Table Of ContentA Study of Blood Iodine and Blood Sugar in Relation
to the Diurnal Temperature Cycle of Male
Hybrid Fowl (Gallus domesticus)
Dissertation
Presented in Partial Fulfillment of the Requirement for the
Degree of Doctor of Philosophy in the Graduate School
of The Ohio State University
By
Carl Richard Reese, B.Sc. in Educ., M.A.
The Ohio State University
19$2
Approved b;
Adviser
Table of Contents
Pages
I Introduction 1-2
II Review of the Literature 3-10
Early history of iodine studies
Discovery of thyroid hormone
Physiological importance of thyroxine
The nature of the thyroid hormone in the blood
Criteria which indicate thyroid activity
Nature and distribution of thyroid hormone in
other tissue
Effect of season on thyroid activity
The effect of environmental temperature on thyroid
activity
Regulatory mechanisms of thyroid activity
Experimental feeding of a goitrogenic agent
III Materials and Methods 11-19
Experimental animals
Care and maintenance of laboratory animals
Temperature cycle determination
Fractionation of blood iodine
Blood sugar determination
Determination of reducing substance other than
glucose
Thiouracil 'feeding experiment
Temperature cycle determination of birds used in
thiouracil experiment
Blood sugar determinations at three temperature
levels
Thyroid weight determination
IV Results of Experimentation 20-29
Temperature study
Iodine and sugar determination
Study of iodine determination technic
Determination of fermentable substance in fowl's
blood
A statistical study of normally-fed fowls compared
to thiouracil-fed fowls
Effect of feeding propyl thiouracil on body tem
perature
Effect of propyl thiouracil on inorganic blood
iodine
L
S00473
I
Effect of propyl thiouracil on the protein-bound
blood iodine
Effect of propyl thiouracil on blood sugar
Effect of propyl thiouracil on body weight and
thyroid gland weight
V Discussion 30-37
General statement
Effect of inorganic blood iodine on thyroid
activity
The relation of blood sugar to the temperature
cycle
The effect of propyl thiouracil
The increase of inorganic blood iodine in thiouracil-
fed fowl
The decrease in protein-bound blood iodine in propyl
thiouracil-fed birds
The decrease of blood sugar associated with fat
deposition in propjrl thiouracil-fed birds
VI Summary and Conclusions 37-38
VII Bibliography 39-42
VIII Appendix
Table of Contents 43-44
Figures 45-58
Tables 59-71
IS A c kn owl ed g ernent s 72
X Autobiography 73
li*
Introduction
This study represents an attempt to answer some questions pre
sented by the problem of thyroxine metabolism. In particular it deals
with the relationship of circulating protein-bound blood iodine to the
diurnal temperature cycle of male fowl Gallus domesticus. Because of
the fact that the greatest amount of thyroid research in the past
has been histological in nature, it was felt that this study should
be directed towards a more complete understanding of the biochemistry
and physiology of the glands. In recent years attention has been
focused upon the measurement of minute amounts of iodine in the blood
and other tissues. The use of such microchemical technics has made
it possible to carry out this program of research based on the deter
mination of small fluctuations of blood iodine.
This research is primarily concerned with the following:
(a) the determinatidn of the diurnal body temperature cycle in males
of normal mature domestic fowl;
(b) the making of microchemical determinations of blood iodine and
blood sugar of these fowls at various periods during the day;
(c) a study of the relationships of blood iodine and blood sugar
values of these fowls to the diurnal body temperature cycle;
(d) the modification of the normal physiology of the fowl by means of
a goitrogenic agent;
(e) a comparison of the blood iodine and blood sugar values in the
individuals that were modified by the goitrogenic agent;
(f) a comparison of the body weight and thyroid weight of the normal
fowl with the body weight and thyroid weight of the modified fowl.
..
1
This research was undertaken because of the practical applica
tion of the results to poultry producers in the relationship between
blood iodine and blood sugar values of modified birds, and growth rate
and fattening rate of poultry. It is hoped that, by careful applica
tion of methods and technics worked out on the domestic fowl, further
related research may be undertaken in the field of game bird and
passerine bird physiology and behavior.
