Neurochemical imaging and depressive behaviours

International Union of Basic and Clinical Pharmacology. CX. Classification of Receptors for 5-hydroxytryptamine; Pharmacology and Function

5-HT receptors expressed throughout the human body are targets for established therapeutics and various drugs in development. Their diversity of structure and function reflects the important role 5-HT receptors play in physiologic and pathophysiological processes. The present review offers a framework for the official receptor nomenclature and a detailed understanding of each of the 14 5-HT receptor subtypes, their roles in the systems of the body, and, where appropriate, the (potential) utility of therapeutics targeting these receptors. SIGNIFICANCE STATEMENT: This review provides a comprehensive account of the classification and function of 5-hydroxytryptamine receptors, including how they are targeted for therapeutic benefit.

Altered resting-state fMRI signals and network topological properties of bipolar depression patients with anxiety symptoms

BACKGROUND

This study aims to explore the changes in functional neuroimaging in bipolar depression patients with anxiety symptoms (BDP-A).

METHODS

Forty-five BDP-A patients, 22 bipolar depression patients without anxiety symptoms (BDP-NA), and 48 healthy controls (HC) were finally involved. The low-frequency oscillation characteristics, functional connectivity (FC), and network properties among the three groups of participants were analyzed.

RESULTS

Compared with the BDP-NA group, BDP-A patients exhibited significantly decreased amplitude of low-frequency fluctuation (ALFF) in the left middle frontal gyrus (MFG), superior occipital gyrus, and inferior parietal, but supramarginal and angular gyri (IPL). Enhanced FC from left IPL to middle temporal gyrus, from left precentral gyrus (PreCG) to bilateral angular gyri, medial superior frontal gyrus, and left superior frontal gyrus (SFG)/MFG were also revealed. Compared with HC, the BDP-A group showed remarkably increased ALFF in the left MFG/PreCG, right superior parietal gyrus, while decreased ALFF in the left inferior frontal gyrus, opercular part, and SFG. In addition, higher regional homogeneity in the left MFG/PreCG was found.

LIMITATIONS

The limitations are as follows: (1) relatively small sample size; (2) not all the patients were drug-naive; (3) lack of pure anxiety disorder patients as a controlled group; (4) mental health conditions of HC were not systemic evaluated.

CONCLUSIONS

BDP-A patients showed significant differences in resting-state fMRI properties when compared with BDP-NA or HC group. These results may infer the dysfunction of the dorsal attention network, the default network, and the fronto-limbic system as well as disrupted brain network efficiency in BDP-A patients.

Oxoisoaporphine Alkaloids: Prospective Anti-Alzheimer's Disease, Anticancer, and Antidepressant Agents

Oxoisoaporphine alkaloids are a family of oxoisoquinoline-derived alkaloids that were first isolated from the rhizome of Menispermum dauricum DC. (Menispermaceae). It has been demonstrated that oxoisoaporphine alkaloids possess various biological properties, such as cholinesterase and β-amyloid inhibition, acting as a topoisomerase intercalator, monoamine oxidase A inhibition, and are expected to become anti-Alzheimer's disease, anticancer, and antidepressant drugs. This review provides an overview of natural sources, synthetic routes, bioactivities, structure-function relationship, and modification investigations into oxoisoaporphine alkaloids, with the aim of providing references to the structure-activity relationships for the design and development of oxoisoaporphine derivatives with higher efficacy and therapeutic potential.

Biomarker approaches in major depressive disorder evaluated in the context of current hypotheses

Major depressive disorder is a heterogeneous disorder, mostly diagnosed on the basis of symptomatic criteria alone. It would be of great help when specific biomarkers for various subtypes and symptom clusters of depression become available to assist in diagnosis and subtyping of depression, and to enable monitoring and prognosis of treatment response. However, currently known biomarkers do not reach sufficient sensitivity and specificity, and often the relation to underlying pathophysiology is unclear. In this review, we evaluate various biomarker approaches in terms of scientific merit and clinical applicability. Finally, we discuss how combined biomarker approaches in both preclinical and clinical studies can help to make the connection between the clinical manifestations of depression and the underlying pathophysiology.

Emotional regulatory function of receptor interacting protein 140 revealed in the ventromedial hypothalamus

Receptor-interacting protein (RIP140) is a transcription co-regulator highly expressed in macrophages to regulate inflammatory and metabolic processes. However, its implication in neurological, cognitive and emotional conditions, and the cellular systems relevant to its biological activity within the central nervous system are currently less clear. A transgenic mouse line with macrophage-specific knockdown of RIP140 was generated (MΦRIPKD mice) and brain-region specific RIP140 knockdown efficiency evaluated. Mice were subjected to a battery of tests, designed to evaluate multiple behavioral domains at naïve or following site-specific RIP140 re-expression. Gene expression analysis assessed TNF-α, IL-1β, TGF-1β, IL1-RA and neuropeptide Y (NPY) expression, and in vitro studies examined the effects of macrophage's RIP140 on astrocytes' NPY production. We found that RIP140 expression was dramatically reduced in macrophages within the ventromedial hypothalamus (VMH) and the cingulate cortex of MΦRIPKD mice. These animals exhibited increased anxiety- and depressive-like behaviors. VMH-targeted RIP140 re-expression in MΦRIPKD mice reversed its depressive- but not its anxiety-like phenotype. Analysis of specific neurochemical changes revealed reduced astrocytic-NPY expression within the hypothalamus of MΦRIPKD mice, and in vitro analysis confirmed that conditioned medium of RIP140-silnenced macrophage culture could no longer stimulate NPY production from astrocytes. The current study revealed an emotional regulatory function of macrophage-derived RIP140 in the VMH, and secondary dysregulation of NPY within hypothalamic astrocyte population, which might be associated with the observed behavioral phenotype of MΦRIPKD mice. This study highlights RIP140 as a novel target for the development of potential therapeutic and intervention strategies for emotional regulation disorders.

