The Central Noradrenergic System in Neurodevelopmental Disorders: Merging Experimental and Clinical Evidence

N-(3-((3-(trifluoromethyl)phenyl)selanyl)prop-2-yn-1-yl) benzamide induces antidepressant-like effect in mice: involvement of the serotonergic system

RATIONALE

Major Depressive Disorder (MDD) significantly impairs the quality of life for those affected. While the exact causes of MDD are not fully understood, the deficit of monoamines, especially serotonin and noradrenaline, is widely accepted. Resistance to long-term treatments and adverse effects are often observed, highlighting the need for new pharmacological therapies. Synthetic organic compounds containing selenium have exhibited pharmacological properties, including potential antidepressant effects.

OBJECTIVE

To evaluate the antidepressant-like effect of N-(3-((3-(trifluoromethyl)phenyl)selenyl)prop-2-yn-1-yl) benzamide (CF3SePB) in mice and the involvement of the serotonergic and noradrenergic systems.

METHODS

Male Swiss mice were treated with CF3SePB (1-50 mg/kg, i.g.) and 30 min later the forced swimming test (FST) or tail suspension test (TST) was performed. To investigate the involvement of the serotonergic and noradrenergic systems in the antidepressant-like effect of CF3SePB, mice were pre-treated with p-CPA (a 5-HT depletor, 100 mg/kg, i.p.) or the receptor antagonists WAY100635 (0.1 mg/kg, s.c., a 5-HT1A receptor antagonist), ketanserin (1 mg/kg, i.p., a 5-HT2A/2C receptor antagonist), ondansetron (1 mg/kg, i.p., a 5-HT3 receptor antagonist), GR110838 (0.1 mg/kg, i.p., a 5-HT4 receptor antagonist), prazosin (1 mg/kg, i.p., an α1-adrenergic receptor antagonist), yohimbine (1 mg/kg, i.p., an α2-adrenergic receptor antagonist) and propranolol (2 mg/kg, i.p., a non-selective beta-adrenergic receptor antagonist) at specific times before CF3SePB (50 mg/kg, i.g.), and after 30 min of CF3SePB administration the FST was performed.

RESULTS

CF3SePB showed an antidepressant-like effect in both FST and TST and this effect was related to the modulation of the serotonergic system, specially the 5-HT1A and 5-HT3 receptors. None of the noradrenergic antagonists prevented the antidepressant-like effect of CF3SePB. The compound exhibited a low potential for inducing acute toxicity in adult female Swiss mice.

CONCLUSION

This study pointed a new compound with antidepressant-like effect, and it could be considered for the development of new antidepressants.

Long sleep time and excessive need for sleep: State of the art and perspectives

The mechanisms underlying the individual need for sleep are unclear. Sleep duration is indeed influenced by multiple factors, such as genetic background, circadian and homeostatic processes, environmental factors, and sometimes transient disturbances such as infections. In some cases, the need for sleep dramatically and chronically increases, inducing a daily-life disability. This "excessive need for sleep" (ENS) was recently proposed and defined in a European Position Paper as a dimension of the hypersomnolence spectrum, "hypersomnia" being the objectified complaint of ENS. The most severe form of ENS has been described in Idiopathic Hypersomnia, a rare neurological disorder, but this disabling symptom can be also found in other hypersomnolence conditions. Because ENS has been defined recently, it remains a symptom poorly investigated and understood. However, protocols of long-term polysomnography recordings have been reported by expert centers in the last decades and open the way to a better understanding of ENS through a neurophysiological approach. In this narrative review, we will 1) present data related to the physiological and pathological variability of sleep duration and their mechanisms, 2) describe the published long-term polysomnography recording protocols, and 3) describe current neurophysiological tools to study sleep microstructure and discuss perspectives for a better understanding of ENS.

Influence of Brainstem's Area A5 on Sympathetic Outflow and Cardiorespiratory Dynamics

Area A5 is a noradrenergic cell group in the brain stem characterised by its important role in triggering sympathetic activity, exerting a profound influence on the sympathetic outflow, which is instrumental in the modulation of cardiovascular functions, stress responses and various other physiological processes that are crucial for adaptation and survival mechanisms. Understanding the role of area A5, therefore, not only provides insights into the basic functioning of the sympathetic nervous system but also sheds light on the neuronal basis of a number of autonomic responses. In this review, we look deeper into the specifics of area A5, exploring its anatomical connections, its neurochemical properties and the mechanisms by which it influences sympathetic nervous system activity and cardiorespiratory regulation and, thus, contributes to the overall dynamics of the autonomic function in regulating body homeostasis.

Exploring the Role of Locus Coeruleus in Alzheimer's Disease: a Comprehensive Update on MRI Studies and Implications

PURPOSE OF REVIEW

Performing a thorough review of magnetic resonance imaging (MRI) studies assessing locus coeruleus (LC) integrity in ageing and Alzheimer's disease (AD), and contextualizing them with current preclinical and neuropathological literature.

RECENT FINDINGS

MRI successfully detected LC alterations in ageing and AD, identifying degenerative phenomena involving this nucleus even in the prodromal stages of the disorder. The degree of LC disruption was also associated with the severity of AD cortical pathology, cognitive and behavioral impairment, and the risk of clinical progression. Locus coeruleus-MRI has proved to be a useful tool to assess the integrity of the central noradrenergic system in vivo in humans. It allowed to test in patients preclinical and experimental hypothesis, thus confirming the specific and marked involvement of the LC in AD and its key pathogenetic role. Locus coeruleus-MRI-related data might represent the theoretical basis on which to start developing noradrenergic drugs to target AD.