The investigation described in this paper was suggested by Dr,
Frank A. Hartman, Department of Physiology, and by Dr. George M.
Curtis, Department of Surgical Research, The Ohio State University.
The practical aspects of the problem such as the use of fowl and their
modification by propyl thiouracil was suggested by Dr. R. G. Jaap,
Department of Poultry Husbandry, The Ohio State University.
Some time was spent in the laboratory of the Department of
Surgical Research, at The Ohio State University, in observing and
practicing iodine fractionation technics. My work in that laboratory
consisted primarily in the determination of inorganic and protein-
bound iodine in the blood of human patients undergoing t^iyroid surgery.
Some time was also spent in observing and practicing cardiac puncture
of fowl at the Veterinary Clinic, The Ohio State University.
Review of the Literature
Since there are, to iry knowledge, no accounts in the literature
of chemical determination of blood iodine concentrations in birds, it
seems advisable that we review some of the literature on the histology
and physiology of the thyroid gland. Such a background is essential
to an understanding of the problems in this report.
Early history of iodine studies. Since the discovery of iodine by
Courtois in 1811 two events stand out in our knowledge of iodine in
relation to physiological processes. First, the discovery of. iodine
in the thyroid gland by Bauman in 1895, and second, the isolation of
crystalline thyroxine by Kendall in 1911u These discoveries in them
selves contributed little to the understanding of physiological proces
ses, but they are important because they have served as an impetus to
painstaking research by many other students who have brought our know
ledge to its present level.
Discovery of the thyroid hormone. Hutchison (1896) and Oswald (1897)
discovered that the iodine present in the thyroid is bound to a
globulin and that this protein is the only one in the gland which
produces a physiological effect on other tissues. This iodothyroglo-
bulin is now considered to be the thyroid hormone. Oswald later found
that practically all the iodine in the thyroid could be extracted
with physiological salt solutions and that nearly all the iodine so
extracted from the colloid was chemically bound and precipitable by
heat coagulation. His method of extraction and purification has been
used with but minor modifications even to the present time.
Physiological importance of thyroxine. Three iodine compounds have
been extracted from thyroid tissue, namely, iodothyroglobulin, diio-
dotryosine, and thyroxine. Kendall (191U) isolated thyroxine from
thyroid tissue. Harrington and Barger (1927) improved Kendall’s
technic of extraction and secured sufficient amount of thyroxine to
determine the empirical and structural formulae. The knowledge of the
nature of the structural formula made it possible for them to show that
thyroxine is a derivative of diiodotryosine and to synthesize it.
Moreover, they were able to prove that the four atoms of iodine in the
thyroxine molecule are important physiologically, because if they are
displaced by hydrogen atoms the compound loses its stimulating action
on metabolism.
The nature of the thyroid hormone in the blood. The form in which
thyroxine is conveyed to the body tissue is a very controversal matter.
It has been fairly well established that thyroxine while still in the
thyroid gland is associated with a protein, and exists in the form of
a thyroglobulin.
Most workers have agreed that thyroglobulin is altered in some
way before or during release from the thyroid into the blood stream.
Taurog and Chaikoff (19U8) and Salter and Johnson (19U8) demonstrated
that the circulating hormone could-be precipitated with the plasma
proteins. The iodine thus precipitated is largely in the form of
thyroxine. Elmer et al. (193U) hydrolized blood plasma with strong
alkali, and by using Leland and Fosterte butanol extracting method
were able to account for I4.O to 60 per cant of the protein-bound iodine
h
as thyroxine. Bassett et al. (19i-il) after enzymatic hydrolysis of
plasma proteins obtained slightly higher values. These percentage
values of thyroxine in the circulating blood are inport ant to this pre
sent research, since only the iodine so bound in the thyroxine molecule
is believed to be physiologically active. Harington and Salter (1930)
have good evidence that circulating thyroxine is bound in peptide
linkage. Biggs et al. (19U2) are of the opinion that thyroxine,
being an amino-acid, is incorporated in the molecule of plasma protein.
