Discrete prefrontal neuronal circuits determine repeated stress-induced behavioral phenotypes in male mice

Development of the rodent prefrontal cortex: circuit formation, plasticity, and impacts of early life stress

The prefrontal cortex (PFC), located at the anterior region of the cerebral cortex, is a multimodal association cortex essential for higher-order brain functions, including decision-making, attentional control, memory processing, and regulation of social behavior. Structural, circuit-level, and functional abnormalities in the PFC are often associated with neurodevelopmental disorders. Here, we review recent findings on the postnatal development of the PFC, with a particular emphasis on rodent studies, to elucidate how its structural and circuit properties are established during critical developmental windows and how these processes influence adult behaviors. Recent evidence also highlights the lasting effects of early life stress on the PFC structure, connectivity, and function. We explore potential mechanisms underlying these stress-induced alterations, with a focus on epigenetic regulation and its implications for PFC maturation and neurodevelopmental disorders. By integrating these insights, this review provides an overview of the developmental processes shaping the PFC and their implications for brain health and disease.

Neural circuits mediating chronic stress: Implications for major depressive disorder

Major depressive disorder (MDD), also known as depression, is a prevalent mental disorder that leads to severe disease burden worldwide. Over the past two decades, significant progress has been made in understanding the pathogenesis and developing novel treatments for MDD. Among the complicated etiologies of MDD, chronic stress is a major risk factor. Exploring the underlying brain circuit mechanisms of chronic stress regulation has been an area of active research for recent years. A growing body of preclinical and clinical research has revealed that abnormalities in the brain circuits are closely associated with failures in coping with stress in depressed individuals. Nevertheless, neural circuit mechanisms underlying chronic stress processing and the onset of depression remain a major puzzle. Here, we review recent literature focusing on circuit- and cell-type-specific dissection of depression-like behaviors in chronic stress-related animal models of MDD and outline the key questions.

Somatostatin-expressing interneurons of prefrontal cortex modulate social deficits in the Magel2 mouse model of autism

Dysfunction in social interactions is a core symptom of autism spectrum disorder (ASD). Nevertheless, the neural mechanisms underlying social deficits in ASD are poorly understood. By integrating electrophysiological, in vivo fiber photometry, viral-mediated tracing, optogenetic and pharmacological stimulation, we show reduced intrinsic excitability and hypoactivity of SOM interneurons in medial prefrontal cortex (mPFC) in Magel2-deficient mice, an established ASD model, were required to social defects. Chemogenetic inhibition of mPFC SOM-containing interneurons resulted in reduced social interaction in wild-type Magel2 mice. These sociability deficits can be rescued by optogenetic activation by excitability of SOM in the mPFC and mPFCSOM-LS inhibitory pathway in Magel 2 knockout mice. These results demonstrate the hypoactivity for SOM action in the mPFC in social impairments, and suggest targeting this mechanism that may prove therapeutically beneficial for mitigating social behavioral disturbances observed in ASD.

Fine-tuning of dopamine receptor signaling with aripiprazole counteracts ketamine's dissociative action, but not its antidepressant effect

Ketamine, a rapid-acting antidepressant, has undesirable psychotomimetic effects, including a dissociative effect. There is currently no effective strategy to suppress these side effects while preserving its antidepressant effect. Here, we investigated the effects of a D2/D3 receptor antagonist and partial agonists on the psychotomimetic and antidepressant effects of ketamine in mice and humans. Aripiprazole, a partial agonist, attenuated the psychotomimetic effect, but maintaining and even enhancing the antidepressant-like effect of ketamine in the forced swim test, whereas raclopride, an antagonist, suppressed both effects in mice. Brain-wide Fos mapping and its network analysis suggested the ventral tegmental area (VTA) as a critical region for distinguishing the effects of aripiprazole and raclopride. In the chronic stress model, local infusion of raclopride into the VTA inhibited ketamine's antidepressant-like effect, accompanied by activation of dopaminergic neurons, suggesting the inhibitory effect of VTA activation on the antidepressant-like effect of ketamine. Consistently, systemic injections of raclopride and brexpiprazole, a partial agonist similar to aripiprazole but closer to an antagonist (lower Emax), activated dopaminergic neurons in the VTA and suppressed ketamine's antidepressant-like effect in the model when co-administered with ketamine, whereas aripiprazole didn't. In line with these results, in a single-arm, double-blinded clinical study of sequential treatments in depressed patients (N = 9), co-administration of 12 mg of aripiprazole suppressed the dissociative symptoms induced by ketamine while maintaining its antidepressant effects. Together, these findings suggest that fine-tuning dopamine receptor signaling with aripiprazole allows selective suppression of ketamine-induced dissociation preserving its antidepressant effects, and that the combined use of aripiprazole and ketamine may be a preferred therapy for treatment-resistant depression.

Unexplained recurrent high fever observed in a depressed adolescent

BACKGROUND

Depressive episodes in adolescents are often accompanied by various physical symptoms, but few studies have explored the association between depression and fever, This case study is the first to report the relationship between unexplained recurrent high fever and depression.

CASE PRESENTATION

H is a 15 year old adolescent female currently in junior year. 2 + months ago, H gradually felt depressed after a class change. Around the time, the patient suddenly developed chills with no obvious trigger and fever. H was treated with anti-infective and anti-viral treatments all of which did not show significant improvement. No significant abnormality was seen in any of the related examinations. Considering that the patient's anxiety, depression and somatic symptoms were obvious during the course of the disease, she was given venlafaxine hydrochloride extended-release capsule 75 mg/d; tandospirone citrate capsule 10 mg Bid; alprazolam tablets 0.4 mg qn to improve mood and sleep; supplemented with transcranial repetitive magnetic stimulation therapy 2 times/d; visible light therapy 1 time/d and psychological counseling once. Over the 6 days of treatment, the patient's body temperature gradually returned to the normal range and her mood improved significantly.

CONCLUSION

Depression should be considered a potential cause of unexplained recurrent fevers in adolescents, even when the temperature is significantly outside the normal range.