It's in the Genes: A New Marker for Sex Differences in Depression and Anxiety

Medial prefrontal cortical PPM1F alters depression-related behaviors by modifying p300 activity via the AMPK signaling pathway

AIMS

Protein phosphatase Mg2+/Mn2+-dependent 1F (PPM1F) is a serine/threonine phosphatase, and its dysfunction in depression in the hippocampal dentate gyrus has been previously identified. Nevertheless, its role in depression of another critical emotion-controlling brain region, the medial prefrontal cortex (mPFC), remains unclear. We explored the functional relevance of PPM1F in the pathogenesis of depression.

METHODS

The gene expression levels and colocalization of PPM1F in the mPFC of depressed mice were measured by real-time PCR, western blot and immunohistochemistry. An adeno-associated virus strategy was applied to determine the impact of knockdown or overexpression of PPM1F in the excitatory neurons on depression-related behaviors under basal and stress conditions in both male and female mice. The neuronal excitability, expression of p300 and AMPK phosphorylation levels in the mPFC after knockdown of PPM1F were measured by electrophysiological recordings, real-time PCR and western blot. The depression-related behavior induced by PPM1F knockdown after AMPKα2 knockout or the antidepressant activity of PPM1F overexpression after inhibiting acetylation activity of p300 was evaluated.

RESULTS

Our results indicate that the expression levels of PPM1F were largely decreased in the mPFC of mice exposed to chronic unpredictable stress (CUS). Behavioral alterations relevant to depression emerged with short hairpin RNA (shRNA)-mediated genetic knockdown of PPM1F in the mPFC, while overexpression of PPM1F produced antidepressant activity and ameliorated behavioral responses to stress in CUS-exposed mice. Molecularly, PPM1F knockdown decreased the excitability of pyramidal neurons in the mPFC, and restoring this low excitability decreased the depression-related behaviors induced by PPM1F knockdown. PPM1F knockdown reduced the expression of CREB-binding protein (CBP)/E1A-associated protein (p300), a histone acetyltransferase (HAT), and induced hyperphosphorylation of AMPK, resulting in microglial activation and upregulation of proinflammatory cytokines. Conditional knockout of AMPK revealed an antidepressant phenotype, which can also block depression-related behaviors induced by PPM1F knockdown. Furthermore, inhibiting the acetylase activity of p300 abolished the beneficial effects of PPM1F elevation on CUS-induced depressive behaviors.

CONCLUSION

Our findings demonstrate that PPM1F in the mPFC modulates depression-related behavioral responses by regulating the function of p300 via the AMPK signaling pathway.

Sex-related effects in major depressive disorder: Results of the European Group for the Study of Resistant Depression

BACKGROUND

Sex-related effects on the evolution and phenotype of major depressive disorder (MDD) were reported previously.

METHODS

This European multicenter cross-sectional study compared sociodemographic, clinical, and treatment patterns between males and females in a real-world sample of 1410 in- and outpatients with current MDD.

RESULTS

Male MDD patients (33.1%) were rather inpatients, suffered from moderate to high suicidality levels, received noradrenergic and specific serotonergic antidepressants (ADs) as first-line AD treatment, generally higher mean AD daily doses, and showed a trend towards a more frequent administration of add-on treatments. Female MDD patients (66.9%) were rather outpatients, experienced lower suicidality levels, comorbid thyroid dysfunction, migraine, asthma, and a trend towards earlier disease onset.

CONCLUSIONS

The identified divergencies may contribute to the concept of male and female depressive syndromes and serve as predictors of disease severity and course, as they reflect phenomena that were repeatedly related to treatment-resistant depression (TRD). Especially the greater necessity of inpatient treatment and more complex psychopharmacotherapy in men may reflect increased therapeutic efforts undertaken to treat suicidality and to avoid TRD. Hence, considering sex may guide the diagnostic and treatment processes towards targeting challenging clinical manifestations including comorbidities and suicidality, and prevention of TRD and chronicity.

Polygenic evidence and overlapped brain functional connectivities for the association between chronic pain and sleep disturbance

Chronic pain and sleep disturbance are highly comorbid disorders, which leads to barriers to treatment and significant healthcare costs. Understanding the underlying genetic and neural mechanisms of the interplay between sleep disturbance and chronic pain is likely to lead to better treatment. In this study, we combined 1206 participants with phenotype data, resting-state functional magnetic resonance imaging (rfMRI) data and genotype data from the Human Connectome Project and two large sample size genome-wide association studies (GWASs) summary data from published studies to identify the genetic and neural bases for the association between pain and sleep disturbance. Pittsburgh sleep quality index (PSQI) score was used for sleep disturbance, pain intensity was measured by Pain Intensity Survey. The result showed chronic pain was significantly correlated with sleep disturbance (r = 0.171, p-value < 0.001). Their genetic correlation was r_g = 0.598 using linkage disequilibrium (LD) score regression analysis. Polygenic score (PGS) association analysis showed PGS of chronic pain was significantly associated with sleep and vice versa. Nine shared functional connectivity (FCs) were identified involving prefrontal cortex, temporal cortex, precentral/postcentral cortex, anterior cingulate cortex, fusiform gyrus and hippocampus. All these FCs mediated the effect of sleep disturbance on pain and seven FCs mediated the effect of pain on sleep disturbance. The chronic pain PGS was positively associated with the FC between middle temporal gyrus and hippocampus, which further mediated the effect of chronic pain PGS on PSQI score. Mendelian randomization analysis implied a possible causal relationship from chronic pain to sleep disturbance was stronger than that of sleep disturbance to chronic pain. The results provided genetic and neural evidence for the association between pain and sleep disturbance, which may inform future treatment approaches for comorbid chronic pain states and sleep disturbance.