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At least 253 records · Page 14Linked to original sources
PubMed1983

Toxicity of sodium bromide in rats: effects on endocrine system and reproduction.

Bromide has a low acute oral toxicity, with LD50 values in rodents ranging from 3500 to 7000 mg/kg body weight. It is rapidly absorbed and steady-state serum levels have been reached in rats within 4 weeks. The biological half-life of bromide, and consequently the serum levels, are strongly dependent on chloride intake. Feeding of sodium bromide to rats for 90 days in concentrations of 0, 75, 300, 1200, 4800 and 19,200 mg/kg diet led to a complex of changes in the endocrine system, thyroid activation being the most prominent. Furthermore, in the highest dose groups a decrease in spermatogenesis in the testes and decreased secretory activity of the prostate or a reduction in the number of corpora lutea in the ovaries were found. A three-generation reproduction study of the same dietary concentrations showed in the two highest dose groups a decrease in fertility which appeared to be reversible upon bromide withdrawal. Macroscopically, no changes in the offspring were observed. From these studies a no-effect level for bromide ion of 240 mg/kg diet was determined, corresponding to a tentative Acceptable Daily Intake (ADI) of 0.12 mg/kg body weight. This is in good agreement with a preliminary ADI of 0.1 mg/kg established in an experiment with human volunteers, but is considerably lower than the ADI of 1 mg/kg estimated by FAO/WHO. It is suggested that bromide exerts an inhibitory effect on the thyroid, resulting in an increased hormonal stimulation of this organ by the pituitary gland.

Absorption↗
PubMed2001

[Nicotine and endocrine system in women].

Cigarette smoking continues to be one of the world's most important substance abuse problems. The widespread and persistent use of cigarettes is caused by the addictiveness of nicotine. A variety of human and animal studies have shown that nicotine can induce changes in hormonal balance in women. A clear understanding of the pharmacokinetics and metabolism of nicotine may support changes in smoking behavior and exposure to tobacco toxins in women and may aid in the development of nicotine replacement products for smoking cessation. This review examines the present state of knowledge concerning the effects of nicotine on the female endocrine system. The first part of this article briefly summarizes recent findings from studies on nicotine metabolism. The second and third parts provide an overview of nicotine effects on hormone levels and the functional consequences of these effects in non-pregnant and pregnant women. In the final part, the influence of hormonal factors and pregnancy on metabolism and the pharmacological effects of nicotine are discussed.

Adult↗
PubMed1994

Trypanosoma cruzi: histopathology of endocrine system in immunocompromised mice.

Naturally immunocompromised athymic mice, neonatal mice and adult outbred OFI mice treated with the immunosuppressive agents cyclophosphamide (CY), dexamethasone (DM) and indomethacin (IM) were infected with trypomastigotes of Trypanosoma cruzi Y and CL strains. 10(4) parasites were used, except in the case of IM treatment, where mice received 10(3) trypomastigotes in one group and 10(5) in another. The course of parasitaemia, tissue distribution of amastigotes and time of mortality were compared with an infected thymus intact control group. Neonate and indomethacin treated mice presented the same pattern of parasitaemia. Death occurred as early as 9-10 days after infection. A single dose of CY 200 mg/kg given 5 days after infection enhanced the parasitaemia and increased the number of parasites in the tissues. All groups were similar in terms of colonization of the endocrine system by parasites and the adrenals showed the highest density of amastigotes nests. The thyroid gland (analysed only in neonates) showed intense amastigote accumulation. Colonization of the ovary was observed with amastigotes in both the theca interna and in the stroma. The testes (also examined only in the neonate) showed that the interstitial cells, the tunica albuginea of the seminiferous tubules and the loose connective tissue were infected. Athymic nude mice showed the most intense parasite colonization of the islets of Langerhans.

Adrenal Glands↗
PubMed1997

[Liver metastases from breast cancer 14 years after radical mastectomy; successful treatment with hepatic arterial infusion chemotherapy and systemic endocrine therapy--a case report].

The patient was a 73-year-old woman who was admitted to our hospital for epigastric discomfort and body weight loss. She had undergone radical right mastectomy in March 1982. Ultrasonography and computed tomography revealed multiple tumors in the liver. Three of the tumor markers (CA-125, CA 19-9, and CA 15-3) were positive. US-guided fine needle aspiration biopsy of the liver tumor showed small atypical cells with solid cell nests. Immunohistochemical tests revealed estrogen receptor was positive. We diagnosed the patient as recurrent breast cancer metastatic to liver, 14 years postoperatively. The liver tumors were successfully controlled with the combination of intra-arterial infusion chemotherapy (5-fluorouracil, epirubicin, and mitomycin C) along with systemic endocrine therapy (medroxyprogesterone acetate and fadrozole hydrochloride hydrate).

