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Increases and Decreases in Arterial Pressure Result in the Activation of Phenotypically Different Populations of Neurons in the Nucleus of the Solitary Tract (NTS)
Author(s) -
Austgen James R,
Friskey Sarah A,
Heesch Cheryl M,
Hasser Eileen M
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1171.18
Subject(s) - solitary tract , baroreflex , rostral ventrolateral medulla , endocrinology , medicine , saline , baroreceptor , tyrosine hydroxylase , solitary nucleus , phenylephrine , mean arterial pressure , chemistry , blood pressure , anesthesia , biology , brainstem , heart rate , central nervous system , dopamine
The NTS is the termination site of multiple visceral afferents, including the arterial baroreceptors. As expected, increasing blood pressure (BP) activates second order baroreflex neurons in the NTS. However, decreasing BP also activates NTS neurons. We hypothesized that different phenotypes of neurons are activated by increases vs. decreases in BP. Male Sprague‐Dawley rats, instrumented with arterial and venous catheters, received microinjections of the retrograde tracer Fluoro‐Gold (FG) into the caudal ventrolateral medulla. After 5d, animals were administered (i.v.) saline, phenylephrine (PE: 15 mg/kg/min), or diazoxide (DZ: 50 mg/kg, supplement 12.5 mg/kg) and monitored for 90 min. Rats were perfused, brains cut into 30 μm coronal sections, and sections immunohistochemically treated for Fos and neuronal nitric oxide synthase (nNOS) or tyrosine hydroxylase (TH). Fos expression was significantly enhanced by increases (PE, 201 ± 39) and decreases (DZ, 206 ± 41) in BP compared to saline (18 ± 6). Increased BP resulted in significantly greater activation of FG (consistent with baroreflex activation) and nNOS containing neurons compared to saline. In contrast, decreases in BP resulted in significantly greater activation of TH containing neurons compared to saline. Thus, phenotypically separate populations of NTS neurons are activated by increases vs. decreases in BP. AHA #0710005Z (JRA); HL54669 (EMH)