Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 4 de 4
Filtrar
Más filtros

Banco de datos
Tipo del documento
País de afiliación
Intervalo de año de publicación
1.
Pharmacology ; 89(5-6): 270-4, 2012.
Artículo en Inglés | MEDLINE | ID: mdl-22517235

RESUMEN

Clonidine is an α(2)-adrenergic agonist, historically known to treat high blood pressure. Further studies showed that it could be used in the treatment of neuropsychiatric disorders. Afterwards, it has been reported that clonidine stimulated growth hormone (GH) release in many species including man. Using a transnasal surgery technique in awake sheep that allowed accessing hypothalamopituitary portal vessels, our laboratory previously reported that the injection of clonidine in sheep induced a significant, immediate and short-lasting increase in peripheral GH and portal GH-releasing hormone (GHRH) levels. In this study, we show that the clonidine-induced peripheral GH and portal GHRH increase in sheep appears to be mediated by the tachykinin NK2 receptor.


Asunto(s)
Agonistas alfa-Adrenérgicos/farmacología , Clonidina/farmacología , Hormona Liberadora de Hormona del Crecimiento/metabolismo , Hormona del Crecimiento/metabolismo , Receptores de Neuroquinina-2/metabolismo , Animales , Benzamidas/farmacología , Masculino , Antagonistas del Receptor de Neuroquinina-1 , Piperidinas/farmacología , Quinuclidinas/farmacología , Receptores de Neuroquinina-1/metabolismo , Receptores de Neuroquinina-2/antagonistas & inhibidores , Ovinos
2.
J Agric Food Chem ; 54(15): 5643-50, 2006 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-16848558

RESUMEN

The specific effects of heat treatment and/or addition of low/high-methylated pectin (LMP/HMP) on the allergenicity of beta-lactoglobulin (beta-Lg) and its hydrolysis products were investigated through a two-step in vitro digestion approach. beta-Lg was first hydrolyzed by pepsin and then by a trypsin/chymotrypsin (T/C) mixture done in a dialysis bag with a molecular weight cutoff of 1000. The protein digestion was followed by SDS-PAGE electrophoresis performed on each digestion product, and their in vitro allergenicity was analyzed by immunoblotting. Such procedure was applied on beta-Lg samples mixed with the two kinds of pectin before or after heating (80 degrees C, 25 min) to determine the respective impact of heat treatment and pectin addition. Heat denaturation improved significantly the susceptibility of beta-Lg against the pepsin and the T/C. This effect, which was coupled to a reduction in immunoreactivity of the digested beta-Lg, appeared to be distinctively modulated by LMP and HMP. Through nonspecific interaction with the beta-Lg, pectin could reduce the accessibility of cleavage sites and/or epitope sequences. This mechanism of action is discussed in relation to the intra- and intermolecular interactions between beta-Lg and pectin initiated under the experimental conditions.


Asunto(s)
Alérgenos/inmunología , Calor , Lactoglobulinas/inmunología , Pectinas/farmacología , Quimotripsina/metabolismo , Hipersensibilidad a los Alimentos , Hidrólisis , Lactoglobulinas/química , Lactoglobulinas/metabolismo , Metilación , Tamaño de la Partícula , Pectinas/química , Pepsina A/metabolismo , Desnaturalización Proteica , Tripsina/metabolismo
3.
J Agric Food Chem ; 52(2): 355-60, 2004 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-14733521

RESUMEN

This paper deals with the influence of different levels of three pectins, low-methylated pectin (LMP), high-methylated pectin (HMP), and low-methylated and amidated pectin (LMA), on the in vitro gastric hydrolysis of beta-lactoglobulin (beta-lg). Proteolysis by pepsin consisted of a 2-h progressive reduction of pH. A turbidity measurement of beta-lg-pectin mixtures was carried out during the proteolysis. The influence of pectins on pepsin enzymatic activity was also evaluated. beta-Lg was resistant to peptic digestion. The presence of each of the three pectins at a concentration of 50 wt % increased the N release at all pH values considered, despite a significant inhibition of the pepsin enzymatic activity with the pectins. The turbidity of beta-lg solutions during proteolysis was reduced by the addition of pectins, because of the formation of electrostatic complexes between this protein and pectins. The increase of N release could be a false positive result due to the difficulty of precipitating protein by trichloroacetic acid because of the formation of electrostatic complexes demonstrated by the decrease of turbidity.


Asunto(s)
Lactoglobulinas/metabolismo , Pectinas/farmacología , Pepsina A/metabolismo , Concentración de Iones de Hidrógeno , Hidrólisis , Lactoglobulinas/química , Metilación , Nefelometría y Turbidimetría , Pectinas/química , Pepsina A/antagonistas & inhibidores , Electricidad Estática
4.
Peptides ; 35(1): 60-4, 2012 May.
Artículo en Inglés | MEDLINE | ID: mdl-22450468

RESUMEN

Substance P is ubiquitous undecapeptide belonging to the tachykinins family. It has been found in the hypothalamus and is involved in the hypothalamo-hypophysial axis in several mammals, including human. Previous studies have shown that substance P increases GH secretions in rats and human. In this study, we have shown that intravenously infused substance P in sheep caused an increased level of Growth Hormone (GH) and GH-Releasing Hormone (GHRH), and decreased Somatotropin Release Inhibiting Hormone (SRIH) secretions. GH was obtained from peripheral blood. GHRH and SRIH were directly collected from hypophysial portal blood, using a trans-nasal surgery technique in a vigil sheep that allowed accessing to hypothalamo-hypophysial portal vessels. Hormones assays were performed by radioimmunoassay (RIA). Moreover, we showed that substance P-induced GH and GHRH secretion appears to be mediated by NK2 tachykinin receptors, since it is specifically blocked by a non peptidic tachykinin NK2 receptor antagonist (SR48968, Sanofi, Montpellier, France) whereas a non peptidic tachykinin NK1 antagonist (SR140333, Sanofi, Montpellier, France) failed to modify GH and GHRH hormones secretions.


Asunto(s)
Hormona Liberadora de Hormona del Crecimiento/metabolismo , Hormona del Crecimiento/metabolismo , Receptores de Neuroquinina-2/metabolismo , Sustancia P/fisiología , Animales , Benzamidas/farmacología , Hormona del Crecimiento/sangre , Hormona Liberadora de Hormona del Crecimiento/sangre , Masculino , Piperidinas/farmacología , Quinuclidinas/farmacología , Receptores de Neuroquinina-2/antagonistas & inhibidores , Ovinos , Somatostatina/sangre , Somatostatina/metabolismo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA