title: [Effects of intracerebroventricular microinjection of L-arginine on exercise capacity and expression of nitric oxide in rat hypothalamus].
abstract: OBJECTIVE
  To explore the relationship between nitric oxide (NO) in central nervous system and exercise-induced fatigue stress and to study the effect of L-arginine (L-Arg), as a substrate of nitric oxide, on the exercise capacity and NO content in the exhausted rat brain and blood.
  
  
  METHODS
  Through an implanted cannula, the normal saline or L-Arg was microinjected into rat's intracerebroventrical for consecutive four days. Then an acute exhaustive model (on the speed of 18 m/min, an inclination of 5 degrees) was established with animal treadmill. The time of exercise till exhaustion was recorded, and the total workload was calculated that represented the exercise capacity. Nitrate and nitrite (NO3/NO2-, NOx-) levels in blood, hypothalamus and hippocampus were assayed.
  
  
  RESULTS
  Both the time of exercise till exhaustion and total workload in the LArg group increased respectively by 51.8% and 50.08% (P < 0.05), compared with those in the control. The NOx- content in hypothalamus in the L-Arg group (8.93 +/- 1.83) micromol/g pro was larger than that in the control (4.25 +/- 0.79) micromol/g pro, (P < 0.01). There was no significant difference in NOx- content in brain and hippocampus between the two groups. The total workload was positively correlated with NOx- concentration in hypothalamus (P < 0.01). However, there was no correlation between workload and changes in hippocampus NOx- content at fatigue.
  
  
  CONCLUSIONS
  Intracerebroventricular microinjection of L-Arg may enhance the exercise capacity and lead to up-regulation of NO by means of L-Arg-NO signal path in the hypothalamus. Hypothalamus may be a key site in brain in the modulation of physiological exercise.
authors.affiliation: Radiology Department, Tangdu Hospital of the Fourth Military Medical University, Xi'an 710038.
authors.forename: Jin-Juan
authors.initials: JJ
authors.lastname: Xue
authors.forename: Hong-Yu
authors.initials: HY
authors.lastname: Liu
mesh_terms: D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology*; D006624:Hippocampus / Q000378:metabolism; D007031:Hypothalamus / Q000378:metabolism*; D020547:Lateral Ventricles; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D009569:Nitric Oxide; D001120:Arginine