Clinical Biochemistry of Domestic Animals (Sixth Edition) - UMK ...

Chapter 21
Clinical Reproductive Endocrinology
Håkan Andersson
1
Department of Integrative Biology
Umea University
Umea, Sweden
I. Introduction
A. De finition of Hormones
B. Chemical Classes of Reproductive Hormones
C. Hormone Receptors
D. Local Conversion of Steroids in Target Tissues
E. Synthesis and Clearance of Hormones
II. Assay Methods
A. Immunoassay
III. Physiology of Reproductive Hormones in the Female
A. Estrus Cycle
B. Control of the Corpus Luteum
C. Early Pregnancy
D. Pregnancy and Parturition
IV. Clinical Aspects of Reproductive Endocrinology
A. Cattle
B. Sheep
C. Pi g
D. Horse
E. Do g
F. Cat
V. General Comments
A. Hormone Concentrations
B. Analysis and Storage Effects
REFERENCES
I . INTRODUCTION
Clinical reproductive endocrinology includes the study
of diseases and secretory status of the endocrine glands
involved in reproduction and their secretory products, the
reproductive hormones. To obtain a satisfactory understanding
of the complex endocrinological events that occur
during normal and abnormal reproductive function, it is
necessary to quantify specific hormones.
Major progress in hormone analytical techniques
occurred as the result of the development of immunoassay
1
Revised and updated by Lars-Erik Edqvist and Mats Forsberg
and related systems. The first of the assays, radioimmunoassay,
was developed in the late 1950s ( Berson and Yalow,
1959 ) with the competitive protein binding assay following
a few years later ( Murphy, 1964 ). Nonradiometric assays
(e.g., enzyme immunoassay) were developed in the 1970s
( Engvall and Perlmann, 1971 ; van Weemen and Schuurs,
1971 ). These assay systems have the characteristics of being
sensitive, specific, relatively inexpensive, and requiring
small amounts of assay material. They have been of special
value for studying endocrinological reproductive function
in domestic animals in that they have made possible the
study of dynamic endocrine changes through the assay of
serial blood samples from the same animal. The immunoassay
systems have also been useful as diagnostic aids for
identifying and elucidating clinical reproductive problems.
In clinical practice, these methods are important from both
a diagnostic and therapy-monitoring point of view.
Because this book deals with clinical biochemistry in
domestic animals, this chapter emphasizes the determination
of hormones and the use of the data as diagnostic aids.
General reproductive endocrinology in domestic species is
broadly covered. Readers specifically interested in this subject
are referred to specialized books dealing with this matter.
A . Definition of Hormones
The best understood humoral control system in the body is
the endocrine system. This system uses specific messengers,
termed hormones , to regulate important body functions. By
the classical definition, hormones are chemical substances
synthesized and secreted by ductless endocrine glands in
minute quantities directly into the blood vascular system
and are transported to a remote target organ where they regulate
the rates of specific biochemical processes. The classic
endocrine glands include the pituitary, thyroid, parathyroid,
adrenal, pancreas, ovary, testis, placenta, and pineal gland.
In the case of reproduction, the pituitary and pineal
glands, the gonads, and the placenta play a primary role
in controlling the system. Other endocrine glands such as
the adrenal and thyroid glands also have some influence
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