Effect of intravaginal instillation of some non-steroidal oral antifertility agents on pregnancy in rats

A study was conducted of the effect of intravaginal instillation of 3 nonsteroidal oran antifertility agents in pregnant rats. The 3 compounds used were 2-phenyl-3-rho-beta-pyrrolidinoethoxyphenyl-6-methox y benzofuran hydrochoride (DBF), 20 mg/kg; 2-phenyl-3-rho-beta-pyrrolidi noethoxyphenyl-naptha (2:1,b furan (NF), 10 mg/kg; and Centchroman, 1.25 mg/kg. These agents were administered on Day 1 postcoitum at the single-day oral contraceptive dose. Control animals were inserted with a pellet containing only carboxymethyl cellulose. Only Centchroman was 100% effective in preventing pregnancy. Even at half the normal dose, Centchroman was effective. Of the 3 compounds, only Centchroman has an antiprogestational property which may be contributing to Centchroman's high antifertility activity by the vaginal route and may prevent side effects.     

Estrogenic activities of nitrophenols in diesel exhaust particles

We recently isolated 3-methyl-4-nitrophenol (4-nitro-m-cresol; PNMC) and 4-nitro-3-phenylphenol (PNMPP) from diesel exhaust particles (DEP) and identified them as vasodilators. Because these compounds are alkylphenolic derivatives that might mimic hormones, we evaluated their estrogenic activity by using recombinant yeast screens, myometrial contractility assays, and in vivo uterotrophic assays. Recombinant yeast screen assays showed that both PNMC and PNMPP possess estrogenic activity. Furthermore, ovariectomized 25-day-old immature female rats injected with PNMC and PNMPP subcutaneously for 2 days showed significant increases in uterine weight among those receiving 100 mg/kg PNMC and 0.1 and 1.0 mg/kg PNMPP. To clarify further the estrogenic activity of PNMC and PNMPP, rat uterine horns were monitored in organ bath chambers for myometrial contractility in response to oxytocin (OT). Significant differences occurred in the initial and maximum contractilities to OT at 0.25 and 25 mIU/ml in uterine horns obtained from animals treated with 100 mg/kg PNMC and in the maximum contractilities to OT at 0.025, 0.25, and 25 mIU/ml in those from rats treated with 0.1 mg/kg PNMPP. These results clearly demonstrated that PNMC and PNMPP in DEP have estrogenic activity both in vitro and in vivo and might therefore be considered as endocrine-disrupting chemicals.     

Estrogenic & antiestrogenic properties of e-492, a nonsteroidal compound.

Estrogenic and antiestrogenic properties of E-492, a nonsteroidal compound (3 methyl-4'-(beta-pyrrolidinoethoxy)-2,3-diphenyl propiophenone), were assessed on the basis of ponderal, histologic, and biochemical changes in the uterus, cervix, and vagina of ovariectomized adult rats. This compound was studied at its maximum effective antifertility dose of .5 mg/kg/day for 5 days. Estradiol-dipropionate (EDP) was studied at a dose of 1 mcg/kg/day. EDP and E-492 separately increased the weight of the 3 genital accessories. Histologically, the organs presented an infantile condition characterized by atrophic epithelia, compact stroma, and inconspicious muscularis. The uterine glycogen level was raised by EDP (p less than .01) but not by E-492 (p greater than .05). Lactic acid was increased by EDP in all target organs (p less than .01) and by E-492 in the uterus and vagina (p less than .01) but not in the cervix (p greater than .05). Combined therapy antagonized EDP effect at the uterine and vaginal levels. Alkaline phosphatase was enhanced by EDP in all 3 organs (p less than .01) and by E-492 in the uterus and cervix (p less than .01). These results indicate that on the basis of changes in weight and histology, E-492 has both estrogenic and antiestrogenic potencies.     

