scholarly journals Alteration of thyroid hormone secretion after long-term exposure to low doses of endocrine disruptor DDT

2014 ◽  
Vol 60 (6) ◽  
pp. 655-660 ◽  
Author(s):  
N.V. Yaglova ◽  
V.V. Yaglov
Keyword(s):  
Thyroid Hormone ◽  
Hormone Secretion ◽  
Thyroid Peroxidase ◽  
Low Doses ◽  
Male Wistar Rats ◽  
Total Thyroxine ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Exogenous Substances

Endocrine disruptors are exogenous substances that exhibit hormone-like action and consequently disrupt homeostatic action of endogenous hormones. DDT is the most common disruptor. The objective was to evaluate changes in thyroid hormone secretion after long-term exposure to low doses of DDT. The experiment was performed on male Wistar rats. The rats were given DDT at doses of 1.89±0.86 мg/kg/day and 7.77±0.17 мg/kg/day for 6 and 10 weeks. Dose dependent increase of serum total thyroxine, total triiodthyronine, and thyroid peroxidase was revealed after 6 weeks exposure. After 10 weeks free thyroxine secretion was reduced. Such alterations of the thyroid status are typical for iodine deficient goiter. The data obtained indicate that the main mechanism of DDT action includes disruption of thyroxine secretion by thyrocytes, but not inhibition of deiodinase activity and decrease of blood thyroid binding proteins.

Evaluation of the Laxative activity of Saponin Enriched Hydroethanolic Pericarp extract of Sapindus emarginatus in Animal models

2020 ◽  
Vol 16 ◽  
Author(s):  
Lalitha Vivekanandan ◽  
Roxanne Gekonge Mandere ◽  
Sivakumar Thangavel
Keyword(s):  
Animal Models ◽  
Gravimetric Analysis ◽  
Triterpene Saponins ◽  
Laxative Effect ◽  
Saponin Content ◽  
The Family ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Efficacious Drug

Background: Constipation is a common, predominant, chronic gastrointestinal functional disorder. The drugs available to treat constipation are limited because of their side effects in long term use. So we need of efficacious drug to treat constipation. Sapindus emarginatus Vahl belongs to the family Sapindaceae, commonly known as soapnut. Traditionally used for the antipruritic, antifertility, constipation, and anti-inflammatory agents. Objective: The present study was undertaken to evaluate the laxative activity of hydroethanolic pericarp extract of Sapindus emarginatus (HESE) in animal models. Methods: The saponin content in extract was measured by gravimetric analysis. The laxative activity of hydroethanolic pericarp extract of Sapindus emarginatus is evaluated by the weight of feces matter, charcoal meal hyperperistalsis test, and loperamide induced constipation model. Results: The saponin content of the soapnut pericarp was 13.48 % and the extract was found to be 11.92 %. The results obtained from these models showed a significant dose-dependent increase in fecal weight, peristalsis index, and moisture content compared to control animals. Conclusion: The present study concluded that the oral administration of HESE showed a significant laxative activity by using different animal models. The presence of triterpene saponins is responsible for this activity. Further studies are needed to confirm their mechanism behind the laxative effect. The administration of extract was found to be a valid candidate in constipation therapy.

POTENTIAL DIURETIC EFFECT OF CURCUMA AMADA ROXB. RHIZOME EXTRACTS

INDIAN DRUGS ◽  
2013 ◽  
Vol 50 (04) ◽  
pp. 34-38
Author(s):  
P Bommannavar ◽  
◽  
K. Patil
Keyword(s):  
Aqueous Extract ◽  
Urine Volume ◽  
Control Group ◽  
Aqueous Extracts ◽  
Diuretic Activity ◽  
Curcuma Amada ◽  
Male Wistar Rats ◽  
Total Urine ◽  
Dose Dependent Increase ◽  
Dose Dependent

The present study was undertaken to establish the diuretic activity of alcoholic and aqueous extract of dried rhizomes of Curcuma amada Roxb in rats. Alcoholic and aqueous extracts of rhizomes were administered to experimental male Wistar rats orally at doses of 250 and 500 mg/kg and compared with furosemide (10 mg/kg) as the reference standard. The parameters measured for diuretic activity were total urine volume, urine electrolyte concentration such as sodium, potassium and chloride have been evaluated. The rats treated with alcoholic and aqueous extract of Curcuma amada in a dose of 250 and 500 mg/kg showed higher urine output when compared to the respective control. Both alcoholic and aqueous extracts have showed a significant dose-dependent increase in the excretion of electrolytes when compared to the control group. The result indicates that alcoholic and aqueous extract is an effective natriuretic and kaliuretic diuretic, which supports the traditional claim about the Curcuma amada Roxb being used as diuretics.

