title: Chronic treadmill running in normotensive rats resets the resting blood pressure to lower levels by upregulating the hypothalamic GABAergic system.
abstract: OBJECTIVE
  The cardiovascular integration center not only sends out signals to offset the stimulus-induced responses but also resets the resting blood pressure. We hypothesize that GABAergic adaptations in the hypothalamus participate in the chronic exercise-induced cardiovascular resetting effects in conscious normotensive animals.
  
  
  METHODS
  Male Wistar rats were subjected to chronic moderate exercise (CME, 8-week treadmill running at moderate intensity). A biotelemetry system was used to measure blood pressure, heart rate, autonomic nervous activities, baroreflex sensitivity and endogenous GABAergic activities in the paraventricular nucleus and the posterior hypothalamic area. Hypothalamic specimens were collected for quantifying GABA-related proteins and GABAergic neurons.
  
  
  RESULTS
  CME reduced resting blood pressure, heart rate, sympathetic activity and enhanced parasympathetic activity and baroreflex sensitivity. Additionally, CME elevated the resting level of hypothalamic GABAergic activities, increased the percentage of GABAergic neurons in the hypothalamus and upregulated the hypothalamic protein levels of neuronal nitric oxide synthase, GAD67 and gephyrin, but not GABAA receptor. Moreover, a single bout of moderate exercise transiently elevated blood pressure and heart rate with prolonged high levels of neural controls (sympathetic activity, baroreflex sensitivity and hypothalamic GABAergic activities). CME accelerated the postexercise recovery in cardiovascular parameters and neural control alterations.
  
  
  CONCLUSIONS
  Chronic treadmill running in normotensive rats augmented the GABAergic system in both paraventricular nucleus and posterior hypothalamic area, resulting in lower resting blood pressure, heart rate and sympathetic tone under conscious unrestraint conditions. This study provides insight into mechanisms important for explaining how chronic exercise resets the resting blood pressure.
authors: Institute of Basic Medical Sciences, National Cheng Kung University, Tainan, Taiwan, ROC.
authors: Yuan-Chang
authors: YC
authors: Hsu
authors: Hsiun-Ing
authors: HI
authors: Chen
authors: Yu-Min
authors: YM
authors: Kuo
authors: Lung
authors: L
authors: Yu
authors: Tung-Yi
authors: TY
authors: Huang
authors: Shean-Jen
authors: SJ
authors: Chen
authors: Jih-Ing
authors: JI
authors: Chuang
authors: Fong-Sen
authors: FS
authors: Wu
authors: Chauying J
authors: CJ
authors: Jen
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism; D003345:Corticosterone / Q000097:blood; D005080:Exercise Test / Q000662:veterinary*; D018756:GABA Antagonists / Q000494:pharmacology; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006439:Hemodynamics; D007034:Hypothalamus, Posterior / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism; D010286:Paraventricular Hypothalamic Nucleus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D018079:Receptors, GABA / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism; D012815:Signal Processing, Computer-Assisted; D013686:Telemetry
chemical_list: D002352:Carrier Proteins; D018756:GABA Antagonists; D008565:Membrane Proteins; D018079:Receptors, GABA; D011963:Receptors, GABA-A; C073441:gephyrin; D052248:Nitric Oxide Synthase Type I; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; D003345:Corticosterone; D001640:Bicuculline