A histopathologic study of the effects of gossypol on the female rat

The purpose of this study was to examine the tissues of female rats treated with gossypol acetic acid for morphologic evidence of an underlying mechanism of infertility. The number of estrous cycles, and body and adrenal weights were also compared. The number of estrous cycles decreased in rats treated with 60 mg/kg gossypol acetic acid for 30 days. Body weights were also reduced in rats treated with 40 mg or 60 mg/kg per day for 30 days when compared to controls. However, no significant differences were found in any group when comparing adrenal weights, adrenal weight/body weight ratios or adrenal histology. The body weight loss was related, at least in part, to diarrhea and dehydration in eight of the treated animals. It is interesting that though the gossypol-treated rats had reduced numbers of estrous cycles, no histopathologic changes were found in their ovaries, uterus or vagina.     

Gossypol: Its toxicological and endocrinological effects in male rabbits

The effects of different doses of orally administered polyphenolic compound ‘Gossypol’ on semen quality, circulating testosterone (T) and fertility of Dutch-belted male rabbits were studied. Bucks fed daily with 80, 40, 20 mg/kg/day gossypol died within 8–17, 23–35 or 35–84 days, respectively, after inicitation of treatment. Following gossypol treatment at 80, 40 or 20 mg/kg/ day, animals lost appetite and body weight, developed hind limb paralysis, breathing difficulties and collapsed while sitting in their cages. At autopsy, the liver and lungs were found congested while the stomach and intestines contained gases. On the other hand, rabbits fed daily with 10 mg/kg/day gossypol exhibited a survival time ranging from 77 to 250 days. Despite the severe side effects resulting in eventual deaths, weekly semen samples from all treated animals did not show any apparent change in sperm motility, morphology or population. Likewise, gossypol-treated males mated to estrous does exhibited a fertility comparable to vehicle-treated controls. Gossypol fed at a dose of 10 mg/kg/day for up to 35 weeks failed to induce sterility. Male rabbits, fed with either 20 or 10 mg/kg/day gossypol, that survived for longer periods of time had substantially reduced T levels by 12–20 weeks depending upon the dose but were fertile at all times. When the $\text{in vitro}$ release of T from the rat testes mince in the presence of hCG and gossypol was evaluated, an inhibition of T release was recorded. It is concluded that although gossypol has been shown to be an effective antifertility agent in several mammalian species, it failed to exhibit such an effect in Dutch-belted rabbits, although serum T levels were reduced. In addition, gossypol exhibited a wide spectrum of toxicity. The $\text{in vitro}$ study demonstrated that high concentration of gossypol can directly inhibit the T synthesis in the testis.     

Drug effects on dieldrin storage in rat tissue

Summary Selected drugs were tested for effectiveness in reducing dieldrin retention by rats. Female rats were fed diets treated to contain 1 ppm dieldrin. The drugs were administered as feed additives or by i.p. injections. The rats were sacrificed after 10 days of treatment and abdominal adipose tissue was analyzed for dieldrin using electron capture gas chromatography. Heptabarbital (40 and 225 mg/kg rat/day), aminopyrine (75 and 350 mg/kg rat/day), tolbutamide (60 and 290 mg/kg rat/day), and phenylbutazone (90 mg/kg rat/day) were effective as feed additives in reducing tissue dieldrin. Heptabarbital was the most effective and reduced the concentration of tissue dieldrin by 80 per cent at the higher dose level. In comparison, DDT (4 mg/kg rat/day) effected a 72 per cent reduction. A contrast with DDT was also observed in trials with i.p. administration of drugs and DDT. In those trials, the duration of the DDT action was apparently greater than that of the drugs. We suggest that suitable drugs might be used to reduce insecticide accumulation in the tissues of animals and man, and for treatment of individuals after over exposure to insecticides. Presented at the 150th meeting, American Chemical Society, Atlantic City, September 15, 1965.     

