The paper describes in vitro model for evaluation of natural mineral adsorbents ability to adsorb mycotoxins. Bentonite, diatomite and zeolite were prepared in the Institute for Technology of Nuclear and Other Mineral Raw Materials, Belgrade. A total of six mycotoxins: aflatoxin B1 (AFL), ochratoxin A (OTA), deoxynivalenol (DON), zearalenone (ZON), diacetoxyscirpenol (DAS) and T-2 toxin were tested in vitro. For adsorption experiments crude extracts of mycotoxins, produced in the Department of Microbiology of Bio-ecological Center in Zrenjanin, were used. The ability for binding mycotoxins was evaluated in the electrolyte 0.1 M K2HPO4 which pH value was adjusted to 3.0 and 6.9, respectively. Mass ratio of individual mycotoxin and natural mineral adsorbent was 1:5000. The experimental mixtures were incubated for 1 hour on a rotary shaker (185 rpm) at room temperature (22-25oC). After incubation the extractions of unadsorbed mycotoxins from the filtrates were performed with organic solvents, and their quantifications were done by thin-layer chromatography (TLC). By the use of TLC method it was noted that bentonite, diatomite and zeolite binded more than 95% of applicated AFL. In the case of OTA only diatomite adsorbed that toxin - adsorption index was 66.67%. Binding of DON has been observed only at pH 3.0 of electrolyte. Its adsorption index varied from 25.00 to 50.00% depending on the type of mineral adsorbent. Effect of electrolyte pH value on the binding of ZON was not so expressed. Its adsorption index ranged from 12.20 to 37.00%. In the case of type A trichothecenes (DAS and T-2 toxin) bentonite, diatomite, and zeolite binded only T-2 toxin. The amount of adsorbed T-2 toxin ranged from 16.66 to 33.33%. The obtained results point out the need for activation or processing of natural mineral adsorbens, especially bentonite and zeolite, in order to increase the efficiency of adsorption of the wider spectrum of mycotoxins.

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The participation of adrenocorticotropic hormone (ACTH) in the control of adrenal glands and the regulation of ACTH secretion in female rats exposed to constant light for six weeks were studied. A significant increase of plasma ACTH (p < 0.05) in rats exposed to constant light is in correlation with an increase of epinephrine (E) synthesis in adrenal gland (p < 0.05) when compared to intact controls. On the other hand, ACTH secretion is in inverse relation with a significantly reduced concentration of dopamine (DA) and norepinephrine (NE) in hypothalamus (p < 0.05). In addition, higher concentration of plasma ACTH in rats exposed to constant light through its effect on the adrenal cortex is responsible for the appearance of polycystic ovaries. As a contribution to this assumption is the result showing an increased concentration of serum progesterone in rats exposed to constant light when compared to corresponding controls which is probably of adrenal origin. These results indicate an inverse relationship between plasma ACTH concentrations and DA and NE concentrations in hypothalamus and that the hypothalamo-pituitary-adrenal axis has a significant role in the regulation of ovarian function.

The concentration of catecholamines in the hypothalamus and reproductive organs of rats with hypothalamic lesions placed on the day of birth was investigated. In an attempt to contribute to the discussion concerning the role of catecholamines in regulation of puberty, the aim of this study was to examine the content of hypothalamic, ovarian and uterine catecholamines in female rats with precocious vaginal opening. The animals were sacrificed on the day of precocious puberty, which occurred at the age of 25.71 +/- 0.98 days. The data obtained were compared with intact (pubertal) controls obtained on the day of vaginal opening (40.13 +/- 1.35 days) as well as in infantile intact controls of corresponding age of the lesioned animals. In the ovaries of both animals (i.e. lesioned and sacrificed on day of vaginal opening and the infantile controls of corresponding age), small and medium sized follicles were present. Ruptured follicles were evident only in the pubertal controls. The mass of ovaries and uteri from lesioned rats was also significantly lower than in the pubertal controls. Concentrations of norepinephrine in both ovaries and uteri on the day of vaginal opening of the animals with posterior hypothalamic lesions and of infantile controls, was significantly higher than in pubertal controls on the day of vaginal opening. Epinephrine was significantly higher in the uterine tissues of lesioned and infantile controls as compared to pubertal animals. The levels of dopamine and norepinephrine in the hypothalamus of lesioned and pubertal controls on the day of vaginal opening were significantly higher than in infantile controls.(ABSTRACT TRUNCATED AT 250 WORDS)

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