Inducing effect of testosterone on the hepatic reduction of zearalenone in the female prepubertal rat

The prepubertal responsiveness of 3α-hydroxysteroid dehydrogenase and zeara-lenone-reducing activity to either a large subcutaneous dose of testosterone or dietary zearalenone was investigated in female rats. Testosterone induced both the activity of the 3α-hydroxysteroid dehydrogenase, with androsterone as substrate, and zearalenone reduction to α- and (β-zearalenol. Zearalenone had no effect on the activity of 3α-hydroxysteroid dehydrogenase, but had a slight inducing effect on the zearalenone reduction to β-zearalenol. Both testosterone and zearalenone had a growth-promoting effect on uterus.     

Determination of the kinetic constants of inhibited acetyl cholinesterase

A method for the determination of kinetic constants of inhibited acetylcholinesterase, in the presence of substrate, is proposed. Theoretical, experimental and data treatment aspects are described for a suitable analysis of inhibitors acting with one or two steps. Limitations of other methods recently reported are pointed out.     

Estrogenic effects of zearalenone on the expression of progestin receptors and sexual behavior in female rats

Zearalenone is a resorcylic acid lactone compound that is produced by fungal infection of edible grains and is believed to influence reproduction by binding to estrogen receptors. In order to study the potential estrogenic effects of this compound in the brain, we examined the effects of zearalenone on the expression of neuronal progestin receptors and feminine sexual behavior in female rats. Ovariectomized rats were treated with zearalenone (0.2, 1.0, or 2.0 mg), estradiol benzoate, or vehicle daily for 3 days. They were then either perfused, and progestin receptors visualized by immunocytochemistry, or injected with progesterone and tested for sexual receptivity with male rats. Progestin receptor-containing cells were counted in the medial preoptic area and ventromedial hypothalamus. The two highest doses of zearalenone increased the concentration of neuronal progestin receptors, as did 10 microg of estradiol. The highest dose of zearalenone (2 mg) also induced progestin receptor staining density comparable to that of 10 microg of estradiol benzoate. In behavioral tests, ovariectomized animals treated with 2 mg of zearalenone followed by progesterone showed levels of sexual receptivity comparable to females treated daily with estradiol benzoate (2 microg) followed by progesterone. These studies suggest that, although structurally distinct and less potent than estradiol, zearalenone can act as an estrogen agonist in the rat brain.     

Distribution of acetyl cholinesterase in the hippocampal region of the guinea pig

Summary 1. The distribution of acetyl cholinesterase (AChE) has been described in the dentate area, a part of the hippocampal region, in the adult guinea pig. The enzyme was demonstrated histochemically with a modification of the Koelle thiocholine method applied to formaldehyde-fixed frozen sections and unfixed cryostat sections. Non-specific cholinesterase was suppressed by ethopropazine, while the staining reaction for AChE was controlled by complete specific inhibition with BW 284c51. A single brain was stained according to the method of Karnovsky and Roots.2. The abundant AChE found in the dentate area exhibited a distinctly stratified distribution pattern. In the molecular layer, strong reaction was present in the outer third and immediately above the granular cell layer, the intermediate zone being light. The granular cell bodies were unstained. In the hilus, five layers showing alternating stronger and weaker reaction for AChE were recognizable.3. In view of the opinions of Cajal, Lorente de Nó, and Blackstad criteria for the definition of the dentate area are discussed. The present results fit into a concept of a layered guinea pig hilus representative of one group of mammals (other members being rabbit, monkey, and man) differing morphologically from the non-layered hilus of rat and mouse. The distribution of metal in the guinea pig hilus supports the concept.4. Possible structural correlates to the AChE are considered and a comparison with the distribution of AChE in the rat, reported earlier, has been made. In the molecular layer, the most striking difference was the heavy activity observed in the outer third in the guinea pig, where the content is moderate in the rat. The granular cell layer appeared virtually identical in both species. In the hilus the stratified pattern in the guinea pig, contrasting with the more diffuse distribution in the rat, essentially reflects the differing structural architectonics in the hilus of the two species.I am indebted to Mrs. L. Knudsen, Mr. A. Meier, Mr. Th. Nielsen, Mrs. K. Sørensen, Miss M. Sørensen, and Miss B. Ørum for skillful technical assistance.This study was supported in part by U.S.P.H.S. Grant NS 07998.     