Estrogenic effects of the ethyl-acetate extract of the stem bark of Erythrina lysistemon Hutch (Fabaceae)

The stem bark of Erythrina lysistemon, one of the traditionally used "women remedies", has been assessed for its estrogenic activity. The ethyl-acetate extract of the stem bark of E. lysistemon showed estrogenic activities in vitro either in a yeast-based estrogen receptor assay or on the estrogen-dependent stimulation of alkaline phosphatase activity in the human endometrial carcinoma cell line Ishikawa. The estrogenic activity was investigated in vivo in young ovariectomized Wistar female rats after a 7-day treatment. The estrogenicity was evaluated through the proliferative status of target sex organs such as uterus and vagina. The results obtained showed that oral administration of 200 mg/kg BW/d of E. lysistemon extract in comparison to untreated ovariectomized rats significantly increased the vaginal epithelial height by 47.23% (from 8.71+/-0.47 to 12.34+/-1.31 microm); and induced a weak increase of uterine epithelial height by 6.76% (from 5.42+/-0.52 to 5.84+/-0.91 microm). Both were not as pronounced as those elicited in the positive control of 100 microg/kg BW/d of ethinylestradiol given orally. Overall our results suggest that the extract of E. lysistemon contains secondary metabolites endowed with estrogenic activity.     

Cyclic variation in rats's uterine fluid phosphatase level after administration of lyndral (17 alpha-ethinyl estradiol).

An oral administration of antifertility drug Lyndral (17 alpha-ethinyl estradiol) at doses 5 micrograms/rat/a week for 3 consecutive weeks altered the internal biochemical milieu of uterus, showing a cyclic variation in both acid and alkaline phosphatase of the uterine fluid with high levels being present at proestrus and estrus in control rats. In Lyndral treated rats acid phosphatase showed a tendency to increase in estrus and metestrus rats, whereas alkaline phosphatase increased significantly during proestrus and estrus stages of the cycle. All these altered phosphatase levels in uterine fluid, after Lyndral treatment, gives some insight into the hormonal sensitiveness of these enzymes.     

Effects of Agomelatine on Oxidative Stress in the Brain of Mice After Chemically Induced Seizures

Agomelatine is a novel antidepressant drug with melatonin receptor agonist and 5-HT(2C) receptor antagonist properties. We analyzed whether agomelatine has antioxidant properties. Antioxidant activity of agomelatine (25, 50, or 75 mg/kg, i.p.) or melatonin (50 mg/kg) was investigated by measuring lipid peroxidation levels, nitrite content, and catalase activities in the prefrontal cortex, striatum, and hippocampus of Swiss mice pentylenetetrazole (PTZ) (85 mg/kg, i.p.), pilocarpine (400 mg/kg, i.p.), picrotoxin (PTX) (7 mg/kg, i.p.), or strychnine (75 mg/kg, i.p.) induced seizure models. In the pilocarpine-induced seizure model, all dosages of agomelatine or melatonin showed a significant decrease in TBARS levels and nitrite content in all brain areas when compared to controls. In the strychnine-induced seizure model, all dosages of agomelatine and melatonin decreased TBARS levels in all brain areas, and agomelatine at low doses (25 or 50 mg/kg) and melatonin decreased nitrite contents, but only agomelatine at 25 or 50 mg/kg showed a significant increase in catalase activity in three brain areas when compared to controls. Neither melatonin nor agomelatine at any dose have shown no antioxidant effects on parameters of oxidative stress produced by PTX- or PTZ-induced seizure models when compared to controls. Our results suggest that agomelatine has antioxidant activity as shown in strychnine- or pilocarpine-induced seizure models.     

3-Alkyl-2-phenylbenzo[b]thiophenes: nonsteroidal estrogen antagonists with mammary tumor inhibiting activity.

A number of 2-(4-hydroxyphenyl)benzo[b]thiophenes with a hydroxy group in position 5 or 6 and a short alkyl group at C-3 were synthesized and studied for their estrogen receptor affinities. Relative binding affinities (RBA) for the calf uterine estrogen receptor ranged from 3 to 60 (17β-estradiol = 100). The highest RBA values were found with ethyl derivatives [3 (5-OH): 60; 7 (6-OH): 28]. In accord with their receptor affinity, all benzothiophenes exhibited endocrine activity in the immature mouse uterine weight test. At doses of 0.25–7.0 mg/kg body weight, they showed partial estrogen antagonism and usually weak estrogenic effects. All compounds entered tests with hormone-sensitive human MCF-7 breast cancer cells. At concentrations of 1μM and higher, most of the derivatives displayed significant inhibition of cell growth. These results prompted us to test them in vivo for cytostatic activity using hormone-dependent MXT mouse mammary tumors. The 5-hydroxy derivatives 3 and 4 strongly inhibited the growth of these tumors. After 4 weeks of treatment with 3 × 4.2 mg/kg of compound 3, the average tumor weight was reduced by 83% vs control (tamoxifen at equimolar dose: 74%). The 6-hydroxy derivative 7 required higher doses (25 mg/kg) to give rise to the same effect. At the end of therapy, no increase of uterine weight due to an estrogenic effect was observed. We assume therefore that the antineoplastic activity of these compounds in this tumor model is due mainly to their estrogen antagonism.     

