Melanin concentrating hormone (MCH): A novel neural pathway for regulation of GnRH neurons

• Published in: Brain research Vol. 1041; no. 2; pp. 117 - 124
• Main Authors: Williamson-Hughes, Patricia S., Grove, Kevin L., Smith, M. Susan
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 18.04.2005; Amsterdam Elsevier; New York, NY
• Subjects: Animals; Anterior Hypothalamic Nucleus - cytology; Anterior Hypothalamic Nucleus - metabolism; Appetite Regulation - physiology; Biological and medical sciences; Confocal microscopy; Estrous Cycle - physiology; Female; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; GnRH; Gonadotropin-Releasing Hormone - metabolism; Hormones and neuropeptides. Regulation; Hypothalamic Area, Lateral - cytology; Hypothalamic Area, Lateral - metabolism; Hypothalamic Hormones - metabolism; Hypothalamo-Hypophyseal System - cytology; Hypothalamo-Hypophyseal System - metabolism; Hypothalamus. Hypophysis. Epiphysis. Urophysis; Immunofluorescence; MCH; MCHR1; Melanins - metabolism; Microscopy, Confocal; Neural Pathways - metabolism; Neuroanatomy; Neurons - metabolism; Pituitary Hormones - metabolism; Preoptic Area - cytology; Preoptic Area - metabolism; Presynaptic Terminals - metabolism; Presynaptic Terminals - ultrastructure; Rats; Rats, Sprague-Dawley; Receptors, Pituitary Hormone - metabolism; Reproduction - physiology; Vertebrates: endocrinology; MCH; Endocrine and autocrine regulation; Neuroanatomy; Confocal microscopy; GnRH; Immunofluorescence; MCHR1; Hypothalamic hormone; Neuron; MCHRI; Melanin concentrating hormone; Gonadotropin RH; Hypothalamohypophysogonadal axis; Hormone releasing factor
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2004.11.066

The link between the state of energy balance and reproductive function is well known. Thus, signals denoting negative energy balance and the accompanying hyperphagic drive are likely to be factors in the suppression of gonadotropin releasing hormone (GnRH) activity. We have previously found that appetite-regulating systems, such as neuropeptide Y (NPY) in the arcuate nucleus (ARH) and orexin in the lateral hypothalamic area (LHA), send fiber projections that come in close apposition with GnRH neurons. Furthermore, the appropriate receptors, NPY Y5 and OR-1, respectively, are coexpressed on GnRH neurons, providing neuroanatomical evidence for a direct link between the NPY and orexin systems and GnRH neurons. Therefore, these orexigenic neuropeptide systems are potential candidates that convey information about energy balance to GnRH neurons. The current studies focused on melanin concentrating hormone (MCH), another orexigenic neuropeptide system located in the LHA that is sensitive to energy balance. The results showed that MCH fiber projections came in close apposition with approximately 85–90% of GnRH cell bodies throughout the preoptic area and anterior hypothalamic area in the rat. In addition, the MCH receptor (MCHR1) was coexpressed on about 50–55% of GnRH neurons. These findings present evidence for a possible direct neuroanatomical pathway by which MCH may play a role in the regulation of GnRH neuronal function. Thus, MCH is another potential signal that may serve to integrate energy balance and reproductive function.