Selegiline ameliorates depression-like behaviors in rodents and modulates hippocampal dopaminergic transmission and synaptic plasticity.

Selegiline, an irreversible inhibitor of monoamine oxidase (MAO)-type B, is widely prescribed for Parkinson's disease and, at higher doses, for major and atypical depression, whereby it is non-selectively inhibitory to both MAO-A and MAO-B activities. MAO inhibitors have been considered to function as antidepressants through MAO-A inhibition. We have previously reported that selegiline exerts antidepressant-like effects in the mouse forced swim test (FST) via dopamine D1 receptor activation.

Selegiline increases on time without exacerbation of dyskinesia in 6-hydroxydopamine-lesioned rats displaying l-Dopa-induced wearing-off and abnormal involuntary movements.

3,4-Dihydroxy-l-phenylalanine (l-Dopa) remains the most effective drug for treating the motor symptoms of Parkinson's disease (PD). However, its long-term use is limited due to motor complications such as wearing-off and dyskinesia. A clinical study in PD patients with motor complications has demonstrated that selegiline, a monoamine oxidase type B inhibitor, is effective in reducing off time without worsening dyskinesia, although another study has shown worsening dyskinesia.

Sgk1 regulates desmoglein 1 expression levels in oligodendrocytes in the mouse corpus callosum after chronic stress exposure.

Major depression, one of the most prevalent mental illnesses, is thought to be a multifactorial disease related to both genetic and environmental factors. However, the genes responsible for and the pathogenesis of major depression at the molecular level remain unclear. Recently, we reported that stressed mice with elevated plasma corticosterone levels show upregulation and activation of serum glucocorticoid-regulated kinase (Sgk1) in oligodendrocytes.

XLMR protein related to neurite extension (Xpn/KIAA2022) regulates cell-cell and cell-matrix adhesion and migration.

X-linked mental retardation (XLMR) is a common cause of moderate to severe intellectual disability in males. XLMR protein related to neurite extension (Xpn, also known as KIAA2022) has been implicated as a gene responsible for XLMR in humans. Although Xpn is highly expressed in the developing brain and is involved in neurite outgrowth in PC12 cells and neurons, little is known about the functional role of Xpn.

Plasma corticosterone activates SGK1 and induces morphological changes in oligodendrocytes in corpus callosum.

Repeated stressful events are known to be associated with onset of depression. Further, stress activates the hypothalamic-pituitary-adrenocortical (HPA) system by elevating plasma cortisol levels. However, little is known about the related downstream molecular pathway.