Martin Silberberg

STEROID HORMONES AND BONE

Publisher Summary Many of the steroid hormones influence skeletal growth, development, and ageing; sex steroids in addition regulate the development of osseous structures representing secondary sex characters, such as horns and antlers. In birds, these steroids also control skeletal changes that are incidental to egg-laying, namely, medullary bone formation. The effects of steroid hormones on bone are thus manifold, and even though some of the end results might appear similar, they can be brought about by different mechanisms. Direct and circumstantial evidence strongly indicates that steroid hormones might act on the skeleton directly without mediation of other endocrine glands. Only a limited number of investigations have been carried out, and so far little information has been forthcoming concerning the skeletal effects of progesterone, of desoxycorticosterone and related substances, and even of the glucocorticoids. Of the steroid hormones tested, only the androgenic 17-ketosteroids in small doses have been shown to increase linear growth; this effect seen only in individuals, whose body growth is retarded because of certain endocrine deficiencies, is related to the increased N retention caused by the 17-ketosteroids.Publisher Summary Many of the steroid hormones influence skeletal growth, development, and ageing; sex steroids in addition regulate the development of osseous structures representing secondary sex characters, such as horns and antlers. In birds, these steroids also control skeletal changes that are incidental to egg-laying, namely, medullary bone formation. The effects of steroid hormones on bone are thus manifold, and even though some of the end results might appear similar, they can be brought about by different mechanisms. Direct and circumstantial evidence strongly indicates that steroid hormones might act on the skeleton directly without mediation of other endocrine glands. Only a limited number of investigations have been carried out, and so far little information has been forthcoming concerning the skeletal effects of progesterone, of desoxycorticosterone and related substances, and even of the glucocorticoids. Of the steroid hormones tested, only the androgenic 17-ketosteroids in small doses have been shown to increase linear growth; this effect seen only in individuals, whose body growth is retarded because of certain endocrine deficiencies, is related to the increased N retention caused by the 17-ketosteroids.

Effects of extract of cattle anterior pituitary gland on endochondral ossification in young guinea pigs.

It has been established that the anterior pituitary gland enhances bodily growth as a whole, but it is not yet known whether it has a specific effect on the growth of cartilage and bone and, if this should be so, wherein the effect consists. We wished, therefore, to study the action of anterior pituitary gland extract on the epiphyseal cartilage and bone formation in young not yet fully grown guinea pigs. About 30 guinea pigs (fall and winter animals) on the average weighing 130 to 220 gm. were injected with from 1 to 1 1/2 cc. extract 1 daily. Additional guinea pigs, of similar weight, were not injected and served as controls. The injections were continued up to 21 days. After 4, 6, 11, 14, and 21 days, the animals were killed and tibia and fibula were used for the study of the epiphyseal line. In each case the specimen, as a whole, was fixed in 10% formalin; then put into absolute alcohol and subsequently transferred into ether for 2 days, in order to remove the fat from the bone-marrow. The bones were then washed in running water and decalcified incompletely in order to preserve and demonstate the calcium salts. In accordance with Pommers method, they were kept about 3 to 8 weeks in Muellers solution, until they had become sufficiently soft for cutting; subsequently they were embedded in celloidin and stained with hematoxylin-eosin or hematoxylin-Van Gieson. After 4 injections, a stimulation of the growth of cartilage and bone can be seen at the epiphyseal line. The undifferentiated mesenchymal cells have become mobilized and transformed into chondrocytes and osteocytes. The columnar resting cartilage cells are increased in size and number, mitotic figures are found everywhere and are more numerous than under normal conditions, the stroma between the cells correspondingly is much diminished in amount. Likewise in the layer of the vesicular cartilage, hyperplasia and hypertrophy are noted. After 7 to 10 injections, the epiphysis as a whole, has become more narrow in comparison with that of the control animals.

ULTRASTRUCTURE OF ARTICULAR CARTILAGE OF MICE TREATED WITH SOMATOTROPHIN.

Administration of somatotropic hormone to newborn or weanling mice of strain C57BL Jax6 for one, two, or four weeks accelerated articular growth and development. The organelles were increased in number and the appearance of granular endoplasmic reticulum, Golgi vacuoles, multivesicular bodies, and glycogen was hastened. Toward the end of the developmental cycle, the chondrocytes swelled excessively and their plasmalemma ruptured without evidence of vascular erosion. After four weeks of treatment, there was premature breakdown of chondrocytes, their place being taken by fibrillar microscars. In the matrix, development of fibers was accentuated. The intensification of fibrillarity was followed by disorientation of the superficial collagen fibers with fraying of the articular covering. The functional significance of these findings, as well as their relation to aging changes in cartilage, is discussed.

Effect of Cattle Anterior Pituitary Extract on Bone and Cartilage of the Joint (Acromegalic arthropathia)

Conclusion In young guinea pigs, under the influence of acid extract of cattle anterior pituitary, the growth-promoting effect manifests itself as acromegalic arthropathia in 2 directions: (1) Hypertrophy and hyperplasia starting in the transitional zone of cartilage then proceeding towards its sliding and pressure zone, and in a later stage leading to its liquefaction and to ulceration of the surface. (2) This stimulation of the growth of cartilage may be followed by calcification. In the latter case the ulcerative processes are less pronounced than in the former. Whether the one or the other of these 2 effects occurs does not depend upon the number of injections given to the animals.