Central effect of endothelin on blood pressure in conscious rats

1989 ◽  
Vol 256 (6) ◽  
pp. H1747-H1751 ◽  
Author(s):  
Y. Ouchi ◽  
S. Kim ◽  
A. C. Souza ◽  
S. Iijima ◽  
A. Hattori ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Conscious Rats ◽  
Arterial Blood ◽  
Norepinephrine Concentration ◽  
Artificial Cerebrospinal Fluid ◽  
Male Wistar Rats ◽  
The Mean ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Lateral Cerebral Ventricle

This study was conducted to investigate the effect of intracerebroventricular administration of endothelin (EDT), a novel potent vasoconstricting peptide, on blood pressure in conscious rats. The lateral cerebral ventricle of male Wistar rats was cannulated, and the femoral artery was also cannulated to measure the mean arterial blood pressure (MABP) and heart rate (HR). EDT dissolved in 10 microliters of artificial cerebrospinal fluid (ACSF) (8.25-66 pmol icv) provoked a dose-dependent increase in MABP. EDT also increased HR, although the effect of 66 pmol was variable. Intracerebroventricular ACSF did not provoke any effects on MABP and HR. Intracerebroventricular EDT also provoked contralateral rotational behavior. Pretreatment with 2 mg/kg iv phenoxybenzamine significantly suppressed the 16.5 pmol icv EDT-induced increase in MABP. Moreover, 16.5 pmol icv EDT markedly increased plasma epinephrine and norepinephrine concentration. These results indicate that EDT has a central pressor action, and the action might be mediated, at least in part, by catecholamine release to the periphery. EDT might play a role in the central control of blood pressure, although the physiological implications have not yet been determined.

scholarly journals Melamine disrupts spatial reversal learning and learning strategy via inhibiting hippocampal BDNF-mediated neural activity

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245326
Author(s):  
Wei Sun ◽  
Yuanhua Wu ◽  
Dongxin Tang ◽  
Xiaoliang Li ◽  
Lei An
Keyword(s):  
Cognitive Flexibility ◽  
Reversal Learning ◽  
Neural Activity ◽  
Learning Strategy ◽  
Learning Deficits ◽  
Place Strategy ◽  
Dependent Learning ◽  
Dose Dependent Increase ◽  
Dose Dependent

Although several studies showed adverse neurotoxic effects of melamine on hippocampus (HPC)-dependent learning and reversal learning, the evidence for this mechanism is still unknown. We recently demonstrated that intra-hippocampal melamine injection affected the induction of long-term depression, which is associated with novelty acquisition and memory consolidation. Here, we infused melamine into the HPC of rats, and employed behavioral tests, immunoblotting, immunocytochemistry and electrophysiological methods to sought evidence for its effects on cognitive flexibility. Rats with intra-hippocampal infusion of melamine displayed dose-dependent increase in trials to the criterion in reversal learning, with no locomotion or motivation defect. Compared with controls, melamine-treated rats avoided HPC-dependent place strategy. Meanwhile, the learning-induced BDNF level in the HPC neurons was significantly reduced. Importantly, bilateral intra-hippocampal BDNF infusion could effectively mitigate the suppressive effects of melamine on neural correlate with reversal performance, and rescue the strategy bias and reversal learning deficits. Our findings provide first evidence for the effect of melamine on cognitive flexibility and suggest that the reversal learning deficit is due to the inability to use place strategy. Furthermore, the suppressive effects of melamine on BDNF-mediated neural activity could be the mechanism, thus advancing the understanding of compulsive behavior in melamine-induced and other neuropsychiatric disorders.

Pituitary responses of seasonally anoestrous ewes to long-term continuous infusion of low doses of GnRH

1989 ◽  
Vol 49 (1) ◽  
pp. 95-102 ◽  
Author(s):  
M. Khalid ◽  
W. Haresign ◽  
M. G. Hunter ◽  
B. J. McLeod
Keyword(s):  
Pituitary Gland ◽  
Continuous Infusion ◽  
Dose Level ◽  
Gnrh Receptor ◽  
Low Doses ◽  
Osmotic Pumps ◽  
Gonadotrophin Releasing Hormone ◽  
Pre Treatment ◽  
Dose Dependent

