Pharmacology and physiopathology of the brain endothelin system: an overview

The endothelin system, consisting of three peptides, two peptidases and two G-protein coupled receptors, is widely expressed in the brain cell types and brain-derived tumor cell lines. The stimulation of endothelin receptors elicits a variety of short- and long-term changes at cellular level but the effects of the pharmacological modulation of the endothelin system in brain physiology and pathophysiology are, at the present time, poorly understood. Altered expression of endothelins (ETs) in reactive astrocytes has been observed in many pathological conditions of the human brain, such as infarcts, lacunae, traumatic conditions, Alzheimer's disease and inflammatory diseases of the brain. In addition, recent studies have shown that endothelin antagonists might inhibit growth and induce cell death in human melanoma cells in vitro and in vivo, and have emphasized a possible role of endothelin peptides as autocrine or paracrine factor in the proliferation and dissemination of tumor cell lines. Given the fact that brain cell and a variety of brain tumor cell lines express functional endothelin receptors, further studies are warranted to demonstrate a possible therapeutic role of endothelin agonists and antagonist in the pharmacological treatment of brain-related diseases and brain tumors.