Roles of microglia in adult hippocampal neurogenesis in depression and their therapeutics.

Adult hippocampal neurogenesis generates functional neurons from neural progenitor cells in the hippocampal dentate gyrus (DG) to complement and repair neurons and neural circuits, thus benefiting the treatment of depression. Increasing evidence has shown that aberrant microglial activity can disrupt the appropriate formation and development of functional properties of neurogenesis, which will play a crucial role in the occurrence and development of depression. However, the mechanisms of the crosstalk between microglia and adult hippocampal neurogenesis in depression are not yet fully understood. Therefore, in this review, we first introduce recent discoveries regarding the roles of microglia and adult hippocampal neurogenesis in the etiology of depression. Then, we systematically discuss the possible mechanisms of how microglia regulate adult hippocampal neurogenesis in depression according to recent studies, which involve toll-like receptors, microglial polarization, fractalkine-C-X3-C motif chemokine receptor 1, hypothalamic-pituitary-adrenal axis, cytokines, brain-derived neurotrophic factor, and the microbiota-gut-brain axis, etc. In addition, we summarize the promising drugs that could improve the adult hippocampal neurogenesis by regulating the microglia. These findings will help us understand the complicated pathological mechanisms of depression and shed light on the development of new treatment strategies for this disease.

Mapping the scientific research on bipolar disorder: A scientometric study of hotspots, bursts, and trends.

Bipolar disorder (BD) is a severe psychiatric illness with an increasing prevalence worldwide. Although the pathological mechanism of and pharmacological interventions for BD have been extensively investigated in preclinical and clinical studies, a scientometric analysis of the developmental trends, interdisciplinary frontiers, and research hotspots in this field has not yet been conducted. Therefore, we performed a comprehensive scientometric review of 55,358 published studies on BD over the past two decades (2002-2021) to identify the most frequently used keywords and explore research hotspots and trajectories. The present findings revealed the main distribution, knowledge structure, topic evolution, and emerging topics of BD research. Analysing the risk factors, pathogenesis, key brain regions, comorbid conditions, and treatment strategies for BD contributed to understanding of the aetiology, progression, and treatment of this disorder. These findings provided substantial support for continued research in this area.