Origin of noradrenergic projections to GnRH perikarya-containing areas in the medial septum-diagonal band and preoptic area.
The purpose of the present study was to identify the sites of origin of the noradrenergic fibers that project to areas containing gonadotropin-releasing hormone (GnRH) perikarya since norepinephrine (NE) is known to influence the activity of GnRH neurons. Fluorescent retrograde tracers were used in combination with immunohistochemistry for dopamine-beta-hydroxylase (DBH) and GnRH. Small volumes of either Fluoro-gold (FG) or Fluoro-Ruby (FR) were pressure injected into areas that contain the largest number of GnRH cell bodies, i.e., the medical septum-diagonal band complex or preoptic area. Retrogradely labeled neurons were observed ipsilaterally in the following noradrenergic cell groups: A2 (in the nucleus tractus solitarii), A1 (in the ventrolateral medulla) and locus coeruleus. Approximately 8% of all DBH-positive neurons within the A2-cell group were retrogradely labeled, while 12% of DBH-ir neurons in the A1-group were double-labeled. Only a few retrogradely labeled DBH-ir neurons were observed in the locus coeruleus (< 1%). Double-labeled neurons were not organized into discrete cell groups, but were dispersed among other NE-neurons within the A2- and A1-cell groups. The highest concentrations of double-labeled neurons were located in the central one-third of both the A2 and A1 cell groups. The results suggest that most noradrenergic terminals in the region of the GnRH perikarya in the medial septum-diagonal band/rostral preoptic area originate from ipsilateral neurons in areas A1 and A2.(ABSTRACT TRUNCATED AT 250 WORDS)
Wright
D E
DE
Department of Anatomy and Neurobiology, University of Kentucky, College of Medicine, Lexington 40536-0084.
Jennes
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D000818:Animals; D001933:Brain Stem / Q000737:chemistry* / Q000648:ultrastructure; D003911:Dextrans; D004299:Dopamine beta-Hydroxylase / Q000032:analysis; D005260:Female; D005456:Fluorescent Dyes; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis*; D007150:Immunohistochemistry; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000737:chemistry* / Q000648:ultrastructure; D009638:Norepinephrine / Q000502:physiology*; D011301:Preoptic Area / Q000737:chemistry* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012235:Rhodamines; D012688:Septum Pellucidum / Q000737:chemistry* / Q000648:ultrastructure; D013266:Stilbamidines
C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D003911:Dextrans; D005456:Fluorescent Dyes; C067661:Fluoro-Ruby; D012235:Rhodamines; D013266:Stilbamidines; D007987:Gonadotropin-Releasing Hormone; D004299:Dopamine beta-Hydroxylase; D009638:Norepinephrine