뇌하수체척출(剔出)이 정상 및 cholesterol 투여 백서의 각장기내 지질분포에 미치는 영향에 관한 형태학적 관찰
Other Titles
(A) histological study on the effects of hypophysectomy in normal and cholesterol-fed rats; with special reference to tissue lipid distribution
Authors
최인준
Issue Date
1964
Description
의학과/박사
Abstract
[한글]
A Histological Study on the Effects of Hypophysectomy in Normal and Cholesterol-fed
Rats; With Special Reference to Tissue Lipid Distribution
In Joon Choi, M.D.
Department of Pathology, College of Medicine, Yonsei University Seoul, Korea
(Directed by Prof. Dong Sik Kim, M.D.)
The relation between plasma lipids and atherosclerosis has been suspected for a
long time and the importance of lipid metabolism in the pathogenesis of
atherosclerosis has since been recognized. In view of the association between high
levels of plasma lipids and atherosclerosis, there have been exceedingly numerous
inverstigations to examine the factors involved in such influence.
Among the factors related to disturbances in lipid metabolism, study on the role
of the endocrine glands and of various hormones has attracted many workers in this
field to clarify the mechanisms involved in such phenomena.
Investigation of the literatures reveals that the pituitary, adrenal glands and
gonads all plays a significant role in the regulation of lipid metabolism. Seifter
et al. and Zarafonetis et al. isolated the so-called "lipid-mobilizing hormone" in
the plasma, and found it to he more abundant in the posterior lobe of the pituitary
than the anterior lobe. Chalmers et al. extracted a "fat-mobilizing substance" in
the urine which was eliminated after hypophysectomy. Rudman et al. also
demonstrated a similar substance in an alkaline extraction of the anterior
pituitary and named it Fraction H. More recently, Williams reported that these
substance must be the growth hormone and ACTH.
The association of hypercholesterolemia and hypothyroidism is a well known
clinical phenomenon and also this has been proven experimentally (Hurxthal et al.,
Wells and Ershoff). There are some who believe that the alterations of lipid
metabolism and the development of atherosclerosis following hypophysectomy were due
to the resultant hypothyroidism and not as a direct effect of hypopituitarism.
The intimate relationship of pituitary and adrenal glands is also very well
known. The role of sex hormone, particularly of estrogen, attracted many
investigators to examine the various factors related to the regulation of lipid
metabolism. Thus, it is quite apparent that the endocrine glands are very
intimately associated with the alterations of lipid metabolism and that the
pituitary gland plays the central role.
However, the majority of these studies have dealt mainly with the fluctuation of
plasma lipid levels and very little attention has bean paid to the lipid
distribution in the various parenchymatous organs, particularly of the endocrine
glands. It is also recognized that the level of plasma lipid alone cannot
thoroughly explain the variegated features of diseases resulting from disturbances
in lipid metabolism. Therefore, study of tile pattern of tissue lipid distribution
in normal and abnormal conditions seems to be quite appropriate and important.
Furthermore, there are still wide differences of opinions as to the mode of action
of the various endocrine factors in the regulation of lipid metabolism.
The purpose of this study is to characterize the pattern of lipid distribution in
various organs after hypophysectomy in normal and cholesterol-fed rats. At the same
time, the influence of cortisone, estrogen, testosterone and thyroxine was
evaluated as to the mechamism(s) involved in their action toward tissue lipid
alterations.
Materials and Methods:
Healthy albino rats of both sexes weighing from 100 to 250 grams were used.
Although a total of 166 rats were subjected to hypophysectormy, the number of
hypophysectomized rats included in the final study was 32 (male 21, female 11)
which survived successful total excision of pituitary. The animals were divided
into 3 major groups: GroupⅠ consisted of 6 rats as normal control group: GroupⅡ
consisted of 12 rats as the cholesterol only feeding group; GroupⅢ consisted of 32
rats which had hypophysectomy. The hypophysectomy group was subdivided into six
groups as follows: Group A consisted of 7 rats haying hypophysectomy only; Group B
consisted of 10 rats receiving cholesterol: Group C consisted of 4 rats receiving
thyroxine plus cholesterol; Group D consisted of 5 rats receiving cortisone plus
cholesterol; GroupE consisted of 3 rats receiving estrogen plus cholesterol: Group
F consisted of 3 rats receiving testosterone plus cholesterol.