Effect of zearalenone on female White Leghorn chickens

Acute toxic effects of purified zearalenone were studied in growing female White Leghorn chickens. In the first experiment, zearalenone in gelatin capsules was administered to 10 chickens (zearalenone-treated chickens [ZC]) in a single oral dose of 15.0 g/kg. Another 10 control chickens (CC) received empty gelatin capsules. All chickens survived the 10-day experiment and did not show any noticeable gross or histopathological lesions. There were no differences between CC and ZC in weight gain, oviduct, comb and liver weights, hematological parameters, and serum cholesterol. ZC had significantly less (P less than 0.05) serum calcium but significantly greater (P less than 0.01) serum phosphorus than CC. In the second experiment, zearalenone was administered orally or intramuscularly (pectoral muscle) at levels of 0, 50, 200, 400, and 800 mg/kg for 7 consecutive days. The oviduct weight increased with increasing toxin levels in both orally (OZC) and intramuscularly (IZC) administered groups: there were more pronounced effects in the IZC. The liver weight increased and comb weight decreased in IZC. The relative estrogenic biopotency of zearalenone in IZC, using estradiol dipropionate as a standard, was 1.37%. The results of this experiment demonstrate that chickens are highly tolerant to zearalenone and that the estrogenic effects of the toxin are greater when it is administered in multiple doses than in a single dose and in IZC than in OZC.     

Additional acetyl cholinesterase inhibitory property of diaryl pyrazoline derivatives

MAO-B and AChE are the two validated targets for Alzheimer’s disease. In pursuit of a single molecule hitting both the targets, we explored a set of previously reported extremely potent MAO-B selective inhibitors, for their additional AChE inhibitory activity. We performed molecular docking studies that formed the basis for in vitro enzyme assay, and provided necessary insights into their binding mode. Most of the compounds were found active at nano molar range, and are consistent with the docking results. The identified dual acting lead molecules may provide the basis for further exploring these chemical moieties.     

Effect of zearalenone on female White Leghorn chickens.

Acute toxic effects of purified zearalenone were studied in growing female White Leghorn chickens. In the first experiment, zearalenone in gelatin capsules was administered to 10 chickens (zearalenone-treated chickens [ZC]) in a single oral dose of 15.0 g/kg. Another 10 control chickens (CC) received empty gelatin capsules. All chickens survived the 10-day experiment and did not show any noticeable gross or histopathological lesions. There were no differences between CC and ZC in weight gain, oviduct, comb and liver weights, hematological parameters, and serum cholesterol. ZC had significantly less (P less than 0.05) serum calcium but significantly greater (P less than 0.01) serum phosphorus than CC. In the second experiment, zearalenone was administered orally or intramuscularly (pectoral muscle) at levels of 0, 50, 200, 400, and 800 mg/kg for 7 consecutive days. The oviduct weight increased with increasing toxin levels in both orally (OZC) and intramuscularly (IZC) administered groups: there were more pronounced effects in the IZC. The liver weight increased and comb weight decreased in IZC. The relative estrogenic biopotency of zearalenone in IZC, using estradiol dipropionate as a standard, was 1.37%. The results of this experiment demonstrate that chickens are highly tolerant to zearalenone and that the estrogenic effects of the toxin are greater when it is administered in multiple doses than in a single dose and in IZC than in OZC.     

The effect of experimental exposure to low doses of zearalenone on uterine histology and morphometry in prepubertal bitches

The experiment involved 30 clinically healthy prepubertal bitches aged approximately 70 days with an estimated initial body weight (BW) of 8 kg. The animals were randomly divided into two experimental groups (EI and EII) and a control group of 10 animals each. Group EI was administered 50 μg zearalenone (ZEN)/kg BW per os for 42 days, group EII received 75 μg zearalenone/kg BW per os for 42 days, and the control group was administered placebo per os for 42 days. The bitches were hysterectomized at the end of treatment, and samples of uterine tissue were collected for histological and morphometric analyses. The results of the study indicate that exposure to very low doses of ZEN (100% and 150% of the NOAEL) causes simple glandular hyperplasia of the endometrium accompanied by adenogenesis, angiogenesis, and vasodilatation with the related consequences. The noted changes were more pronounced in group EI and less visible in group EII in comparison with group C, which could be indicative of a hormetic dose response.     

Effect of the fungal toxin (zearalenone) on the reproductive system and fertility of male and female rats.

The fertility-inhibiting effects of long-term (8 weeks) consumption of maize infected with a fungus producing F2 toxin (zearalenone) was studied in adult male and female albino rats. The fertility rate was further decreased by 25-30% if the animals were kept on contaminated diet up to 14 weeks. The gonadal weight was decreased, follicular maturation and spermatogenesis were disturbed. The toxic diet consumed by mothers during pregnancy and lactation induced permanent changes in reproductive organs, disorders in vaginal cyclicity and disturbed fertility in the offspring. Neonatal administration of purified F2 toxin provoked similar changes. It is suggested that this fungal toxin may cause sterility syndrome in the offspring, similar to that produced by androgen or estrogen administration.     

