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Exp Clin Endocrinol Diabetes 1989; 94(4/05): 133-140
DOI: 10.1055/s-0029-1210889
Original

© J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart · New York

Identification of Hypophysiotropic Luteinizing Hormone-Releasing Hormone (LHRH) Neurons by Combined Retrograde Labeling and Immunocytochemistry*)

I. Merchenthaler, G. Sétáló, P. Petrusz, A. Negro-Vilar, B. Flerkó
  • Department of Anatomy, University Medical School, Pécs, Hungary
  • Department of Cell Biology and Anatomy, University of North Carolina, Chapel Hill, North Carolina, USA; and National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
*) Dedicated to Professor Dr. sc. med. Günter Dörner on the occasion of his 60th birthday.
Further Information

Publication History

1988

Publication Date:
16 July 2009 (online)

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Summary

The decapeptide luteinizing hormone-releasing hormone (LHRH) is produced by telencephalic and diencephalic neurons and transported to the median eminence (ME). After having been released from nerve terminals, it is carried by the hypophysial portal vessels to the anterior pituitary, where it stimulates the production and release of luteinizing hormone (LH) and follicle stimulating hormone (FSH). Those LHRH neurons which project to the ME represent the final common pathway for the regulation of the pituitary/gonadal axis. We identified these neurons by injecting a retrograde tracer, the lectin wheat germ agglutinin (WGA), into the external zone of the ME. Eight to 24 hours later colchicine was given into the lateral ventricle and 24–48 hours after the WGA injection the animals were sacrificed. Vibratome sections of the brains were stained simultaneously for WGA and LHRH with a dual immunocytochemical technique.

Approximately 70% of the LHRH neurons in the septum and the anterior hypothalamus were double-labeled, indicating that they projected to the ME. Double labeled LHRH cells were either smooth, fusiform or „spiny”. WGA-accumulating LHRH perikarya were intermixed with single-labeled LHRH cells. The remaining 30% of the LHRH neurons which were not labeled with WGA appeared to project to different hypothalamic and extrahypothalamic areas of the brain.

Our results suggest that there are at least two populations of LHRH neurons, one with access to the portal capillaries of the ME and functionally related to the regulation of the pituitary, and one without access to capillaries of the ME, functionally probably related to intracerebral neurotransmission or modulation. In addition, some LHRH neurons may have axon collaterals which can reach multiple targets within the central nervous system.

Key words

LHRH - Immunocytochemistry - Double labeling - Wheat germ agglutinin - Retrograde labeling

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