INFLAMMATORY RESPONSES DURING PREGNANCY IN THE RAT, AND THE EFFECTS OF SEX HORMONES AND PLACENTAL EXTRACTS ON INFLAMMATORY POTENTIAL1

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Abstract
The weight of the granulomas induced by subcutaneously implanted cotton pellets was much less in pregnant than in nonpregnant rats. Removal of the following organs or combinations of organs did not alter the pregnant-nonpregnant differences: adrenals; pituitary; adrenals and pituitary; adrenals and ovaries; pituitary and ovaries; pituitary and fetuses; adrenals and fetuses. After concomitant extirpation of pituitary, ovaries and gravid uterus the pregnant animals produced granulomas as heavy as those produced by intact or similarly operated nonpregnant rats. Adrenals of intact pregnant rats were no heavier than those of intact nonpregnant rats. Pregnant animals deprived of pituitary and fetuses had atropic adrenals. Placentas of pregnant animals deprived of their fetuses and their pituitaries or adrenals were smaller than those of intact pregnant rats. Progesterone and estrone did not inhibit granuloma growth in intact or adrenalectomized rats. Human placental extracts inhibited granuloma growth in adrenalectomized rats when given subchronically and protected the knee joint against formaldehyde injury when given acutely. Results substantiate the suggestion that the placenta is an extra-adrenal source of the anti-inflammatory substances produced by the pregnant rat.