The distribution of lamprey GnRH-III in brains of adult sea lampreys (Petromyzon marinus).

Abstract

In the sea lamprey, Petromyzon marinus, two forms of GnRH, lamprey GnRH-I and -III, have been demonstrated to be neurohormones regulating the pituitary-gonadal axis. The objective of the present study was to determine the distribution of lamprey GnRH-III in the brains of adult sea lampreys and to compare it to the distribution of lamprey GnRH-I. For this purpose, two kinds of immunostaining were employed: one was a single immunostaining by one of two GnRH antibodies using two successive sections; the other was double immunostaining of a single section. A dense accumulation of neuronal cells immunoreactive (ir) to antisera against either lamprey GnRH-I or -III was found in the arc-shaped preoptico-anterior hypothalamic area. Additional smaller numbers of irGnRH cells were found in the periventricular zone of the posterior hypothalamus. In the above-mentioned locations, the distribution of both irGnRH-I and -III cells was intermixed and very similar, but the cells exhibiting GnRH-III immunoreactivity were distinctly different from those exhibiting GnRH-I immunoreactivity. The relative numbers of irGnRH-III cells were larger than those of irGnRH-I cells in the preoptico-anterior hypothalamic area, and more than 90% of GnRH cells in the posterior hypothalamus were irGnRH-III cells. Both irGnRH-I and -III cells projected their fibers primarily into the neurohypophysis. The relative densities of the accumulated irGnRH-III fibers were similar to those of irGnRH-I fibers in the anterior neurohypophysis but higher than those of irGnRH-I fibers in the posterior neurohypophysis. The present study provides further immunocytochemical data to the already compelling physiological evidence that indicates that both lamprey GnRH-I and -III act through the hypothalamic-pituitary-gonadal axis to modulate reproductive processes in the sea lamprey.

• Authors: M Nozaki, K Ominato, A Gorbman, S A Sower
• Journal: General and comparative endocrinology (Gen Comp Endocrinol) Vol. 118 Issue 1 Pg. 57-67 (Apr 2000) ISSN: 0016-6480 [Print] United States
• PMID: 10753567 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: Copyright 2000 Academic Press.

Chemical References

• Protein Isoforms
• Gonadotropin-Releasing Hormone

Topics

• Animals
• Brain (cytology)
• Brain Chemistry (physiology)
• Female
• Gonadotropin-Releasing Hormone (metabolism)
• Immunohistochemistry
• Lampreys (metabolism)
• Larva
• Male
• Nerve Fibers (metabolism)
• Neurons (drug effects, metabolism)
• Protein Isoforms (metabolism)