title: Histamine-immunoreactive neurons of the tuberomammillary nucleus are innervated by alpha-melanocyte stimulating hormone-containing axons. Generation of a new histamine antiserum for ultrastructural studies.
abstract: Leptin regulates the release of histamine in the hypothalamus, however, the histaminergic neurons contain few leptin receptors. To reveal that alpha-melanocyte stimulating hormone (alpha-MSH)-containing neurons of the arcuate nucleus may mediate the effects of leptin to the histaminergic neurons, we studied the putative innervation of histamine-immunoreactive (IR) neurons by alpha-MSH-containing axons using double-labeling immunocytochemistry. In order to analyze the relationship of alpha-MSH- and histamine-IR elements, we also generated an antiserum against histamine that is compatible with acrolein-based fixatives commonly used for immuno-electron microscopic studies. The apposition of alpha-MSH-IR axons to histaminergic neurons was observed in all five subnuclei of the tuberomammillary nucleus. Both axo-somatic and axo-dendritic contacts were found. At the ultrastructural level, silver-intensified colloidal gold particles identified the histaminergic neurons, whose ultrastructure was well preserved after fixation with acrolein demonstrating that the new antiserum is a useful tool for the ultrastructural examination of the histaminergic system. The histamine-IR cells received synaptic inputs from alpha-MSH-IR axon terminals visualized by diaminobenzidine. These data indicate that alpha-MSH-synthesizing neurons innervate histaminergic neurons in the tuberomammillary nucleus and may relay the hormonal influence of leptin to the histaminergic system.
authors.affiliation: Department of Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43, 1083, Budapest, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Fekete
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Liposits
mesh_terms: D000171:Acrolein; D000818:Animals; D001369:Axons / Q000378:metabolism* / Q000648:ultrastructure; D005247:Feeding Behavior / Q000502:physiology*; D006632:Histamine / Q000276:immunology / Q000378:metabolism*; D007026:Hypothalamic Area, Lateral / Q000502:physiology* / Q000648:ultrastructure; D007106:Immune Sera / Q000276:immunology; D015151:Immunoblotting; D007124:Immunoenzyme Techniques / Q000379:methods; D007150:Immunohistochemistry; D020738:Leptin / Q000378:metabolism; D008854:Microscopy, Electron; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure; D012710:Serum Albumin, Bovine; D000521:alpha-MSH / Q000378:metabolism*
chemical_list: D007106:Immune Sera; D020738:Leptin; D012710:Serum Albumin, Bovine; D000521:alpha-MSH; D000171:Acrolein; D006632:Histamine