Development of glands of internal secretion in birds and immaturely-born mammals

Certain general problems on foundation of the hormonal regulation mechanisms during the prenatal and early postnatal ontogenesis are discussed basing on the authors' own results and on the literature data. They concern development of the hypophysis and peripheral target-glands in immaturely-bone Mammalia and fowls. The data on foundation of the endocrine glands functional activity are compared in rats and hens. The notion on a relative autonomous hormonal function of the peripheral endocrine glands at early stages of ontogenesis is motivated.     

Secretory activity of the brain and peripheral organs: Spontaneous and stimulated release of noradrenaline in the ontogenesis of rats

Spontaneous and K⁺-stimulated release of noradrenaline from the hypothalamus, adrenal gland, and organ of Zuckerkandl under their flowing incubation was investigated in the perinatal period of ontogenesis of rats. The results suggest that, during the investigated period of ontogenesis, adrenal glands are the main source of noradrenaline in the blood, whereas the contributions of the organ of Zuckerkandl and the brain are not as significant and change during this period.     

Development of the hormonal reaction to stress in the ontogenesis of the baboon Papio hamadryas

The hormonal reaction of adrenal and gonadal glands of baboons at various ages was studied under 2 hr immobilization stress condition. Concentrations of cortisol, 11-deoxycortisol, 17-hydroxypregnenolone, dehydroepiandrosterone and testosterone were determined by radioimmunoassay in the monkey blood plasma at different times during the stress reaction. A more pronounced reaction of adrenal cortex was shown in 1 year old baboons. The peak of cortisol level in immature monkeys under stress conditions was registered much earlier than in adult monkeys.     

Morphometric structure of thyroid and adrenal glands in bulls under different modes of adaptive technology

This work was carried out to study dynamics of morphometric structure of thyroid and adrenal glands in bulls brought up in early postnatal ontogenesis at lowered (-4.4-(-)8.0 degree centigrade) and raised (8.7-20.5 degree centigrade) environment temperature with further grow and fattening using intensive technology with application of new biogenic matters. For the first time it has been experimentally proved the expediency of correction of morphometric structure of investigated endocrine glands in bulls under condition of joint application of Suvar with Polistim or with DAFS-25 during the various periods of postnatal ontogenesis. Special features of morphometric structures of the thyroid glands (diameter, the area of follicles, thickness of thyroid epithelium, follicles index) and the adrenal glands (weight, width of zones of cortical and brain substances, the areas of cells and nuclei, and nuclear cytoplasmic ratio) in animals maintained under condition of adaptive technology have been investigated. It has been established that the endocrine glands morphometric parameters in bulls brought up at both lowered and raised temperature are more relief under combined effect of Suvar and DAFS-25 than Suvar and Polistim.     

Histochemical and morphometrical changes in the adrenal glands in the course of circulatory failure.

The histological and biochemical changes in adrenal function has been studied in 50 male cats with circulatory failure. The adrenal glands were examined by morphometric, histochemical and histoenzymological methods after a preliminarily study of the histoenzymological profile of the adrenal glands in intact animals. Five hours after hypotension induced by intravenous injection of trimethaphan and 5 hours after a single massive bleeding, a decrease in adrenal function was observed. Adrenal insufficiency especially of the glucocorticoid release in the course of acute circulatory failure can be considered as a peculiar adaptation of the organism to preserve its life. The demonstrated decrease of adrenal function in the first hours of hypoxia may help in planning hormonal therapy under suitable conditions.     

Effect of interleukin-1 on adrenal function in mice

The influence of macrophage secretion product on the functional activity of the adrenal glands has been studied in mice. It has been shown that intravenously injected interleukin-1 caused dose-dependent increase in corticosterone content in the blood plasma. The hormonal response of the adrenal glands to interleukin-1 injection was abolished by the inhibition of prostaglandin synthesis. The results obtained indicate that interleukin-1 stimulates the functional activity of the adrenal glands, with the effect mediated by prostaglandins.     

