Naslov
STUDIES ON EFFECTS OF ATRAZINE ON PITUITARY - OVARIAN AXIS

Autori
Kniewald, Jasna

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Triazine Research Meeting - Mode of Action / Wetzel, Larry - Greensboro (NC) : Novartis, Greensboro, 1997, 5-6

Skup
Triazine Research Meeting - Mode of Action

Mjesto i datum
Hilton Head Island (SC), Sjedinjene Američke Države; Gruzija, 21.04.1997. - 22.04.1997

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
atrazine; female rat; reproduction; pituitary; ovary

Sažetak
Results presented on Figures 3 to 12 are published, and the details are available in the paper: Šimić, B., Kniewald, J., Kniewald, Z.: Effects of Atrazine on Reproductive Performance in the Rat, Journal of Applied Toxicology 14 (1994) 401-404. Experimental design of the experiments with atrazine influence (120 mg/kg/b.w./7 days/daily oral intubation) and short introduction to the values measured in the experiments (body weight and organ weights of Fo females and males; ovarian cycling, conception rate and litter size; sex of offsprings) are shown in Figures 3 and 4. An applied atrazine dose to both female and male Fisher rats caused statistically significant loss of body weight in both sexes during the period of treatment. After the cessation of treatment the body weight of female rats remained below control body weights at least for 2 weeks. In male rats the difference in body weights narrowed with time and reached control level 5 days after the last dose (Figures 5 and 6). Atrazine caused a significant increase in the relative weights of ovaries, but at the same time the decrease in the relative weights of uterus (Figure 7). The effects of 7-day atrazine treatment on the relative weights of particular organs in male rats are presented in Figure 8. The relative weight of prostate, seminal vesicles and pituitary were consistently increased, with the exception of seminal vesicles on the 1st day after the last treatment. The difference between controls and atrazine-treated rats became more pronounced for prostate on post-treatment day 14 and for pituitary on post-treatment days 14 and 21. Atrazine treatment prolonged the estrus cycle in 19 of the 25 experimental animals (Figure 9). The period in which the vaginal smears were leucocytic and clasiffied as diestrus had started during the treatment and, according to cycling history, lasted for average of 10.5 days. The average period between the cessation of the treatment and the appearance of vaginal pro-estrus was 6.2 days. Regular 4-day cycles followed the first appearence of pro-estrus. The animals treated with paraffin oil (control group) had normal estrus cycles and vaginal pro-estrus was confirmed on expected days. As a result of disturbed ovarian cycling, the rate of successful mating decreased in the first week after treatment when both sexes were exposed or exposed females were mated with an unexposed male. No similar effect was observed when only the males were exposed (Figure 10). Atrazine didn’t influence significantly the litter size or sex ratio of F2 progeny (Figure 11). In Figure 12 the conclusions are summarized in several items. In Figure 13 are summarized the results previously published: Težak, Ž., Šimić, B., Kniewald, J.: Effects of pesticides on oestradiol-receptor complex formation in rat uterus cytosol, Food and Chemical Toxicology 30 (1992) 879-885. Atrazine, both in vitro (0.232-0.696 mmol of atrazine in the medium) and in vivo (30-120 mg atrazine/kg b.w./7 days/daily oral intubation), inhibited the formation of a specific estradiol-receptor complex in the rat uterus cytosol vs. control value.The affinity of binding wasn’t modifed under the atrazine influence and the dissociation constant of the complex (Kd value) was of the same order of magnitude. The inhibition was found to be fully non-competitive. The possible ultrastructural changes in the female rat reproductive organs were tested after atrazine dose 120 mg/kg b.w./10 days/daily i.p. The enclosed Figures 14 and 15 present the protocols for the histochemical study in pituitary, ovary and uterus, and the immunohistochemical study in pituitary for LH and FSH. The immunohistochemical determinations of FSH and LH secreted from the basophilic cells are shown in Figure 16. In atrazine treated female rat FSH is decreased and at the same time LH content is increased. The uterine tube is presented by the transverse section in Figure 17, with the longitudinal muscle outside and circular muscle inside. It is seen also the mucosal folds epithelium equiped with thickness cells. In atrazine treated the epithelium layer is much thinner and the cross section through the uterus is presenting lot of cysts and an irregular shape of the uterine tube. Atrazine involved reduction of estrogen synthesis and as a consequence the epithelium cells are much thinner than in controls at the regular conditions. Figure 18 presents different cycle phases. Before atrazine treatment estrus cycle of rats was present, the development of the ovarian Grafian follicles in the different stages (red arrow shows the degenerating Graff follicle and blue arrow shows the secondary follicle) was found. In atrazine treated ovary we were not able to find any follicle at the developmental stage and the animal has shown permanent diestrus. Figure 19 summarizes the findings of the ultrastructural changes in the female reproductive organs.

Izvorni jezik
Engleski

Znanstvena područja
Prehrambena tehnologija

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