Background and Purpose-Recent evidence strongly suggests that endothelins (ETs) play an important role in the regulation of blood-brain barrier (BBB) functions. The aim of the present study was to evaluate the role of ETs on edema formation and BBB permeability change after cerebral ischemia/reperfusion. Methods-We examined the brain tissue ET-1 content and evaluated the time and dose response of the therapeutic effects of the specific ET type A receptor (ET A ) antagonist, S-0139, on brain edema formation, development of infarction, and disruption of BBB after 1 hour of middle cerebral artery occlusion (MCAO) in rats. Results-After 1-hour MCAO and reperfusion, the brain ET-1 content did not change during the first 3 hours, increased at 6 hours, and rose almost continuously over 48 hours in the ischemic region as well as in the ischemic rim. Rats infused with S-0139 (0.03 to 1.0 mg/kg per hour) during reperfusion showed dose-dependent and significant attenuation of the increase in brain water content 24 hours after reperfusion. When the infusion of S-0139 was begun after 10 minutes and 1 hour of reperfusion, the brain edema formation and infarct size were significantly attenuated. Furthermore, posttreatment with S-0139 significantly attenuated the increased Evans blue dye-quantified albumin extravasation and improved the mortality of animals after cerebral ischemia/reperfusion. 4 -6 have been implicated in physiological and pathophysiological roles by modulating neuronal functions and regulation of cerebral blood flow and metabolism. Conclusions-OurA marked elevation in plasma or brain ET-1 levels has been reported in patients with ischemic stroke and in animals with cerebral ischemia. 7-11 Topical ET-1 can reduce cerebral blood flow and induce neuronal damage. 12 Moreover, ET receptor antagonists have been demonstrated to decrease the neuronal damage in experimental models. [13][14][15][16] Thus, the roles of ETs on the pathogenesis of cerebral ischemic injury have been implicated, but the precise mechanisms are unclear.Disruption of blood-brain barrier (BBB) and edema formation are induced by ischemia and have been implicated in the progression of ischemic brain injury. 17,18 Recently, it has been suggested that ETs regulate BBB functions. 19,20 Stanimirovic et al 20 have demonstrated that ET-1 induces 51 Cr release from human brain endothelial cells, which suggests that ET-1 enhances the permeability of BBB. These findings may implicate ET-1 in the pathogenesis of brain edema accompanying cerebrovascular disorders. However, few studies have analyzed the role of ETs on BBB dysfunction and edema formation in experimental cerebral ischemia. Thus, the aims of the present study were to evaluate the time course of brain ET-1 content and to analyze the roles of ETs on edema formation and the change of BBB permeability after cerebral ischemia/reperfusion. Materials and MethodsAll procedures performed on the animals in the present study were conducted in accordance with the National Institutes of Health guidelines ...

Neudesin is a secreted protein with neurotrophic activity in neurons and undifferentiated neural cells. We report here that neudesin is an extracellular heme-binding protein and that its neurotrophic activity is dependent on the binding of heme to its cytochrome b 5 -like heme/steroid-binding domain. At first, we found that at least a portion of the purified recombinant neudesin appeared to bind hemin because the purified neudesin solution was tinged with green and had a sharp absorbance peak at 402 nm. The addition of exogenous hemin extensively increased the amount of heminbound neudesin. In contrast, neudesin⌬HBD, a mutant lacking the heme-binding domain, could not bind hemin.

Neudesin encodes a secreted signal with neurotrophic activity in neurons. Most neurotrophic factors are involved in neural cell proliferation and/or differentiation. However, the role of neudesin in neural development remains to be elucidated. We examined the expression of neudesin in mouse embryonic cerebral cortex and cultured mouse neural precursor cells and its roles in neural development. Neudesin was expressed in the embryonic cerebral cortex early in development. Its expression was observed mainly in the preplate, where mostly postmitotic neural cells existed. Because neudesin mRNA was expressed in the neural precursor cells before the appearance of neurons, the roles of neudesin in neural development were examined by using the precursor cells. Neudesin significantly promoted neuronal differentiation and overrode the undifferentiated state of the neural precursor cells sustained by fibroblast growth factor 2 (FGF2). In contrast, it inhibited the differentiation of astrocytes. In addition, neudesin transiently promoted neural cell proliferation early in the developmental process. The effect on cell proliferation was distinct from that of FGF2, a self-renewal-promoting factor for neural precursor cells. The differentiation was mediated though activation of the protein kinase A (PKA) and phosphatidylinositol-3 kinase (PI-3K) pathways. In contrast, the proliferation was mediated through the mitogen-activated protein kinase and PKA pathways. The expression profile and activity indicate that neudesin plays unique roles in neural development. The present findings have revealed new potential roles of neudesin in neural cell proliferation and neuronal differentiation.

Progesterone receptor membrane component 1 (PGRMC1), PGRMC2, neudesin, and neuferricin all contain a cytochrome b5-like heme/steroid-binding domain and belong to the membrane-associated progesterone receptor (MAPR) family. Their amino acid sequences are well conserved among vertebrates, from humans to zebrafish. MAPR family genes are abundantly expressed in the central nervous system and exhibit neurotrophic effects in neural cells. During lipid metabolism, PGRMC1 regulates cholesterol synthesis, and neudesin plays a role in adipogenesis. Their bioactivities are dependent on the binding of heme to their cytochrome b5-like heme/steroid-binding domains. Conversely, it has been reported that the binding of steroids to MAPR family proteins induces biological responses that are unrelated to the nuclear steroid receptors. The interaction between PGRMC1 and progesterone promotes cell survival and damage resistance by progesterone. Moreover, MAPR family proteins exhibit a unique expression pattern in breast cancer, indicating the possibility of using MAPR family members as drug target in breast cancer. In this review, we summarize the identification, structure, and bioactivity of members of the MAPR family, and present an essential overview of the current understanding of their physiological roles.