Expression patterns of the regulatory proteins G protein-coupled receptor kinase 2 and beta-arrestin 1 during rat postnatal brain development - Effect of hypothyroidism

G protein-coupled receptor kinase 2 (GRK2) and beta-arrestin 1 are key regu latory proteins that modulate the desensitization and resensitization of a wide variety of G protein-coupled receptors (GPCRs) involved in brain funct ions. In this report, we describe the postnatal developmental profile of th e mRNA and protein levels of GRK2 and beta-arrestin 1 in rat brain. The exp ression levels of GRK2 and beta-arrestin 1 display a marked increase at the second and third week after birth, respectively, consistent with an involv ement of these proteins in brain maturation processes. However, the express ion attained at birth and during the first postnatal week with respect to a dult values (45-70% for GRK2, approximate to 30% for beta-arrestin 1) is re latively high compared to that reported for several GPCRs, indicating the e xistence of changes in the ratio of receptors to their regulatory proteins during brain development. On the other hand, we report that experimental hy pothyroidism results in changes in the patterns of expression of GRK2 and b eta-arrestin 1 in cerebral cortex, leading to a 25-30% reduction in GRK2 le vels at several stages of development. Such changes could help to explain t he alterations in GPCR signaling that occur during this pathophysiological condition.