Hypophysectomy was performed by the transauricular method. All animals after
hypophysectomy received 0.01 mg./gm. body weight of cortisone, 0.05cc/gm of 5%
glucose solution into the peritoneal cavity, and 0.05mg/gm. body weight of
sigmamycin intramuscularly for 2 successive days. Each extracted pituitary was
examined under the microscope every time to confirm its total excision. This was
checked again at the time of autopsy and the partially removed cases were excluded
from the final analysis.
300 mg. of cholesterol was given daily starting two days after hypophysectomy
until the end of the experiment. The dose of thyroxine was 0.5 mg./kg. per day,
cortisone 0.5 mg/kg. per day, estrogen 0.02 mg/kg. per every other day as was
testosterone, 0.42mg/kg. These were given for the last 20 days of the experiment.
The animals were sacrificed at intervals of 3, 5 and 8 weeks. The organs were
grossly inspected and fixed in 10% neutral formalin. The fresh weight of the
thyroid, adrenals, testes and ovaries was recorded Paraffin sections were prepared
for hematoxylin and rosin, and for Periodic Acid Schiff's reaction. Frozen sections
were stained with Oil Red 0 for the demonstration of fat in the tissues.
Results:
1. Normal control group (Group Ⅰ); The adrenal glands showed intense
sudanophilic lipid droplets in all layers but their intensity was more marked in
the zona glomerulosa. The bona fasciculata contained slightly less and the bona
reticularis the least. There was a very narrow lipid-free zone between the zona
glomerulosa and zona fasciculata.
All of the other organs examined showed the usual histological appearance. Fat
stanis of the thyroid, liver and kidney failed to reveal stainable fat, but fat
stains of the testes and ovary showed the usual lipid distribution.
2. Cholesterol only feeding group (GroupⅡ); Cholesterol feeding in normal rats
caused considerable changes in the various organs. The adrenal glands not only
showed increase in weight and size but also the lipid drop키eta were markedly
increased both in number and size. All layers contained prominent lipid droplets.
At the end of 8 weeks of cholesterol feeding, the lipid-free zone in the normal
adrenals became also filled with lipid. The liver also demonstrated fine
sudanophilic droplets within the Kupffer cells and the hepatic cells at the end of
3 weeks which became progressively intensified as the time lapsed. The kidney
showed demonstrable lipid droplets in the glomeruli and in the distal tubules.
The thyroid showed features of follicular hyperplasia but no significant lipid
droplets. In many areas the lining epithelium skewed papillary infoldings and the
cytoplasm contained many PAS positive materials. The testes and ovary were not
significantly altered when compared with the normal control group.
3. Hypophysectomy group (GroupⅢ); As expected the hypophysectomy produced
profound morphologic alterations. The adrenal glands showed atrolhy, but the
relative size of the zona glomerulosa, particularly of the subglomerulosal layer
(lipid-free zone), was progressively broadened as the time lapsed. The zone
fasciculata was extremely atrophic, on the other hand, and the zona reticularis was
also thinned. The examination of lipid pattern revealed that the zone glomerulosa
persistently showed demonstrable lipids throughout the experiment but the other
zones demonstrated progressive loss of lipid substance.
In this group the lipid droplets in the liver and kidney became demonstrable
which was not the case in normal control animals. The thyroid showed marked
flattening of the follicular lining epithelium, storage of colloid substance, and
no significantly demonstrable lipids. The testes and ovaries showed varying degrees
of atrophy, in association with reduced lipid pattern in the ovary, but there was a
significantly increased irregular and larger lipid materials in the seminiferous
tubules of the testes.
