Antidepressant Effects of Soyo-san on Immobilization Stress in Ovariectomized Female Rats

Abstract

Depressive disorders are among the most frequently occurring psychiatric diseases, and are prevalent in at least 15% of the population. However, the prevalence of depressive disorders is twice as high in women as in men.1) The higher incidence and severity of depression is associated with the presence or absence of ovarian hormones.2) The ovarian hormones related to the menopause-induced depression influence the hippocampal anatomy and physiology; thus, they affect behavior in adult female rats. [3][4][5] The hippocampus plays an important role in the negative feedback mechanism of the limbic-hypothalamic-pituitary adrenal (LHPA) axis. It expresses high levels of adrenal steroid receptors and is especially susceptible to damage as a result of stress. 6,7) In the hippocampus, stress hormones induce regression of the dendritic processes and cell death, inhibit neurogenesis, and impair the ability of neurons to survive noxious stimuli such as seizure, hypoxia-ischemia, metabolic poisons, hypoglycemia and oxygen radical generators.8) The damage caused by a heightened stress response resulting from dysregulation of the LHPA axis is hypothesized to play a role in the reduced hippocampal volume often associated with major depression.9,10) Several neurotransmitter systems implicated in the regulation of the HPA axis have been hypothesized to be dysfunctional in major depression, including acetylcholine (ACh), norepnephrine, serotonin and dopamine.11) The central cholinergic neurons are of putative relevance to major depression. 12)Soyo-san consists of 9 kinds of medicinal herbs: Paeoliae Radix Alba, Atractylodis Macrocephalae Rhizoma, Angelicae Gigantis Radix, Poria, Liriopis Tuber, Bupleuri Radix, Menthae Herba, Glycyrrhizae Radix and Zingiberis Rhizoma Recens. Soyo-san is a traditional oriental herbal medicine, and it has been used in the treatment of mental stress, hypochondriac distensive pain, hysteria and manic-depressive illness. The various findings of recent preclinical studies have supported the therapeutic value of Soyo-san in a clinical setting. 13,14) In laboratory studies of animals, Soyo-san has also been shown to have antidepressive-like effects when using the tail suspension and forced swimming tests. 15,16) In animal models, it was suggested that exposure to uncontrollable and stressful life events led to a feeling of 'loss of control' which ultimately led to depression. In this 'learned helplessness' response, animals exposed to stressors have impaired performance in learning and memory.17)The aim of the present study was to explore the behavioral and the neurobiological effects of Soyo-san on ovariectomized female rats and to form a basis for clinical treatment. Soya-san's antidepressant effect was tested via a Morris water maze (MWM) and an elevated pulse maze (EPM), and we measured the serum corticosterone and immunohistochemical changes of acetylcholine in the brain. MATERIALS AND METHODSPreparation of Drug Soyo-san was prepared by mixing the 9 crude drugs in the same ratio (Table 1). It was provi...

The Characteristics of Supramammillary Cells Projecting to the Hippocampus in Stress Response in the Rat

“…The cholinergic system is known to be involved in the information processing related to hippocampal learning and memory, and the central cholinergic neurons are of putative relevance to major depression [23]. Learning and memory in mammals, including humans, is dependent on the neurotransmitter acetylcholine, in the basal forebrain and hippocampus [24].…”

Effect of <i>Bupleurum falcatum</i> on the Stress-Induced Impairment of Spatial Working Memory in Rats

“…[3][4][5] Repeated stress causes numerous neurochemical and neuroanatomical changes in the brain, mainly in the hippocampus, including excessive activity of the hypothalamo-pituitary-adrenal (HPA) axis. 6) As a result, neurogenesis is reduced, hippocampal areas CA1 and CA3 undergo dendritic remodeling, 7,8) and neuronal atrophy occurs, leading to a decrease in neuronal volume and the total number of neurons and their branches. 9) Hippocampal neurons, which are known to play an important role in learning and memory, are particularly vulnerable to neuronal injury produced by stress-induced glucocorticoid (GC) levels, 10) resulting in deficits in spatial memory tasks, 11) and synaptic plasticity.…”

Protective effects of blueberry drink on cognitive impairment induced by chronic mild stress in adult rats

“…It has been shown that psychological stress can induce dysfunctions in the nervous system, including cognitive impairment, anxiety, and insomnia [ 3 ]. Recent studies have shown that both intense acute and chronic stress can have detrimental neurocognitive effects [ 4 5 ], and repeated stress induces neurochemical and neuroanatomical changes in the brain, mainly in the HPA axis [ 6 ]. Memory and learning performances were also observed to decrease under chronic stress [ 7 ].…”