[The spectroscopic method of investigation in analysis of the endocrine system].
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Blood↗
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Noradrenaline and adrenaline in mammalian tissues; distribution under normal and pathological conditions with special reference to the endocrine system.
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Animals↗
Surgery and the endocrine system.
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Endocrine Glands↗
Recent advances in our understanding of the vitamin D endocrine system.
Vitamin D3 gives rise to at least one hormone in which the kidney is utilized as an endocrine system. This hormone arises from 25-OH-D3 which in turn is synthesized in the liver from vitamin D3. The production of this calcium and phosphorus mobilizing hormone, namely 1,25-(OH)2D3, is strongly regulated by the need for calcium and phosphorus. The regulation of its production can occur only after initial 1,25-(OH)2D3 is made and brings about the appearance of 25-OH-D3-24hydroxylase. The need for calcium brings about a stimulation of parathyroid hormone secretion. The parathyroid hormone suppresses the 24-hydroxylase and stimulates the 1-hydroxylase. Alternatively, the need for phosphorus directly stimulates the 1-hydroxylase and suppresses the 24-hydroxylase. The 24-hydroxylation appears to be the initial reaction leading to the inactivation and excretion of vitamin D whereas the 1-hydroxylation is the reaction bringing about the activation of the molecule to 1,25-(OH)2D3. The 1,25-(OH)2D3, the 25-OH-D3 and an analog of 1,25-(OH)2D3, namely 1alpha-OH-D3, are potentially extremely useful in the treatment of metabolic bone diseases such as renal osteodystrophy, hepatically related disorders of calcium and bone metabolism, hypoparathyroidism, and vitamin D dependency disease. The 1alpha-OH-D3 is effective by virtue of its conversion to 1,25-(OH)2D3. The 25-hydroxylation of both 1alpha-OH-D3 and vitamin D3 itself occurs predominantly in the liver. Finally, it is not entirely settled whether 1,25-(OH)2D3 is active directly in all of the functions of viramin D or whether it must be further converted metabolically. A new metabolic pathway for vitamin D has been discovered in which 1,25-(OH)2D3 loses its 26 and 27 carbons to carbon dioxide, producing an unknown metabolite. It is not certain whether this pathway represents degradation of the 1,25-(OH)2D3 or its further activation.
25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
[Reaction of the endocrine system to continuous and intermittent electromagnetic fields].
This paper reviews Soviet and foreign data about the effects of low frequency electromagnetic fields of continuous and intermittent generation on the endocrine system of animals and humans. It has been shown that the pituitary-adrenal, pituitary-thyroid and reproductive systems are sensitive to these effects. It is postulated that the endocrine responses to electromagnetic effects are similar to the general adaptive reactions to various pathophysiological exposures.
Animals↗
The diffuse endocrine system in cystic fibrosis.
The pathology, aetiology and clinical features of cystic fibrosis (CF) are briefly reviewed. The diffuse endocrine system (DES) may be involved in either a primary or secondary manner. Carbohydrate intolerance is common and the release of islet hormones is deficient, as is the release of the intestinal hormone gastric inhibitory polypeptide (GIP). The post-prandial responses of insulin and GIP can be improved by substituting an elemental meal, suggesting that malabsorption and local intestinal factors could be causative in the deficient responses. Vasoactive intestinal polypeptide-like immunoreactive (VIP-LI) cell numbers are increased in CF and an intimate association with mucous cells is noted suggesting a paracrine relationship. These findings could have implications in the diagnosis, management and aetiology of CF.
Atrophy↗
Somatostatin-immunoreactive cells in the gastro-entero-pancreatic endocrine system of Xenopus laevis.
Somatostatin-like immunoreactivity has been demonstrated in cells of the gastro-entero-pancreatic endocrine system of Xenopus laevis (Amphibia) using peroxidase-anti-peroxidase immunohistochemistry. The identified cells of the gastro-intestinal tract correspond to the "Open-Paraneurons" of FUJITA (1974). Somatostatin-immunoreactive cells were found in the stomach (fundic and pyloric region), the duodenum and in the anterior ileum, but not in the colon. The dimensions of these 'Somatostatin-Open-Paraneurons' were measured: mean maximum height = 41.31 micron (S.D. = 10.87 micron), mean maximum breadth = 8.73 micron (S.D. = 2.31 micron). Frequency distributions of the maximum height and of the maximum breadth were processed by use of a computer. Somatostatin-immunoreactive cells in the pancreatic islets occupied about 15 to 25% of the total islets volume. These cells are "Closed-Paraneurons" (according to FUJITA 1974) with a mean diameter of 11.68 micron (S.D. = 2.61 micron).