Aged↗
PubMed2003

Influence of enteric helminths on the distribution of intestinal endocrine cells belonging to the diffuse endocrine system in brown trout, Salmo trutta L.

The presence of intestinal helminths in the alimentary canal of brown trout, Salmo trutta L., can alter the number of cells that synthesize modulatory peptides. A total of 167 brown trout were collected from tributaries of the River Brenta (northern Italy), of which 119 (71.3%) specimens were infected with enteric helminths, 28 with the acanthocephalan Pomphorhynchus laevis Müller, 1776 with intensity of infection ranging from 1 to 162 (18.57 +/- 30.79) worms per host and 67 fish with the cestode Cyathocephalus truncatus Pallas, 1781. Intensity of infection with C. truncatus ranged from 1 to 85 (6.87 +/- 12.59) per fish. In 24 fish there were concurrent infections of both species of helminths. The caecal and middle regions of the intestine were the most heavily parasitized. Immunohistochemical tests showed a decrease in endocrine cells (ECs) of the diffuse endocrine system (DES) positive to gastrin, cholecystokinin-8, bombesin and secretin antisera in the intestine of the infected trout. The number of ECs immunoreactive to anti-glucagon serum did not show differences in the digestive tract of uninfected brown trout and in conspecifics parasitized with P. laevis. The density of cells containing glucagon-like material was low in the fish parasitized with C. truncatus. The results suggest that endoparasitic helminths induce alterations in the DES of infected S. trutta.

Animals↗
PubMed1982

New developments in the vitamin D endocrine system.

Vitamin D must be altered first by 25-hydroxylation in the liver and subsequently by 1-hydroxylation in the kidney in order to stimulate intestinal calcium transport, bone calcium mobilization, intestinal phosphate transport, and renal tubular reabsorption of calcium. Other pathways of vitamin D metabolism are described, and evidence is presented which indicates that only 25- and 1-hydroxylation pathways are activation mechanisms. The 1 alpha-hydroxylation step is regulated by the need for calcium and the need for phosphorus. The vitamin D hormone, 1,25-dihydroxyvitamin D3, appears to act in target tissues by virtue of interacting with a receptor appearing in the nucleus and eliciting transcription of specific genetic information that codes for calcium and phosphorus transport proteins. Diseases of calcium and phosphorus metabolism in which there is a disturbance of the vitamin D endocrine system and the use of the vitamin D metabolites are discussed.

Bone Diseases, Metabolic↗
PubMed1986

Cyclic changes in plasma calcium and the calcium homeostatic endocrine system of the postparturient dairy cow.

Plasma Ca, P, Mg, parathyroid hormone, and 1,25-dihydroxyvitamin D were measured in blood samples taken daily from d 5 before until d 15 to 30 after calving in 28 aged dairy cows (5 yr or older) and 9 first lactation cows. Subnormal plasma Ca concentrations were defined as being below the lower limit (2.18 mmol/L) of the 99% confidence interval for lactating cows outside the month of calving. A parturient minimum in plasma Ca and P concentrations occurred usually within 24 h after calving in all animals. Plasma mineral changes very similar to those at parturition were observed in 50% of the aged cows at one, two, or even three later occasions during the 1st mo postpartum. Interval between subsequent subnormal Ca minima in these Ca-cycling cows was 7 to 10 d. The function of the Ca regulating endocrine systems appeared adequate. Calcium cycling with increased amplitude could be induced by feeding 200 micrograms/d of 1,25-dihydroxyvitamin D3 for about 5 d around parturition (8 animals). The hypocalcemic episode was more pronounced than in untreated cows, and Ca cycling was traced throughout the 1st mo of lactation. Similar treatment also induced Ca cycling in 4 heifers, whereas 8 untreated heifers showed no tendency to Ca cycling in the postparturient period. The hypothesis is put forward that variations in intestinal Ca absorption induced by 1,25-dihydroxyvitamin D3 are the primary cause of the cyclic changes in plasma Ca postpartum of the aged dairy cow.

Aging↗
PubMed2003

Klotho, a gene related to a syndrome resembling human premature aging, functions in a negative regulatory circuit of vitamin D endocrine system.

