Differential Expression of AngII receptors in developing rat hindbrain

ARCE ME, MANZUR MJ, CIUFFO GM

Bariloche, Rio Negro, Argentina

Workshop; Combined meetings: “Gene Expression and RNA Processing” and “Cell Biology, Signaling and Alternative Splicing”.; 2007

ICGEB, EURASNET,AGENCIA

Angiotensin II (Ang II) exerts its physiological effects through binding to membrane receptors classified by their pharmacological characteristics as AT1 and AT2 receptors. Ang II receptor expression  is highly modulated during development suggesting a role of these receptors in growth and organogenesis . The AT2 receptor knock-out mice exhibit impaired drinking behavior and motor capability. Also, mental retardation has been associated to a mutation of the AGTR2 gene. In rodents, cerebellum development is mainly postnatal and it extends for 20 days after birth. In the present study we selected different development stages of the hindbrain to study the expression level and localization of Ang II receptors . Localization of Ang II receptors was studied by binding autoradiography in hindbrain of pups at different stages after birth. AT2 receptors localized to a number of sensory and motor nuclei at the rat hindbrain at ages PND8 and PND15. The molecular layer of cerebellum was labeled with AT1 receptors. AT2 receptor binding colocalized with Purkinje cells identified with molecular markers, zebrin and calbindin, by immunofluorescence assays. The expression of Ang II receptors was also determined by RT-PCR, and semiquantified by multiplex RT-PCR with GAPDH expression. PCR fragments of AT1 and AT2 receptors were subcloned and labeled with 35S ATP by random priming. Receptor expression was analyzed by Northern Blot. The highest expression of AT2 receptor was observed at the age of PND15 in agreement with the establishment of the olivo-cerebellar connection, a crucial stage in hindbrain development. The coincidence of the temporal expression of Ang II AT2 receptors and mobility acquisition suggests the involvement of these receptors in the maturation of brain-cerebellum connections.