Animals↗
Regulation of the vitamin D endocrine system located in the kidney.
During the past decade, it has been clearly established that the kidney is an endocrine organ which converts 25-hydroxyvitamin D to the active hormone 1,25-dihydroxyvitamin D. The kidney and intestine are the sites of an alternative hydroxylation which places an 24 hydroxyl in the R position on either 25-hydroxyvitamin D or 1,25-dihydroxyvitamin D. The production of 1,25-dihydroxyvitamin D is stimulated by hypocalcemia through the parathyroid gland, hypophosphatemia, the sex hormones and the peptide hormones insulin and prolactin. This vitamin D based endocrine system is of central importance in regulating calcium and phosphorus metabolism and its disturbances result in a variety of pathological conditions.
Animals↗
Vulnerability of the endocrine system to xenobiotic influence.
Natural sex hormones are most important factors guaranteeing the homeostasis of male and female sexual functions, including sexual differentiation and reproduction. Main target tissues include bone and skin, cardiovascular system, and possibly central nervous and immune systems. In medicine, synthetic hormonal substances with agonistic and antagonistic properties have been widely used for decades. Therapeutic benefit is the aim, and the many possibilities to interfere with normal or pathological hormonal situations are rather well understood. Synthetic hormonal agonists or (partial) antagonists may exhibit specific affinities to special receptors resulting in a spectrum of organotropies, or they may even induce opposite actions on different targets. Although not a new issue, environmental substances mimicking potentials of sex hormones have recently gained increased attention. There is not need to reinvent the wheel, since most (adverse) effects may be revealed with today's routine procedures used for testing medicinal substances, but some additional testing strategies should be included. Adverse effects of ecohormones may preferentially affect systems other than the human organism (assuming lower exposure and possibly lower susceptibility). Nevertheless, this survey is confined to possible alterations in the mammalian organism, since such effects are best understood from numerous experimental studies and clinical trials.
Animals↗
The role of the endocrine system in baboon maternal behavior.
BACKGROUND: Human mothers display a wide range of parenting skills, and although we have gathered a large body of evidence on a variety of factors affecting maternal behavior, we still know relatively little about the physiologic correlates of variation in parental behavior in primates. METHODS: Excreted gonadal and adrenal steroids were measured across parturition in a large sample (n = 89) of group-living female baboons. Maternal behavior data were collected during the first 2 months of infants' life. RESULTS: We found that changes in the excreted sex steroid hormones and cortisol were associated with baboon mothers' infant-directed behaviors. Mothers who displayed more stress-related behaviors, who were also prone to maintain less contact with their infants, had higher postpartum cortisol levels, higher prepartum pregnanediol-3-glucoronide (PdG) levels, and lower postpartum PdG levels. Mothers with higher prepartum cortisol levels showed higher levels of infant-directed affiliative behaviors. CONCLUSIONS: These results point toward the importance of the whole endocrine system as a functional unit in terms of enhancing maternal care in primates. The dramatic physiologic changes occurring across parturition may act, in coordination with the cognitive-experiential system, to help the mother cope with the additional challenges imposed by the newborn.
Animals↗
Cutaneous photosynthesis of vitamin D: an evolutionary highly-conserved endocrine system that protects against environmental hazards including UV-radiation and microbial infections.
Phytoplankton and zooplankton have been producing vitamin D for more than 500 million years. While the function of vitamin D in the physiology of lower non-vertebrate organisms is not well understood, it is known that most vertebrates need vitamin D to develop and maintain a healthy mineralized skeleton. However, recent findings have demonstrated that 1,25(OH)2D, the biologically-active vitamin D metabolite, exerts a multitude of important physiological effects independently of the regulation of calcium and bone metabolism. These new functions of vitamin D include protection against cancer and other diseases in various tissues. In this review, current knowledge of an additional new function of the cutaneous photosynthesis of vitamin D, that has recently emerged, is summarized: the role of vitamin D as an evolutionary highly-conserved endocrine system that protects the skin and other tissues against environmental hazards, including ionizing and UV-radiation, microbial infections and oxidative stress, is discussed.
Endocrine System↗
[Characteristics of the endocrine system in Drosophila melanogaster 1 (2)gl mutants, differing in time of death].
