Publisher Summary

This chapter gives an overview of the different aspects of hormone biosynthesis and transformation. The concentrations of many hormones increase during pregnancy in humans and in different animal species because of additional production by the fetus, the placenta, and the maternal compartments. The contribution by the three compartments is not the same because each of the three chambers utilizes different precursors; biosynthetic pathways are not the same and may change within the same tissue as pregnancy progresses. All three compartments are equally important in hormone formation and that the progress of normal pregnancy depends on the proper functioning of all the three units. A study of the biosynthesis and metabolism of the various polypeptide hormones followed by steroid hormones is done by reviewing these hormones and attempting to locate their sites of origin and action in both the fetus and the placenta. Interestingly, fetal hormonal biosynthetic potential appears early during gestation. The investigation of steroidogenesis indicates that in the fetal compartment, it is regulated by the hypothalamic-pituitary axis.

CONTENTS

INTRODUCTION

The concentrations of many hormones increase during pregnancy in humans and in different animal species, due to additional production by the fetus, the placenta and the maternal compartments. The contribution by the three compartments is not the same because each of the three utilizes different precursors; biosynthetic pathways are not the same and may change within the same tissue as pregnancy progresses. To study the different aspects of hormone biosynthesis and transformation and to determine production rates different techniques are used:

The use of tracer doses administered into the feto-placental unit in situ through the umbilical vein (A) is one of the best tools to study hormone biosynthesis and metabolism in physiological conditions. The other techniques provide information about enzyme selectivity and of hormonal production by each compartment.

Westin et al. (1958) and Nyberg and Westin (1962) were pioneers in the use of the human fetal perfusion technique which was extensively exploited by others in the sixties in cases of patients scheduled for therapeutic abortion. Because of concern for the mother’s well being and moral considerations, methods outlined under A, B, C, and D have rarely been used in recent years. During the sixties Diczfalusy and his co-workers in Stockholm developed a series of techniques shown in Figs 2.1–2.4. The methods include the techniques for perfusion in situ through the umbilical vein in the isolated feto-placental unit or in situ placental perfusions. The group coined the...