Toxicity of pure alkaloid of Tylophora asthamatica in male rat

Administration of pure alkaloid of T. asthamatica, suspended in peanut oil and given in single doses (12-100 mg/kg) by gavage, to male rats caused inactivity, respiratory distress, salivation, nasal discharge and diarrhoea. The oral LD50 value of the alkaloid was 35.32 mg/kg. In short term toxicity study daily doses of the alkaloid (1.25, 2.5, 5 and 10 mg/kg) were given to male rats for 15 days. Smaller doses of the alkaloid (1.25 and 2.5 mg/kg/day) produced no signs of poisoning or death in animals; while 5 mg/kg/day produced signs of poisoning and death of two animals, 10 mg/kg/day caused death of all the animals within 7 days. Activities of glutamic oxaloacetic transaminase, glutamic pyruvic transaminase and alkaline phosphatase were significant and associated with morphological changes in liver. The alkaloid also caused marked changes in the morphology of seminiferous tubules and spermatogenic activity of experimental animals. Since the alkaloid is effective in microgram quantities, the non toxic effects observed after daily doses of 1.25 mg/kg in male rats assume great therapeutic significance.     

Methanolic extract of Cuminum cyminum inhibits ovariectomy-induced bone loss in rats

Several animal and clinical studies have shown that phytoestrogens, plant-derived estrogenic compounds, can be useful in treating postmenopausal osteoporosis. Phytoestrogens and phytoestrogen-containing plants are currently under active investigation for their role in estrogen-related disorders. The present study deals with anti-osteoporotic evaluation of phytoestrogen-rich plant Cuminum cyminum, commonly known as cumin. Adult Sprague-Dawley rats were bilaterally ovariectomized (OVX) and randomly assigned to 3 groups (10 rats/group). Additional 10 animals were sham operated. OVX and sham control groups were orally administered with vehicle while the other two OVX groups were administered 0.15 mg/kg estradiol and 1 g/kg of methanolic extract of Cuminum cyminum fruits (MCC) in two divided doses for 10 weeks. At the end of the study blood, bones and uteri of the animals were collected. Serum was evaluated for calcium, phosphorus, alkaline phosphatase and tartarate resistant acid phosphatase. Bone density, ash density, mineral content and mechanical strength of bones were evaluated. Scanning electron microscopic (SEM) analysis of bones (tibia) was performed. Results were analyzed using ANOVA and Tukeys multiple comparison test. MCC (1 g/kg, p.o.) significantly reduced urinary calcium excretion and significantly increased calcium content and mechanical strength of bones in comparison to OVX control. It showed greater bone and ash densities and improved microarchitecture of bones in SEM analysis. Unlike estradiol it did not affect body weight gain and weight of atrophic uterus in OVX animals. MCC prevented ovariectomy-induced bone loss in rats with no anabolic effect on atrophic uterus. The osteoprotective effect was comparable with estradiol.     

The nNOS inhibitor,AR-R17477AR,prevents the loss of NF68 immunoreactivity induced by methamphetamine in the mouse striatum

