Galanin immunoreactivity in hypothalamic neurons: further evidence for multiple chemical messengers in the tuberomammillary nucleus

J Comp Neurol. 1986 Aug 1;250(1):58-64. doi: 10.1002/cne.902500105.

Abstract

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.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Galanin
  • Histamine / metabolism*
  • Histocytochemistry
  • Hypothalamus / immunology*
  • Hypothalamus, Posterior / cytology
  • Hypothalamus, Posterior / immunology*
  • Hypothalamus, Posterior / metabolism
  • Hypothalamus, Posterior / ultrastructure
  • Immunochemistry
  • Male
  • Mammillary Bodies
  • Microscopy, Electron
  • Neurons / immunology*
  • Neurons / metabolism
  • Neurons / ultrastructure
  • Peptides / immunology*
  • Rats
  • Rats, Inbred Strains

Substances

  • Peptides
  • Histamine
  • Galanin