Pituitary Contents of Beta-Endorphin, Dynorphin, Substance P, Cholecystokinin and Somatostatin in Rats with Streptozotocin-lnduced Diabetes

Tang, Florence; Wong, Rachel P.P.

doi:10.1159/000109172

Cited by 5 publications

(8 citation statements)

References 23 publications

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“…There were decreases in body weights and increases in serum glucose levels in STZ-diabetic rats as reported previously from our laboratory [18,21] . The high serum glucose levels in the insulin-treated STZ-diabetic rats have been explained before [18] as due to the wearing off of the effect of the last insulin injection which had been made on the afternoon before the day of killing.…”

Section: Discussionsupporting

confidence: 86%

Adrenomedullin Gene Expression and Peptide Levels in the Heart and Blood Vessels of Streptozotocin-diabetic Rats

Tang

Hwang²,

Wong³

et al. 2007

Horm Metab Res

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The aim of the present study was to assess the changes in gene expression and peptide adrenomedullin (AM) levels in cardiovascular and other tissues in the streptozotocin-diabetic rats. For this purpose, diabetes was induced by intraperitoneal injection of streptozotocin (STZ, 65 mg/Kg body weight). Half of the diabetic rats were subcutaneously injected with insulin in the afternoon (4 units/day) one week after STZ injection until the day before killing. Control rats received only saline injection. AM mRNA was determined in cardiovascular and other tissues of streptozotocin-diabetic rats using solution-hybridization-RNase protection assay. Circulating AM and peptide AM in cardiovascular and other tissues were estimated using a specific radioimmunoassay. There were increases in preproAM mRNA levels in the left and right ventricles and in the thoracic aorta in both the 2-week and 4-week diabetic rats, but not in the two atria, the mesenteric artery and the lung. In the 2-week diabetic rats, there were decreases in AM contents in the two atria and the lung but an increase in the thoracic aorta. In the 4-week diabetic rats, there were bigger decreases in the atria and also a decrease in the left ventricle. The plasma AM levels were not changed but there was an increase in the excretion of AM in the urine. Our results suggest a possible increase in AM release in the heart and the thoracic aorta in the 2-week and 4-week diabetic rats.

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Section: Discussionsupporting

confidence: 86%

Adrenomedullin Gene Expression and Peptide Levels in the Heart and Blood Vessels of Streptozotocin-diabetic Rats

Tang

Hwang²,

Wong³

et al. 2007

Horm Metab Res

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“…Plasma ANP returned to normal when the rats were rendered normoglycaemic with insulin. It is pertinent to note that blood glucose in the insulin replacement rats were slightly above that in the controls in spite of daily treatment by long acting insulin [15]. Al- though an increase of blood glucose may increase plasma volume and thus also ANP secretion and plasma ANP concentrations, the finding of a normal plasma ANP concentration in rats on insulin replacement (Fig.…”

Section: Discussionmentioning

confidence: 89%

“…Perhaps the atrial cells are more susceptible than ventricular cells to the adverse effects of the lack of insulin or hyperglycaemia with the result that atrial synthesis of ANP is impaired. Another possibility is the effect of glucocorticosteroids which are elevated in STZ rats [15] on ventricular release of ANP. This mediated glucocorticosteroid effect is greater on the ventricle than on the atrium [28].…”

Section: Discussionmentioning

confidence: 99%

Streptozotocin-induced diabetes has differential effects on atrial natriuretic peptide synthesis in the rat atrium and ventricle: a study by solution-hybridization-RNase protection assay