When cholesterol was fed to this group of animals, there were no significant
histological difference from the group having hypophysectomy only but the lipid
content of the adrenal glands was greater. However this increase was less than that
seen in the normal control animals. The liver and the kidney both revealed that
there were increase in lipid comparable to that seen in cholesterol-fed animals
without hypophysectomy. The thyroid, testes and ovary all showed changes similar to
the group having hypophysectomy only.
Administration of thyroxine did not affect the lipid distribution of adrenal
cortex, thyroid, ovary, and testes but the lipid un hepatic lobules and kidney
tubules were markedly reduced.
Cortisone administration caused lipid depletion in the adrenal glands but the
thyroid, liver and kidney showed no significant alteration of lipid pattern.
Estrogen and testosterone likewise did not influence the pattern of lipids in the
liver and kidney. However estrogen increased the adrenal and ovarian lipids and
testosterone, the adrenal and testicular lipids.
Conclusion:
1. Cholesterol feeding caused significant alterations in the tissue lipid
distrioution, particularly of the adrenal glands, liver and kidney. The thyroid
gland became hyperplastic.
2. Hypophysectomy alone induced atrophic changes of the examined endocrine organs
and alterations in the lipid distribution of the adrenals, liver, kidney, ovary and
testes.
3. Cholesterol supplementation in hypophysectomized animals caused no significant
alterations in the pattern of tissue lipid distribution as compared with that of
the cholesterol-fed rats, but the intensity and the amount of lipid was much less
in the former.
4. Administration of thyroxine caused profound influences on the lipids seen in
the liver and kidney but none on the adrenal lipids. On the other hand, cortisone,
estrogen and testosterone influenced lipid pattern of the adrenal glands but not of
the liver and kidney. It appears that the thyroid gland influences the lipid
distribution of the adrenal glands through the mediation of pituitary gland, but
is directly concerned with the lipid pattern of the liver and kidney. Cortisone
does not appear to act directly on the lipid pattern of the liver and kidney
although it is directly related to the adrenal lipids. Estrogen and testosterone
also do not appear to directly influence the pattern of the liver and kidney lipid
but estrogen may be directly related to the alterations of the lipid in the inner
cortex of the adrenals and of the ovary. Also testosterone may be related directly
to the alterations of the lipid in the inner cortex of the adrenals and of the
testes.
It appears that alterations in the tissue lipid pattern of the liver and kidney
may be related to the resultant hypothyroidism following hypophysectomy. On the
contrary the lipid pattern of the adrenal, ovary and testes may be related directly
to the effect of the hypophysectomy.
[영문]
The relation between plasma lipids and atherosclerosis has been suspected for a long time and the importance of lipid metabolism in the pathogenesis of atherosclerosis has since been recognized. In view of the association between high levels of plasma lipids and atherosclerosis, there have been exceedingly numerous
inverstigations to examine the factors involved in such influence.
Among the factors related to disturbances in lipid metabolism, study on the role of the endocrine glands and of various hormones has attracted many workers in this field to clarify the mechanisms involved in such phenomena.
Investigation of the literatures reveals that the pituitary, adrenal glands and gonads all plays a significant role in the regulation of lipid metabolism. Seifter et al. and Zarafonetis et al. isolated the so-called "lipid-mobilizing hormone" in the plasma, and found it to he more abundant in the posterior lobe of the pituitary than the anterior lobe. Chalmers et al. extracted a "fat-mobilizing substance" in the urine which was eliminated after hypophysectomy. Rudman et al. also demonstrated a similar substance in an alkaline extraction of the anterior pituitary and named it Fraction H. More recently, Williams reported that these
substance must be the growth hormone and ACTH.
The association of hypercholesterolemia and hypothyroidism is a well known clinical phenomenon and also this has been proven experimentally (Hurxthal et al., Wells and Ershoff). There are some who believe that the alterations of lipid metabolism and the development of atherosclerosis following hypophysectomy were due
to the resultant hypothyroidism and not as a direct effect of hypopituitarism.
