Neural interaction between galanin-like peptide (GALP)- and luteinizing hormone-releasing hormone (LHRH)-containing neurons.
Galanin-like peptide (GALP), commonly known as an appetite-regulating peptide, has been shown to increase plasma luteinizing hormone (LH) through luteinizing hormone-releasing hormone (LHRH). This led us to investigate, using both light and electron microscopy, whether GALP-containing neurons in the rat brain make direct inputs to LHRH-containing neurons. As LHRH-containing neurons are very difficult to demonstrate immunohistochemically with LHRH antiserum without colchicine treatment, we used a transgenic rat in which LHRH tagged with enhanced green fluorescence protein facilitated the precise detection of LHRH-producing neuronal cell bodies and processes. This is the first study to report on synaptic inputs to LHRH-containing neurons at the ultrastructural level using this transgenic model. We also used immunohistochemistry to investigate the neuronal interaction between GALP- and LHRH-containing neurons. The experiments revealed that GALP-containing nerve terminals lie in close apposition with LHRH-containing cell bodies and processes in the medial preoptic area and the bed nucleus of the stria terminalis. At the ultrastructural level, the GALP-positive nerve terminals were found to make axo-somatic and axo-dendritic synaptic contacts with the EGFP-positive neurons in these areas. These results strongly suggest that GALP-containing neurons provide direct input to LHRH-containing neurons and that GALP plays a crucial role in the regulation of LH secretion via LHRH.
Takenoya
Fumiko
F
Department of Anatomy I, Showa University School of Medicine, Tokyo 142-8555, Japan.
Guan
Jian-Lian
JL
Kato
Masakatsu
M
Sakuma
Yasuo
Y
Kintaka
Yuri
Y
Kitamura
Yoshitaka
Y
Kitamura
Shinji
S
Okuda
Hiromi
H
Takeuchi
Masao
M
Kageyama
Haruaki
H
Shioda
Seiji
S
D000818:Animals; D030801:Animals, Genetically Modified; D005456:Fluorescent Dyes / Q000032:analysis; D044089:Galanin-Like Peptide / Q000096:biosynthesis*; D007987:Gonadotropin-Releasing Hormone / Q000096:biosynthesis* / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics; D007150:Immunohistochemistry; D008297:Male; D009474:Neurons / Q000378:metabolism* / Q000648:ultrastructure; D011301:Preoptic Area / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D012686:Septal Nuclei / Q000378:metabolism* / Q000648:ultrastructure; D013569:Synapses / Q000648:ultrastructure*
D005456:Fluorescent Dyes; D044089:Galanin-Like Peptide; D011993:Recombinant Fusion Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D007987:Gonadotropin-Releasing Hormone