Cohn (19ij6) believes that the circulating thyroid hormone is in weak
combination with' the plasma proteins, perhaps by adsorption or weak
covalent bonds.
Criteria which indicate thyroid activity. Hertz and Boberts (19U1)
have found that the stimulus which increases the activity of the
thyroid is produced by a pituitary hormone. The presence of the hor
mone is indicated by the following:
(a) an increase in epithelial components of the thyroid
(hyperplasia) which result in an increased weight of the
gland3
(b) loss of colloid in the follicles;
(c) a decrease in iodine content of the thyroid;
(d) an increase in height of secretory cells and in increase
in total volpme of secretory tissue;
(e) increased organic iodine in the blood;
(f) increased basal metabolic rate.
A lack of the thyrotropic stimulus with a decrease in thyroid activity
is indicated by the opposite conditions.
5
Experimental work of various workers supports the above stated
relationships. Marine (1935) observed that the iodine store of the
thyroid varies inversely with the degree of active hyperplasia. In
extreme degrees of hyperplasia the iodine store of the thyroid is
exhausted. By hyperplasia he refers to the histology of the gland
where one finds high cuboidal epithelial cells, and less colloid.
Marine further observed that when the acini of the thyroid contain much
colloid, the epithelial cells are flattened and the gland is usually
rich in iodine. Stalter (19U0) stated that trWhen the thyroid is sec
reting hormone at full capacity, its total iodine reserve may be de
pleated to less than 1/10 normal. Its thyroxine-like reserve may
disappear, presumably because it is removed as fast as it if formed”.
These observations indicate that the more rapidly the thyroid
hormone is secreted into the blood stream, the lower its thyroid
iodine content and consequently the higher the level of protein-bound
iodine in the blood.
The nature and distribution of thyroid hormone in other tissues. The
work of Wallace and Brodie (1936) shows that concentrations of inorganic
iodine in all tissues is the same as that of the plasma. The protein-
bound iodine content of tissues is similar to that of the blood plasma.
However, the iodine content varies among the different protein fractions
of these tissues. These workers concluded that organic iodine occur-
ing in the thyroid glands was not free thyroxine but is altered into
thyroxine before or during release into the blood stream. They further
suggested that iodine might be incorporated into an enzyme system, and
proposed the name thyrenzyme.
. .
6
Effect of season on thyroid activity. Many studies have been made to
determine changes in thyroid activity. It has been established that
the thyroids of mammals undergo seasonal changes. Seidell and Fenger
(1913) demonstrated that the thyroids of sheep, hogs and cattle had a
maximum iodine content in late summer. Kendall, and Simonsen (1928)
confirmed these observations by showing a higher thyroxine content in
the thyroids of mammals in midsummer as compared to that in February.
An opposite relationship apparently exists in the fowl. Cruick-
shank (1929) found that a higher thyroid iodine content occurs in
the winter months. Seasonal variation in thyroid weight, according
to Cruickshank1s findings, parallels the iodine content, that is,,it
Is greater in the winter months and smaller in the summer months.
This opposite relation of the thyroid iodine content in mammals
as compared to fowl may be explained on the basis that little storage
of colloid occurs in the fowl thyroid during the stammer. The increased
weight of the fowl thyroid in summer may be due to hyperplasia, an
increase in cell components. These are seasonal relationships.
The effect of environmental temperature on thyroid activity. It has
been established that low controlled environmental temperature stimu
lates the thyroid to increased production of thyroxine. Astwood and
Dempsy (19<U3) found that the thyroid glands of rats preduced thyroid
hormone at the rate of 9.5 gamma of thyroxine per day when the rats
were kept at 1°C. The daily secretion rate was 1.7 gamma of thyroxine
at a temperature of 35°C.
Seasonal variation in the histology of the thyroid and the rate
of thyroxine secretion may be due, in a large measure, to changes in
;7.
