Transcriptome Changes in Three Brain Regions during Chronic Lithium Administration in the Rat Models of Mania and Depression

Lithium therapy subdues neuroinflammation to maintain pyramidal cells arborization and rescues neurobehavioural impairments in ovariectomized rats

Oestrogen deprivation as a consequence of menopause alters the brain neuronal circuit and results in the development of neurobehavioural symptoms later. Hormone replacement therapy to some extent helps to overcome these abnormalities but is associated with various adverse events. Lithium therapy is being used to manage multiple neuropsychiatric disorders and is reported to maintain structural synaptic plasticity, suppress neuroinflammation, and promote adult neurogenesis. The present study examined the effect of lithium treatment on the neurobehavioural impairments in ovariectomized rat model mimicking clinical postmenopausal condition. A protective effect of lithium treatment was observed on the reconsolidation of spatial and recognition memory along with depression-like behaviour in ovariectomized rats. The Golgi-Cox staining revealed increased dendritic length and spine density in the pyramidal neurons of the CA1 region of the hippocampus, layer V of the somatosensory cortex, and layer II/III of the prefrontal cortex in the treated group. A significant reduction in pro-inflammatory markers, Il2, II6, and Il1b, was observed in the hippocampus, somatosensory cortex, and prefrontal cortex following lithium treatment. mRNA expression studies of Gfap and Pparg, along with histopathological analysis, suggested reactive astrogliosis to be a major contributor of neuroinflammation in ovariectomized rats that was normalized following lithium treatment. Further, the treatment inhibited Gsk-3β activity and maintained the normal level of β-catenin, CREB, and BDNF. The results revealed a defensive role of lithium against ovariectomy-induced neurobehavioural impairments, thus suggesting it to be a potential therapeutic agent for managing postmenopausal neurological symptoms.

Electroacupuncture Reverses CUMS-Induced Depression-Like Behaviors and LTP Impairment in Hippocampus by Downregulating NR2B and CaMK II Expression

Objective

Depression is a global mental health problem with high disability rate, which brings a huge disease burden to the world. Electroacupuncture (EA) has been shown to be an effective method for the treatment of depression. However, the mechanism underling the antidepressant effect of EA has not been clearly clarified. The change of synaptic plasticity is the focus in the study of antidepressant mechanism. This study will observe the effect of EA on LTP of hippocampal synaptic plasticity and explore its possible mechanism.

Methods

The depression-like behavior rat model was established by chronic unpredictable mild stress (CUMS). EA stimulation (Hegu and Taichong) was used to treat the depressed rats. The depression-like behavior of rats was tested by weight measurement, open field test, depression preference test, and novelty suppressed feeding test. Long-term potentiation (LTP) was recorded at CA1 synapses in hippocampal slices by electrophysiological method. N-methyl-D-aspartate receptor subunit 2B (NR2B) and calmodulin-dependent protein kinase II (CaMK II) protein levels were examined by using western blot.

Results

After the establishment of CUMS-induced depression model, the weight gain rate, sucrose preference rate, line crossing number, and rearing times of rats decreased, and feeding time increased. At the same time, the LTP in hippocampus was impaired, and the expressions of NR2B and CaMK II were upregulated. After EA treatment, the depression-like behavior of rats was improved, the impairment of LTP was reversed, and the expression levels of NR2B and CaMK II protein were downregulated.

Conclusion

EA can ameliorate depression-like behaviors by restoring LTP induction, downregulating NR2B and CaMK II expression in CUMS model rats, which might be part of the mechanism of EA antidepressant.

Inflammation-Related Changes in Mood Disorders and the Immunomodulatory Role of Lithium

Mood disorders are chronic, recurrent diseases characterized by changes in mood and emotions. The most common are major depressive disorder (MDD) and bipolar disorder (BD). Molecular biology studies have indicated an involvement of the immune system in the pathogenesis of mood disorders, and showed their correlation with altered levels of inflammatory markers and energy metabolism. Previous reports, including meta-analyses, also suggested the role of microglia activation in the M1 polarized macrophages, reflecting the pro-inflammatory phenotype. Lithium is an effective mood stabilizer used to treat both manic and depressive episodes in bipolar disorder, and as an augmentation of the antidepressant treatment of depression with a multidimensional mode of action. This review aims to summarize the molecular studies regarding inflammation, microglia activation and energy metabolism changes in mood disorders. We also aimed to outline the impact of lithium on these changes and discuss its immunomodulatory effect in mood disorders.