三甲基氯化锡引起低血钾症的肾脏机制探讨

目的探讨三甲基氯化锡(trim ethyltin ch loride,TMT)引起低血钾症的肾脏机制。方法将SD大鼠随机分成3组,每组10只,分别经腹腔注射TMT 0、10.0、21.5 m g/kg,测定0.5 h、1 d、3 d、6 d和11 d血浆的钾。将大鼠随机分成2组,每组10只,分别经腹腔注射TMT 0、10.0 m g/kg,测定1 d、6 d和11 d的24 h尿量和尿钾浓度。将大鼠随机分成6组,每组10只,分别经腹腔注射TMT 0、10.0 m g/kg,测定1 d、6 d和11 d的肾小管上皮细胞膜钠钾ATP酶的活力。结果大鼠腹腔注射TMT 10.0、21.5 m g/kg后0.5 h,血钾显著下降(P<0.05),6 d和11 d血钾仍低于正常水平(P<0.05);给予TMT 10.0 m g/kg后1 d、6 d和11 d,尿量先增后减、尿排总钾均显著增加(P<0.05);1 d、6 d和11 d肾小管上皮细胞膜钠钾ATP酶活力均显著低于对照组(P<0.01)。结论TMT引起低血钾症的主要原因是肾脏排钾持续增多,其机制与TMT引起肾小管细胞膜钠钾ATP酶活力下降,进而引起K 的重吸收下降有关。     

Fetal growth in rats treated with lapachol

Lapachol is a naphthoquinone well known for its therapeutic potential. Previous studies have shown that lapachol does not interfere with embryonic development during the pre-implantation period. However, when administered during the organogenic period at the same dose level, it induces a high fetal death incidence. To evaluate the effect of lapachol during fetogenesis, 20 pregnant Wistar rats were randomly divided into two groups: vehicle (10 mL of a 50% aqueous ethanol solution/kg body weight) and treated (100 mg of lapachol/kg body weight). Lapachol was administered from the 17th to 20th day of pregnancy. The following variables were analyzed: maternal body weight from 16th to 21st day of pregnancy, food intake from 17th to 21st day of pregnancy, clinical signs of physical discomfort, ovarian weights, implantations, resorptions and mortality indices, fetal and placenta weights, external malformations, and fetal organ weights. Results indicated that lapachol was not toxic to mothers, although it was fetotoxic leading to fetal growth retardation.     

Dose-response study of effect of oleuropein, an olive oil polyphenol, in an ovariectomy/inflammation experimental model of bone loss in the rat

BACKGROUND & AIMS: This study was carried out to assess the dose-dependent bone-sparing effect of oleuropein, an olive oil phenolic compound with anti-inflammatory and anti-oxidative properties, on bone loss induced by talc granulomatosis in oestrogen-deficient rat. METHODS: Among 98 rats, 20 were sham-operated (SH) while the others (78) were ovariectomised (OVX). The SH and 26 OVX rats (controls) were given a standard diet for 100 days. The 52 remaining OVX rats were allocated to 4 groups that received oleuropein at 2.5, 5, 10 or 15 mg/kg body weight per day for 100 days. Three weeks before necropsy, an inflammation was induced by subcutaneous injections of talc in half of the SH and OVX rats and in all oleuropein-treated animals. RESULTS: Castration was associated with a decreased bone mineral density (BMD). In OVX rats, inflammation, characterised by an increase of the spleen weight and plasma fibrinogen levels, exacerbated this bone loss, as shown by values of BMD of the total femur metaphyseal and diaphyseal subregions. The 4 doses of oleuropein reduced bone loss and improved inflammatory biomarkers excepted for 5mg/kg BW. CONCLUSIONS: Every dose of oleuropein elicited protective effects on bone mass in this model of ovariectomy associated with inflammation, probably by modulating inflammatory parameters.     

Sensitivity of young rats to nicotine exposure: Physiological and biochemical parameters

This work has investigated the effects of prolonged exposure of young rats to nicotine on some physiological and biochemical parameters. Wistar male rats (30 days old) were treated (s.c.) with saline or nicotine 5mg/kg/day for 28 or 56 days. They received five injections (1mg/kg) per day (8, 10, 12:00 a.m., 2 and 4:00 p.m.) on the dark period of the cycle. Nicotine exposure for 56 days reduced body and liver weights. Moreover, nicotine exposure for 28 or 56 days decreased the hepatic glycogen but not blood glucose levels. The activities of blood and hepatic PBG-synthase, and blood and cerebral acetylcholinesterase were not affected by in vivo exposure. However, these activities were inhibited by nicotine in vitro. Results show that although high levels of plasma cotinine were found in both intervals of exposures, the parameters here analyzed were not affected by prolonged nicotine exposure except the storage of glucose, and body and liver weights.     

