High-fat feeding alters the cardiovascular role of the hypothalamic paraventricular nucleus.
Increased sympathetic nerve activity is associated with obesity-related hypertension, but the underlying central neural mechanisms are not clear. We examined the role of the hypothalamic paraventricular nucleus (PVN) in the regulation of sympathetic nerve activity in rats fed a normal chow diet (controls) and rats fed a high-fat diet (36% fat) over 12 wk. The effects on blood pressure, heart rate, and lumbar sympathetic nerve activity (LSNA) induced by microinjection of the GABA(A) receptor agonist muscimol or the antagonist bicuculline were monitored in anesthetized rats. Body weight of rats fed the high-fat diet was not significantly different from controls, but a significant 80% increase in epididymal fat mass, significantly elevated fasting blood glucose, and significantly impaired glucose tolerance were observed in rats fed the high-fat diet. Resting blood pressure and heart rate were not significantly different between rats fed the high-fat diet and controls. Muscimol microinjected into the PVN elicited a greater reduction of blood pressure and LSNA in rats fed the high-fat diet than controls: -14 +/- 6 vs. -7 +/- 2 mmHg and -35 +/- 6 vs. -10 +/- 9% (P < 0.05). Microinjection of bicuculline into the PVN increased blood pressure and LSNA, but the responses were similar in rats fed the high-fat diet and controls. In conclusion, the role of the paraventricular nucleus in cardiovascular regulation can be altered by a diet high in fat, even when hypertension and obesity are absent.
Chen
Feng
F
School of Medical Sciences and Health Innovations Research Institute, RMIT University, Victoria, Australia.
Cham
Joo Lee
JL
Badoer
Emilio
E
D000273:Adipose Tissue / Q000502:physiology; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D001835:Body Weight / Q000502:physiology; D002319:Cardiovascular System / Q000294:innervation; D004041:Dietary Fats / Q000494:pharmacology*; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D005951:Glucose Tolerance Test; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D008845:Microinjections; D009118:Muscimol / Q000494:pharmacology; D009765:Obesity / Q000503:physiopathology*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000502:physiology*
D001786:Blood Glucose; D004041:Dietary Fats; D018755:GABA Agonists; D018756:GABA Antagonists; D009118:Muscimol; D001640:Bicuculline