Kwan

Tang

1998

Diabetologia

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Atrial natriuretic peptide (ANP), a 28 amino acid peptide hormone, is mainly synthesized by the atria and heart ventricles and is released in response to acute and chronic extracellular volume expansion. ANP facilitates the excretion of water and sodium and has a vasodilator effect on the blood vessels [1,2]. The release, storage and synthesis of ANP in the heart are intimately linked to changes in intravascular volume and blood pressure [3].Diabetes mellitus may lead to abnormalities in fluid and electrolyte balance and consequently affect blood volume and blood pressure [4]. Alterations in renin-angiotensin-aldosterone system and arginine vasopression (AVP) secretion, the two well-known mechanisms of controlling extracellular fluid volume homeostasis, have been observed both in humans with diabetes mellitus and in rats treated with alloxan [5]. Atrial natriuretic peptide also plays an important role in body fluid and electrolyte balances and in regulating blood pressure [1,2]. Plasma ANP concentrations have been reported to be either increased [6] or normal [7] in Type-I diabetic patients compared with normal subjects. Plasma ANP concentrations in chronic STZ-diabetic rats have also been shown to increase [8,9,10, 11] though unaltered plasma ANP concentrations have been reported [12,13]. It is still not clear whether the increased plasma ANP concentrations are due to increase in cardiac ANP secretion. Therefore, this study was to examine ANP content in the brain, the atria and the ventricles of the heart and the plasma. ANP mRNA expression in the atria and the ventricles were also quantified using solution-hybridization-RNase protection assay. Diabetologia (1998) Summary In rats with streptozotocin (STZ)-diabetes for 2 or 4 weeks, the atrial natriuretic peptide (ANP) concentrations in the atria decreased whilst that of ANP in the plasma and ventricles increased. ANP concentrations in the hypothalamus and in the brainstem did not change in either 2-or 4-week diabetic rats. Atrial ANP content was partly restored by insulin replacement in 4-week diabetic rats. Plasma ANP concentrations and ventricular ANP contents were reversed to normal by insulin treatment in both 2-and 4-week diabetic rats. Solution-hybridization-RNaseprotection assay showed a significant increase in the preproANP mRNA expression in the ventricles but not in the atria. These results indicated that the STZdiabetes increased the synthesis of ANP in the ventricles and consequently its release from the ventricles. The synthesis of ANP in the atria did not change as judged from the preproANP mRNA expression but the release of ANP from the atria might also be increased for ANP content decreased in the atria. The reason for the difference in the response of atrial and ventricular preproANP concentrations to STZ-diabetes is not known. [Diabetologia (1998) 41: 660±665]

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“…Somatostatin is one of the most important regulators of the HPT axis, due to its suppression of TRH and TSH secretion [44,45]. There is evidence that in DM1 somatostatin level can be increased, as shown in human DM1 and in the gastrointestinal tract of nonobese diabetic mice [46][47][48], or can be unchanged or reduced, as demonstrated in rats with STZ-induced DM [49][50][51].…”

Section: Endocrine Researchmentioning

confidence: 99%

The Influence of Intranasal Insulin on Hypothalamic-Pituitary-Thyroid Axis in Normal and Diabetic Rats

et al. 2015

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The functions of hypothalamic-pituitary-thyroid axis are attenuated in type 1 diabetes mellitus due to insulin deficiency. The use of intranasally administered insulin is of considerable interest for treatment of diabetes and cognitive disorders, but its effect on the thyroid system has not been investigated yet. We studied the influence of long-term treatment with intranasal insulin on the hypothalamic-pituitary-thyroid axis of nondiabetic rats and diabetic animals with streptozotocin models of acute and mild type 1 diabetes mellitus. This treatment was carried out for 28 days in acute (daily does of 0.3, 0.6, and 1.5?IU of insulin per rat) and for 135 days in mild diabetes (daily dose of 0.45?IU/rat). Nondiabetic rats were treated in a similar manner. Intranasal insulin in both models of diabetes resulted in the improvement of thyroid status; manifested as increase of thyroid hormones levels and restoration of response to thyroliberin. In acute diabetes, a daily dose of 0.6?IU/rat was the most effective. Twenty eight days treatment of nondiabetic rats with intranasal insulin at a dose of 0.3?IU/rat resulted in a significant increase of free and total thyroxine levels. Longer treatment of rats with mild diabetes and nondiabetic animals significantly increased thyrotropin level. Thus, long-term intranasal insulin treatment restored the hypothalamic-pituitary-thyroid axis function in type 1 diabetes, but led to a significant increase in the thyrotropin level, which must be considered when designing a strategy for the use of intranasal insulin in clinical applications.

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Pituitary Contents of Beta-Endorphin, Dynorphin, Substance P, Cholecystokinin and Somatostatin in Rats with Streptozotocin-lnduced Diabetes

Cited by 5 publications

References 23 publications

Adrenomedullin Gene Expression and Peptide Levels in the Heart and Blood Vessels of Streptozotocin-diabetic Rats

Adrenomedullin Gene Expression and Peptide Levels in the Heart and Blood Vessels of Streptozotocin-diabetic Rats

Streptozotocin-induced diabetes has differential effects on atrial natriuretic peptide synthesis in the rat atrium and ventricle: a study by solution-hybridization-RNase protection assay

The Influence of Intranasal Insulin on Hypothalamic-Pituitary-Thyroid Axis in Normal and Diabetic Rats

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