Latent Sex Differences in CaMKII-nNOS Signaling That Underlie Antidepressant-Like Effects of Yueju-Ganmaidazao Decoction in the Hippocampus

γ-Oryzanol Ameliorates Depressive Behavior in Ovariectomized Mice by Regulating Hippocampal Nitric Oxide Synthase: A Potential Therapy for Menopausal Depression

SCOPE

Depression is a severe mental condition, common among menopausal women. γ-Oryzanol (ORY) has various biological properties; however, the effect of ORY on menopausal depression and its underlying mechanisms have not been investigated.

METHODS AND RESULTS

ORY is orally administered to ovariectomized (OVX) mice for 20 weeks. ORY administration results in lower immobility time in the tail suspension and forced swim test and increases locomotor activity in the open field test. In the primary hippocampal neurons and hippocampi of OVX mice, ORY treatment increases nitric oxide (NO) production and neuronal NO synthase (nNOS) expression. Further, the phosphorylation of extracellular signal-regulated kinase (ERK), cAMP response element-binding protein (CREB), and tropomyosin receptor kinase B, along with the expression of brain-derived neurotrophic factior (BDNF), is upregulated. These stimulatory effects of ORY are diminished by treatment with estrogen receptor β (ERβ) antagonist. ORY similarly interacts with ERβ in the molecular docking analysis. Moreover, intracerebroventricular injection of 7-nitroindazole, a nNOS inhibitor, abolishes the antidepressant effects of ORY.

CONCLUSIONS

The results indicate that ORY attenuates depressive behavior in OVX mice by upregulating ERβ-mediated hippocampal nNOS expression and activating the ERK-CREB-BDNF signaling networks. The findings suggest that ORY is a potential therapeutic agent for attenuating menopausal depression.

Chronic unpredictable stress induces depression/anxiety-related behaviors and alterations of hippocampal monoamine receptor mRNA expression in female mice at different ages

Depression and anxiety are the most common mental health disorders. Though they affect people at any age and occur more often in females, the pathophysiological changes under these conditions are less investigated. In the present study, we examined the effects of age and stress on depression- and anxiety-related behaviors in female mice. Saccharin preference and the open field test were carried out before and after chronic unpredictable stress in 4-, 14- and 25-month-old female mice. After behavioral tests, mRNA levels of monoamine receptors in the hippocampus were measured by real-time RT-PCR. Chronic unpredictable stress decreased saccharin preference in 4-, 14- and 25-month-old mice and the time spent in the center in the open field test in 25-month-old mice. For monoamine receptors, analysis of variance revealed significant effects of age on mRNA levels of Htr1a, Htr2a, Htr6, Adra1a, Adrb2, and Adrb3, significant effects of stress on mRNA levels of Htr4, Adra2c, Adrb1, and Adrb2, and interactions of age × stress on mRNA levels of Htr1a, Htr5b, Adra1d, Adra2a, Adra2c, and Adrb1. Chronic unpredictable stress decreased mRNA levels of Htr4, Htr5b, Adra2c, and Adrb1 in 4-month-old female mice. Correlations were observed between saccharin preference and mRNA levels of Htr4, Htr5b, Htr6, Adra1d, Adra2a, and Adra2c in 4-month-old mice and between the time spent in the center in the open field test and mRNA levels of Htr1b in 4-month-old mice, Htr3a, Htr7, and Adrb2 in 14-month-old mice, and Drd2 in 4- and 14-month-old mice. Our findings support that stress induces depression- and anxiety-related behaviors and the expression of hippocampal monoamine receptors in an age-dependent manner in female mice.

Sex differences in the association between serum α-Klotho and depression in middle-aged and elderly individuals: A cross-sectional study from NHANES 2007-2016

BACKGROUND

Klotho is a well-known anti-aging protein that exerts pleiotropic effects; however, little is known regarding serum α-Klotho in the context of depression. Here, we evaluated the association between serum α-Klotho levels and depression in middle-aged and older individuals.

METHODS

In this cross-sectional study, data were collected from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2016 with a total of 5272 participants who were ≥40 years of age. Depression was evaluated using the 9-item Patient Health Questionnaire (PHQ-9). The association between serum α-Klotho levels and depression was determined on the basis of multivariable logistic regression models.

RESULTS

The mean age of the enrolled adults was 58.94 ± 10.54 years, of which 49.5 % were female. When serum α-Klotho was log10-transformed, it was significantly inversely associated with depression in females in the final adjusted model (odds ratio [OR], 0.32; 95 % confidence interval [CI], 0.12-0.85). In the contrast, serum α-Klotho (log10) was significantly positively associated with depression in males in one of the adjusted models (OR, 3.71; 95 % CI, 1.17-11.8), and this disappeared after adjusting other covariates (all P > 0.05). Based on further stratified respective analyses of females and males, the results were stable.