A comparative study of the state of the endocrine system and one of the larval organs, the salivary gland, has been carried out in larvae homozygous for the 1(2)gl gene. They differ in time of death (death at the third larval instar--larval allele, and at the prepupal state--prepupal allele). It is shown that homozygotes for the larval and prepupal allele have underdeveloped prothoracal glands. Corpora allata in homozygotes for the larval allele does not differ from the norm. Corpora allata in homozygotes for the prepupal allele is decreased proportionally to the decrease of prothoracal glands. A decrease of gland size is due to a decrease of the volume of cell but not to their number; this decrease is accompanied by the decrease of their relative DNA content. Salivary glands in homozygotes are reduced and comprise 80% of the normal size in homozygotes for the prepupal allele and 50% for homozygotes for the larval allele. Polyteny level in the salivary gland nuclei is much decreased as compared with the normal level. DNA level is more reduced in larvae homozygous for the larval allele.
Animals↗
Rheumatoid arthritis and juvenile chronic arthritis: the role of the neuro-endocrine system.
Various factors determine the outcome of rheumatoid arthritis and juvenile chronic arthritis. One of these factors is the neuro-endocrine system. In rheumatoid arthritis as well as in juvenile chronic arthritis, alterations of the autonomous nervous system do occur. In polyarticular and systemic juvenile chronic arthritis, during active disease the sensitivity for catecholamines changes. Under these conditions catecholamines cannot inhibit the immune response, which may have negative consequences for the course of the disease. In certain autoimmune animal models defects in the hypothalamus-pituitary-adrenal axis play a role in the pathogenesis of the disease. Studies in rheumatoid arthritis suggest a subtle insufficiency of the hypothalamus-pituitary-adrenal-axis in rheumatoid arthritis. Proinflammatory substances such as Substance P, as well as (locally produced) opioids may contribute to disease activity.
Animals↗
Correlation of mechanistic data and histopathology in the evaluation of selected toxic endpoints of the endocrine system.
The objective of this review is to correlate endocrinologic data from mechanistic studies with quantitative histopathology in selected examples of toxic endpoints of the endocrine system in laboratory animals. Mechanistic data can aid in the interpretation of animal toxicology findings and help clarify their significance in risk assessment. Endocrine organs of rodents frequently undergo proliferative changes with advancing age and following chronic exposure to large doses of xenobiotic chemicals, and the sensitivity of rodent endocrine tissues appears to be increasing. Many xenobiotic chemicals in large doses disrupt thyroid function in rodents either by a direct effect on the thyroid influencing synthesis of thyroid hormones or by adversely influencing their peripheral metabolism. A number of chemicals disrupt thyroid function by inhibiting the important enzyme, thyroperoxidase (TPO). A contemporary example of a chemical acting as TPO-inhibitor is sulfamethazine. In short-term mechanistic studies in rats there was a log-dose response relationship in circulating levels of thyroid and pituitary hormones plus a similar non-linear dose-response in morphologic changes in thyroid follicular cells. Endocrinologic data from mechanistic studies and histopathologic/ultrastructural findings will also be presented for the effects of the food color, FDC Red No. 3 (Erythrosine), on the thyroid gland in rats and parathyroid hormone-related protein (a major causative factor in cancer-associated hypercalcemia) on parathyroid chief cells in mice.
Animals↗
Proliferative activity of neuroendocrine tumours of the gastroenteropancreatic endocrine system: DNA flow cytometric and immunohistological investigations.
The proliferative activity of 16 tumour specimens from 13 patients with neuroendocrine tumours of the gastroenteropancreatic endocrine system was studied by DNA flow cytometry and immunohistology for the nuclear Ki67 proliferation antigen. Equivalent results were obtained with both methods, which showed the proliferative activity of gastroenteropancreatic neuroendocrine tumours to be heterogeneous. In four malignant small intestinal carcinoids and one extravisceral carcinoid localised in the retroperitoneum the percentage (index) of proliferating tumour cells as measured by DNA flow cytometry ranged from 2.9 to 36.2% corresponding to low, moderate, or high proliferative activity. In four malignant pancreatic endocrine tumours and their metastases indices ranged from 8.7 to 18.3%, corresponding to low, moderate, or high proliferative activity. In four benign pancreatic endocrine tumours indices ranged from 4.3 to 7.7%, all corresponding to low proliferative activity. This heterogeneity of proliferative activity may in part explain the heterogeneous results reported of chemotherapy treatment. As chemotherapy of tumours is largely affected by favourable cell cycling kinetics, individual diagnostic investigations of the proliferative activity of these neuroendocrine tumours may be of value for identifying patients suitable for this treatment.
