Sites of action of thyrotropin-releasing hormone on central nervous system neurons revealed by expression of the immediate-early gene c-fos in the rat

Ghrelin produces antidepressant-like effect in the estrogen deficient mice

Recent evidence shows that ghrelin plays an important role in depression. However, it was little known whether ghrelin produces antidepressant-like effect in the ovariectomized mice. The present study was aimed to investigate the antidepressant-like effects of the ghrelin in ovariectomized mice. In the forced swim test, ghrelin significantly decreased immobility time, reversing the “depressive-like” effect observed in ovariectomized mice, and this effect was reversed by the tamoxifen. In addition, immunohistochemical study indicated that ghrelin treatment reversed the reductions in c-Fos expression induced by ovariectomy. An estrogen antagonist tamoxifen also antagonized the effect of ghrelin on the c-Fos expression. Furthermore, the western blotting indicated that brain-derived neurotrophic factor (BDNF) in the hippocampus, but not phosphorylated cAMP response element-binding protein (pCREB)/CREB in the frontal cortex, were affected by ghrelin treatment. Ghrelin treatment significantly increased BrdU expression. Therefore, these findings suggest that ghrelin produces antidepressant-like effects in ovariectomized mice, and estrogen receptor may be involved in the antidepressant-like effects of the ghrelin.

Berberine produces antidepressant-like effects in ovariectomized mice

Berberine has been reports to have antidepressant-like effects. However, it is seldom known whether berberine produces antidepressant-like effects in ovariectomized mice, which exhibit depressive-like responses. To examine the antidepressant-like effects of berberine in ovariectomized mice, behavioral tests were conducted, including the forced swimming test and the open field test. To elucidate the mechanisms, levels of BDNF, phosphorylated CREB and phosphorylated eEF2 were analyzed by western blotting, and c-Fos induction was examined by immunohistochemistry. In the forced swimming test, berberine decreased the immobility time in a dose-dependent manner, reversing the depressive-like effect observed in ovariectomized mice, and this effect was blocked by the 5-HT₂ antagonist ketanserin. In addition, western blotting indicated that BDNF and peEF₂ in the hippocampus, but not pCREB/CREB in the frontal cortex, were affected by berberine treatment. Furthermore, immunohistochemistry demonstrated that the reduction in c-Fos induced by ovariectomy were greater after berberine treatment. Ketanserin also antagonized the effect of berberine on the c-Fos expression. Our findings suggest that berberine exerts antidepressant-like effects in ovariectomized mice, and 5-HT₂ receptor activation may be partially related to the antidepressant-like effects of the berberine by BDNF-CREB and eEF₂ pathways.

Messenger RNA and microRNA profiling during early mouse EB formation

Embryonic stem (ES) cells can be induced to differentiate into embryoid bodies (EBs) in a synchronised manner when plated at a fixed density in hanging drops. This differentiation procedure mimics post-implantation development in mouse embryos and also serves as the starting point of protocols used in differentiation of stem cells into various lineages. Currently, little is known about the potential influence of microRNAs (miRNAs) on mRNA expression patterns during EB formation. We have measured mRNA and miRNA expression in developing EBs plated in hanging drops until day 3, when discrete structural changes occur involving their differentiation into three germ layers. We observe significant alterations in mRNA and miRNA expression profiles during this early developmental time frame, in particular of genes involved in germ layer formation, stem cell pluripotency and nervous system development. Computational target prediction using Pictar, TargetScan and miRBase Targets reveals an enrichment of binding sites corresponding to differentially and highly expressed miRNAs in stem cell pluripotency genes and a neuroectodermal marker, Nes. We also find that members of let-7 family are significantly down-regulated at day 3 and the corresponding up-regulated genes are enriched in let-7 seed sequences. These results depict how miRNA expression changes may affect the expression of mRNAs involved in EB formation on a genome-wide scale. Understanding the regulatory effects of miRNAs during EB formation may enable more efficient derivation of different cell types in culture.