The effect of a deficiency of the hormones of the peripheral endocrine glands on behavioral, learning and memory processes]

A comparative study of the effects of thyroid, adrenal, and gonadal deficit on capability for learning, retention of memory traces, and behavior was carried out in male rats under conditions of hormonal disbalance produced by extirpation of the endocrine glands. Behavior of animals was tested during the active and passive avoidance learning and in the open field. It was found out that the extirpation of the peripheral endocrine glands impairs learning and reproduction of the acquired reaction and alters the behavior. The results suggest that corticosteroid hormones take part in learning and behavior. Gonadal and thyroid hormones appear to exert a modulating influence on the higher nervous activity.     

Effect of zinc deficiency and zinc supplementation on adrenals,plasma steroids and thymus in rats

Weanling rats were given diets deficient in or supplemented with zinc. Within a few weeks there were increases in the weight of the adrenal glands and in the concentration of cholesterol and 11-hydroxycorticosteroids in the adrenal glands of the zinc deficient animals. The decrease in cholesterol concentration due to ACTH administration was greater in zinc-deficient than in supplemented rats. After four weeks on the zinc-deficient diet rats had smaller thymus glands than zinc-supplemented rats but zinc-deficient diets had no such effect on adrenalectomised rats. The addition of 2 mg zinc/ml drinking water had no effect on adrenal weight or thymus weight but increased plasma 11-hydroxysteroids after 30 days. The possible connection between zinc intake and resistance to injury and disease is discussed.     

The in vivo production of corticosteroids by the adrenals in rats of the SSHR hypertensive strain

The review contains the hormonal characteristic of the line of stress sensitive hypertensive rats (SSHR) developed from normotensive Wistar rats (WR) during genetic selection. The in vivo production mineralo- and glucocorticoids by rat adrenal glands is estimated. It is shown that SSHR have an increased level of glucocorticoids. The biochemical features of pathogenesis of essential hypertension are discussed.     

Characteristics of microbial association in secretions of various mammalian sebaceous glands

The following secretions of mammalian skin glands were subjected to a microbiological survey: the middle-abdominal glands of great and Mongolian gerbils, the preputial gland of musk deer, the perineal organ of African civet cat, the interdigital skin regions and interdigital glands of bison, European bison, European roe deer, and musk deer. All the secretions were found to contain microbial associations. The composition of bacterial species in the secretions and the quantity of microorganisms varied among different animal species, during the ontogenesis of an animal, and depended on the topography of a gland on an animal body as well as on its functional state in different seasons or upon hormonal changes. The secretions of certain glands contain factors which determine the composition of microbial species in a particular ecological niche and the stability of such a cenosis.     

Sex differences in adrenocortical structure and function

Summary Adrenal glands of adult male hamsters are larger and secrete more cortisol than those of females. Stereology was therefore used to study zonal and cellular aspects of development of the adrenal cortex of male and female hamsters. Adrenal glands were studied at weekly intervals from day 21 to day 77 of postnatal ontogenesis. Within this period, body weight did not differ significantly between the sexes. During development, absolute and relative adrenal weights were higher in males; their zona glomerulosa (ZG), zona fasciculata (ZF) and zona reticularis (ZR) become markedly larger than those in females. No marked changes in the volume of individual ZG cells occurred although ZF cells and ZR cells become larger in male than female animals. The total number of adrenocortical cells increased within the period studied, a greater increase being observed in ZG and ZF in males. No distinct sex difference was observed in the number of ZR cells throughout development. From day 56 of postnatal life the adrenal cortex of male hamster contained more parenchymal cells than the female gland. These results thus indicate that sex differences in hamster adrenal cortex depend upon changes in number and size of parenchymal cells.Supported in part by a grant from the Committee of Zoology, Polish Academy of Sciences     

