Comparison of melanin-concentrating hormone and hypocretin/orexin peptide expression patterns in a current parceling scheme of the lateral hypothalamic zone.
The distribution of hypothalamic neurons expressing the peptides melanin-concentrating hormone (MCH; 'MCH neurons') or hypocretin/orexin (H/O; 'H/O neurons') was assessed with immunocytochemistry in male rats at high spatial resolution. Data were plotted on a rat brain atlas that includes a recently revised parcellation scheme for the lateral hypothalamic zone. Quantitative analysis revealed approximately three times more MCH neurons than H/O neurons in the hypothalamus, and approximately twice as many within the parcellations of the lateral hypothalamic area (LHA). The LHA contained 60% of MCH neurons and 81% of H/O neurons, and the same five LHA regions contained the vast majority of MCH (87%) or H/O (93%) neurons present within the LHA: namely the LHA dorsal region (LHAd: 31% of H/O; 38% of MCH), suprafornical region (LHAs: 28% of H/O; 11% of MCH), ventral region medial zone (LHAvm: 15% of H/O; 16% of MCH), juxtadorsomedial region (LHAjd: 14% of H/O and MCH) and magnocellular nucleus (LHAm: 5% of H/O; 7% of MCH). The zona incerta (ZI) contained 18% of MCH neurons. A high co-abundance of MCH and H/O neurons outside of the LHA was present in the posterior hypothalamic nucleus (PH: 11% of H/O; 9% of MCH). Morphological analysis revealed MCH and H/O neurons as typically tri-polar with irregularly shaped somata. These data provide a quantitative analysis of neurons expressing either MCH or H/O peptides within the rat hypothalamus, and they clarify differences in the distribution pattern for different subsets of these neuron types, especially within the LHA.
Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-2520, USA. joelhahn@usc.edu
Joel D
JD
Hahn
D000818:Animals; D007026:Hypothalamic Area, Lateral / Q000378:metabolism*; D007028:Hypothalamic Hormones / Q000096:biosynthesis*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008543:Melanins / Q000096:biosynthesis*; D009474:Neurons / Q000378:metabolism; D009479:Neuropeptides / Q000096:biosynthesis*; D000068797:Orexins; D010907:Pituitary Hormones / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley
D007028:Hypothalamic Hormones; D047908:Intracellular Signaling Peptides and Proteins; D008543:Melanins; D009479:Neuropeptides; D000068797:Orexins; D010907:Pituitary Hormones; C019463:melanin-concentrating hormone