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43. Bi-directional associations between galanin and luteinizing hormone-releasing hormone neuronal systems in the human diencephalon

Author

Dudás, B. and Merchenthaler, I.

Subjects
*LUTEINIZING hormone releasing hormone, *IMMUNOCYTOCHEMISTRY, *GONADOTROPIN, *METALLOENZYMES
Abstract

Evidence suggests that galanin plays an important role in the regulation of reproduction in the rat. Galanin is colocalized with luteinizing hormone (LH)–releasing hormone (LHRH) in a subset of LHRH neurons in female rats and galanin-immunoreactive (galanin-IR) nerve terminals innervate LHRH neurons. Recent studies indicate that galanin may control gonadal functions in rats at two different levels: (i) via direct modulation of pituitary LH secretion and/or (ii) indirectly via the regulation of the hypothalamic LHRH release. However, the morphological substrate of any similar modulation is not known in human. In the present series of experiments we first mapped the galanin-IR and LHRH-IR neural elements in human brain, utilizing single label immunohistochemistry. Then, following the superimposition of the maps of these systems, the overlapping sites were identified with double labeling immunocytochemistry and examined in order to verify the putative juxtapositions between galanin-IR and LHRH-IR structures. LHRH and galanin immunoreactivity were detected mainly in the medial basal hypothalamus, in the medial preoptic area and along the diagonal band of Broca. Careful examination of the IR elements in the overlapping areas revealed close, bi-directional contacts between galanin-IR and LHRH-IR structures, which have been verified in semithin plastic sections. These galanin-LHRH and LHRH-galanin juxtapositions were most numerous in the medial preoptic area and in the infundibulum/median eminence of the human diencephalon.In conclusion, the present study is the first to reveal bi-directional juxtapositions between galanin- and LHRH-IR neural elements in the human diencephalon. These galanin–LHRH and LHRH–galanin contacts may be functional synapses, and they may be the morphological substrate of the galanin-controlled gonadal functions in humans. [Copyright &y& Elsevier]

Published
2004
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48. Copper-H2O2 oxidation strikingly improves silver intensification of the nickel-diaminobenzidine (Ni-DAB) end-product of the peroxidase reaction.

Author

Gallyas, F and Merchenthaler, I

Abstract

We propose an improved silver procedure for intensification of peroxidase staining. It utilizes the high argyrophilia of polymerized Ni-DAB as a chromogen of peroxidase histochemistry, and the capacity of Cu++-catalyzed H2O2 oxidation to suppress tissue argyrophilia without influencing the argyrophilia of the polymerized Ni-DAB. This procedure is much more effective than any previously proposed intensification technique. When used in somatostatin histochemistry, it reveals perikarya, fibers, and nerve terminals in locations at which they have never been detected in preparations where only the DAB polymer was silver-intensified.

Published
1988
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