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Leptin acts in the forebrain to increase gain of baroreflex control of lumbar sympathetic nerve activity and heart rate
Author(s) -
Li Baoxin,
Cassaglia Priscila A.,
Brooks Virginia L.
Publication year - 2012
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.26.1_supplement.891.11
Subject(s) - baroreflex , leptin , heart rate , medicine , endocrinology , anesthesia , blood pressure , obesity
Leptin increases lumbar sympathetic nerve activity (LSNA), but whether leptin also enhances baroreflex control of LSNA and heart rate (HR) is unclear. To test this hypothesis, leptin was infused into the lateral cerebroventricle (ICV) of α ‐chloralose anesthetized male SD rats. Baroreflex function was assessed hourly for 2 hrs using a 4 parameter sigmoidal fit of HR and LSNA responses to slow ramp (3–5 min) changes in arterial pressure (AP), induced by iv infusion of nitroprusside and phenylephrine. After 2 hr, leptin (3μg, n=5) increased (P<0.05) the maximum gain (BRG) of LSNA (from 4.0±0.6 to 6.9±1.4 %/mmHg) and HR (from 2.5±0.2 to 3.4±0.5 bpm/mmHg), as well as LSNA (to 204±20 % control), HR (from 327±6 to 395±13 bpm), the reflex LSNA maximum (from 185±12 to 370 ± 38%), the HR maximum (from 399±12 to 472±20 bpm), and mean AP (from 111±3 to124±4 mmHg). A lower dose of leptin (1.5 μg; n=5) transiently increased LSNA BRG at 1 hr (from 3.1±0.6 to 5.5±1.2 %/mmHg; P<0.05); other parameters were not significantly altered. ICV infusion of the artificial CSF vehicle (n=5) had no effects. To test if leptin acts in the brainstem to improve baroreflex function, leptin (3 μg) was infused into the 4 th ventricle (n=4). However, no significant changes in LSNA BRG (4.2±0.5 to 4.1±0.5 %/mmHg), HR BRG (2.2 ±0.6 to 2.3±0.5 bpm /mmHg), or other parameters were observed. In conclusion, leptin acts in the forebrain to enhance baroreflex control of HR and LSNA, by increasing BRG and maximum reflex HR and LSNA. Support: HL088552.