Effects of Combined Administration of Extracts of Anterior Lobe of Pituitary and of Potassium Iodide on Thyroid Gland

In former investigations from this laboratory Loeb, 1 Gray 2 and Rabinovitch 3 have shown that potassium iodide may exert, a stimulating effect on the thyroid gland of the guinea pig. It does not prevent compensatory hypertrophy, but may modify its character; in the normal gland it may increase the mitotic activity as much as 40-60 times, and quite commonly increases it 20 times. Furthermore, it produces a slight increase in the size of the acinus cells and a slight softening of the colloid and a very marked increase in the number of phagocytes in the colloid. Loeb 4 has shown that oral administration of anterior pituitary substance (Armour & Co.) prevents compensatory hypertrophy of the thyroid gland and McCordock 5 has shown that it prevents the hyperplasia caused by potassium iodide. However, if instead of oral administration of anterior pituitary we give daily subcutaneous injections of either acid or alkaline extracts of anterior pituitary, no inhibition of the thyroid gland results, but, on the contrary, a very pronounced stimulation (Loeb and Bassett 6 ). Hyperplasia and hypertrophy of the acinar epithelium, liquefaction and absorption of the colloid proceed very rapidly. After 7 daily injections of such extracts extreme changes are found in the gland resembling in many respects those obtained in typical cases of Graves disease. We have then in potassium iodide and in acid or alkaline extract of anterior pituitary gland 2 substances which stimulate the thyroid gland of the guinea pig and which produce a very pronounced cell proliferation in the epithelium of the acini. They differ, especially, in that the hypertrophy and softening of the colloid caused by KI is very slight as compared with the pronounced effects of anterior pituitary extracts and secondly, in that, under the influence of anterior pituitary extract, the colloid is rapidly absorbed from the acini, whereas under the influence of KI it is only slightly softened and largely retained in the acini.

Susceptibility to Estrogen of Breast, Vagina, and Endometrium of Various Strains of Mice.∗

Summary In ovariectomized mice of strains with different mammary cancer incidence (C57. Dba, A), injected with equal amounts of alpha estradiol benzoate, the response of mammary gland, vagina and endometrium respectively varied in degree: Mice of strain C57 showed less mammary stimulation than mice of strains Dba or A. The vaginal epithelium was most sensitive in mice of strain C57, slower in responding in mice of strain Dba, and least responsive in mice of strain A. The endometrium reacted most vigorously in mice of strain C57, and less actively in strains Dba and A. Differences in the mammary cancer incidence of the strains examined are considered to be due to differences in tissue susceptibility rather than to genetic differences in the output of estrogen.

Mammary Cancer in Castrate Male Mice Receiving Ovarian and Hypophyseal Grafts at Various Ages.

Summary Syngenesiotransplants of ovaries made at one month of age caused mammary cancer in 5% of castrate male mice of strain A. The tumor incidence rose to 32.5%, if anterior hypophyses were grafted together with ovaries. Transplantation of anterior hypophyses alone failed to produce breast cancer. No mammary tumors occurred in castrates into which ovaries, anterior hypo- physes alone or anterior hypophyses in combination with ovaries were grafted at 7 months of age. Thus in male mice, an age factor which is independent of the testicle operates in the production of breast cancer by ovarian and anterior hypophyseal grafts.

Inhibition of Endochondral Ossification in Pantothenic Acid Deficiency

Summary In growing mice, pantothenic acid is essential for the growth of the skeleton. Deficiency of this vitamin causes inhibition of growth and endochondral ossification. The male reacts more quickly to lack of pantothenic acid than the female. On feeding an adequate stock diet subsequent to a prolonged deficiency, growth of cartilage and ossification are resumed rapidly and may surpass in intensity the processes seen in normal nondeficient animals. In the adult mouse, skeletal changes were not observed under the influence of pantothenic acid deficiency.

Adrenals and Anterior Hypophysis in Leukemogenesis of Mice.

Summary In newborn mice of strain A7 orchidectomy slight increased the incidence of leukemia. In such castrates, adrenal transplants doubled the incidence and conspicuously advanced the onset of the disease. Hypophyseal transplants made in conjunction with adrenal grafts increased the incidence of leukemia 4 times over that seen in non-grafted castrates. Prolonged hyperpituitarism associated with hyperadrenalism apparently exerted this leukemogenic effect.

Male Sex Hormone and Osteo-Arthrosis in Mice

Male mice of strains susceptible to osteo-arthrosis are usually more prone to develop the disease than females 710#{149} This sex difference might either be genetically determined or be due to differences in the action of male or female sex hormones, respectively. Orchiectomy performed in the growing male animal decreased both the incidence and the severity of degenerative joint disease . These results may be related to the general delay of skeletal development and aging that are observed in the castrate or they may be the consequence of the withdrawal of a specific metabolic stimulation exerted by testicular secretions on the articular tissues. In an attempt to analyze the problem further, we studied the influence of the administration of male sex hormone on the articulations of male mice. Since these