Oral ethanol reinforcement in the rat: effects of acute amphetamine

Six male Long Evans rats, reduced to 80% body weight by food restriction, were trained to lever press using 5% ethanol and water reinforcement on a concurrent FR8 FR8 schedule. After responding had stabilized, d-amphetamine (0.25 mg/kg, 0.50 mg/kg, and 1.00 mg/kg) or drug vehicle was injected 15 minutes before the 30-minute sessions. In comparison with the vehicle injections, the 0.25 mg/kg amphetamine dose was followed by a nonsignificant trend towards increased ethanol responding, the 0.50 mg/kg dose produced no trend, and the 1.00 mg/kg dose significantly decreased ethanol responding. These effects resemble those of amphetamine on food responding by food-deprived rats. Since both ethanol and amphetamine act upon brain catecholamine systems, possible involvement of catecholamines in reinforcement and arousal was discussed in relation to these results.     

Effect of melatonin on the induction of foci of aberrant crypts in the colon by azoxymethane in rats

Objective A program of research was established on the question whether melatonin played a chemopreventive role in the development of foci of aberrant crypts in the intestinal tract of male rats. Male F344 rats were injected i.p. with an aqueous solution of 15 mg/kg azoxymethane (AOM) on day 50 and day 57, and a group was also injected i.p with 0.5 mg melatonin in 0.5 ml of 10% ethanol solution 5 times per week beginning at age 47 days. Foci and multiplicity of aberrant crypts were determined after 8 weeks. These groups of animals were kept in light daily from 4∶30 to 16∶30. Results In the group receiving AOM and the melatonin injections, there were fewer foci of aberrant crypts in the colon and the average number of crypts was lower after 8 weeks, compared to the group on AOM alone. Conclusions Melatonin inhibited the formation of foci of aberrant crypts in the descending colon of rats. Also, it reduced the number of aberrant crypts per focus from foci with 3 and more aberrant crypts. Presented at the Annual Meeting of the American Association for Cancer Research on July 14, 2003 in Washington, D.C.     

Quantitative analysis of germ cells and Leydig cells in rat made infertile with gossypol

This study utilized improved methods of fixation and plastic embedding to quantitatively evaluate the effects of gossypol on germ cells and Leydig cells in testes of rats made infertile with gossypol. Rats were fed by gavage with 10, 20 or 30 mg/kg per day of gossypol for 9 weeks; control animals received the vehicle alone. Numbers of A spermatogonia, preleptotene and pachytene spermatocytes, and step 7 or 8 spermatids per Sertoli cell were counted in stages VII-VIII of the cycle of the seminiferous epithelium. Although high doses (30 mg/kg) of gossypol produced a significant decrease in the relative number of germ cells compared with vehicle-treated controls, no significant deviation in the relative number of germ cells was noted between controls and rats made infertile with 10 or 20 mg/kg/day of gossypol. Stereologic techniques were used to assess the changes in the Leydig cells. No significant deviation in the Leydig cell morphology, cell number, or cell volume was noted as a result of gossypol treatment at the dose levels employed. It appears that germ cell depletion, such as that caused by high doses of gossypol, is not mediated by a change in Leydig cell function. The present report emphasizes the importance of studies to determine the minimal effective doses for gossypol's antifertility activity in animal models as well as in man.     

Testicular toxicity evaluation of two antimony compounds, antimony trioxide and antimony potassium tartrate, in rats and mice

Objectives Testicular toxicities of antimony compounds were evaluated in rats and mice. The slightly water-soluble antimony compound antimony trioxide (ATO) and the highly water-soluble antimony compound antimony potassium tartrate (APT) were examined. Methods Daily doses of the compounds were 27.4, 12.0 and 1,200 mg/kg body weight in the APT group, low-ATO group and high-ATO group, respectively. The corresponding daily doses of antimony were 10, 10 and 1,000 mg/kg body weight, in the APT group, low-ATO group and high-ATO group, respectively. Both compounds were administered by gavage: rats, 3 days per week for 4 weeks; mice, 5 days per week for 4 weeks. Results Neither compound reduced the weights of reproductive organs or accessory sex organs nor affected sperm parameters. Few marked histopathologic changes were found in the testes of the treated animals. Even at 1,200 mg/kg body weight, which is greater than the LD₅₀ of APT, ATO produced no effects. Conclusions In this study, it was found that ATO and APT are not toxic to testes in rodents.     

