Neurons in the hypothalamic paraventricular nucleus that project to the rostral ventrolateral medulla are not activated by hypotension.
The retrogradely-transported tracer, rhodamine-tagged microspheres was injected into the pressor region of the rostral ventrolateral medulla (RVLM) to enable detection of paraventricular neurons in the hypothalamus that project to the RVLM. The protein, Fos, was detected immunohistochemically and used to highlight neurons that were activated by hypotension (-16+/-5 mmHg) induced by diazoxide (30 mg/kg s.c.). Compared to controls, Fos production was increased by three-fold in the parvocellular paraventricular nucleus but there was no significant increase in the number of retrogradely-labelled cells that expressed Fos. The results suggest paraventricular nucleus (PVN) neurons projecting to the RVLM are not activated by hypotension.
Badoer
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Department of Medicine, Monash University, Monash Medical Centre, Clayton Rd., Clayton 3168, Melbourne, Victoria, Australia. emilio.badoer@med.monash.edu.au
D000818:Animals; D001370:Axonal Transport / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D002404:Catheterization; D002452:Cell Count; D002467:Cell Nucleus / Q000737:chemistry; D003981:Diazoxide / Q000008:administration & dosage / Q000494:pharmacology; D007022:Hypotension / Q000503:physiopathology*; D007279:Injections, Subcutaneous; D008526:Medulla Oblongata / Q000502:physiology*; D008845:Microinjections; D008863:Microspheres; D009434:Neural Pathways / Q000502:physiology; D009474:Neurons / Q000502:physiology*; D010286:Paraventricular Hypothalamic Nucleus / Q000737:chemistry / Q000166:cytology* / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012235:Rhodamines / Q000032:analysis / Q000378:metabolism
D016760:Proto-Oncogene Proteins c-fos; D012235:Rhodamines; D003981:Diazoxide