The present study examined the time-course and regionally-selective changes in the levels of the neurofilament protein NF68 in the mouse brain induced by methamphetamine (METH). The ability of low ambient temperature, or of the specific neuronal nitric oxide synthase (nNOS) inhibitor AR-R17477AR, to protect against both long-term striatal NF68 and dopamine loss induced by METH (3 mg/kg, i.p.) was also studied. Seven days after METH administration (3, 6 and 9 mg/kg, i.p., three times at 3 h intervals), mice showed a reduction of about 40% in immunoreactivity for NF68 in the striatum. This effect was not produced in cortex after METH administration at the dose of 3 mg/kg. No difference from controls was observed when measurements were carried out 1 h and 24 h after the last METH injection at the dose of 3 mg/kg. The loss of NF68 immunoreactivity seems to be associated with the long-term dopamine depletion induced by METH, since no change in serotonin concentration is observed in either the striatum or cortex 7 days after dosing. Animals kept at a room temperature of 4 degrees C showed a loss of NF68 similar to those treated at 22 degrees C but an attenuation of dopamine depletion in the striatum. Pre-treatment with AR-R17477AR (5 mg/kg, s.c.) 30 min before each of the three METH (3 mg/kg, i.p.) injections provided complete protection against METH-induced loss of NF68 immunoreactivity and attenuated the decrease in striatal dopamine and HVA concentrations by about 50%. These data indicate that both the reduction of NF68 immunoreactivity and the loss of dopamine concentration are due to an oxidative stress process mediated by reactive nitrogen species, and are not due to changes in body temperature.     

Favorable combination effects of the leukotriene synthesis inhibitor BAY X 1005 and dexamethasone on edema formation in the arachidonic acid-induced mouse ear inflammation test

The effects of a combination of the leukotriene synthesis inhibitor (LSI) BAY X 1005 with the glucocorticosteroid dexamethasone were studied in the arachidonic acid (AA)-induced mouse ear inflammation test (AA-MEIT). We have determined the dose-dependent effects of dexamethasone to reduce edema formation when a combination of 25 mg/kg BAY X 1005 and increasing dosages of dexamethasone was administered orally (p.o.). The inhibition of ear thicknesses increases with the combination therapy were compared with the inhibition observed when both compounds were applied alone.The edema inhibition at the fixed oral dose of 25 mg/kg p.o. BAY X 1005 was 57±2%. Dexamethasone alone dose-dependently inhibited edema formation with a flat inhibition curve at dosages ranging from 0.008 mg/kg (11±13%) to 0.5 mg/kg (65±11%). In combination with BAY X 1005, the corresponding inhibition curve for dexamethasone was shifted upward starting from 56±13% at 0.008 mg/kg. At the two highest dexamethasone dosages (0.125 mg/kg and 0.5 mg/kg) an identical inhibition (86±10%) was observed indicating a plateauing of the antiedematous effect of this combination. The results indicate that at suitable dosages (0.031 mg/kg and 0.125 mg/kg) the effects of BAY X 1005 and dexamethasone were additive.To further corroborate the combination effects of BAY X 1005 and dexamethasone the 5-HT receptor antagonist methysergide and the H1 receptor antagonist pyrilamine were employed as a pretreatment to eliminate mouse-specific inflammation responses. In the methysergide/pyrilamine (12.5 mg/kg s.c. each)-conditioned AA-MEIT model 85±3% edema reduction were observed with BAY X 1005 and 74±3% with dexamethasone. The combination of 25 mg/kg BAY X 1005 and 0.5 mg/kg dexamethasone was slightly more effective in the conditioned AA-MEIT (90±3%) than either compound alone.Our results demonstrate that the LSI BAY X 1005 interacted favorably with the glucocorticosteroid dexamethasone suggesting a potentially useful new combination strategy to treat acute inflammatory disease conditions. This effect can be explained on the basis of the mechanisms of action of both therapeutic principles.     

3-Alkyl-2-phenylbenzo[b]thiophenes: Nonsteroidal estrogen antagonists with mammary tumor inhibiting activity

A number of 2-(4-hydroxyphenyl)benzo[b]thiophenes with a hydroxy group in position 5 or 6 and a short alkyl group at C-3 were synthesized and studied for their estrogen receptor affinities. Relative binding affinities (RBA) for the calf uterine estrogen receptor ranged from 3 to 60 (17β-estradiol = 100). The highest RBA values were found with ethyl derivatives [3 (5-OH): 60; 7 (6-OH): 28]. In accord with their receptor affinity, all benzothiophenes exhibited endocrine activity in the immature mouse uterine weight test. At doses of 0.25–7.0 mg/kg body weight, they showed partial estrogen antagonism and usually weak estrogenic effects. All compounds entered tests with hormone-sensitive human MCF-7 breast cancer cells. At concentrations of 1μM and higher, most of the derivatives displayed significant inhibition of cell growth. These results prompted us to test them in vivo for cytostatic activity using hormone-dependent MXT mouse mammary tumors. The 5-hydroxy derivatives 3 and 4 strongly inhibited the growth of these tumors. After 4 weeks of treatment with 3 × 4.2 mg/kg of compound 3, the average tumor weight was reduced by 83% vs control (tamoxifen at equimolar dose: 74%). The 6-hydroxy derivative 7 required higher doses (25 mg/kg) to give rise to the same effect. At the end of therapy, no increase of uterine weight due to an estrogenic effect was observed. We assume therefore that the antineoplastic activity of these compounds in this tumor model is due mainly to their estrogen antagonism.     