The effects of exercise on milk yield, milk composition, and offspring growth in rats

This study examined effects of exercise training throughout pregnancy and lactation upon selected indicators of lactational performance in Wistar rats. During the 7 wk prior to mating, experimental female rats were gradually trained to swim for 2 h/day, 5 days/wk with a 3% tail weight; they continued swimming until the 19th day of pregnancy. Control animals remained sedentary. Swimming resumed during days 2-14 of lactation. Food intake was greater in exercised rats during the lactation period. Body weights of the two groups were comparable. Mild yield (day 10), energy content (day 15), and protein and fat concentrations did not differ, but milk of exercised rats had a lower lactose concentration. The exercise regimen had no statistically significant effect on litter size or on offspring weight to day 15. This study indicates that moderate-intensity, aerobic exercise does not markedly affect the lactational performance of ad libitum-fed rats.     

Immature rat uterotrophic assay of bisphenol A

We used the immature rat uterotrophic assay to determine the estrogenicity of bisphenol A (BPA). We administered BPA (in sesame oil) to rats subcutaneously (sc; 0, 8, 40, and 160 mg/kg/day) or orally (0, 40, 160, and 800 mg/kg/day) for 3 days beginning on postnatal day (PND) 18; rats were sacrificed 24 hr after the last administration. Uterine wet, blotted, and relative weights increased in all groups given BPA sc. After oral administration, uterine relative weight increased in 160 and 800 mg/kg BPA groups, and wet and blotted weights increased in the 800 mg/kg BPA group. Plasma concentrations of BPA at 1 hr after the last administration were detected in all groups given BPA sc and in groups given 160 and 800 mg/kg BPA orally, with a dose-response effect. The study was then reproduced under the same conditions. After sc injections, uterine wet and blotted weights increased in the 40 and 160 mg/kg BPA groups, and relative weight increased in all groups given BPA sc. By contrast, uterine wet, blotted, and relative weights increased only in the 160 and 800 mg/kg oral BPA groups. Also, to examine time-course changes in uterine weight, we administered BPA (in sesame oil) sc from PND 18 to PND 20 for 3 days at doses of 0, 8, 40, and 160 mg/kg/day; uterine weights were then measured at 6, 12, 18, and 24 hr after the last administration. Uterine wet, blotted, and relative weights increased in all BPA groups at 6 and 24 hr and in 40 and 160 mg/kg BPA groups at 12 hr. By contrast, at 18 hr, uterine wet, blotted, and relative blotted weights increased in all BPA groups and relative wet weight increased in 40 and 160 mg/kg BPA groups. The percentage increases in uterine wet and relative weights of 40 and 160 mg/kg BPA groups at 6 hr were higher than those at 24 hr relative to the controls, but the coefficient of variation in these weights in the group given 8 mg/kg BPA at 24 hr was smaller than that at 6 hr. These findings demonstrate BPA-induced uterotrophy in the immature uterotrophic assay in rats administered 8 mg/kg/day sc and in rats given 160 mg/kg/day orally, and suggest that the autopsy at 24 hr after the last administration is suitable.     

1-(2,4-Dichlorobenzyl)-1 H-lndazole-3-Carboxylic Acid (DICA), an Exfoliative Antispermatogenic Agent in the Rat

The oral administration of 50 mg DICA/kg at nine weekly or four monthly intervals produced partially reversible infertility in male rats as judged by the results of serial mating and testicular histology. Oral 500 mg DICA/kg doses administered at the same intervals produced permanent sterility. Single oral doses of 50 or 500 mg DICA/kg elevated mean FSH concentrations on days 2, 3, and 7 but did not affect LH or testosterone. Mean plasma concentration peaked at 74 μg/ml 4 hr after a 50 mg/kg dose of uniformly tritiated DICA; 24 hr later, it had declined rapidly to 5.5 μg/ml. The drug did not have a strong affinity for any tissue studied including the testis. DICA-induced exfoliation of immature germ cells was first observed 4 hr after administration and led to significantly reduced testis weights by day 2. Neither single doses of 10-250 mg DICA/kg nor five daily doses of 10-100 mg DICA/kg reduced seminal vesicle, ventral prostate, or body weights of male rats. Chronic weekly DICA administration did reduce mean seminal vesicle weight. These studies have shown that DICA is an effective, partially reversible antifertility agent that directly affects the rat testis.     

