Constitutive patterns of RANTES, MCP-1 and MIP-1 alpha expression at the mRNA and protein level during postnatal development of the rat brain.

The importance of chemokines seems to extend far beyond their well-known role as mediators of an inflammatory response. The most interesting hypothesis is that these molecules may influence the migration of progenitor cells during development. Primary sensory neurones have been shown to migrate towards RANTES in vitro. Recent evidence has revealed that MCP-1, MIP-1alpha and MIP-1beta are potent chemoattractants for glial cell populations. The exact role of the constitutive appearance of chemokines in the CNS during postnatal development is still largely unknown. The intention was to show whether constitutive temporal and spatial profiles of RANTES, MCP-1 and MIP-1alpha expression vary during the postnatal development of the rat brain. RT-PCR was used to assess the levels of mRNA production at different developmental stages. Semi-quantitative analysis of the immunofluorescence signal from glial cells harbouring chemokines was used to determine the spatial-temporal patterns of protein expression. It has been shown here that all chemokines are constitutive factors within the brain microenvironments where the postnatal migration phenomenon occurs. The chemokines were characterised by variable temporal patterns of mRNA production and distinct spatial-temporal patterns of protein appearance. This may support the differences between RANTES, MCP-1 and MIP-1alpha functional significance in vivo in terms of influence on the migration of distinct cell populations.