Reactivation of immobilized acetyl cholinesterase in an amperometric biosensor for organophosphorus pesticide

Biosensors based on acetyl cholinesterase (AChE) inhibition have been known for monitoring of pesticides in food and water samples. However, strong inhibition of the enzyme is a major drawback in practical application of the biosensor which can be overcome by reactivation of the enzyme for repeated use. In the present study, enzyme reactivation by oximes was explored for this purpose. Two oximes viz., 1,1'-trimethylene bis 4-formylpyridinium bromide dioxime (TMB-4) and pyridine 2-aldoxime methiodide (2-PAM) were compared for the reactivation of the immobilized AChE. TMB-4 was found to be a more efficient reactivator under repeated use, retaining more than 60% of initial activity after 11 reuses, whereas in the case of 2-PAM, the activity retention dropped to less than 50% after only 6 reuses. Investigations also showed that reactivation must be effected within 10 min after each analysis to eliminate the ageing effect, which reduces the efficiency of reactivation.     

芹菜素对雌性大鼠生殖轴的影响

目的：探讨芹菜素在10-9mol/L浓度时对雌性大鼠生殖功能的影响。方法：应用侧脑室注射方法观察芹菜素对雌性大鼠生殖轴激素含量的影响。在侧脑室注射后第3天取血浆,采用放免技术测定血浆中促性腺激素释放激素（GnRH）、卵泡刺激素（FSH）、黄体生成素（LH）、雌二醇（E2）、孕酮（P）的含量。结果：在给药后第3天血浆中促性腺激素释放激素（GnRH）、卵泡刺激素（FSH）、黄体生成素（LH）的含量增加而雌二醇（E2）、孕酮（P）的含量降低,差异有显著性。结论：芹菜素抑制雌二醇（E2）合成中芳香化酶的活性实现对雌二醇（E2）、孕酮（P）分泌的抑制。芹菜素通过影响雌激素受体而使下丘脑的促性腺激素释放激素（GnRH）和腺垂体的卵泡刺激素（FSH）、黄体生成素（LH）分泌增加。     

Lack of effect of melatonin on sexual maturation in female rats

Daily subcutaneous injections of 100 micrograms melatonin given to prepubertal female rats housed in 14L:10D or 12L:12D failed to delay puberty as evidenced by the age at which vaginal opening occurred; neither the Sprague-Dawley nor the Wistar strain rats were responsive to melatonin treatment. Reproductive organ weights (ovaries and uteri) at vaginal opening were unaffected by such treatment. Administration of melatonin through the drinking water in doses of 100, 500 or 1000 micrograms/day did not alter the timing of puberty or the reproductive organ weights in rats of the Sprague-Dawley or Long-Evans strains (housed in 12L:12D). Our experimental methods are identical to a previous report and we have no explanation for our failure to reproduce the earlier results.     

Transient effect of single or repeated acute deoxynivalenol and zearalenone dietary challenge on fecal microbiota composition in female finishing pigs

Mycotoxins are a major contaminant of pig feed and have negative effects on health and performance. The present study investigated the impact of single or repeated acute challenges with a diet naturally contaminated with deoxynivalenol (DON) and zearalenone (ZEN) on growth performances of finishing pigs and their fecal microbiota composition. A total of 160 pigs (castrated males and females) in two successive batches were randomly divided into four experimental groups of 40 pigs each. The control group received a control finisher diet from 99 to 154 days of age. Challenged groups were subjected to a 7-day acute challenge by being fed a DON- and ZEN-contaminated diet (3.02 mg DON/kg feed and 0.76 mg ZEN/kg feed) at 113 days (group DC), 134 days (group CD) or both 113 and 134 days (group DD). Microbiota composition was analyzed via 16S rRNA sequencing from fecal samples collected from the 80 females at 99, 119, 140 and 154 days. Challenged pigs (i.e. groups DC, CD and DD) reduced their average daily feed intake by 25% and 27% (P < 0.001) and feed efficiency by 34% and 28% (P < 0.05) during the first and second mycotoxin exposure, respectively. Microbiota composition was affected by mycotoxin exposure (P = 0.07 during the first exposure and P = 0.01 during the second exposure). At the family level, mycotoxin exposure significantly (P < 0.05) decreased the relative abundances of Ruminococcaceae, Streptococcaceae and Veillonellaceae and increased that of Erysipelotrichaceae at both 119 and 140 days of age. After the 7-day DON/ZEN challenge, the relative abundance of 6 to 148 operational taxonomic units (OTUs) differed among the treatment groups. However, none of these OTUs changed in all treatment groups. Using 27 functional pathways, pigs exposed to DON/ZEN challenges could be distinguished from control pigs using sparse partial least squares discriminant analysis, with a 15% misclassification rate. Regarding the functionality of these predictors, two pathways were involved in detoxifying mycotoxins: drug metabolism and xenobiotic metabolism by cytochrome P450. In challenged pigs, microbiota composition returned to the initial state within 3 weeks after the end of a single or repeated DON/ZEN challenge, highlighting the resilience of the gut microbiome. The feeding and growth performances of the pigs during challenge periods were significantly correlated with biological pathways related to health problems and modifications in host metabolism. To conclude, short-term DON/ZEN challenges resulted in transient modifications in the composition and functions of fecal microbiota.