7-3-Chlorophenypiperazinylalkyl derivatives of 8-alkoxy-purine-2,6-dione as a serotonin receptor ligands with potential antidepressant activity

BACKGROUND

The previous study showed that arylpiperazine can condition affinity to α-adrenoceptors, 5-HT1A/5-HT2A receptors and compounds with arylpiperazine had antidepressant-like effect. The aim of this study was to determine the antidepressant-like activity of new arylpiperazines containing novel 8-alkoxy-purine-2,6-dione fragments.

METHODS

New 3-chloroarylpiperazinylalkyl analogs of 8-alkoxy-purine-2,6-dione and their purine-2,6,8-trione analogs (2-5) were tested for their α1, α2, 5-HT1A,5-HT2A, and 5-HT7 receptor affinities in radioreceptor binding study. Moreover, in search for potential antidepressant properties of these compounds, the forced swim test in mice was conducted.

RESULTS

Compounds 2 and 3 were potent 5-HT1A receptor ligands with Ki within the range on 12-15 nM. All investigated compounds were found to be highly active 5-HT2A receptor (Ki 15-28 nM) and α1 adrenoceptor (Ki 21-89 nM) ligands. In the forced swim test all the compounds showed a significantly activity in spite of their reducing ability of locomotor activity. The most potent effect was produced by compound 4 and 5, which reduced the immobility time in this test in all used doses.

CONCLUSION

In our study the most potent antidepressant-like activity was produced by compounds 4 and 5, which are selective for the 5-HT2A and α1 receptors.

Depression and cardiovascular disease in women: is there a common immunological basis? A theoretical synthesis

Clinical studies have established an inherent comorbidity between depression and the development of cardiovascular disease (CVD). Furthermore, this comorbidity seems to be more amplified in women than in men. To further investigate this comorbidity, a thorough literature review was conducted on studies from 1992 to date. The PubMed database was accessed using the keywords: cardiovascular disease, inflammation, depression, and sex differences. Both human and animal studies were considered. This review takes the standpoint that depression and CVD are both inflammatory disorders, and that their co-occurrence may be related to how the hypothalamic–pituitary–adrenal axis, serotonergic transmission and circulation, and the renin–angiotensin–aldosterone system via angiotensin II are affected by the excess secretion of proinflammatory cytokines. More recently, preliminary research attributes this systemic inflammation to a global deficiency in CD4+CD25+FOXP3 regulatory T cells. 17-β estradiol and progesterone mediated modulation of cytokine secretion may partially explain the sex differences observed. These hormones and reproductive events associated with hormonal fluctuations are discussed in depth, including the analysis of perinatal models of depression and CVD, including preeclampsia. However, as evidenced by this review, there is a need for mechanistic research in humans to truly understand the nature and directionality of the relationship between depression and CVD.

Intracellular pathways of antipsychotic combined therapies: implication for psychiatric disorders treatment

Dysfunctions in the interplay among multiple neurotransmitter systems have been implicated in the wide range of behavioral, emotional and cognitive symptoms displayed by major psychiatric disorders, such as schizophrenia, bipolar disorder or major depression. The complex clinical presentation of these pathologies often needs the use of multiple pharmacological treatments, in particular (1) when monotherapy provides insufficient improvement of the core symptoms; (2) when there are concurrent additional symptoms requiring more than one class of medication and (3) in order to improve tolerability, by using two compounds below their individual dose thresholds to limit side effects. To date, the choice of drug combinations is based on empirical paradigm guided by clinical response. Nonetheless, several preclinical studies have demonstrated that drugs commonly used to treat psychiatric disorders may impact common intracellular target molecules (e.g. Akt/GSK-3 pathway, MAP kinases pathway, postsynaptic density proteins). These findings support the hypothesis that convergence at crucial steps of transductional pathways could be responsible for synergistic effects obtained in clinical practice by the co-administration of those apparently heterogeneous pharmacological compounds. Here we review the most recent evidence on the molecular crossroads in antipsychotic combined therapies with antidepressants, mood stabilizers, and benzodiazepines, as well as with antipsychotics. We first discuss clinical clues and efficacy of such combinations. Then we focus on the pharmacodynamics and on the intracellular pathways underpinning the synergistic, or concurrent, effects of each therapeutic add-on strategy, as well as we also critically appraise how pharmacological research may provide new insights on the putative molecular mechanisms underlying major psychiatric disorders.