LIMITATIONS

The cross-sectional study could not yield any conclusions regarding causality.

CONCLUSIONS

In the present study, serum α-Klotho levels were negatively related to the prevalence of depression in middle-aged and elderly women. This study provides new evidence of sex differences in the association between serum α-Klotho levels and depression.

Maternal Immune Activation Induces Adolescent Cognitive Deficits Preceded by Developmental Perturbations in Cortical Reelin Signalling

Exposure to maternal immune activation (MIA) in utero significantly elevates the risk of developing schizophrenia and other neurodevelopmental disorders. To understand the biological mechanisms underlying the link between MIA and increased risk, preclinical animal models have focussed on specific signalling pathways in the brain that mediate symptoms associated with neurodevelopmental disorders such as cognitive dysfunction. Reelin signalling in multiple brain regions is involved in neuronal migration, synaptic plasticity and long-term potentiation, and has been implicated in cognitive deficits. However, how regulation of Reelin expression is affected by MIA across cortical development and associated cognitive functions remains largely unclear. Using a MIA rat model, here we demonstrate cognitive deficits in adolescent object-location memory in MIA offspring and reductions in Reln expression prenatally and in the adult prefrontal cortex. Further, developmental disturbances in gene/protein expression and DNA methylation of downstream signalling components occurred subsequent to MIA-induced Reelin dysregulation and prior to cognitive deficits. We propose that MIA-induced dysregulation of Reelin signalling contributes to the emergence of prefrontal cortex-mediated cognitive deficits through altered NMDA receptor function, resulting in inefficient long-term potentiation. Our data suggest a developmental window during which attenuation of Reelin signalling may provide a possible therapeutic target.

Postsynaptic Proteins at Excitatory Synapses in the Brain—Relationship with Depressive Disorders

Depressive disorders (DDs) are an increasingly common health problem that affects all age groups. DDs pathogenesis is multifactorial. However, it was proven that stress is one of the most important environmental factors contributing to the development of these conditions. In recent years, there has been growing interest in the role of the glutamatergic system in the context of pharmacotherapy of DDs. Thus, it has become increasingly important to explore the functioning of excitatory synapses in pathogenesis and pharmacological treatment of psychiatric disorders (including DDs). This knowledge may lead to the description of new mechanisms of depression and indicate new potential targets for the pharmacotherapy of illness. An excitatory synapse is a highly complex and very dynamic structure, containing a vast number of proteins. This review aimed to discuss in detail the role of the key postsynaptic proteins (e.g., NMDAR, AMPAR, mGluR5, PSD-95, Homer, NOS etc.) in the excitatory synapse and to systematize the knowledge about changes that occur in the clinical course of depression and after antidepressant treatment. In addition, a discussion on the potential use of ligands and/or modulators of postsynaptic proteins at the excitatory synapse has been presented.

TRPM2 mediates CaMKⅡ-Beclin-1 signaling in early cortical injury after induced subarachnoid hemorrhage in mice

BACKGROUND

Though early brain injury (EBI) is the primary cause of poor outcomes among patients with subarachnoid hemorrhage (SAH), its exact molecular mechanisms remain unclear. Improved the understanding of how transient receptor potential melastatin-related 2 (TRPM2) is involved in SAH-induced EBI will help develop novel interventions.

METHODS

Wild type (WT) male C57BL/6J mice were subjected to SAH for 12 h, 24 h or 48 h, after which neurological scores and pathological changes in the hippocampus (CA3, DG, and CA1) and temporal base cortex were observed. Expressions of TRPM2, Ca²⁺/calmodulin (CaM)-dependent protein kinase Ⅱ (CaMKⅡ), and Beclin-1 in hippocampus (CA3, DG, and CA1) and temporal base cortex were compared across post-SAH timepoints. TRPM2-deficient (TRPM2^-/-) male C57BL/6 J mice and a CaMKⅡ inhibitor (KN-93) were used to analyze the effects oTRPM2 on the CaMKⅡ-Beclin-1 signaling post SAH.

RESULTS

Neurological and temporal base cortex deterioration were more severe with increased time post-SAH induction, whereas hippocampal damage was not observed. Post-SAH, TRPM2-CaMKⅡ-Beclin-1 cascade was activated in the temporal base cortex, but not the hippocampus. Using TRPM2^-/- mice and KN-93 administration, SAH-induced EBI was improved, and CaMKⅡ and Beclin-1 expressions in the temporal base cortex were significantly decreased compared with WT mice. TRPM2^-/- mice also showed better neurological improvement compared with KN-93 treated mice.

CONCLUSION

TRPM2 mediates CaMKⅡ-Beclin-1 signaling that aggravates SAH-induced EBI in the temporal base cortex. TRPM2 may be an alternative therapy target in EBI after SAH.

DATA AVAILABILITY

The datasets generated and/or analysed during the current study are available from the corresponding author.