Effect of inflammatory challenge on hypothalamic neurons expressing orexinergic and melanin-concentrating hormone.
Neurons containing the hypothalamic peptides orexin-A (hypocretin 1) and melanin-concentrating hormone (MCH) have been reported numerous roles in the regulation of the sleep-wake cycle, energy balance and feeding behavior. We investigated the response of these cells to repeated administration of low doses of endotoxin lipopolysaccharide (LPS) in mice. Adult male C57/6J mice where intraperitoneally (i.p.) injected with either LPS or phosphate-buffered saline (PBS) weekly for either 4 or 8 weeks, and afterwards were sacrificed at different time intervals from last injection. A significant drop in orexin-containing neuron number, but not in numbers of MCH or neuronal nuclear antigen (NeuN)-immunoreactive neurons, was observed after 8 weeks of LPS treatment, as compared to PBS treatment. Orexin expression entirely returned to control levels 30 days after the last LPS injection in mice treated for 8 weeks. These data strongly suggest the occurrence of selective alterations of orexinergic system, reversible over time, following repeated and intermittent systemic inflammatory challenge in mice.
Department of Morphology, Surgery and Experimental Medicine, University of Ferrara, Ferrara, Italy. Electronic address: plmmra@unife.it.
Maria
M
Palomba
Department of Basic Health Sciences, College of Applied Medical Sciences, Qassim University, Buraydah, Saudi Arabia.
Paul Faustin
PF
Seke Etet
Department of Biomedical and Specialty Surgical Sciences, Section of Human Physiology, University of Ferrara, Ferrara, Italy.
Carlo
C
Veronesi
D000818:Animals; D002452:Cell Count; D007028:Hypothalamic Hormones / Q000378:metabolism*; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D007249:Inflammation / Q000378:metabolism / Q000473:pathology; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D008543:Melanins / Q000378:metabolism*; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D000068797:Orexins; D010907:Pituitary Hormones / Q000378:metabolism*
C000596229:HCRT protein, human; D007028:Hypothalamic Hormones; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides; D008543:Melanins; D009479:Neuropeptides; D000068797:Orexins; D010907:Pituitary Hormones; C019463:melanin-concentrating hormone
Immune-to-brain signaling; Lipopolysaccaride; MCH; Orexin; Systemic inflammation