Cerebellar Granule Cell Genesis in the Hydrocortisone-Treated Rat

Abstract

The development of the cerebellar cortex was studied by quantitative light microscopic methods in rats treated with hydrocortisone on postnatal days 7–18. This treatment resulted in a decreased number of cells in the external granular layer (EGL) and an early disappearance of the EGL. In the adult cerebellum of these neonatally treated animals, the total number of granule cells in lobule VIII was decreased by 41% and that of molecular layer microneurons by 28%. Autoradiographic determinations of the ''birthdays'' (time of origin) of cerebellar microneurons showed that the peaks of cell formation in the internal granular and molecular layers occurred at earlier ages than in controls. In the granule cell population, this observation was the result of both decreased cell proliferation during the treatment and premature cessation of division in granule cell precursors in the EGL. The morphological effects of ''late'' hydrocortisone treatment on the cerebellum observed in this study are compared with those of ''early'' hydrocortisone treatment on days 1–4 and those of thyroid hormone from previous studies. It is suggested that endogenous levels of both thyroid and glucocorticoid hormones during the neonatal period may influence the rate of neurogenesis in the postnatal rat cerebellum.

Hedgehog signaling has a protective effect in glucocorticoid-induced mouse neonatal brain injury through an 11βHSD2-dependent mechanism

“…Together with the decreased EGL/IGL ratio ( Figure 2J), these findings suggest that GCs act primarily to inhibit proliferation and promote CGNP cell cycle exit and premature differentiation. This results in a decrease in ultimate granule neuron numbers, as has been observed in previous studies (12,26). Figure 3, A and B), whereas the MR was not expressed ( Figure 3, C and D), which suggests that GR is the major mediator of GC effects in developing cerebellum at the stages analyzed.…”

Adult neurogenesis and brain regeneration in zebrafish

“…They can positively or negatively affect the neurogenesis in adult brains. For instance steroid hormones increases formation of granule cells in the cerebellum and hippocampus (Bohn and Lauder, 1980;McEwen, 1996;Montaron et al, 2003), while thyroid hormone has a complex involvement in progenitor cell proliferation in the brain as it can both suppress and enhance it (Lemkine et al, 2005;Desouza et al, 2005;Kapoor et al, 2011). Other hormones such as gonadal hormone, prolactin or estrogen were suggested to have a positive effect on progenitor cell proliferation (Brown et al, 1993;Shingo et al, 2003;Barha et al, 2009;Kordower et al, 2010).…”

Clonal analysis reveals granule cell behaviors and compartmentalization that determine the folded morphology of the cerebellum

“…An increase or decrease in the production of gcs results in a corresponding change in the size of folia (Altman et al, 1969;Bohn and Lauder, 1980;Corrales et al, 2006;Lewis et al, 2004;Noguchi et al, 2008). Gcs are generated by a unique germinal zone termed the external gc layer (EGL), which covers the surface of the mouse Cb from embryonic day (E) 15.5 to postnatal day (P) 16 (Altman and Bayer, 1997;Sillitoe and Joyner, 2007;Sudarov and Joyner, 2007).…”