Changes in the hypothalamo-pituitary-adrenocortical and hypothalamo-pituitary-thyroid axes in diabetic rats acclimated to moderate hyperthermic environment

We examined the effect of acclimation to moderate hyperthermic environment on the ACTH, TSH, T₃, T₄ and corticosterone level, as well as the relative weight of hypophysis, thyroid and adrenal glands in streptozotocin-diabetic rats. Increased activity of the hypothalamo-pituitary-adrenocortical (HPA) axis has been demonstrated in diabetic animals, whereas insulin treatment restores the changes. Heat acclimation reduces the level of ACTH and corticosterone in control animals and moderates the hormonal disturbances caused by diabetes. Simultaneously, our study revealed impairment in the activity of the hypothalamo-pituitary-thyroid (HPT) axis. Acclimation to 35±1 °C resulted in significantly lower T₃ and T₄ levels in control, diabetic and insulin-treated animals. Relative weight of the hypophysis, thyroid and adrenal glands is decreased in heat-acclimated rats. Our assumption is that there might be a cross tolerance between diabetes and heat acclimation on a hormonal level.     

The effect of hydra peptide morphogen on the levels of beta-endorphin and some blood and adrenal hormones in albino rats]

The influence of PMH on the level of beta-endorphin and some hormones of blood and adrenal glands was studied. The dose A (10 mkg/kg) and dose W (100 mkg/kg) of PMH were used in our experiments. Earlier it has been discovered, that PMH in such doses stimulated the processes of cell division in 24 hours since the moment of injection. The stimulation was dose-dependent. Within 24 hours PMH in A dose decreased the concentration of beta-endorphin in the blood 2.7-fold, ad in dose W increased it 2 times. The level of corticosterone in blood and adrenal glands after the injection of PMH in dose A exceeded the control data trustworthy in 4 and 24 hours since the moment of injection. In dose B in 4 hours 1.5-fold reduction of corticosterone concentration took place in the blood. Increase in epinephrine level in adrenal glands was observed after PMH administration in two doses. Content of T3 increased in 4 hours after PMH injection in dose B. The role of hormonal changes in stimulating cell division accompanied by PMH injection is discussed. The data received show that PMH influences directly proliferative processes.     

Effects of stress upon the oxidative metabolism and its correlation with gastric ulcer formation: the role of sex.

The metabolic-oxidative activity of different nervous and glandular structures (amygdala, hypothalamus, lateral-frontal cerebral cortex, adrenal glands) in male and female rats under acute stress caused by physical immobilization, was determined. The sexual cycle of the female rat was controlled by examination of their vaginal frotis. One experimental group during estrus and another one during diestrus were selected. At the same time ovariectomy was performed on an experimental group in order to eliminate the hormonal influences of the ovary. Results show there are no significant differerneces in the oxidative metabolism. Nor in the numbers of ulcers. Hypothalamus-hypophyseal-adrenocortical activation was made manifest on obtaining significant differences in the weight of the adrenal glands, a fact long ago reported in a number of studies. Necropsy showed severe gastric hemorrhages and ulcer in the stomach. Nevertheless, no significant differences between the distinc experimental groups were obtained. The likely participation of sexual hormones in female rats is discussed in the light of our results.     

白暨豚肾上腺的研究

白鱀豚肾上腺重与体重的平均比值为0.25克/公斤,皮质体积与髓质体积的比值为6.59。白鱀豚肾上腺的组织结构与其它海豚相似,它有比较发达的球状带。讨论了白鱀豚肾上腺形态变化在年龄生长、授乳等生理过程和在自然环境、豢养环境生态适应上的意义。并报道了一例罕见的白鱀豚肾上腺先天性表皮样囊肿。       

Characteristics of Basic Parameters of the Hormonal Function of the Adrenal Cortex and Its Modification in Rat Ontogenesis

