treatment in men with infertility caused by the toxic components of cigarette smoke.     

吡哆素L-2-吡咯烷酮-5-羧酸酯对大鼠的生殖毒性

目的　研究吡哆素L 2 吡咯烷酮 5 羧酸酯对大鼠的生殖毒性。方法　雄鼠 80只 ,雌鼠 12 4只随机分 4组 ,溶剂对照组 ,3个剂量组吡哆素L 2 吡咯烷酮 5 羧酸酯分别为 4 0 0、80 0和 16 0 0mg/kg。雄鼠交配前连续给药 6 0d ,交配期间继续给药 ;雌鼠交配前连续给药 14d ,交配后给药至妊娠第 14天 ;分别观察生殖毒性试验指标。结果　 4 0 0mg/kg组无明显毒副反应 ,80 0mg/kg组有个别鼠出现后肢麻痹 ,16 0 0mg/kg引起雌雄大鼠后肢麻痹 ,消瘦。吡哆素L 2 吡咯烷酮 5 羧酸酯 16 0 0mg/kg使雄鼠的交配率下降 5 0 % ,有统计学显著性。 80 0mg/kg组生育鼠 7只 ,16 0 0mg/kg组未生育 ,对雄鼠的生育率有统计学显著影响。 80 0mg/kg组雄鼠的精子数为 (5 9 4 0± 2 1 71)× 10 5,16 0 0mg/kg组雄鼠的精子数为 (0 4 0± 0 14 )× 10 5。 80 0mg/kg组活胎数为 (8± 3)只 ,16 0 0mg/kg组无受孕鼠。结论　吡哆素L 2 吡咯烷酮 5 羧酸酯在本实验条件对SD大鼠无致畸性 ,无作用剂量为4 0 0mg/kg ,发育毒性的无作用剂量小于 4 0 0mg/kg。     

杀虫磺原药大鼠亚慢性毒性研究

目的研究杀虫磺原药对大鼠亚慢性经口毒性,探讨其亚慢性毒性的阈作用剂量和最大无作用剂量。方法雌鼠剂量以135、67.50、22.50mg/kg,雄鼠剂量以157.5、78.752、6.25mg/kg,连续90d给予杀虫磺原药,观察动物的一般状况,体重增长及血液、生化指标并解剖进行病理检查。结果杀虫磺原药高剂量组动物,染毒8周后出现被毛蓬松、活动减少、体重减轻等症状;染毒结束后血清中谷草转氨酶（AST）升高,肝及雄鼠肾脏器系数增大,组织病理学检查显示：肝细胞明显浊肿,胞浆疏松,汇管区可见慢性炎细胞浸润。中剂量组动物染毒结束后谷草转氨酶（AST）显著升高,雄鼠肾脏器系数增大;肝细胞病变相同,但程度较轻。低剂量组动物一般行为、体重增长、尿常规、血液学、血液生化学、脏器重量、脏器系数及病理学检查均未见变化。结论本实验条件下,初步确定大鼠90d亚慢性经口最大无作用剂量,雌性为22.50mg/kg;雄性为26.25mg/kg。     

Combined administration of low-dose gossypol acetic acid with desogestrel/mini-dose ethinylestradiol/testosterone undecanoate as an oral contraceptive for men

To evaluate the efficacy and feasibility of a new regimen of low-dose gossypol acetic acid (GA) combined with desogestrel/ethinylestradiol and testosterone undecanoate (DSG/E/TU) as a male contraceptive, adult male rats were fed orally with GA (12.5 mg/kg/day) and DSG (0.125 mg/kg)/E (0.025 mg/kg)/TU (100 mg/kg) daily for 8 weeks as loading dose until infertility, and a similar low dose of GA alone for infertility maintenance. Control animals were administered a single low dose of GA (12.5 mg/kg/day) or DSG (0.125 mg/kg)/E (0.025 mg/kg)/TU (100 mg/kg), and vehicle, respectively. Results demonstrated that the combined dosage regimen could damage epididymal sperm motility and density, and induce infertility within 8 weeks in rats; the infertility could be consistently sustained by giving single GA (12.5 mg/kg/day), and was reversible in about 8 weeks following withdrawal of gossypol. The regimen rendered treated male rats with spermiation failure within a period of 6-20 weeks of treatment. Also, the serum luteinizing hormone, follicle-stimulating hormone and testicular interstitial fluid testosterone levels showed a transient decrease at the end of 6 or 8 weeks, which returned to control levels after 8 weeks of recovery phase. No hypokalemia or other adverse effects in viscera were observed. These results provide a promising approach to using the new regimen for the development of an effective and reversible oral male contraceptive.     

