Role of Melanin Concentrating Hormone (MCH) Containing Neurons in the Lateral Hypothalamus in Cardiorespiratory Control and Energy Balance
Author | : Ningjing Li |
Publisher | : |
Total Pages | : 300 |
Release | : 2013 |
ISBN-10 | : OCLC:855764445 |
ISBN-13 | : |
Rating | : 4/5 ( Downloads) |
Download or read book Role of Melanin Concentrating Hormone (MCH) Containing Neurons in the Lateral Hypothalamus in Cardiorespiratory Control and Energy Balance written by Ningjing Li and published by . This book was released on 2013 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: The lateral hypothalamus is a brain region involved in the regulation of feeding, glucose homeostasis, sleep/wake cycle, and autonomic nervous system (ANS). Melanin concentrating hormone (MCH) containing neurons, located in the lateral hypothalamus, project widely throughout the central nervous system, including the brain regions that are involved in central chemoreception, food intake, and sleep. These neurons also have multisynaptic connections with the phrenic motoneurons and the ANS. My overall hypothesis is that the lateral hypothalamus is a central chemoreceptor site and hypothalamic MCH neurons play a role in central chemoreception, cardiovascular control, and energy balance. Electroencephalogram (EEG) and electromyogram (EMG) electrodes were surgically implanted to record vigilance states. Arterial catheters were implanted for blood pressure and heart rate recordings. Whole body plethysmography was used to measure ventilation and metabolic rate while breathing in room air of 5% CO2. In the first series of experiments, reverse-microdialysis was used to focally deliver artificial cerebrospinal fluid (aCSF) equilibrated with 25% CO2 to perifornical-lateral hypothalamic area (PF-LHA) in conscious rats while breathing in room air. In the second series of experiments, siRNA was used to knock down the expression of the MCH precursor gene (pMCH) to lower the levels of MCH in the brain. In the third series of experiments, acute central injection of MCH was applied in the third ventricle. Focal acidification in the PF-LHA caused an increase in ventilation only during quiet wakefulness, suggesting that the PF-LHA functions as a central chemoreceptor site and does so in a vigilance-state dependent manner. Knockdown of the pMCH expression resulted in an increase in the ventilatory response to 5% CO2 only during quiet wakefulness, accompanied by an increased metabolic rate, a reduced body weight and glucose level, as well as a disturbed sleep-wake cycle. Central injection of MCH induced food and water intake and lowered metabolic rate and blood pressure. Overall, these results indicate that hypothalamic MCH neurons are involved in central chemoreception in wakefulness, and suggest that disturbance of their function could contribute to obesity and obesity-related breathing and metabolic disorders.