The intimate relationship of pituitary and adrenal glands is also very well known. The role of sex hormone, particularly of estrogen, attracted many investigators to examine the various factors related to the regulation of lipid metabolism. Thus, it is quite apparent that the endocrine glands are very intimately associated with the alterations of lipid metabolism and that the
pituitary gland plays the central role.
However, the majority of these studies have dealt mainly with the fluctuation of plasma lipid levels and very little attention has bean paid to the lipid distribution in the various parenchymatous organs, particularly of the endocrine glands. It is also recognized that the level of plasma lipid alone cannot
thoroughly explain the variegated features of diseases resulting from disturbances in lipid metabolism. Therefore, study of tile pattern of tissue lipid distribution in normal and abnormal conditions seems to be quite appropriate and important.
Furthermore, there are still wide differences of opinions as to the mode of action of the various endocrine factors in the regulation of lipid metabolism.
The purpose of this study is to characterize the pattern of lipid distribution in various organs after hypophysectomy in normal and cholesterol-fed rats. At the same time, the influence of cortisone, estrogen, testosterone and thyroxine was evaluated as to the mechamism(s) involved in their action toward tissue lipid alterations.
Materials and Methods:
Healthy albino rats of both sexes weighing from 100 to 250 grams were used.
Although a total of 166 rats were subjected to hypophysectormy, the number of hypophysectomized rats included in the final study was 32 (male 21, female 11) which survived successful total excision of pituitary. The animals were divided into 3 major groups: GroupⅠ consisted of 6 rats as normal control group: GroupⅡ consisted of 12 rats as the cholesterol only feeding group; GroupⅢ consisted of 32 rats which had hypophysectomy. The hypophysectomy group was subdivided into six groups as follows: Group A consisted of 7 rats haying hypophysectomy only; Group B
consisted of 10 rats receiving cholesterol: Group C consisted of 4 rats receiving thyroxine plus cholesterol; Group D consisted of 5 rats receiving cortisone plus cholesterol; GroupE consisted of 3 rats receiving estrogen plus cholesterol: Group F consisted of 3 rats receiving testosterone plus cholesterol.
Hypophysectomy was performed by the transauricular method. All animals after hypophysectomy received 0.01 mg./gm. body weight of cortisone, 0.05cc/gm of 5% glucose solution into the peritoneal cavity, and 0.05mg/gm. body weight of sigmamycin intramuscularly for 2 successive days. Each extracted pituitary was examined under the microscope every time to confirm its total excision. This was checked again at the time of autopsy and the partially removed cases were excluded from the final analysis.
300 mg. of cholesterol was given daily starting two days after hypophysectomy until the end of the experiment. The dose of thyroxine was 0.5 mg./kg. per day, cortisone 0.5 mg/kg. per day, estrogen 0.02 mg/kg. per every other day as was testosterone, 0.42mg/kg. These were given for the last 20 days of the experiment.
The animals were sacrificed at intervals of 3, 5 and 8 weeks. The organs were grossly inspected and fixed in 10% neutral formalin. The fresh weight of the thyroid, adrenals, testes and ovaries was recorded Paraffin sections were prepared for hematoxylin and rosin, and for Periodic Acid Schiff's reaction. Frozen sections were stained with Oil Red 0 for the demonstration of fat in the tissues.
Results:
1. Normal control group (Group Ⅰ); The adrenal glands showed intense sudanophilic lipid droplets in all layers but their intensity was more marked in the zona glomerulosa. The bona fasciculata contained slightly less and the bona reticularis the least. There was a very narrow lipid-free zone between the zona
glomerulosa and zona fasciculata.
All of the other organs examined showed the usual histological appearance. Fat stanis of the thyroid, liver and kidney failed to reveal stainable fat, but fat stains of the testes and ovary showed the usual lipid distribution.
2. Cholesterol only feeding group (GroupⅡ); Cholesterol feeding in normal rats caused considerable changes in the various organs. The adrenal glands not only showed increase in weight and size but also the lipid drop키eta were markedly increased both in number and size. All layers contained prominent lipid droplets.
