Microglia shape de pineal gland

M.P. IBAÑEZ RODRÍGUEZ; S. NOCTOR; E. MUÑOZ

Mar del Plata

Congreso; SAN2015; 2015

Sociedad Argentina de Investigación en Neurociencias-SAN

Microglia are the phagocytic cells of the CNS. In this work we studied their distribution and role in the developing and adult rat pineal gland (PG) under normal and inflammatory conditions. We found that microglial cells with active ameboid morphology invade the PG from the early stages of organogenesis onwards. The number of microglial cells per PG and their phagocytic capacity based on the lysosomal marker ED1/CD68 increased towards adulthood. Microglia were in very close contact and in some cases engulfing Pax6+ precursor cells, nerve fibers and blood vessels, but not mature pinealocytes. We used Pax6, an essential determinant of PG genesis, and the microglial marker Iba1 to analyze cell-cell interactions. While Pax6+ cells decreased throughout PG development, the proportion of phagocytosed precursors increased. Microglia were challenged in the adult PG by superior sympathetic ganglionectomy (SCGx) and decentralization (SCGd). Both procedures increased the number of microglia and their phagocytic capacity compared to the sham group four days after surgery. These results illustrate the responsiveness that these cells have to relatively subtle changes in the surrounding microenvironment. In conclusion, we postulate that microglia have a key role in helping to regulate morphogenesis and function in the PG by phagocytosing precursor cells, remodeling blood vessels and pruning sympathetic nerve fibers; activities that could be carried out in collaboration with astrocytes.