Immunohistochemical evidence for synaptic connections between pro-opiomelanocortin-immunoreactive axons and LH-RH neurons in the preoptic area of the rat.
Connections between adrenocorticotropic hormone (ACTH)-immunoreactive neurons in the arcuate nucleus and the preoptic area were studied in the female rat. ACTH-immunopositive terminals were observed in the medial preoptic area in contact with dendritic shafts, while in the ventrolateral preoptic area the majority of ACTH-immunoreactive synapses were found on dendritic spines. Double-label electron microscopic immunocytochemistry using peroxidase and avidin-ferritin as contrasting electron-dense markers revealed numerous synaptic contacts between ACTH-immunopositive boutons and luteinizing hormone-releasing hormone (LH-RH)-immunoreactive dendritic shafts in the medial preoptic area. Following injection of horseradish peroxidase (HRP) into the medial preoptic area, retrogradely HRP-labeled perikarya were observed throughout the arcuate nucleus. Double-staining experiments revealed that a proportion of these retrogradely labeled cells, in the ventromedial arcuate nucleus, are also immunoreactive for ACTH. These results suggest that pro-opiomelanocortin peptide-producing neurons in the ventromedial arcuate nucleus project to the medial preoptic area. Some of these neurons establish direct synaptic contacts with LH-RH-immunoreactive cells.
Leranth
C
C
Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, CT 06510.
MacLusky
N J
NJ
Shanabrough
M
M
Naftolin
F
F
D000324:Adrenocorticotropic Hormone / Q000032:analysis; D000818:Animals; D001370:Axonal Transport; D001369:Axons / Q000502:physiology* / Q000648:ultrastructure; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000032:analysis*; D006735:Horseradish Peroxidase; D008854:Microscopy, Electron; D009474:Neurons / Q000502:physiology*; D011301:Preoptic Area / Q000502:physiology* / Q000648:ultrastructure; D011333:Pro-Opiomelanocortin / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure
D007987:Gonadotropin-Releasing Hormone; D011333:Pro-Opiomelanocortin; D000324:Adrenocorticotropic Hormone; D006735:Horseradish Peroxidase