The stress-reactivity of the pituitary-adrenocortical system (PAS) as assessed by the dynamics of the blood corticosterone level changes was studied in rats administered with cortisol at different periods of their pre- and postnatal ontogenesis. The participation of the activation and deactivation mechanisms in this process was estimated by means of a mathematical modeling, using the basic parameters of hormonal wave. It is established that in the one-month old rat pups born from mothers injected with cortisol from the day 14 to 18 of pregnancy, the basal and stress-evoked PAS activity was not essentially changed, whereas the adult animals demonstrated a faster decrease of the stress-induced corticosterone level. Injection of cortisol at the early neonatal ontogenesis (1–5 day of life) decreased the basal and stress-induced corticosterone levels at the morning hours in one-month old rats, whereas in adult rats it increased the PAS stress-reactivity. Injection of cortisol in the late neonatal ontogenesis, i.e., during the period of formation of the sensory systems (opening of the ears, eyes, maximal motor activity) resulted predominantly in changing the time of completion of the stress-induced hormonal response that became longer than in control animals of the same age. With the aid of mathematical modeling, we have found that at the early neonatal period of development the hormonal exposure mainly increases the rate of PAS activation, whereas injection of glucocorticoids at the late neonatal period changes PAS regulation by a feedback mechanism, thus decreasing the rate of system inactivation and increasing the time of completion of PAS stress-induced reaction. It is concluded that the phenotypic reorganization of PAS stress-reactivity by exogenous corticosteroids depends on the time of their action on development of the excitatory and inhibitory mechanisms during the critical periods of their formation.     

Adrenalectomy in the ferret

A simple adrenalectomy technique is presented for the ferret (Mustela putorius furo). The adrenal glands were removed in two operations with an interim recovery period of approximately 1 week. The right adrenal should be removed first, as the surgery is complicated on that side by fascia which binds the adrenal to the inferior vena cava. Salt solution (1% NaCl) in place of water will maintain sodium balance.     

Serum prolactin levels and prolactin binding activity in adrenals and kidneys of male rats after dehydration, salt loading, and unilateral nephrectomy.

Serum prolactin (PRL) levels and PRL binding activity in microsomal membranes from kidneys and adrenals were measured in control, water-deprived, unilaterally nephrectomized, and salt-loaded male rats. Unilateral nephrectomy and water deprivation increased serum prolactin levels significantly. Unilateral nephrectomy did not alter PRL binding activity in the kidneys, but significantly increased it in the adrenal glands. Salt loading had no effect on serum prolactin levels or PRL binding in the kidneys; but significantly increased PRL binding in the adrenal glands. Inhibition curves and tests of cross reactivity with LH, FSH, TSH, and GH showed that binding of PRL to its receptors in the kidneys and adrenals was specific. These observations suggest that PRL has a role in salt and water metabolism and that PRL receptors in the kidney and adrenals participate in this regulatory system.     

Morphological and functional changes in several endocrine glands induced by hypothyroidism in the rat

The effect of hypothyroidism upon the morphology and the function of several endocrine glands was studied in radiothyroidectomized male rats. It was found that T3, T4, insulin, prolactin and corticosterone levels were significantly lower in hypothyroid rats. TSH levels were significantly higher in these animals while no changes were depicted in testosterone levels. The administration of T4 drew back to normal range the above-mentioned altered serum hormone levels. The studies performed with light microscopy revealed alterations only in the TSH secretory cells of the adenohypophysis. Conversely, when using the electron microscope to study the different endocrine glands, clear alterations were depicted in the TSH and prolactin secretory cells of the adenohypophysis, as well as in the pancreatic B cells and the cells of the zona fasciculata of the adrenal cortex. No abnormal changes were demonstrable at the level of the seminiferous tubules of the testis. All the above morphological changes were corrected by the administration of T4 to hypothyroid rats. These results suggest that the hypothyroid state is a complex hormonal dysfunction rather than a single hormonal defect. The secretory alterations are accompanied by fine cellular alterations in the corresponding glands.