Intrinsic estrogenicity of some progestagenic drugs.

The intrinsic estrogenic activity of some progestins cannot be properly evaluated by using hormone responsive systems when the chosen end-points are also sensitive to progestagenic activity, usually antagonistic of estrogenic actions. We have therefore applied to the evaluation of some drugs commonly used in contraceptive and hormone replacement formulations a recently developed in vitro method to estimate estrogenic activities, which is based on measurements of the estrogen-stimulated alkaline phosphatase activity in cells of the Ishikawa-Var I human endometrial adenocarcinoma line, a response not influenced by progestins. Whereas progesterone, medroxyprogesterone acetate and danazol were found to be devoid of estrogenic activity in this assay, Org OD-14, norethynodrel, gestrinone (R 2323), norethindrone and dl-norgestrel provoked half maximal increases in alkaline phosphatase activity at concentrations (EC-50) of 7, 14, 140, 200 and 2900 nM, respectively, under conditions in which the corresponding value for estradiol was 8 pM. This intrinsic estrogenic activity can be inhibited by antiestrogens, as verified by reversing the effect of R 2323 with 4-hydroxytamoxifen. Since prostaglandin F2 alpha output by secretory endometrium is increased by estrogens and diminished by progestins, this end-point can serve to evaluate the net effect of drugs with intrinsic estrogenic and progestagenic activities. For instance, R 2323 showed estrogenic activity in this assay whereas Org OD-14 did not. The same in vitro system can be used to evaluate estrogen antagonistic activities of test compounds, using estradiol as the agonist. These in vitro systems are useful in establishing a profile of activities of a drug on a relevant human target tissue, in the screening of synthetic or natural compounds under investigation, and in studies on structure/action relationships.     

Food-associated estrogenic compounds induce estrogen receptor-mediated luciferase gene expression in transgenic male mice

The present paper aims at clarifying to what extent seven food-associated compounds, shown before to be estrogenic in vitro, can induce estrogenic effects in male mice with an estrogen receptor (ER)-mediated luciferase (luc) reporter gene system. The luc induction was determined in different tissues 8h after dosing the ER-luc male mice intraperitoneally (IP) or 14h after oral dosing. Estradiol-propionate (EP) was used as a positive control at 0.3 and 1mg/kg bodyweight (bw), DMSO as solvent control. The food-associated estrogenic compounds tested at non-toxic doses were bisphenol A (BPA) and nonylphenol (NP) (both at 10 and 50mg/kgbw), dichlorodiphenyldichloroethylene (p,p'-DDE; at 5 and 25mg/kgbw), quercetin (at 1.66 and 16.6mg/kgbw), di-isoheptyl phthalate (DIHP), di-(2-ethylhexyl) phthalate (DEHP) and di-(2-ethylhexyl) adipate (DEHA) all at 30 and 100mg/kgbw. In general IP dosing resulted in higher luc inductions than oral dosing. EP induced luc activity in the liver in a statistically significant dose-related way with the highest induction of all compounds tested which was 20,000 times higher than the induction by the DMSO-control. NP, DDE, DEHA and DIHP did not induce luc activity in any of the tissues tested. BPA induced luc in the liver up to 420 times via both exposure routes. BPA, DEHP and quercetin induced luc activity in the liver after oral exposure. BPA (50mg/kgbw IP) also induced luc activity in the testis, kidneys and tibia. The current study reveals that biomarker-responses in ER-luc male mice occur after a single oral exposure to food-associated estrogenic model compounds at exposure levels 10 to 10(4) times higher than the established TDI's for some of these compounds. Given the facts that (i) the present study did not include chronic exposure and that (ii) simultaneous exposure to multiple estrogenic compounds may be a realistic exposure scenario, it remains to be seen whether this margin is sufficiently high.     

