Oxytocin testing and reproductive health: Status and clinical applications

Type 1 melanocortin receptors in pro-opiomelanocortin-, vasopressin-, and oxytocin-immunopositive neurons in different areas of mouse brain

Information on the localization of the Type 1 melanocortin receptors (MC1Rs) in different regions of the brain is very scarce. As a result, the role of MC1Rs in the functioning of brain neurons and in the central regulation of physiological functions has not been studied. This work aimed to study the expression and distribution of MС1Rs in different brain areas of female C57Bl/6J mice. Using real-time polymerase chain reaction, we demonstrated the Mс1R gene expression in the cerebral cortex, midbrain, hypothalamus, medulla oblongata, and hippocampus. Using an immunohistochemical approach, we showed the MС1R localization in neurons of the hypothalamic arcuate, paraventricular and supraoptic nuclei, nucleus tractus solitarius (NTS), dorsal hippocampus, substantia nigra, and cerebral cortex. Using double immunolabeling, the MC1Rs were visualized on the surface and in the bodies and outgrowths of pro-opiomelanocortin (POMC)-immunopositive neurons in the hypothalamic arcuate nucleus, NTS, hippocampal CA3 and CA1 regions, and cerebral cortex. Co-localization with POMC indicates that MC1R, like MC3R, is able to function as an autoreceptor. In the paraventricular and supraoptic nuclei, MC1Rs were visualized on the surface and in the cell bodies of vasopressin- and oxytocin-immunopositive neurons, indicating a relationship between hypothalamic MC1R signaling and vasopressin and oxytocin production. The data obtained indicate a wide distribution of MC1Rs in different areas of the mouse brain and their localization in POMC-, vasopressin- and oxytocin-immunopositive neurons, which may indicate the participation of MC1Rs in the control of many physiological processes in the central nervous system.

LncRNA Gm14205 induces astrocytic NLRP3 inflammasome activation via inhibiting oxytocin receptor in postpartum depression

Postpartum depression (PPD) is a kind of mental disorder characterized by persistent low emotions in puerperium. The most significant physiological change in postpartum is lactation which is regulated by oxytocin receptor (OXTR). However, whether OXTR is related to pathological process of PPD and the potential mechanism still remain unclear. In the present study, we prepared hormone-simulated pregnancy (HSP)-induced PPD mouse model and found that the protein level of OXTR in hippocampus of PPD model mice was down-regulated and Nod-like receptor protein 3 (NLRP3) inflammasome was activated. We identified five long non-coding RNAs (lncRNAs) related to PPD by transcriptome sequencing, including three up-regulated and two down-regulated. The five lncRNAs were associated with the signaling pathway of OXTR according to the bioinformatics analysis. Furthermore, we focused on one of the five lncRNAs, Gm14205, and found that it targeted OXTR which inhibited astrocytic NLRP3 inflammasome activation in hippocampal primary astrocytes. These findings illustrate that OXTR has protective effects in PPD by inhibiting NLRP3 inflammasome activation and provides a new strategy for targeting lncRNA Gm14205 in the pathogenesis of PPD.

Oxytocin signaling in the treatment of drug addiction: Therapeutic opportunities and challenges

Drug addiction is one of the leading causes of mortality worldwide. Despite great advances were achieved in understanding the neurobiology of drug addiction, the therapeutic options are severely limited, with poor effectiveness and serious side effects. The neuropeptide oxytocin (OXT) is well known for its effects on uterine contraction, sexual/maternal behaviors, social affiliation, stress and learning/memory by interacting with the OXT receptor and other neuromodulators. Emerging evidence suggests that the acute or chronic exposure to drugs can affect the OXT system. Additionally, OXT administration can ameliorate a wide range of abused drug-induced neurobehavioral changes. Overall, OXT not only suppresses drug reward in the binge stage of drug addiction, but also reduces stress responses and social impairments during the withdrawal stage and, finally, prevents drug/cue/stress-induced reinstatement. More importantly, clinical studies have also shown that OXT can exert beneficial effects on reducing substance use disorders of a series of drugs, such as heroin, cocaine, alcohol, cannabis and nicotine. Thus, the present review focuses on the role of OXT in treating drug addiction, including the preclinical and clinical therapeutic potential of OXT and its analogs on the neurobiological perspectives of drugs, to provide a better insight of the efficacy of OXT as a clinical addiction therapeutic agent.