At the end of 8 weeks of cholesterol feeding, the lipid-free zone in the normal adrenals became also filled with lipid. The liver also demonstrated fine sudanophilic droplets within the Kupffer cells and the hepatic cells at the end of 3 weeks which became progressively intensified as the time lapsed. The kidney showed demonstrable lipid droplets in the glomeruli and in the distal tubules.
The thyroid showed features of follicular hyperplasia but no significant lipid droplets. In many areas the lining epithelium skewed papillary infoldings and the cytoplasm contained many PAS positive materials. The testes and ovary were not significantly altered when compared with the normal control group.
3. Hypophysectomy group (GroupⅢ); As expected the hypophysectomy produced profound morphologic alterations. The adrenal glands showed atrolhy, but the relative size of the zona glomerulosa, particularly of the subglomerulosal layer (lipid-free zone), was progressively broadened as the time lapsed. The zone fasciculata was extremely atrophic, on the other hand, and the zona reticularis was also thinned. The examination of lipid pattern revealed that the zone glomerulosa persistently showed demonstrable lipids throughout the experiment but the other
zones demonstrated progressive loss of lipid substance.
In this group the lipid droplets in the liver and kidney became demonstrable which was not the case in normal control animals. The thyroid showed marked flattening of the follicular lining epithelium, storage of colloid substance, and no significantly demonstrable lipids. The testes and ovaries showed varying degrees of atrophy, in association with reduced lipid pattern in the ovary, but there was a significantly increased irregular and larger lipid materials in the seminiferous tubules of the testes.
When cholesterol was fed to this group of animals, there were no significant histological difference from the group having hypophysectomy only but the lipid content of the adrenal glands was greater. However this increase was less than that seen in the normal control animals. The liver and the kidney both revealed that there were increase in lipid comparable to that seen in cholesterol-fed animals without hypophysectomy. The thyroid, testes and ovary all showed changes similar to the group having hypophysectomy only.
Administration of thyroxine did not affect the lipid distribution of adrenal cortex, thyroid, ovary, and testes but the lipid un hepatic lobules and kidney tubules were markedly reduced.
Cortisone administration caused lipid depletion in the adrenal glands but the thyroid, liver and kidney showed no significant alteration of lipid pattern.
Estrogen and testosterone likewise did not influence the pattern of lipids in the liver and kidney. However estrogen increased the adrenal and ovarian lipids and testosterone, the adrenal and testicular lipids.
Conclusion:
1. Cholesterol feeding caused significant alterations in the tissue lipid distrioution, particularly of the adrenal glands, liver and kidney. The thyroid gland became hyperplastic.
2. Hypophysectomy alone induced atrophic changes of the examined endocrine organs and alterations in the lipid distribution of the adrenals, liver, kidney, ovary and
testes.
3. Cholesterol supplementation in hypophysectomized animals caused no significant alterations in the pattern of tissue lipid distribution as compared with that of the cholesterol-fed rats, but the intensity and the amount of lipid was much less in the former.
4. Administration of thyroxine caused profound influences on the lipids seen in the liver and kidney but none on the adrenal lipids. On the other hand, cortisone, estrogen and testosterone influenced lipid pattern of the adrenal glands but not of the liver and kidney. It appears that the thyroid gland influences the lipid distribution of the adrenal glands through the mediation of pituitary gland, but is directly concerned with the lipid pattern of the liver and kidney. Cortisone does not appear to act directly on the lipid pattern of the liver and kidney
although it is directly related to the adrenal lipids. Estrogen and testosterone also do not appear to directly influence the pattern of the liver and kidney lipid but estrogen may be directly related to the alterations of the lipid in the inner cortex of the adrenals and of the ovary. Also testosterone may be related directly to the alterations of the lipid in the inner cortex of the adrenals and of the testes.
It appears that alterations in the tissue lipid pattern of the liver and kidney may be related to the resultant hypothyroidism following hypophysectomy. On the contrary the lipid pattern of the adrenal, ovary and testes may be related directly to the effect of the hypophysectomy.