Objective: To investigate the effect of fatigue and restraint stress on the expressions of CPT (carnitine palmitoyltransferase)-I, PPAR (peroxisome proliferator-activated receptor) δ, 5-HT (hydroxytryptamine) 1D and 5-HT2A receptors in aorta of rats.
Methods: A total of 45 healthy male Wistar rats were randomly divided into control group, excessive fatigue group and restraint stress group (n = 15 each). The general condition, morphological changes of aortic endothelium cell and the blood levels of ET-1 (endothelin) and NO (nitric oxide) were observed. The real-time reverse transcription PCR (polymerase chain reaction) and Western blot were used to detect the gene and protein expressions of CPT-I, PPAR δ, 5-HT1D and 5-HT2A receptors in aorta.
Results: Compared with control group, the structural damages of endothelial cell were induced by excessive fatigue and restraint stress. The plasma levels of ET-1 increased [(124 ± 18) ng/L vs (161 ± 18) ng/L, (154 ± 17) ng/L] (P < 0.01, P < 0.05) while the serum levels of NO decreased [(63 ± 16) µmol/L vs (39 ± 8) µmol/L, (41 ± 7) µmol/L] (P < 0.05); the mRNA expressions of CPT-Iand PPARδ decreased in excessive fatigue rats, [(1.23 ± 0.21) vs (0.42 ± 0.05)], [(1.09 ± 0.10) vs (0.25 ± 0.07)] (P < 0.01); the protein expressions of CPT-Iand PPARδ decreased in excessive fatigue rats, [(1.32 ± 0.07) vs (0.83 ± 0.04)], [(1.41 ± 0.05) vs. (0.75 ± 0.06)]; the mRNA and protein expressions of 5-HT1D receptor decreased in excessive fatigue rats and restraint stress rats, [(1.10 ± 0.15) vs (0.46 ± 0.13), (0.45 ± 0.02)], [(1.19 ± 0.05) vs (0.71 ± 0.06), (0.70 ± 0.05)] (P < 0.01); the mRNA and protein expressions of 5-HT2A receptor increased in excessive fatigue rats and restraint stress rats, [(0.99 ± 0.08) vs (6.73 ± 0.46), (7.01 ± 1.56)], [(0.64 ± 0.03) vs (0.79 ± 0.05), (0.82 ± 0.03)] (P < 0.01).
Conclusion: Excessive fatigue and restraint stress can injure the structure and function of endothelial cell. The changes in energy of abnormal carnitine metabolism and 5-HT receptors may play important roles.