Amelioration of beryllium induced alterations in hepatorenal biochemistry and ultramorphology by co-administration of tiferron and adjuvants

Influence of adjuvants i.e., α-tocopherol (25 mg/kg, p.o.) and piperine (10 mg/kg, p.o.) on therapeutic potential of chelator tiferron (300 mg/kg, i.p.) was evaluated to encounter toxicogenic events of beryllium exposure. Albino rats were exposed to beryllium nitrate (1 mg/kg, i.p.) daily for 28 days followed by treatment of aforesaid therapeutic agents for 5 consecutive days. Results were considered to be significant at p ≤0.01 and p ≤0.05. Exposure to beryllium increased its concentration in liver, kidney and serum causing significant alterations in the activity of CYP-450 2E1 system, microsomal lipid peroxidation and protein; alkaline phosphtase, lactate dehydrogenase, γ-glutamyl transpeptidase, bilirubin, creatinine and urea in serum; activity of acid phosphatase, alkaline phosphatase, adenosine triphosphatase, glucose-6-phosphatase and succinic dehydrogenase in liver and kidney. Beryllium exposure also induced severe alterations in histopathology and ultramorphology of liver and kidney proving its toxic consequences at cellular level. Tiferron along with adjuvants dramatically reversed alterations of all variables more towards control rather than individual treatment. Study concluded that tiferron in combination with α-tocopherol and piperine respectively was beneficial in diluting beryllium induced systemic toxicity; however, combination of tiferron and piperine presented more pronounced therapeutic potential.     

Cytochemical alterations of adrenals in lead-treated rats

Cytochemical investigations of steroid 3 beta-delta 5-OHD, sudanophilic substances, adenosine triphosphatase (ATPase), and adenosine monophosphatase (AMPase) activities in the adrenal of male young rats that had received lead acetate daily at dosages of 1 mg, 2 mg, 4 mg and 6 mg/kg intraperitoneally for 30 days revealed that lead treatment with low dosages (1 mg and 2 mg/kg) accelerated both cortical and medullary functions. Treatment with high dosages (4 mg and 6 mg/kg), however, inhibited the function of adrenals in both regions. Histochemical studies showed that the alteration in enzymatic activities in cortical and medullary regions revealed the possible mechanism of action of lead on the adrenals.     

Antiestrogenic and antitumor properties of the new triphenylethylene derivative toremifene in the rat

The effects of toremifene, a new triphenylethylene derivative, on the uterus and DMBA-induced mammary tumors in rats were compared to tamoxifen. The ability of toremifene to compete with [3H]estradiol for cytoplasmic estrogen receptor from rat uterus was similar to tamoxifen, the IC50 being 26 and 23 microM respectively. In immature intact rats the two compounds, administered orally for three consecutive days, had similar intrinsic partial estrogenic efficacy, at 50 mg/kg, about 40% of that of estradiol benzoate (EB). However, at doses less than or equal to 10 mg/kg, the estrogenic effect of toremifene was seen at doses about 40 times higher than that of tamoxifen. The two compounds, administered together with a standard dose of EB, expressed the same maximal antiestrogenic efficacy (about 65% inhibition) at 50 mg/kg. However, the minimal effective antiestrogenic dose of toremifene was about 10 times that of tamoxifen and the ratio between antiestrogenic/estrogenic properties was favourable to toremifene. The duration of the antiestrogenic (antiuterotrophic) effect of a single oral dose (10 mg/kg) of the two compounds proved similar: at least 4 days in intact rats and 3 days in ovariectomized rats. In DMBA-induced tumor bearing rats toremifene was administered p.o., 6 times/week for 4 weeks at 0.08, 0.4, 2, 10 and 50 mg/kg. It was effective at the doses of 2, 10 and 50 mg/kg, inducing 39, 35 and 46% tumor regressions. The activity of toremifene at the minimal effective dose of 2 mg/kg was then compared with that of tamoxifen given at the same dose level. The compounds had comparable activity (47 vs 44% tumor regressions).     