ABSTRACTThe response to long-term continuous infusion of gonadotrophin releasing hormone(GnRH)was monitored in progesterone-treated seasonally anoestrous ewes. Using osmotic pumps, groups of five ewes eachreceived 0(controls),125, 250, 500 or 1000 ng GnRH per h subcutaneously for a period of 21 days. Bloodsamples were collecte dat 30-minintervals from 6 h before until 24 h after the start of treatment and then for 8-h periods on days 2, 8, 15 and 21. After 21 days of treatment all the ewes were slaughtered to determine pituitary GnRH receptor numbers. Continuous infusion of GnRH resulted in a short-lived (2day)increase in plasma LH and oestradiol concentrations after which they were not different from the pre-treatment values. Over the later period of treatment when the pituitary gland was not responding to the exogenous GnRH(days 8, 15 and 21), LH episodes(presumably due to endogenous GnRH secretion fromthe hypothalamus) were observed. Continuous infusion of GnRH was also associated with a suppression in plasma FSH concentrations, the duration of which was dose-dependent. Only at the highest GnRH dose level(1000 ng/h)was there a significant reductionin pituitary GnRH receptor content.

Effect of atropine on pancreatic response to HCl and secretin

1981 ◽  
Vol 240 (5) ◽  
pp. G376-G380 ◽  
Author(s):  
M. V. Singer ◽  
T. E. Solomon ◽  
H. Rammert ◽  
F. Caspary ◽  
W. Niebel ◽  
...  
Keyword(s):  
Atropine Sulfate ◽  
Secretory Response ◽  
Low Doses ◽  
Cholinergic Activity ◽  
Pancreatic Fistulas ◽  
High Doses ◽  
Protein Response ◽  
Dose Dependent Increase ◽  
Protein Output ◽  
Dose Dependent

In dogs with gastric and pancreatic fistulas, we studied the effect of atropine on the pancreatic secretory response to secretin and intestinal HCl. Atropine sulfate (20 micrograms.kg-1.h-1 iv) significantly depressed basal bicarbonate and protein output. Atropine depressed bicarbonate responses to low doses (62.5, 125, 250, and 500 ng.kg-1.h-1) of secretin but had no significant effect on responses to high doses (1,000 and 2,000 ng.kg-1.h-1). Secretin, with or without atropine, did not stimulate pancreatic protein output above basal. Atropine depressed bicarbonate responses to low loads (3, 6, and 12 mmol.h-1) of HCl but had no significant effect on responses to high loads (12, 24, and 48 mmol.h-1). Intraduodenal HCl produced a dose-dependent increase in protein output. Atropine abolished protein responses to low loads (3 and 6 mmol.h-1) but did not affect responses to high loads (24 and 48 mmol.h-1) of HCl. These findings are compatible with the hypotheses that a) endogenous cholinergic activity augments the pancreatic bicarbonate response to secretin, and b) the pancreatic protein response to intraduodenal HCl is, at least in part, mediated cholinergically.

scholarly journals No dose-dependent increase in fracture risk after long-term exposure to high doses of retinol or beta-carotene

2012 ◽  
Vol 24 (4) ◽  
pp. 1285-1293 ◽  
Author(s):  
G. L. Ambrosini ◽  
A. P. Bremner ◽  
A. Reid ◽  
D. Mackerras ◽  
H. Alfonso ◽  
...  
Keyword(s):  
Fracture Risk ◽  
Beta Carotene ◽  
High Doses ◽  
Dose Dependent Increase ◽  
Dose Dependent

LONG-TERM CONTROL OF THYROTOXICOSIS WITH THE BETA-BLOCKER SOTALOL - A MODEL OF UNTREATED HYPERTHYROIDISM?

1978 ◽  
Vol 87 (4) ◽  
pp. 734-742 ◽  
Author(s):  
Peter Wahlberg ◽  
Sten-Anders Carlsson
Keyword(s):  
Thyroid Hormone ◽  
Thyroid Function ◽  
Beta Blocker ◽  
Clinical Symptoms ◽  
Symptom Control ◽  
Hormone Secretion ◽  
Antithyroid Drugs ◽  
Beta Blockade ◽  
Trh Stimulation

