Membrane Melatonin Receptors Activated Cell Signaling in Physiology and Disease

The pineal hormone melatonin has attracted great scientific interest since its discovery in 1958. Despite the enormous number of basic and clinical studies the exact role of melatonin in respect to human physiology remains elusive. In humans, two high-affinity receptors for melatonin, MT1 and MT2, belonging to the family of G protein-coupled receptors (GPCRs) have been cloned and identified. The two receptor types activate Gi proteins and MT2 couples additionally to Gq proteins to modulate intracellular events. The individual effects of MT1 and MT2 receptor activation in a variety of cells are complemented by their ability to form homo- and heterodimers, the functional relevance of which is yet to be confirmed. Recently, several melatonin receptor genetic polymorphisms were discovered and implicated in pathology—for instance in type 2 diabetes, autoimmune disease, and cancer. The circadian patterns of melatonin secretion, its pleiotropic effects depending on cell type and condition, and the already demonstrated cross-talks of melatonin receptors with other signal transduction pathways further contribute to the perplexity of research on the role of the pineal hormone in humans. In this review we try to summarize the current knowledge on the membrane melatonin receptor activated cell signaling in physiology and pathology and their relevance to certain disease conditions including cancer.

Raw and wine processed Schisandra chinensis regulate NREM-sleep and alleviate cardiovascular dysfunction associated with insomnia by modulating HPA Axis

Clinical studies have shown that insomnia and anxiety are usually accompanied by cardiovascular dysfunction. In traditional Chinese medicine, Schisandra chinensis (SC) and wine processed Schisandra chinensis (WSC) are mainly used for the treatment of dysphoria, palpitation and insomnia. However, little attention was paid to its mechanism. In this study, we monitored the effect of SC and WSC on the nervous system and cardiovascular system of free-moving rats in the real-time. Our results show that SC and WSC can alleviate cardiovascular dysfunction while promoting sleep, and we further explored their potential mechanisms. HPLC-QTOF-MS was used for the quality control of chemical components in SC and WSC. Data sciences international (DSI) physiological telemetry system was applied to collect the electroencephalogram (EEG), electrocardiogram (ECG) and other parameters of free-moving rats to understand the effects of long-term intake of SC and WSC on rats. The content of Cortisol (CORT), neurotransmitters and amino acids in rat pituitary and hypothalamus were analyzed by UPLC-MS to determine the activity of HPA axis. The expression of melatonin receptor MT1 was analyzed by immunofluorescence technique. Our results suggested that SC and WSC may play the role of promoting sleep by increasing the expression level of melatonin receptor MT1 in hypothalamus, and modulate the activity of HPA axis by regulating the levels of the related neurotransmitters and amino acid, so as to improve the abnormal cardiovascular system of rats. This study may provide theoretical support for explicating the advantages of SC and other phytomedicines in the treatment of insomnia.

Association of alcohol withdrawal severity with MTNR1A (rs34532313) and MTNR1B (rs10830963) genes polymorphisms

Alcohol withdrawal is the most threatening condition encountered in patients with alcohol use disorder. Our study aimed to investigate the association of alcohol withdrawal severity with polymorphic variants in melatonin receptor genes. Methods. The clinical study was carried out on the basis of the Republican Narcological Dispensary №1 in Ufa and the Republican Narcological Dispensary №2 in Sterlitamak. Genetic analysis was performed at the Department of Personalised Psychiatry and Neurology at the V.M. Bekhterev Research Centre, Saint Petersburg. The final sample consisted of 307 subjects. Results. Carriers of the TT genotype of the MTNR1A gene (rs34532313) were found to have less hypertension during alcohol withdrawal than carriers of the other genotypes. In comparison, carriers of the GG genotype of the MTNR1B gene (rs10830963) experienced more symptoms than other genotypes: paroxysmal sweating, visual hallucinations, anxiety, and overall CIWA-Ar score. Conclusions. Thus, it can be concluded that the TT genotype of MTNR1A gene (rs34532313) is associated with a lower risk of hypertension during alcohol withdrawal compared to carriers of other gene genotypes. The GG genotype of MTNR1B gene (rs10830963) is associated with severe withdrawal. In general, it can be concluded that melatonin receptors are involved in the pathogenesis of alcohol withdrawal and the severe of some of its symptoms.