Toxicity of metepa to rats: With notes on two other chemosterilants

Although tepa, metepa, and apholate are only moderately toxic to rats by the oral route, the dermal toxicity of the first two is relatively high as compared with that of conventional insecticides. In the experiments reported, metepa caused no damage to the intestinal epithelium of rats, except following single doses in the fatal range. The organ primarily affected by repeated small doses of metepa is the testis; the ovaries and bone marrow are damaged only by higher dosage levels. Metepa at an oral dosage of 5 mg/kg/day (about 4% of the acute oral LD₅₀ level daily) produced severe reduction of fertility of male rats within 22 days, sterility within 70 days, and testicular atrophy within 77 days. Half that dosage produced a smaller reduction in fertility and only partial testicular atrophy in some rats within 197 days. Dosages of 1.25 mg/kg/day or less produced no detectable effect on fertility and no histological change in the testis in 197 days. The survival of newborn rats was not affected by any dosage given to their sires.     

邻苯二甲酸二丁酯宫内和哺乳期染毒对F_1代雄性大鼠的生殖发育毒性

目的　观察邻苯二甲酸二丁酯 (DBP)对F1代仔鼠的发育状况及性成熟期雄性仔鼠生殖系统损害情况 ,并期望得到现有文献中缺如的DBP对F1代仔鼠生殖发育毒性的最大无作用剂量 (NOAEL)。方法　选择在宫内暴露期和哺乳期 (受孕第 2天至仔鼠 2 1天断奶 ) ,通过灌胃方式给母鼠染毒 (DBP终浓度分别为 0、5 0、2 5 0和 5 0 0mg (kg·d) ,观察对仔鼠的影响。结果　DBP对母鼠无明显影响 ,中高剂量组 [2 5 0、5 0 0mg (kg·d) ]对F1代雄性仔鼠的出生体重、每窝活产数、体重增长及雄性仔鼠肛殖距有明显影响 ,对性成熟期雄性仔鼠生殖系统损害尤为严重 ,可观察到小睾丸、附睾发育不全甚至缺失、睾丸未降等现象 ,附睾尾精子参数和睾丸精子头计数及附睾、肝、肾、前列腺的脏器系数明显降低 ,而与激素合成相关的垂体系数却略有上升。低剂量组未观察到有害影响。结论　雄性生殖系统是DBP作用的主要靶器官 ,幼年敏感期所受的损害部分不可逆 ,并得到DBP经口染毒对F1代仔鼠生殖发育毒性的NOAEL为 5 0mg (kg·d)。据此 ,进一步提出DBP经口摄入的参考剂量 (RfD)为 5 0 0 μg (kg·d)。     

Failure of indomethacin in limiting the fertilizing capacity of the epididymal spermatozoa in rats

Surgical separation of epididymides from the testes at the testis-caput junction retained the fertilizing capacity of the confined spermatozoa up to three weeks. However, mating with these animals four weeks following the surgical manipulation proved to be consistently infertile. Chronic treatment of indomethacin at a dose of 2.5 mg/kg bw on alternate days beginning on the day of operation resulted in regression of testicular weight (P<0.01), though the fertilizing capacity of the epididymal spermatozoa was maintained as good as found in controls.     

Radioprotective effects of sodium tungstate on hematopoietic injury by exposure to 60Co gamma-rays in Wistar rats.

Radioprotective effects of sodium tungstate (ST) on 60Co gamma-ray induced decrease in hematocrit value and in survival rate in Wistar strain male rats were examined. A long-term administration of ST (less than 150 mg/kg body weight/day) for 60-300 days had no significant effects on body and organs weights and survival days. The LD50/60 in 20 weeks old rats was 220 mg/kg body weight/day. Daily administration of 38, 75 or 150 mg from 7 days before and after irradiation to 60 days significantly mitigated the decrease in hematocrit values, especially at 23 days after irradiation (P < 0.05). The highest mitigation rate of the decrease in hematocrit value was observed in rats administered at a dose of 38 mg ST/day. Simultaneously, a dose of 38 mg ST/day inhibited lethal effect of 60Co gamma-rays significantly. The dose-reduction factor for survival of 38 mg ST administered rats was 1.14.