Regulation of the norepinephrine transporter by endothelins: a potential therapeutic target.

Neuronal norepinephrine (NE) uptake is a crucial step in noradrenergic neurotransmission that regulates NE concentration in the synaptic cleft. It is a key mechanism mediated by the NE transporter (NET) which takes the neurotransmitter into the presynaptic neuron terminal or the adrenal medulla chromaffin cell. The activity of NET is short and long terms modulated by phosphorylation mediated by protein kinases A, C, and G and calcium-calmodulin-dependent protein kinase, whereas the transporter availability at the cell surface is regulated by glycosylation.

Involvement of endothelins in deoxycorticosterone acetate-salt hypertension through the modulation of noradrenergic transmission in the rat posterior hypothalamus.

What is the central question of this study? Does ex vivo administration of endothelin-1 and endothelin-3 regulate noradrenergic transmission in the posterior hypothalamus of deoxycorticosterone acetate-salt hypertensive rats compared with normotensive rats? What is the main finding and its importance? Endothelin-1 and endothelin-3 enhanced diverse mechanisms leading to increased noradrenergic transmission in the posterior hypothalamus of deoxycorticosterone acetate-salt hypertensive rats. Unveiling the role of brain endothelins in hypertension would probably favour the development of new therapeutic targets for the treatment of essential hypertension, which still represents a challenging disease with high mortality. Brain catecholamines participate in diverse biological functions regulated by the hypothalamus.

Enhanced assymetrical noradrenergic transmission in the olfactory bulb of deoxycorticosterone acetate-salt hypertensive rats.

The ablation of olfactory bulb induces critical changes in dopamine, and monoamine oxidase activity in the brain stem. Growing evidence supports the participation of this telencephalic region in the regulation blood pressure and cardiovascular activity but little is known about its contribution to hypertension. We have previously reported that in the olfactory bulb of normotensive rats endothelins enhance noradrenergic activity by increasing tyrosine hydroxylase activity and norepinephrine release.

Involvement of membrane tubulin in erythrocyte deformability and blood pressure.

Objective: To test the hypothesis that erythrocyte deformability is influenced by changes in the content of membrane tubulin (Mem-tub).

Methods And Results: Human erythrocytes contain tubulin distributed in three pools (membrane, sedimentable, soluble). Erythrocytes from hypertensive humans have a higher proportion of Mem-tub.

Endothelin-1 and -3 modulate the neuronal norepinephrine transporter through multiple signalling pathways in the rat posterior hypothalamus.

We have previously reported that endothelin-1 and -3 modulate different steps of noradrenergic transmission in the hypothalamus. We showed that endothelins modify neuronal norepinephrine transport activity through the regulation of the kinetic constant and internalization. In the present work we sought to define the endothelin receptors and intracellular mechanisms involved in the down-regulation of neuronal norepinephrine uptake induced by endothelin-1 and -3 in the rat posterior hypothalamic region.

Regulation of the neuronal norepinephrine transporter by endothelin-1 and -3 in the rat anterior and posterior hypothalamus.

We previously reported that endothelin-1 and endothelin-3 modulate norepinephrine neuronal release and tyrosine hydroxylase activity and expression in the hypothalamus. In the present study we sought to establish the role of endothelin-1 and -3 in the regulation of norepinephrine uptake in the anterior and posterior hypothalamus. Results showed that in the anterior hypothalamus endothelin-3 increased neuronal norepinephrine uptake whereas endothelin-1 decreased it.

Short-term regulation of tyrosine hydroxylase activity and expression by endothelin-1 and endothelin-3 in the rat posterior hypothalamus.

Brain catecholamines are involved in several biological functions regulated by the hypothalamus. We have previously reported that endothelin-1 and -3 (ET-1 and ET-3) modulate norepinephrine release in the anterior and posterior hypothalamus. As tyrosine hydroxylase (TH) is the rate-limiting enzyme in catecholamine biosynthesis, the aim of the present work was to investigate the effects of ET-1 and ET-3 on TH activity, total enzyme level and the phosphorylated forms of TH in the rat posterior hypothalamus.