Natural and lesion-induced apoptosis in the rat striatum during development

Cell death atlas of the postnatal mouse ventral forebrain and hypothalamus: effects of age and sex

Naturally occurring cell death is essential to the development of the mammalian nervous system. Although the importance of developmental cell death has been appreciated for decades, there is no comprehensive account of cell death across brain areas in the mouse. Moreover, several regional sex differences in cell death have been described for the ventral forebrain and hypothalamus, but it is not known how widespread the phenomenon is. We used immunohistochemical detection of activated caspase-3 to identify dying cells in the brains of male and female mice from postnatal day (P) 1 to P11. Cell death density, total number of dying cells, and regional volume were determined in 16 regions of the hypothalamus and ventral forebrain (the anterior hypothalamus, arcuate nucleus, anteroventral periventricular nucleus, medial preoptic nucleus, paraventricular nucleus, suprachiasmatic nucleus, and ventromedial nucleus of the hypothalamus; the basolateral, central, and medial amygdala; the lateral and principal nuclei of the bed nuclei of the stria terminalis; the caudate-putamen; the globus pallidus; the lateral septum; and the islands of Calleja). All regions showed a significant effect of age on cell death. The timing of peak cell death varied between P1 to P7, and the average rate of cell death varied tenfold among regions. Several significant sex differences in cell death and/or regional volume were detected. These data address large gaps in the developmental literature and suggest interesting region-specific differences in the prevalence and timing of cell death in the hypothalamus and ventral forebrain.

Acute inflammation alters adult hippocampal neurogenesis in a multiple sclerosis mouse model

Neural precursor cells (NPCs) located in the subgranular zone (SGZ) of the dentate gyrus (DG) give rise to thousands of new cells every day, mainly hippocampal neurons, which are integrated into existing neuronal circuits. Aging and chronic degenerative disorders have been shown to impair hippocampal neurogenesis, but the consequence of inflammation is somewhat controversial. The present study demonstrates that the inflammatory environment prevailing in the brain of experimental autoimmune encephalomyelitis (EAE) mice enhances the proliferation of NPCs in SGZ of the dorsal DG and alters the proportion between radial glial cells and newborn neuroblasts. The injection protocol of the cell cycle marker bromodeoxyuridine and the immunohistochemical techniques that were employed revealed that the proliferation of NPCs is increased approximately twofold in the SGZ of the dorsal DG of EAE mice, at the acute phase of the disease. However, although EAE animals exhibited significant higher percentage of newborn radial-glia-like NPCs, the mean percentage of newborn neuroblasts rather was decreased, indicating that the robust NPCs proliferation is not followed by a proportional production of newborn neurons. Significant positive correlations were detected between the number of proliferating cells in the SGZ and the clinical score or degree of brain inflammation of diseased animals. Finally, enhanced neuroproliferation in the acute phase of EAE was not found to trigger compensatory apoptotic mechanisms. The possible causes of altered neurogenesis observed in this study emphasize the need to understand more precisely the mechanisms regulating adult neurogenesis under both normal and pathological conditions.

Knockdown of glycogen synthase kinase 3 beta attenuates 6-hydroxydopamine-induced apoptosis in SH-SY5Y cells

Glycogen synthase kinase 3 beta (GSK3β) plays a critical role in signal transductions concerning neuronal death. In the present study, we investigated the potential role of GSK3β in 6-hydroxydopamine (6-OHDA)-induced toxicity in human neuroblastoma cell line SH-SY5Y. We assessed the apoptotic proteins and the relative levels of pGSK3β (Ser9) and pGSK3β (Tyr216) to GSK3β in 6-OHDA-treated SH-SY5Y. Furthermore, we downregulated the expression of GSK3β by short hairpin RNA (shRNA) interference and compared the cell viability and expression of apoptotic proteins in knockdown group with those in control group under the treatment of 6-OHDA. We found that 6-OHDA increased the expression of caspase-3 and caspase-9 but not caspase-8. Additionally, 6-OHDA decreased the ratio of pGSK3β (Ser9)/GSK3β and increased the ratio of pGSK3β (Tyr216)/GSK3β. Moreover, 6-OHDA induced less cell viability loss and lower expression of caspase-9 and caspase-3 in GSK3β knockdown group compared with control. The present data indicate that 6-OHDA may induce apoptosis in SH-SY5Y via the intrinsic death pathway and GSK3β knockdown can partly attenuate 6-OHDA-induced neuronal death and apoptosis, suggesting that GSK3β may have the potential to serve as a therapeutic target for PD.