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  • Author: T Nobunaga x
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The synthesis and release of prolactin in rats were significantly higher at oestrus than at any other stage of the cycle, when measurements were made between 10.00 and 11.00 h (Ieiri, Akikusa & Yamamoto, 1971). Since considerable evidence indicates that stimulation of prolactin release begins on the afternoon of the day of pro-oestrus (Ieiri et al. 1971), synthesis and release were measured in the afternoon of the day of each stage of the oestrous cycle to determine the fluctuations of these parameters in the course of the cycle.

Adult female rats of the Wistar strain showing regular 4-day cycles were used. Animals were killed by decapitation between 16.00 and 17.00 h. Each isolated anterior pituitary was incubated with [14C]leucine. All the experimental conditions were the same as described previously (Ieiri et al. 1971).

The anterior pituitary functions were estimated by counting the radioactivity of [14C]leucine incorporated into prolactin

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T Okada, N Matsuzaki, K Sawai, T Nobunaga, K Shimoya, K Suzuki, N Taniguchi, F Saji, and Y Murata

Chorioamnionitis has been shown to be one of the most important factors in inducing preterm delivery. The present study was undertaken to examine the effects of chorioamnionitis on placental endocrine functions. Preterm placentas with histologic chorioamnionitis produced smaller amounts of human chorionic gonadotropin (hCG) and human placental lactogen (hPL) than those without chorioamnionitis (P < 0.001). To examine the mechanism involved in the suppression of placental endocrine functions induced by chorioamnionitis, we initially confirmed the expression of lipopolysaccharide (LPS) receptor, i.e. the CD14 molecule, on trophoblasts by Northern blot analysis and immunohistochemistry. We then stimulated purified trophoblasts with LPS, which is the major agent which induces inflammatory responses in the host via the LPS receptor. The trophoblasts stimulated with LPS produced reduced amounts of hCG, hPL, and progesterone in a time- and dose-dependent fashion in spite of the induced manganese-superoxide dismutase (SOD) synthesis. Stimulation of trophoblasts with hypoxanthine and xanthine oxidase resulted in suppressed hCG production, while the simultaneous addition of SOD into the culture medium reversed the suppression of hCG production. LPS in the placenta with chorioamnionitis might directly stimulate trophoblasts through the LPS receptor (CD14), thus reducing placental endocrine functions. Superoxide anions which exogenously act on trophoblasts might be generated by simultaneous stimulation of neutrophils and monocytes at the feto-maternal interface by LPS, and additively reduce placental endocrine functions.