Hepatoprotective effect of bis(4‐methylbenzoyl) diselenide against CCl4‐induced oxidative damage in mice

From a pharmacological point of view, organoseleniums are compounds with important and interesting antioxidant and biological activities. The aim of this study was to evaluate the hepatoprotective effect of bis(4‐methylbenzoyl) diselenide (BMD) against carbon tetrachloride (CCl₄)–induced oxidative damage in mice. The animals received BMD (25 mg/kg p.o., for 3 days), and after 1 day, CCl₄ (1 mg/kg body weight) was administered by intraperitoneal route. One day after the CCl₄ exposure, the animals were euthanized for biochemical and histological analysis. Treatment with BMD (25 mg/kg p.o.) protected against aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma‐glutamyl transferase and lactate dehydrogenase activity increases induced by CCl₄ plasma exposure. Treatment with BMD (25 mg/kg) protected against increases in thiobarbituric reactive species and decreasing non‐protein thiols and ascorbic acid levels in liver of mice. Catalase and superoxide dismutase activity inhibition in the liver caused by CCl₄ were protected by treatment with BMD (25 mg/kg). Glutathione S‐transferase activity was inhibited by CCl₄ and remained unaltered even after treatment with BMD. Sections of liver from CCl₄‐exposed mice presented an intense infiltration of inflammatory cells and loss of the cellular architecture. BMD (25 mg/kg) attenuated CCl₄‐induced hepatic histological alterations. The results demonstrated the hepatoprotective effects of BMD in the mouse liver, possibly by modulating the antioxidant status. Copyright © 2012 John Wiley & Sons, Ltd.     

Estrogenic activity of zearalenone and zearalanol in the neonatal rat uterus

Fusarium sp. contaminated feedstuffs elicit adverse estrogenic effects in several commercially important animal species via the mycotoxin zearalenone. An estrogenically active synthetic derivative, zearalanol, is used as an anabolic agent in cattle. Since estrogens can irreversibly alter target tissue development, we investigated the estrogenic activity of these compounds in the neonatal rat uterus. Both induced dose-dependent premature uterine growth when injected daily on postnatal days 1-5 (ED50 = 1.3 mg/kg BW). Nuclear estrogen receptor levels dramatically increased 1 hour after either a single injection on day 5 or after five daily injections. In 5-day-old animals, the translocated nuclear receptor was characterized as a single class of binding sites with a dissociation constant (KD) for estradiol (E2) of 1 nM. At 15 days, zearalanol-treated animals showed greater uterine nuclear receptor retention than zearalenone-treated animals. In 5-day-old animals, single mycotoxin doses induced five fold elevations of ornithine decarboxylase (ODC) at 6 hours. Unlike the growth response, ODC dose-response studies showed zearalanol to be about 20-fold more effective than zearalenone. Time course studies revealed that a low dose of zearalenone, but not of zearalanol, resulted in a shift in peak activity from 6 to 8 hours. These data suggest that metabolism of zearalenone may be important in short-term pharmacodynamics. In a competitive binding assay, neither compound competed [3H]E2 from the E2 binding site on alpha-fetoprotein. We conclude that the uterine growth response and ODC induction demonstrate the neonatal estrogenic action of these mycotoxins, apparently mediated via the estrogen receptor. The greater effectiveness of zearalanol in inducing ODC may be related to nuclear retention and/or zearalenone metabolism.     

Effects of 2,2'4,4'5,5'-hexachlorobiphenyl (PCB 153) on plasma sex steroids and vitellogenin in rockfish (Sebastes schlegeli)

We examined the estrogenic effect of 2,2'4,4'5,5'-hexachlorobiphenyl (PCB 153) on the rockfish, Sebastes schlegeli. We measured levels of plasma estradiol-17beta (E(2)) and testosterone (T) by radioimmunoassay (RIA). Plasma concentrations of T and 17alpha-hydroxyprogesterone in female and male fish injected with PCB 153 using two dosages (0.16 mg/kg body weight. and 0.57 mg/kg) did not differ significantly between sexes or from sham-injected controls of the same sex. Plasma concentrations of E(2) in females injected with PCB 153 (both levels) increased at 12 and 24 h. Concentrations of plasma vitellogenin (VTG) in females increased 72 h after injection with PCB 153 and reached 0.38 and 1.25 mg/mL, respectively. No VTG was detected in males injected with the same dosage. These results suggest that PCB 153 may lead to the production VTG in female rockfish through a synergistic effect with E(2), resulting in indirect disruption of the aromatization process.