The klotho gene encodes a novel type I membrane protein of beta-glycosidase family and is expressed principally in distal tubule cells of the kidney and choroid plexus in the brain. These mutants displayed abnormal calcium and phosphorus homeostasis together with increased serum 1,25-(OH)2D. In kl-/- mice at the age of 3 wk, elevated levels of serum calcium (10.9 +/- 0.31 mg/dl vs. 10.0 +/- 0.048 mg/dl in wild-type mice), phosphorus (14.7 +/- 1.1 mg/dl vs. 9.7 +/- 1.5 mg/dl in wild type) and most notably, 1,25-(OH)2D (403 +/- 99.7 mg/dl vs. 88.0 +/- 34.0 mg/dl in wild type) were observed. Reduction of serum 1,25-(OH)2D concentrations by dietary restriction resulted in alleviation of most of the phenotypes, suggesting that they are downstream events resulting from elevated 1,25-(OH)2D. We searched for the signals that lead to up-regulation of vitamin D activating enzymes. We examined the response of 1alpha-hydroxylase gene expression to calcium regulating hormones, such as PTH, calcitonin, and 1,25-(OH)2D3. These pathways were intact in klotho null mutant mice, suggesting the existence of alternate regulatory circuits. We also found that the administration of 1,25-(OH)2D3 induced the expression of klotho in the kidney. These observations suggest that klotho may participate in a negative regulatory circuit of the vitamin D endocrine system, through the regulation of 1alpha-hydroxylase gene expression.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed2006

Pharmacokinetics and systemic endocrine effects of the phyto-oestrogen 8-prenylnaringenin after single oral doses to postmenopausal women.

AIMS: Pre-clinical data suggest that the racemic phyto-oestrogen 8-prenylnaringenin (8-PN) may have beneficial effects in postmenopausal women and may become an alternative to classical hormone replacement therapy (HRT) treatment regimes. The aim of this study was to investigate the pharmacokinetics, endocrine effects and tolerability of chemically synthesized 8-PN in postmenopausal women. METHODS: The study was performed using a randomized, double-blind, placebo-controlled, dose-escalation design with three groups of eight healthy postmenopausal women. In each group six subjects received 8-PN and two subjects placebo. 8-PN was given orally in doses of 50, 250 or 750 mg. Drug concentrations in serum, urine and faeces were measured up to 48 h and follicle-stimulating hormone/luteinizing hormone (LH) concentrations up to 24 h. RESULTS: All treatments were well tolerated and associated with a low incidence of (drug unrelated) adverse events. Serum concentrations of free 8-PN showed rapid drug absorption and secondary peaks suggestive of marked enterohepatic recirculation. Independent of the treatment group, approximately 30% of the dose was recovered in excreta as free compound or conjugates over the 48-h observation period. The first C(max) and AUC(0-48 h) showed dose linearity with ratios of 1 : 4.5 : 13.6 (C(max)) and 1 : 5.2 : 17.1 (AUC). The750- mg dose decreased LH concentrations by 16.7% (95% confidence interval 0.5, 30.2). CONCLUSION: Single oral doses of up to 750 mg 8-PN were well tolerated by postmenopausal women. The pharmacokinetic profile of 8-PN was characterized by rapid and probably complete enteral absorption, high metabolic stability, pronounced enterohepatic recirculation and tight dose linearity. The decrease in LH serum concentrations found after the highest dose demonstrates the ability of 8-PN to exert systemic endocrine effects in postmenopausal women.

Administration, Oral↗
PubMed1984

[Endocrine system of the kidneys in nephrogenic arterial hypertension: functional and morphological analysis].

The renin-angiotensin (juxtaglomerular apparatus--JGA) and prostaglandin [interstitial cells (IC) of renal medulla and nephrocytes of collecting tubules (NCT)] systems of the kidneys were studied in 72 patients (renal biopsies, nephrectomy, morphofunctional correlations) with the nephrogenic arterial hypertension (vasorenal hypertension, chronic glomerulonephritis, pyelonephritis). Histological and electron-microscopic methods were used; the renin activity was determined in the peripheral blood and blood from the renal veins. The results were analysed mathematically and statistically using an original programme. It is shown that stereotype cyclic changes develop in the endocrine renal system of patients with renal hypertension and they reflect the stages of initial hyperfunction (ultrastructural hyperplasia of JGA cells with appearance of numerous immature granules; ultrastructural moderate hyperplasia of medulla IC; increase of blood renin activity), discoordination of functions (progressing JGA hyperfunction and depletion of prostaglandin synthetic function of medulla IC; compensatory activation of NCT; further increase of the blood renin activity) and depletion (atrophy and fibroblastic transformation of the JGA of the majority of nephrons and of medulla IC). The stages of renal endocrine system alterations in the arterial hypertension are the manifestation of compensatory and adaptive response. Morphofunctional analysis with the use of morphometry and mathematical statistics are necessary for the objective evaluation of this response.

Adult↗
PubMedDate not supplied

[The effect of a course of naftusia water intake on the gastroenteropancreatic endocrine system].

Intake of naftusia mineral water influences insulin, glucagon and gastrin secretion measured in patients with chronic acalculous cholecystitis in the following manner: initial low insulin and glucagon, normal gastrin levels rise; initial elevated gastrin and normal glucagon lower at the start of the treatment. The course of naftusia crenotherapy resulted in adaptation to water intake as evidenced by normalization of high gastrin, low glucagon levels in minimal rise of insulin.

Animals↗