Replicated risk CACNA1C variants for major psychiatric disorders may serve as potential therapeutic targets for the shared depressive endophenotype

Genome-wide association studies (GWASs) have reported numerous associations between risk variants and major psychiatric disorders (MPDs) including schizophrenia (SCZ), bipolar disorder (BPD), major depressive disorder (MDD) and others. We reviewed all of the published GWASs, and extracted the genome-wide significant (p<10^-6) and replicated associations between risk SNPs and MPDs. We found the associations of 6 variants located in 6 genes, including L type voltage-gated calcium channel (LTCCs) subunit alpha1 C gene (CACNA1C), that were genome-wide significant (2.0×10 ^-8 ≤p≤1.0×10 ^-6 ) and replicated at single-point level across at least two GWASs. Among them, the associations between MPDs and rs1006737 within CACNA1C are most robust. Thus, as a next step, the expression of the replicated risk genes in human hippocampus was analyzed. We found CACNA1C had significant mRNA expression in human hippocampus in two independent cohorts. Finally, we tried to elucidate the roles of venlafaxine and ω-3 PUFAs in the mRNA expression regulation of the replicated risk genes in hippocampus. We used cDNA chip-based microarray profiling to explore the transcriptome-wide mRNA expression regulation by ω-3 PUFAs (0.72/kg/d) and venlafaxine (0.25/kg/d) treatment in chronic mild stress (CMS) rats. ω-3 PUFAs and venlafaxine treatment elicited significant CACNA1C up-regulation. We concluded that CACNA1C might confer the genetic vulnerability to the shared depressive symptoms across MPDs and CACNA1C might be the therapeutic target for depressive endophenotype as well.

Orphan G Protein Coupled Receptors in Affective Disorders

G protein coupled receptors (GPCRs) are the main mediators of signal transduction in the central nervous system. Therefore, it is not surprising that many GPCRs have long been investigated for their role in the development of anxiety and mood disorders, as well as in the mechanism of action of antidepressant therapies. Importantly, the endogenous ligands for a large group of GPCRs have not yet been identified and are therefore known as orphan GPCRs (oGPCRs). Nonetheless, growing evidence from animal studies, together with genome wide association studies (GWAS) and post-mortem transcriptomic analysis in patients, pointed at many oGPCRs as potential pharmacological targets. Among these discoveries, we summarize in this review how emotional behaviors are modulated by the following oGPCRs: ADGRB2 (BAI2), ADGRG1 (GPR56), GPR3, GPR26, GPR37, GPR50, GPR52, GPR61, GPR62, GPR88, GPR135, GPR158, and GPRC5B.

Early intervention in bipolar disorder, part II: therapeutics

Recent evidence has shown that early pharmacological and psychosocial treatment dramatically ameliorates poor prognosis and outcome for individuals with psychotic disorders, reducing conversion rates to full-blown illness and decreasing symptom severity. In a companion paper, we discussed methodological issues pertaining to early intervention in bipolar disorder (BPD), reviewed clinical studies that focus on high-risk subjects as well as first-episode patients, and reviewed findings from brain imaging studies in the offspring of individuals with BPD as well as in first-episode patients. In this paper, we discuss how drugs that modulate cellular and neural plasticity cascades are likely to benefit patients in the very early stages of BPD, because they target some of the core pathophysiological mechanisms of this devastating illness. Cellular and molecular mechanisms of action of agents with neurotrophic and neuroplastic properties are discussed, with a particular emphasis on lithium and valproate. We also discuss their potential use as early intervention strategies for improving symptoms and functioning in patients in the earliest stages of BPD, as well as high-risk individuals.

Early intervention in bipolar disorder, part I: clinical and imaging findings

The concept of prevention is not new to psychiatry and has long been recognized in general medicine. Recent evidence has highlighted that early pharmacological and psychosocial treatment dramatically ameliorates poor prognosis and outcome for individuals with psychotic disorders, reducing conversion rates to full-blown illness and decreasing symptom severity. Nevertheless, despite the many recent advances in our thinking about early intervention, the need for early intervention in bipolar disorder (BPD) is an area that has been relatively neglected. This review attempts to synthesize what is currently known about early intervention in BPD. We discuss methodological issues pertaining to this topic, review clinical studies that focus on high-risk subjects as well as first-episode patients and review findings from brain imaging studies in the offspring of individuals with BPD as well as in first-episode patients. A companion paper discusses the cellular and molecular mechanisms of action of agents with neurotrophic and neuroplastic properties, with a particular emphasis on lithium and valproate.