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The mycotoxin zearalenone is often found in cereals and animal feeds. The intake of zearalenone through food can result in the hyperestrogenic syndrome, and is related to ovarian structural and functional alterations in mammals. It competitively binds to estrogen receptors and generates oxidative stress. Melatonin is a hormone produced by the pineal gland with a strong effect on reproduction as it inhibits the hypothalamic-pituitary-gonadal axis. It has also direct and indirect antioxidative effects in the ovarian tissues. Our aim was to explore the effect of melatonin on the histological changes of the ovary induced by zearalenone. Forty female Wistar rats were divided into five equal groups and treated for 28 days according to the following scheme: 1. Zearalenone vehiculum (sunflower oil)- treated group, 2. Melatonin vehiculum- (5% ethanol in Ringer) treated control group, 3. group treated with zearalenone (0.3 mg/kg b.w), 4. group treated with melatonin (10 mg/kg b.w) and 5. group of rats treated with zearalenone (0.3 mg/kg b.w) and melatonin (10 mg/kg b.w). Zearalenone induced degenerative changes in all developmental forms of ovarian follicles, hypertrophy of stroma with blood vessel dilatation and hyperemia. The concomitant application of melatonin and zearalenone resulted in milder morphological changes of the ovary, especially of preovulative follicles. Melatonin administration prevents the zaeralenone-induced structural alterations on an ovary. Keywords: zearalenone, melatonin, rat, ovary, histology

Research in this study had the character of retrospective study for which we used 24 adult female Wistar rats, who we reared under standardized laboratory conditions and divided into two groups: experimental and control. The experimental group consisted of a total of 12 animals who were classified into 2 subgroups: Z1 and Z2. The control group consisted of 12 untreated animals who were divided into 2 subgroups: K1 and K2. Once a day at regular intervals we applied by the gastric probe mycotoxin zearalenone previously dissolved in sunflower oil. To the animals in the control group we applied sunflower oil only. Dose of toxin administered was 0,5 mg/kg body weight, and a period of observation spanned two different time intervals-14 and 28 days.After completing the application of toxins, the animals were sacrificed under the general ether anesthesia and by the rules of autopsy techniques. Taken ovaries were prepared for histological and stereological analysis.Structural changes in the ovaries of treated animals were observed as degenerative changes, primarily at the level of the ovarian follicles and corpora lutea. The apparent findings in the stroma were in terms of its hipercelularity and marked hyperemia of the blood vessels. The longer the application period, the more pronounced the changes.The resulting qualitative histological changes in the ovaries of treated rats were objectified quantitatively - by stereology. We found changes in terms of decreasing volume density of functional elements of the parenchyma (ovarian follicles and corpora lutea), and increased volume density of ovarian stroma with blood vessels.Key words: zearalenone, rat, ovary, qualitative changes, stereology

Studies in animals have suggested that intraneural application of local anesthetics may cause mechanical injury and pressure ischemia of nerve fascicles. Previous studies, however, have used small animal models and clinically irrelevant injection speed or equipment. Our hypothesis is that an intraneural injection is heralded by higher injection pressure and leads to neurologic impairment in pigs. Ten pigs of mixed breed were studied. After general anesthesia, the sciatic nerves (n = 20) were exposed bilaterally. Under direct vision, a 25-gauge insulated nerve block needle was placed either extraperineurally (n = 10) or subperineurially (n = 10), and 4 ml of preservative-free lidocaine 2% was injected using an automated infusion pump (15 ml / min). Injection pressure data were acquired using an in-line manometer coupled to a computer via an analog-to-digital conversion board. After injection, the animals were awakened and subjected to serial neurologic examinations during the 24 post-intervention hours. All but two perineural injections resulted in injection pressures below 20 psi. In contrast, intraneural injections resulted in significantly higher peak pressures. In 7 (70%) intraneural injections, the injections pressures were over 20 psi (20-50 psi). Neurologic function returned to baseline within 24 hours in all sciatic nerve receiving perineural injections. In contrast, residual neurologic impairment was present in 7 sciatic nerves after intraneural injection; residual neurologic impairment was associated with injection pressures > 20 psi. The results indicate that high injection pressure during intraneural injection may be indicative of intrafascicular injection and may predict the development of neurologic injury.Key words: nerve block, injection pressure, neurologic injury, pigs