Endurance training effects on striatal D2 dopamine receptor binding and striatal dopamine metabolites in presenescent older rats
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Endurance training is associated with higher binding of 3H-spiperone to striatal D2 dopamine receptors of rats sacrificed 48 h following the last exercise bout (Gilliam et al. 1984). In the present study we investigated the effects of endurance training in presenescent older rats on the relationship between steady-state levels of DA and its metabolites in striatum versus the affinity and density of striatal D2 DA receptors. Citrate synthase activity of the gastrocnemius-plantaris muscle was 29.06±2.27 μmole/g wet wt in 21-month-old trained rats versus 22.88±1.13 μmole/g wet wt in 21-month-old untrained animals.
DOPAC levels and DOPAC/DA ratios were greater in the old controls. Endurance training was associated with lower DOPAC levels in the 21-month-old animals. Thus, endurance training may postpone selectively changes in DA metabolism over a portion of the lifespan.
As expected, the number of D2 DA binding sites was reduced with age (6 months B max:429±21 fmoles/mg protein; 21 months:355±20) with no change in affinity. The Bmax of old runners was significantly higher (457 ± 38 fmoles/mg protein) than that of old controls. Thus, endurance training appears to exert a protective effect on D2 dopamine receptors during the lifespan. Taken together, the present results suggest that there may be a possible reciprocal relationship between changes in DA metabolites and DA binding as a function of exercise in presenescent older rats, and that endurance training may decelerate the effects of age both on nigrostriatal dopamine neurons and on striatal D2 dopamine receptors during a portion of the lifespan.
- Endurance training effects on striatal D2 dopamine receptor binding and striatal dopamine metabolites in presenescent older rats
Volume 92, Issue 2 , pp 236-240
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- Basal ganglia
- D2 dopamine receptor
- Dopamine metabolites
- Endurance training
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- Author Affiliations
- 1. Department of Health and Physical Education, University of Texas, 78712, Austin, TX, USA
- 2. Institute for Neuroscience, Department of Pharmacology and Toxicology, College of Pharmacy, University of Texas, 78712, Austin, TX, USA