Influence of 2-bromopropane on reproductive system--short-term administration of 2-bromopropane inhibits ovulation in F344 rats.

The present study was performed to investigate the toxic effects of 2-bromopropane (2BP) on the female reproductive system. Female F344 rats were administered 2BP (500 or 1000 mg/kg, i.p.) at intervals of 2 or 3 days for 15-17 days. The body weights were measured and estrous stages were observed throughout the experimental period. Ovulation, organ weights, ovarian histology, and blood biochemistry were investigated on the terminal day of the experiment. Uterine weights in rats treated with 2BP were significantly lower than those in control animals. Body, liver, kidney, and adrenal weights in 2BP-treated rats showed no significant differences from control values. 2BP treatment prolonged estrous cycles and decreased the number of ovulated ova in spontaneous ovulation. In addition, histological examinations showed that the preovulatory follicles in the ovary were altered markedly in 2BP groups. These results show that even in short-term treatment, 2BP injured the ovary, particularly the preovulatory follicles. It appears that these damages of the preovulatory follicles induced by 2BP reduced the numbers of spontaneously ovulated ova in female F344 rats.     

Effect of neonatal exposure to estrogenic compounds on development of the excurrent ducts of the rat testis through puberty to adulthood

Neonatal exposure to diethylstilbestrol (DES) can alter the structure of the testicular excurrent ducts in rats. We characterized these changes according to dose and time posttreatment and established whether potent estrogens (ethinyl estradiol), environmental estrogens (genistein, octylphenol, bisphenol A, parabens), and tamoxifen induce such changes. Rats were administered these compounds neonatally and assessed at several time points during (day 10, or day 18 for some treatments) and after (days 18, 25, 35, and 75) the treatment period to detect any changes in testis weight, distension of the rete testis and efferent ducts, epithelial cell height in the efferent ducts, and immunoexpression of the water channel aquaporin-1 (AQP-1). Treatment with DES (10, 1, or 0.1 microg/injection; equivalent to 0.37, 0.037, or 0.0037 mg/kg/day, respectively) induced dose-dependent changes in testis weight and all parameters. These effects were most pronounced at days 18 and 25 and appeared to lessen with time, although some persisted into adulthood. Neonatal treatment with ethinyl estradiol (10 microg/injection; equivalent to 0.37 mg/kg/day) caused changes broadly similar to those induced by 10 mg DES. Administration of tamoxifen (2 mg/kg/day) caused changes at 18 days that were similar to those induced by 1 microg DES. Treatment with genistein (4 mg/kg/day), octylphenol (2 mg/injection; equivalent to 150 mg/kg/day), or bisphenol A (0.5 mg/injection; equivalent to 37 mg/kg/day) caused minor but significant (p<0.05) decreases in epithelial cell height of the efferent ducts at days 18 and/or 25. In animals that were followed through to 35 days and/or adulthood, these changes were no longer obvious; other parameters were either unaffected or were affected only marginally and transiently. Administration of parabens (2 mg/kg/day) had no detectable effect on any parameter at day 18. To establish whether these effects of estrogens were direct or indirect (i.e., resulting from reduced follicle-stimulating hormone/luteinizing hormone secretion), the above end points were assessed in animals in which gonadotropin secretion was suppressed neonatally by administration of a gonadotropin-releasing hormone antagonist. This treatment permanently reduced testis weight, but did not affect any of the other end points, apart from a minor transient reduction in efferent duct epithelial cell height at 18 days. This study suggests that structural and functional (expression of AQP-1) development of the excurrent ducts is susceptible to impairment by neonatal estrogen exposure, probably as a consequence of direct effects. The magnitude and duration of adverse changes induced by treatment with a range of estrogenic compounds was broadly comparable to their estrogenic potencies reported from in vitro assays.     

