Melanocortin-4 receptor expression in the rostral ventromedial medulla involved in modulation of nociception in transgenic mice.

The rostral ventromedial medulla (RVM) is a prominent component of the descending modulatory system involved in the control of spinal nociceptive transmission. In the current study, we investigated melanocortin-4 receptor (MC4R) expression in the RVM, where the neurons involved in modulation of nociception reside. Using a line of mice expressing green fluorescent protein (GFP) under the control of the MC4R promoter, we found a large number of GFP-positive neurons in the RVM [nucleus raphe magnus (NRM) and nucleus gigantocellularis pars α (NGCα)]. Fluorescence immunohistochemistry revealed that approximately 10% of MC4R-GFP-positive neurons coexpressed tyrosine hydroxylase, indicating that they were catecholaminergic, whereas 50%-75% of those coexpressed tryptophan hydroxylase, indicating that they were serotonergic. Our findings support the hypothesis that MC4R signaling in RVM may modulate the activity of serotonergic sympathetic outflow sensitive to nociceptive signals, and that MC4R signaling in RVM may contribute to the descending modulation of nociceptive transmission.

The Application of Deep Brain Stimulation for Parkinson's Disease on the Motor Pathway: A Bibliometric Analysis across 10 Years.

BACKGROUND AND OBJECTIVE: Since its initial report by James Parkinson in 1817, Parkinson's disease (PD) has remained a central subject of research and clinical advancement. The disease is estimated to affect approximately 1% of adults aged 60 and above. Deep brain stimulation, emerging as an alternative therapy for end-stage cases, has offered a lifeline to numerous patients. This review aimed to analyze publications pertaining to the impact of deep brain stimulation on the motor pathway in patients with PD over the last decade. METHODS: Data were obtained from the Web of Science Core Collection through the library of Huazhong University of Science and Technology (China). The search strategy encompassed the following keywords: "deep brain stimulation", "Parkinson's disease", "motor pathway", and "human", from January 1, 2012, to December 1, 2022. Additionally, this review visualized the findings using the Citespace software. RESULTS: The results indicated that the United States, the United Kingdom, Germany, and China were the primary contributors to this research field. University College London, Capital Medical University, and Maastricht University were the top 3 research institutions in the research area. Tom Foltynie ranked first with 6 publications, and the journals of Brain and Brain Stimulation published the greatest number of relevant articles. The prevailing research focal points in this domain, as determined by keywords "burst analysis", "encompassed neuronal activity", "nucleus", "hyper direct pathway", etc. CONCLUSION: This study has provided a new perspective through bibliometric analysis of the deep brain stimulation therapy for treating patients with PD, which can shed light on future research to advance our comprehension of this particular field of study.

Mapping Changes of Whole Brain Blood Flow in Rats with Myocardial Ischemia/Reperfusion Injury Assessed by Positron Emission Tomography.

18F-labeled fluorodeoxyglucose positron emission tomography (18F-FDG PET) is the most sensitive tool for studying brain metabolism in vivo. We investigated the image patterns of 18F-FDG PET during reperfusion injury and correlated changes of whole brain blood flow utilizing a rat myocardial ischemia/reperfusion injury (MIRI) model. The results assessed by echocardiography indicated resultant cardiac dysfunction after ischemia-reperfusion in the rat heart. It was found that the average standardized uptake value (SUVaverage) of the whole brain was significantly decreased in model rats, and the glucose uptake of different brain regions including accumbens core/shell (Acb), left caudate putamen (LCPu), hippocampus (HIP), left hypothalamus (LHYP), olfactory (OLF), superior colliculus (SC), right midbrain (RMID), ventral tegmental area (VTA), inferior colliculus (IC) and left thalamus whole (LTHA) was significantly decreased in MIRI rats whereas no significant difference was found in the SUVaverage of amygdala (AMY), right CPu, RHYP, right HYP, left MID, right THA, pons and medulla oblongata (MO). These 18F-FDG PET data provide a reliable identification method for brain metabolic changes in rats with MIRI.

Melanocortin-4 receptor expression in the cuneiform nucleus is involved in modulation of opioidergic signaling.

Substantial evidence has suggested that deep brain stimulation of the cuneiform nucleus has become a remarkable treatment option for intractable pain, but the possible mechanism is poorly understood. Using a melanocortin-4 receptor (MC4R)-green fluorescent protein (GFP) reporter knockin mouse, we showed that a large number of MC4R-GFP-positive neurons were expressed in the cuneiform nucleus. Immunofluorescence revealed that approximately 40%-50% of MC4R-GFP-positive neurons expressed mu opioid receptors, indicating that they were opioidergic signaling. Our findings support the hypothesis that MC4R expression in the cuneiform nucleus is involved in the modulation of opioidergic signaling.