In this theory, the depression after acute stroke is attributed to the destruction of noradrenergic neurons and 5-HTergic neurons and related pathways Trichostatin A price resulting in the reduction of norepinephrine and 5-HT. The neurogenesis is closely related to the occurrence of PSD. It has been shown that cerebral ischemic rats presented depression, which could be alleviated by the increased neurogenesis in the hippocampus. Of importance, this alleviation could be induced by antidepressants, in which 5-HT may play an important role. Studies on stroke rehabilitation demonstrate that 5-HT deficiency could reduce the neurogenesis in the hippocampal dentate gyrus. As a neurotransmitter, 5-HT is involved in the neuronal plasticity via maintaining the synaptic communication between cortex and hippocampus.
In addition, 5-HT is an initial signal in the differentiation of neuronal precursor cells into neurons. In vivo studies have revealed that 5-HT plays a crucial role in the neurogenesis of the hippocampus [17].Mental stress may inhibit the synthesis of brain-derived neurotrophic factor (BDNF) in the hippocampus which may be a contribution to the occurrence of depression. All the anti-depressants may increase the synthesis of BDNF and its signal transduction in the hippocampus and frontal cortex. However, injection of BDNF into the dopamine pathway of mesolimbic system could elicit depression-like response. It is currently accepted that stroke may cause the reduction or even deficiency of BDNF, which is an important factor in the cause of PSD.
Other relevant factors including anatomic location of lesions, gene polymorphism, inflammatory cytokines, alteration of circadian rhythm, and social and psychological factors may also function in the occurrence of PSD. However, the specific relationship between these factors and PSD has not been confirmed [18�C20].3. Regulatory Role of miRNAs in Stroke3.1. Upregulation or Downregulation of miRNAs in StrokeIn stroke, upregulation or downregulation of miRNA may be observed in the brain and serum. It was recently reported that miR-210 was closely related to hypozia and downregulation of miR-210 was detected in the plasma of stroke patients [21]. Moreover, the miR-210 level can also be used to predict the clinical outcomes of stroke patients. Tan et al.
[22] detected the increasing expression of miRNAs in the serum of patients with ischemic stroke, and the pattern and level of miRNAs expression varied in different types of stroke. Some studies also found that miRNA expression was different between males and females, suggesting Carfilzomib that miRNAs might be involved in the influence of gender on the response after stroke. Thus, we infer that miRNA expression is definitely changed after stroke, which may also be used in the diagnosis and prognosis of stroke patients.