Methylmercury chloride-induced and antagonist-reverted succinic dehydrogenase changes in the brain and trigeminal ganglia of the rat

The effect of methylmercury chloride (MMC) toxicity and its antagonism by chelating agents (N-acetyl-DL-homocysteine thiolactone and 2,3-dimercaptosuccinic acid) on succinic dehydrogenase (SDH) activity of fore-, mid-, and hindbrain and trigeminal ganglia of rats is reported in this study. A dose of 10 mg MMC/kg body weight was injected subcutaneously for 2, 7, and 15 days. The chelating agents were also injected subcutaneously in two separate groups of MMC-treated animals except in group 3. In the latter case MMC was injected in two groups of rats for 7 days, and thereafter antagonists were administered daily (40 mg/kg) for 1 week. The result shows inhibition of the enzyme with MMC in all groups and its restoration by N-acetyl-DL-homocysteine thiolactone; 2,3-dimercaptosuccinic acid, however, further reduced the enzyme level. The significance of inhibition of the enzyme in relation to tissue respiration and ATP production is discussed and the capacities of antagonists in the restoration of the SDH level are also analyzed.     

Effect of paraquat administered intraperitoneally on the nonpolar lipids of rabbits

Rabbits were injected intraperitoneally with 3, 6, or 12 mg of paraquat/kg/day for a period of 3, 7, or 14 days. Rabbits receiving 3 or 6 mg of paraquat/kg/day showed a significant loss of body weight at 7 days of the treatment. Liver, kidney, heart, and lungs demonstrated a significant decrease in their weights in the first 3 days of paraquat treatment. A decrease in total lipids, total triglycerides, and total cholesterol of both liver and kidney was observed. This decrease was accompanied by a significant increase in plasma total triglycerides and total cholesterol at 7 days of paraquat treatment. The ratio of cholesterol to cholesterol esters in liver decreased after 3 days of paraquat treatment after which it showed a consistent increase until the 14th day of the paraquat treatment. In kidney, this ratio increased for up to 7 days of paraquat treatment followed by a decrease at the 14th day. These results indicate, contrary to earlier reports, that rabbits are susceptible to paraquat toxicity.     

腺嘌呤致大鼠少精子症模型的实验研究

目的：探讨腺嘌呤致大鼠少精子症模型的最佳剂量和造模时间点。方法：用0.5％羧甲基纤维素钠溶液,将腺嘌呤按0、20、25、30、35mg／ml浓度配制,75只大鼠按体重随机分为5组（0、200、250、300、350mg／kg）,每组15只,按1ml／100g灌胃,1次／日。造模10d、20d、30d各处死一批,共3批。观察大鼠一般状态,取附睾尾作精子计数及形态学观察,取血测肝、肾功能及生殖激素,称量肝、肾及生殖器官湿重并计算脏器指数,切片进行病理形态学观察。结果：各模型组相继出现不同程度的肾阳虚体征;尿素氮（BUN）、肌酐（CRE）第10d开始明显升高;20d开始血清睾酮明显下降;随着造模时间的延长和剂量的增加,精子密度和活力出现不同程度的降低,畸形率上升,并呈一定的时效和量效关系。肝、肾指数明显升高,生殖器官指数明显降低;造模30d时,多数模型组睾丸内生精细胞和附睾精子数量减少。结论：腺嘌呤致大鼠少精子症模型的最佳剂量为250mg／kg,造模时间点为20d。     

Antifertility and endocrine activities of gossypol in rodents

Reversible male antifertility activity was obtained with orally administered gossypol acetic acid in rats at 20 mg/kg/day and in hamsters at 10 mg/kg/day but not in mice at dosages up to 40 mg/kg/day. An increased number of degenerating spermatocytes was found in the testicular tubular lumens of rats. Pigment-laden cells containing an intracytoplasmic lipofuscin-like material were noted in the testis and epididymal interstitium in rats and mice. Gossypol was also tested in the female for effects on ovulation and pregnancy. Gossypol did not inhibit ovulation in the rat at dosages up to 80 mg/kg/day but did cause 90% inhibition of pregnancy in mice treated with 80 mg/kg/day during the first two weeks of pregnancy. In several standard endocrine bioassays, gossypol did not demonstrate estrogenic, antiestrogenic, androgenic or antiandrogenic activities, but it did potentiate the androgenicity of methyltestosterone.