Although most new neurons express both GR and MR after 4 weeks of maturation, relatively few progenitor cells express glucorticoid receptors (Cameron et al., 1993a; Garcia et al., 2004a). This raises the possibility that adrenal steroid-mediated changes in the rate of cell proliferation in the dentate gyrus occur indirectly. There are several possible mechanisms whereby such an indirect effect could occur. For instance, glucocorticoids might affect neurogenesis by influencing neighboring, more mature, granule neurons. This could occur either by altering the survival of granule cells directly or by affecting their afferent inputs.