Adult↗
Effect of domestically-made levonorgestrel-releasing intrauterine device on the endocrine system and menstruation in monkeys.
Effect of domestically-made levonorgestrel-releasing intrauterine device (LNG, release rate, 6 micrograms/day) on the endocrine system and menstruation in monkeys was investigated. The results showed that the Estradiol (E2) and progesterone (P) levels were significantly decreased 2 ovulatory cycles after insertion of the devices as compared with those before insertion in 3 monkeys (P > 0.001), suggesting an evident ovulation-suppressing effect. In 1 monkey, the E2 and P levels were the same before and after insertion, and expulsion of device was found in the monkey later. The plasma LNG concentration in 3 animals was 493.69-454.60 pg/ml and plasma LNG was not detected in 1 monkey. The hormone level returned to normal level after removal of the devices.
Animals↗
In vitro comparison of the vitamin D endocrine system in 1,25(OH)2D3-responsive and -resistant melanoma cells.
We studied effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], its analog seocalcitol (EB 1089), and 25-hydroxyvitamin D3 [25(OH)D3], on the growth of seven melanoma cell lines. While three cell lines (MeWo, SK-Mel-28, SM) responded to antiproliferative effects of active vitamin D analogs, the others (SK-Mel-5, SK-Mel-25, IGR, MeUuso) were resistant. A strong induction (7000-fold) of 1,25-dihydroxyvitamin D-24-hydroxylase (24OHase, CYP24) mRNA was detected in responsive cell lines along with 1,25(OH)2D3-treatment, indicating functional integrity of vitamin D receptor (VDR)-mediated transcription. In contrast, induction of 24OHase was much lower in resistant melanoma cells (70-fold). VDR mRNA was induced up to 3-fold both in responsive and resistant cell lines along with 1,25(OH)2D3-treatment. RNA for vitamin D-activating enzymes vitamin D-25-hydroxylase (25OHase, CYP27A1) and 25-hydroxyvitamin D-lalpha-hydroxylase (lalphaOHase, CYP27B1) was detected in all melanoma cell lines analyzed, additionally we show splicing variants of lalphaOHase in SK-Mel-28 cells. Expression of 250Hase and laOHase was marginally modulated along with treatment. Proliferation of melanoma cells was not inhibited by treatment with 25(OH)D3, indicating no significant stimulation of endogeneous production of antiproliferative acting 1,25(OH)2D3. In conclusion, we characterize the vitamin D endocrine system in melanoma cells and demonstrate that the majority of melanoma cell lines analyzed is resistant to antiproliferative effects of 1,25(OH)2D3. It can be speculated that these alterations are of importance for pathogenesis and growth of metastasizing malignant melanoma. Additionally, our findings indicate that only a minority of cases with metastasizing melanoma may represent a promising target for palliative treatment with new vitamin D analogs that exert little calcemic side effects or for pharmacological modulation of 1,25(OH)2D3-synthesis/metabolism.
25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
Cyclic hormonogenesis in gray collie dogs: interactions of hematopoietic and endocrine systems.
Cortisol, ACTH, T4, and T3 concentrations were determined in six cyclic hematopoietic (CH) dogs to determine if hormonal cycles were a feature of this hematopoietic disorder. It was determined that there were 12- to 14-day cycles of these hormones in CH dogs. Plasma cortisol and ACTH concentrations peaked 4-8 days after the onset of neutropenia and were concurrent with peak neutrophil counts. The peak ACTH concentration occurred 1-2 days before or concurrent with the cortisol peak concentration. T4 and T3 peak concentrations were opposite the cortisol cycles, and maximal concentrations were seen when cortisol levels were lowest. ACTH, GH-releasing factor and TRH response tests were performed in the CH dogs. No frank deficiencies in hormone production were seen with the ACTH, GH-releasing factor, and TRH responses in CH dogs relative to those in normal dogs. It was concluded that cyclic hormonogenesis is a central feature of CH disease. These findings are the first demonstration of extrahematopoietic system cyclicity in this rare disease and suggest the presence of common regulatory factors in the hematopoietic and endocrine systems.
Adrenocorticotropic Hormone↗