The aim of this study was to determine the influence of unilateral, intraovarian infusions of Escherichia coli endotoxin (LPS, lipopolysaccharide, serotyp 055:B5) on the concentration of progesterone (P4), testosterone (T), estradiol-17ß (E2) and luteinizing hormone (LH) in peripheral and ovarian blood plasma of gilts. The morphology of ovaries was also estimated. Fourteen sexually matured gilts with controlled estrous cycle were used. The animals were randomly divided into two groups: I (treated; n=7), and II (control; n=7). In the group I, 2 mg of LPS in 1 ml of saline was infused into the hilus of one ovary from the 15th to the 19lh day of the estrous cycle, twice a day (at 06:00 and 18:00). At the same time, 1 ml of saline was infused into the hilus of the contralateral ovary and into both ovaries of the control gilts (Gr. II). From the 15lh to the 7th day of the next estrous cycle blood samples from the jugular vein were collected with various frequency. Additionally, on the 7th day, during the laparotomy, blood samples from the utero-ovarian vein of each ovary were collected and then both ovaries were dissected out to estimate their morphology. Plasma hormone concentrations were determined by radioimmunoassay (RIA). Macroscopic investigation revealed the presence of cysts in both ovaries after unilateral, intraovarian LPS infusions but the number of cysts in the LPS-treated ovaries was higher (P < 0.05) than that in the contralateral ones. In LPS-infused ovaries, numbers of follicles and corpora lutea were lower (P < 0.05) than those in the contralateral and control ovaries. In LPS-treated gilts, P4 concentrations in peripheral blood was increased (P < 0.05-0.001) as compared to that found in the control group in the period from the 21lh to the 7lh day of the next estrous cycle. After LPS infusions, the level of P4 in blood plasma from the utero-ovarian vein of both ovaries was higher (P < 0.05) than that observed in the control group. Moreover, the concentration of P4 was higher (P < 0.05) in LPS-infused ovary than that found in the contralateral one. During the consecutive days of the study, the T level in peripheral and ovarian blood remained unchanged in both the control and LPS-treated groups. In the gilts receiving LPS, the peripheral level of E2 decreased (P < 0.01-0.001) as compared to that found in the control animals from the 20th to the 7lh day of the next estrous cycle. On the 7lh day, the plasma concentration of E2 in the utero-ovarian vein was lower in LPS-treated gilts (P < 0.05) than that found in the control group. This study revealed that infusions of LPS into the hilus of one ovary in gilts caused morphological changes in both ovaries and deviations from normal plasma hormonal profiles. These disturbances partly depended on the location of LPS infusions. The results obtained suggest that the pathologically changed ovary can affect the pituitary function and steroidogenesis of the contralateral ovary what leads to disturbances in the physiologic rythm of the estrous cycle in females.
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