Expression of Tyrosine Hydroxylase is Negatively Regulated Via Prion Protein.

Cellular prion protein (PrP(C)) is a glycoprotein of the plasma membrane that plays pleiotropic functions by interacting with multiple signaling complexes at the cell surface. Recently, a number of studies have reported the involvement of PrP(C) in dopamine metabolism and signaling, including its interactions with tyrosine hydroxylase (TH) and dopamine receptors. However, the outcomes reported by independent studies are still debatable. Therefore in this study, we investigated the effects of PrP(C) on the TH expression during the differentiation of N2a cells with dibutyryl-cAMP, a well-known cAMP analog that activates TH transcription. Upon differentiation, TH was induced with concomitant reduction of PrP(C) at protein level, but not at mRNA level. shRNA-mediated PrP(C) reduction increased the basal level of TH at both mRNA and protein levels without dibutyryl-cAMP treatment. This phenotype was reversed by re-expression of PrP(C). PrP(C) knockdown also potentiated the effect of dibutyryl-cAMP on TH expression. Our findings suggest that PrP(C) has suppressive effects on TH expression. As a consequence, altered PrP(C) functions may affect the regulation of dopamine metabolism and related neurological disorders.

Relações entre o potássio da dieta e a pressão arterial / Relationship between dietary potassium and blood pressure

A alta ingestão de potássio está associada com níveis reduzidos de pressão arterial. Estudos têm demonstrado que a excreção de potássio na urina representa a quantidade de potássio ingerido na dieta, podendo ser um marcador da efetividade da terapia anti-hipertensiva e de desfechos cerebrovasculares. A suplementação de potássio possui efeito hipotensor em pacientes com hipertensão moderada, e estudos clínicos têm revelado que dietoterapia baseada em frutas, verduras e legumes ricos em potássio podem reduzir a pressão arterial, quando associada à redução de sódio na dieta. As dietas que produzam uma relação de concentrações urinárias < 1,0 (Na/K) entre o sódio e o potássio têm importantes efeitos na pressão arterial. Arecomendação é que seja ingerido aproximadamente 4,7g/dia de potássio na dieta por pacientes com hipertensão arterial. A adição de potássio na dieta de forma suplementada, ou por meiode uma dieta com alimentos ricos nesse mineral, pode ser um adjuvante eficiente na terapia farmacológica anti-hipertensiva dos pacientes com hipertensão arterial.

High potassium intake is associated with low levels of blood pressure. Studies have shown that urinary potassium excretion represents the amount of intake, thus it became an effective way to know the efficiency of the antihypertensive therapy as well as vascular complications and stroke. Potassium supplementation has hypotensive effect in patients with moderate hypertension, and clinical studies have shown that diet therapy based on fruits and vegetables rich in potassium can reduce blood pressure, when associated with dietary sodium reduction. Diets that produce urinary concentrations < 1.0 regarding the sodium/potassium rate (Na/K) have important effects on blood pressure. The recommendation is the ingestion of approximately 4.7g/day of potassium in diet for patients with hypertension. Addition of potassium in the diet as a supplement or increasing the intake of foods rich in this mineral may be an effective coadjuvant antihypertensive therapy to patients with hypertension.