ABSTRACT Five patients with hyperthyroidism and no goitre were treated only by beta blockade with sotalol. All but one became clinically euthyroid, although the thyroid hormone values in their sera remained high. The TSH response to intravenous TRH remained absent. One patient had fluctuating thyroid hormone values, one has had borderline values for 20 months, one had a hormonal recovery within 6 months, one became clinically thyrotoxic and was switched to carbimazole, and one who had first been treated with carbimazole and had a relapse of high hormone values at 3 months and of clinical symptoms within 9 months after cessation of carbimazole treatment became clinically euthyroid with beta blockade. Sotalol offers a symptom control of hyperthyroidism without lowering the thyroid function, and thus makes it possible to study the long-term hormonal pattern of hyperthyroidism without suppression of thyroid hormone secretion. The results show that the course of hyperthyroidism may vary in duration and pattern. TRH stimulation may cause none or a small TSH response even when the disease is in hormonal remission. The cause of this phenomenon is discussed. The duration of hyperthyroidism cannot be forecast by present methods, and this should be borne in mind when patients are treated with antithyroid drugs for this disorder.

Interleukin 6 inhibits human thyroid peroxidase gene expression

1991 ◽  
Vol 124 (3) ◽  
pp. 290-294 ◽  
Author(s):  
Tan Tominaga ◽  
Shunichi Yamashita ◽  
Yuji Nagayama ◽  
Shigeki Morita ◽  
Naokata Yokoyama ◽  
...  
Keyword(s):  
Gene Expression ◽  
Interleukin 6 ◽  
Interleukin 1 ◽  
Hormone Secretion ◽  
Interferon Γ ◽  
Human Thyroid ◽  
Thyroid Peroxidase ◽  
Dependent Manner ◽  
Human Thyroid Peroxidase ◽  
Dose Dependent

Abstract. It has been reported that cytokines, especially interleukin 1 and interferon-γ, inhibit the thyroid hormone secretion and the gene expression of human thyroid peroxidase and thyroglobulin. Interleukin 6 has recently been found to be an important cytokine for the regulation of immunoendocrine interaction and intrathyroidal production of interleukin 6 has been reported. Therefore, we investigated the regulation of thyroid hormone secretion and thyroid peroxidase messenger RNA by interleukin 6 in human thyrocytes to clarify further the functional role of interleukin 6 in thyroid glands. Thyrocytes dispersed from Graves' thyroid tissues were incubated with TSH with or without interleukin 6. TSH (5 U/l stimulated the expression of thyroid peroxidase mRNA transcripts (4.0, 3.2, 2.1, and 1.7 kb, respectively), although unstimulated thyrocytes contained the low level of 3.2 kb thyroid peroxidase mRNA transcript. Interleukin 6 (104-105 U/l) inhibited TSH-induced thyroid peroxidase mRNA in a dose-dependent manner, although the basal level of thyroid peroxidase mRNA expression was not suppressed by interleukin 6. Interleukin 6 also inhibited 8-bromo-cyclic adenosine monophosphate-induced thyroid peroxidase mRNA levels. In contrast, the γ-action mRNA hybridization signal was not altered in control or treated cells. Subsequently, interleukin 6 inhibited TSH-induced T3 secretion in a dose-dependent manner after 72 h treatment. However, interleukin 6 did not affect DNA synthesis. Pretreatment with specific antibody against interleukin 6 selectively restored the inhibitory effect of interleukin 6 on thyroid peroxidase gene expression. Our results suggest that interleukin 6 plays an inhibitory role in the thyroid gland, in addition to interleukin 1 and interferon γ.

scholarly journals Honeybee colonies compensate for pesticide-induced effects on royal jelly composition and brood survival with increased brood production

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matthias Schott ◽  
Maximilian Sandmann ◽  
James E. Cresswell ◽  
Matthias A. Becher ◽  
Gerrit Eichner ◽  
...  
Keyword(s):  
Royal Jelly ◽  
Brood Production ◽  
Initiation Rate ◽  
Term Survival ◽  
Individual Level ◽  
Sublethal Doses ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Colony Level

AbstractSublethal doses of pesticides affect individual honeybees, but colony-level effects are less well understood and it is unclear how the two levels integrate. We studied the effect of the neonicotinoid pesticide clothianidin at field realistic concentrations on small colonies. We found that exposure to clothianidin affected worker jelly production of individual workers and created a strong dose-dependent increase in mortality of individual larvae, but strikingly the population size of capped brood remained stable. Thus, hives exhibited short-term resilience. Using a demographic matrix model, we found that the basis of resilience in dosed colonies was a substantive increase in brood initiation rate to compensate for increased brood mortality. However, computer simulation of full size colonies revealed that the increase in brood initiation led to severe reductions in colony reproduction (swarming) and long-term survival. This experiment reveals social regulatory mechanisms on colony-level that enable honeybees to partly compensate for effects on individual level.

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