Nitric oxide synthase-containing magnocellular neurons of the rat hypothalamus synthesize oxytocin and vasopressin and express Fos following stress stimuli.
We investigated the chemical and anatomical features of nitric oxide synthase (NOS)-containing neurons in the paraventricular and supraoptic nuclei in the rat hypothalamus using combinations of enzyme histochemistry, in situ hybridization and immuno-histochemistry. Neurons expressing NOS mRNA completely overlapped with NADPH-diaphorase-positive neurons. Topographical distribution of NOS was segregated from that of CRF-containing parvicellular neurons in the posterior paraventricular nucleus but overlapped with that of magnocellular neurons. In the paraventricular nucleus, 70% of oxytocin neurons contained NOS, which corresponded to one half of NOS neurons. About one third of vasopressin-immunoreactive neurons were NADPH-diaphorase-positive and the same proportion of NADPH-diaphorase-positive neurons were vasopressin-immunoreactive. In the supraoptic nucleus, 50% of oxytocin neurons were NADPH-diaphorase-positive, which corresponded to 40% of NOS neurons. About 25% of vasopressin neurons were NADPH-diaphorase-positive, and 30% of NADPH-diaphorase-positive neurons were vasopressin-immunoreactive. When NADPH-diaphorase histochemistry was performed first, subsequent immunostaining was markedly perturbed. Using fluoro-gold as a retrograde tracer, 4% of NADPH-diaphorase-positive neurons were shown to contribute to the descending projection to the spinal cord. About 40%-50% of NADPH-diaphorase-positive neurons exhibited Fos immunoreactivity after injection of lipopolysaccharide or hypertonic saline, while only 10%-15% of these neurons expressed Fos in response to immobilization or pain. Endogenous NO may be involved in the regulation of magnocellular functions, especially when the internal environment is disturbed.
Hatakeyama
S
S
Department of Anatomy and Neurobiology, Wakayama Medical College, Japan.
Kawai
Y
Y
Ueyama
T
T
Senba
E
E
D000818:Animals; D001370:Axonal Transport; D008058:Dihydrolipoamide Dehydrogenase / Q000032:analysis / Q000096:biosynthesis; D004926:Escherichia coli; D005456:Fluorescent Dyes; D016762:Genes, fos; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008070:Lipopolysaccharides / Q000494:pharmacology; D008297:Male; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D010121:Oxytocin / Q000096:biosynthesis*; D010146:Pain; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical; D012462:Saline Solution, Hypertonic / Q000494:pharmacology; D013116:Spinal Cord / Q000502:physiology; D013266:Stilbamidines; D013312:Stress, Physiological; D013315:Stress, Psychological; D013495:Supraoptic Nucleus / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors; D014667:Vasopressins / Q000096:biosynthesis*
C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D005456:Fluorescent Dyes; D008070:Lipopolysaccharides; D016760:Proto-Oncogene Proteins c-fos; D012462:Saline Solution, Hypertonic; D013266:Stilbamidines; D014667:Vasopressins; D010121:Oxytocin; D019001:Nitric Oxide Synthase; D008058:Dihydrolipoamide Dehydrogenase