The effects of prenatal stress on the Purkinje cell neurogenesis.

In the developing cerebellum, generation times of macroneurons and microneurons occur during pre- and postnatal period, respectively. In this study, to investigate the effects of prenatal stress exposure on cerebellar neuronal development, the granule-to-Purkinje cell ratio of stressed animals was compared with their age-matched controls. In the experimental group, pregnant dams were immobilized on their gestational day 7 and 14, for 6 h. The cerebella of the offspring were removed at postnatal day (P) 30, and granule-to-Purkinje cell ratios, obtained by dividing the numerical density of granule cells (NVg) by that of Purkinje cells (NVP), were found significantly reduced (24%) in the stressed animals. Since volume fraction of granular to molecular layer or white matter to whole cortex was not affected from stress exposure, the deficit seen in this ratio reflects an existent increase in the numerical density of Purkinje cells, rather than a decrease in the number of granule cells. In parallel, the linear density of Purkinje cells (NBP) and the percentage of proliferating cells, immunolabeled with BrdU, were also found significantly higher in stressed animals. Taken together, our results demonstrate that intrauterine stress changes the morphology and numerical density of cerebellar neurons by primarily affecting the actively dividing cells during the selected stress period.