INVESTIGADORES
GIRONACCI Mariela Mercedes
congresos y reuniones científicas
Título:
Angiotensin-(1-7) downregulates tyrosine hydroxylase in neurons from spontaneuosly hypertensive rats
Autor/es:
LOPEZ VERRILLI, M. ALEJANDRA, GIRONACCI, MARIELA
Lugar:
Miami, USA
Reunión:
Congreso; XVIIth Scientific Sessions of the Inter-American Society of Hypertension; 2007
Institución organizadora:
Inter-American Society of Hypertension
Resumen:
TitleAngiotensin-(1-7) downregulates tyrosine hydroxylase in neurons from spontaneuosly hypertensive rats Authors M. ALEJANDRA, LOPEZ VERRILLI; MARIELA M. GIRONACCI. Dpto. Química Biológica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina.   Background Release of norepinephrine (NE) by hypothalamic nuclei contributes to regulation of blood pressure by altering sympathetic nervous system activity. It has been demonstrated that angiotensin (Ang) II enhances sympathetic outflow and produces sympathetic hyperactivity in hypertension. It has been suggested that the renin-angiotensin system may counteract  pressor effects of Ang II by Ang-(1-7) generation, an antihypertensive component of this system. We  have determined that, in contrast to Ang II, Ang-(1?7) reduces NE release in isolated hypothalami from spontaneously hypertensive rats(SHR) and in this way it may decrease sympathetic activity.   Objective Since we have previously showed that Ang-(1-7) decreases NE release and that this effect may be correlated with a diminished NE synthesis, our aim was to investigate the effect of Ang-(1?7) on tyrosine hydroxilase (TH) activity and expression at the central level. TH catalyzes the first and rate-limiting step in cathecolamines biosynthesis: the convertion of L-tyr into L-DOPA and water.   Methods TH activity was measured in isolated hipothalami from 3-month-old WKY and SHR rats by the release of tritiated water from 3H-L-tyrosine. TH expression was determined by western blot in primary neuronal cultures from hipothalami of one-day-old normotensive controls (WKY) and SHR rats. Noradrenergic neurons were characterized by double labeling immunocytochemistry  using a specific anti-neuron and an anti-TH antibodies.   Results Basal TH activity was significantly higher in hypothalami from SHR than from WKY (P