Mechanisms of lipopolysaccharide-induced changes in effects of contractile agonists on pregnant rat myometrium
Section snippets
Administration of LPS
Adult female Wistar rats (150-200 g), obtained from the Laboratory Animal Resource Section, Indian Veterinary Research Institute, Izatnagar, were used in this study as per the Institutional Policy on Animal Use. Pregnancy was confirmed (designated as day 1 of gestation) by the presence of sperms in the vaginal smear. On day 17 of gestation, laparotomy was conducted in all rats under ketamine anesthesia (100 mg/kg body weight intramuscularly). LPS (Escherichia coli serotype 055:B5,
Effect of LPS on spontaneous rhythmic contractions of pregnant rat uterus
Figure 1, A, shows the recording of spontaneous rhythmic contractions of uterine strips, isolated from normal saline solution–treated (control) and LPS-treated pregnant rats, LPS treatment significantly (P<.05) increased the amplitude of spontaneous rhythmic contractions compared with controls, although maximal effects did not differ significantly (Table). LPS, however, had no effect on the frequency of rhythmic contractions (Figure 1, C).
Effect of LPS on uterine contractions induced by oxytocin, 5-HT, carboprost, and BAY K8644
Figure 2, A, depicts the effect of intrauterine
Comment
The most important observations of this study are as follows: (1) intrauterine LPS treatment enhanced spontaneous rhythmic contractions and contractions elicited with oxytocin, 5-HT, and BAY K8644 in isolated uteri obtained from the 19-day pregnant rats, (2) LPS-treatment, however, had no effect on contractions elicited with carboprost, (3) nimesulide failed to attenuate the increased rhythmic contractions induced by LPS; however, it antagonized the increased sensitivity of uterine strips to
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