Prostaglandin Administration to Pregnant Rats: Effects on Pituitary-Target Gland Systems of Mother,Fetus and Neonate 1

Abstract

Summary and Conclusions

Acute administration of PGE₁ in graded doses (0.25-1.0 mg) to pregnant rats in late gestation (21st day) induced significant release of TSH, prolactin and LH from the maternal pituitary. Plasma levels of PRL and TSH were elevated (three- to fivefold) in cesarean sectioned mothers given 4-5 sc injections of PGEr, higher doses also stimulated LH release. Comparable increases in blood TSH and PRL levels were also found in their newborn but no indication of enhanced hormone release from the fetal hypophysis was noted. Histologic alterations were observed in the ovary (luteal cell hypertrophy, cytoplasmic clearing, nuclear condensation, sinusoidal distension) of mothers receiving PGE₁ treatment. Thyroidal radioiodine accumulation in mother, fetus and neonate were usually decreased whereas thyroid:blood radioactivity ratios were consistently increased.

It is concluded that PGE₁. treatment of the pregnant rat near term stimulates release of hormones from the pituitary in mothers (TSH, LH, PRL) and in their newborn (TSH, PRL). The results also strongly suggest that PGE₁ administration may induce morphologic and functional changes in target endocrines (ovary, thyroid) by direct and separate actions.

The authors wish to express their gratitude to Dr. R. W. Bates, Dr. Albert Parlow, and the NIAMDD for the prolactin and TSH preparations and procedures for performing these RIA assays; to Dr. G. Niswender for the LH method and antiovine LH serum, and to Dr. L. Reichert who supplied the LH reference and iodination preparation.