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Tyrosine hydroxylase activity in the endocrine pancreas: changes induced by short-term dietary manipulation

BACKGROUND: Tyrosine hydroxylase (TH) activity and its possible participation in the control of insulin secretion were studied in pancreatic islets of adult Wistar rats fed a standard commercial diet (SD) or carbohydrates alone (CHD) for one week. TH activity, norepinephrine (NE) content, and glucos...

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Autores principales: Borelli, María I, Rubio, Modesto, García, María E, Flores, Luis E, Gagliardino, Juan J
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2003
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC153518/
https://www.ncbi.nlm.nih.gov/pubmed/12659644
http://dx.doi.org/10.1186/1472-6823-3-2
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author Borelli, María I
Rubio, Modesto
García, María E
Flores, Luis E
Gagliardino, Juan J
author_facet Borelli, María I
Rubio, Modesto
García, María E
Flores, Luis E
Gagliardino, Juan J
author_sort Borelli, María I
collection PubMed
description BACKGROUND: Tyrosine hydroxylase (TH) activity and its possible participation in the control of insulin secretion were studied in pancreatic islets of adult Wistar rats fed a standard commercial diet (SD) or carbohydrates alone (CHD) for one week. TH activity, norepinephrine (NE) content, and glucose-induced insulin secretion were assessed. Blood glucose and insulin levels were measured at the time of sacrifice. RESULTS: CHD rats had significantly higher blood glucose and lower insulin levels than SD rats (114.5 ± 6.7 vs 80.7 ± 7.25 mg/dl, p < 0.001; 20.25 ± 2.45 vs 42.5 ± 4.99 μU/ml, p < 0.01, respectively). Whereas TH activity was significantly higher in CHD isolated islets (600 ± 60 vs 330 ± 40 pmol/mg protein/h; p < 0.001), NE content was significantly lower (18 ± 1 vs 31 ± 5 pmol/mg protein), suggesting that TH activity would be inhibited by the end-products of catecholamines (CAs) biosynthetic pathway. A similar TH activity was found in control and solarectomized rats (330 ± 40 vs 300 ± 80 pmol/mg protein/h), suggesting an endogenous rather than a neural origin of TH activity. CHD islets released significantly less insulin in response to glucose than SD islets (7.4 ± 0.9 vs 11.4 ± 1.1 ng/islet/h; p < 0.02). CONCLUSIONS: TH activity is present in islet cells; dietary manipulation simultaneously induces an increase in this activity together with a decrease in glucose-induced insulin secretion in rat islets. TH activity – and the consequent endogenous CAs turnover – would participate in the paracrine control of insulin secretion.
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spelling pubmed-1535182003-04-19 Tyrosine hydroxylase activity in the endocrine pancreas: changes induced by short-term dietary manipulation Borelli, María I Rubio, Modesto García, María E Flores, Luis E Gagliardino, Juan J BMC Endocr Disord Research Article BACKGROUND: Tyrosine hydroxylase (TH) activity and its possible participation in the control of insulin secretion were studied in pancreatic islets of adult Wistar rats fed a standard commercial diet (SD) or carbohydrates alone (CHD) for one week. TH activity, norepinephrine (NE) content, and glucose-induced insulin secretion were assessed. Blood glucose and insulin levels were measured at the time of sacrifice. RESULTS: CHD rats had significantly higher blood glucose and lower insulin levels than SD rats (114.5 ± 6.7 vs 80.7 ± 7.25 mg/dl, p < 0.001; 20.25 ± 2.45 vs 42.5 ± 4.99 μU/ml, p < 0.01, respectively). Whereas TH activity was significantly higher in CHD isolated islets (600 ± 60 vs 330 ± 40 pmol/mg protein/h; p < 0.001), NE content was significantly lower (18 ± 1 vs 31 ± 5 pmol/mg protein), suggesting that TH activity would be inhibited by the end-products of catecholamines (CAs) biosynthetic pathway. A similar TH activity was found in control and solarectomized rats (330 ± 40 vs 300 ± 80 pmol/mg protein/h), suggesting an endogenous rather than a neural origin of TH activity. CHD islets released significantly less insulin in response to glucose than SD islets (7.4 ± 0.9 vs 11.4 ± 1.1 ng/islet/h; p < 0.02). CONCLUSIONS: TH activity is present in islet cells; dietary manipulation simultaneously induces an increase in this activity together with a decrease in glucose-induced insulin secretion in rat islets. TH activity – and the consequent endogenous CAs turnover – would participate in the paracrine control of insulin secretion. BioMed Central 2003-03-24 /pmc/articles/PMC153518/ /pubmed/12659644 http://dx.doi.org/10.1186/1472-6823-3-2 Text en Copyright © 2003 Borelli et al; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
spellingShingle Research Article
Borelli, María I
Rubio, Modesto
García, María E
Flores, Luis E
Gagliardino, Juan J
Tyrosine hydroxylase activity in the endocrine pancreas: changes induced by short-term dietary manipulation
title Tyrosine hydroxylase activity in the endocrine pancreas: changes induced by short-term dietary manipulation
title_full Tyrosine hydroxylase activity in the endocrine pancreas: changes induced by short-term dietary manipulation
title_fullStr Tyrosine hydroxylase activity in the endocrine pancreas: changes induced by short-term dietary manipulation
title_full_unstemmed Tyrosine hydroxylase activity in the endocrine pancreas: changes induced by short-term dietary manipulation
title_short Tyrosine hydroxylase activity in the endocrine pancreas: changes induced by short-term dietary manipulation
title_sort tyrosine hydroxylase activity in the endocrine pancreas: changes induced by short-term dietary manipulation
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC153518/
https://www.ncbi.nlm.nih.gov/pubmed/12659644
http://dx.doi.org/10.1186/1472-6823-3-2
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