Autocrine endothelial regulation in brain stem vessels of newborn piglets

Vasoactive intestinal peptide (VIP) is known as a potent regulator for the development of the central nervous system (CNS). The neonatal period of bra in development is characterised by rapid cellular proliferation in parallel with neuronal differentiation and angiogenesis. We examined the expression of native VIP and the VIP receptor-associated protein by immunohistochemis try as well as the expression of VIP mRNA by irt situ hybridisation in the brain stem of newborn piglets. We found both the mRNA and the protein of VI P as well as the VIP receptor-associated protein in endothelial cells of ve ins, arteries and capillaries in the marginal zone of brain stem tissue sec tions, especially in pens and mesencephalon, as well as in pial vessels. Th e coexpression of native VIP, VIP mRNA and the VIP receptor-associated prot ein within the endothelium suggests the presence of an autocrine loop, whic h has been detected so far only in neuroblastoma cells. This expression pat tern gives evidence to the immaturity of endothelial cells at birth and the presence of an adaptive response in the VIP-regulated system during the ch ange from intra- to extrauterine life.