Galanin immunoreactivity in hypothalamic neurons: further evidence for multiple chemical messengers in the tuberomammillary nucleus.
By using a specific antibody against the 29 amino-acid peptide galanin (Gal) with light and electron microscopic immunocytochemistry, we have studied the distribution of Gal immunoreactivity in the posterior hypothalamic magnocellular neurons of the rat. In colchicine-treated rats, a large number of Gal-immunoreactive cells were identified within all subdivisions of the tuberomammillary nucleus. The majority of these cells are large multipolar or fusiform neurons, with long, sparsely branching dendrites. A small number project to the ventral hippocampus, as shown by experiments with the retrograde tracing of Fast Blue. Ultrastructural examination of the Gal-immunoreactive cells confirms their indentity as magnocellular neurons, with dense deposits of immunoreaction product, particularly in small ribosomal arrays and in large, dense-cored vesicles. Axosomatic synapses occur on these neurons. The axonal boutons synapse with asymmetric and symmetric junctions and contain small synaptic vesicles as well as numerous large, dense-cored vesicles, which display Gal immunoreactivity. Sequential staining of thin, alternate sections with antibodies against Gal and L-histidine decarboxylase (HDCase; EC 4.1.1.22) showed colocalization of Galand HDCase-immunoreactivities in a majority of tuberomammilary neurons. The finding of Gal immunoreactivity within histamine-producing neurons of the tuberomammillary nucleus adds to the multiplicity of potential neuronal messengers utilized by these cells.
D000818:Animals; D019004:Galanin; D006632:Histamine / Q000378:metabolism*; D006651:Histocytochemistry; D007031:Hypothalamus / Q000276:immunology*; D007034:Hypothalamus, Posterior / Q000166:cytology / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure; D007120:Immunochemistry; D008297:Male; D008326:Mammillary Bodies; D008854:Microscopy, Electron; D009474:Neurons / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure; D010455:Peptides / Q000276:immunology*; D051381:Rats; D011919:Rats, Inbred Strains
D010455:Peptides; D006632:Histamine; D019004:Galanin