Expression of the nerve growth factor-induced gene B-beta in the developing rat brain and retina

The nerve growth factor-induced gene B-beta (NGFI-Bbeta, Nurr1) is a member of the nuclear receptor superfamily that is expressed predominantly in the central nervous system. We used an antibody against the human NGFI-Bbeta to observe the protein expression in neuronal cells in the retina, cerebral neocortex, and midbrain of humans and rats. To provide further insight into the role of NGFI-Bbeta in the differentiation of neuronal cells, we also examined the expression of NGFI-Bbeta in rat ontogeny. A few cells in the midbrain showed the expression of NGFIBbeta from 12 days of gestation, and NGFI-Bbeta positive cells increased in the neocortex, claustrum, thalamus and hypothalamus in the subsequent fetal days. NGFI-Bbeta-positive cells appeared in the inner nuclear layer of the retina at 18 days of gestation and also in the ganglion cell layer after birth. An immunohistochemical study on the expression of proliferating cell nuclear antigen (PCNA) demonstrated that NGFI-Bbeta-positive cells were not proliferating cells. These findings suggest that NGFI-Bbeta plays an important role during the postmitotic differentiation of neuronal cells in the brain and retina.