18 - Volume Transmission-Mediated Protective Impact of Choroid Plexus—Cerebrospinal Fluid Growth Factors on Forebrain Ischemic Injury

Abstract

This chapter discusses the growth factors that contribute to neuronal repair. Following brain or spinal cord ischemia, there is compensatory upregulation and distribution of growth factors that contribute to neuronal repair. Working homeostatically with glial and cerebral endothelial cells, the epithelium of the choroid plexus secretes numerous peptides and proteins into the cerebrospinal fluid (CSF), which convey these trophic factors, by volume transmission, to neurons at damage sites. The chapter also argues that forebrain injury by transient global or focal ischemia results in considerable morbidity to choroid epithelial cells at the blood–CSF barrier. However, despite marked ischemic damage to the choroidal parenchyma, restorative processes ensure that the structural and functional integrity of this transport interface is regained within several hours of interrupted blood flow. Also, there is an injury-induced elevation of growth factors in CSF and tissues bordering the cerebroventricular system. The working hypothesis used for the forebrain injury model is that the lateral choroid plexus–ventricular CSF system has an integral role in minimizing damage to adjacent regions by acting as a source in supplying trophic factors and as a sink in removing potentially deleterious metabolites.