BACKGROUND: Spleen is correlated with mitochondrion. The "spleen governs movement and transformation of food and liquids" in traditional Chinese medicine refers to not only the digestion and absorption of food in gastrointestinal tract, but also the process of biological oxidation and energy production of mitochondrion.OBJECTIVE: To analyze the effects of Si-Jun-Zi decoction (SJZD), a typical prescription for invigorating spleen and replenishing qi, on repairing the mitochondrial damage of cells of liver, myocardium, gastric mucosa and skeletal muscle in rats with spleen asthenia.DESIGN: A randomized controlled observation.SETTINGS: Second Department of Internal Medicine, the First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine;Guangzhou University of Traditional Chinese Medicine.MATERIALS: The experiments were carried out in the internal medicine laboratory, the First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine and the testing center of Guangzhou University of Traditional Chinese Medicine from June to December in 2004. Forty SD rats were provided by the animal center of Guangzhou University of Traditional Chinese Medicine. Xiao Cheng-Qi decoction consisted of officinal magnolia bark, immature bitter orange and rhubarb according to the ratio of 3:3:2; SJZD consisted of radix codonopsitis pilosulae, largehead atractylodes rhizome, India bread and liquorice root according to the ratio of 2:2:2:1, and it was provided by the Department of Pharmacy, the First Affiliated Hospital of Guangzhou University of Traditional Chinese Medicine,and made into 100% decoction.METHODS: After raised for 1 week, the SD rats were divided randomlyinto 4 groups: normal control group, spleen asthenia group, natural convalescence group and SJZD-treated group, and the rats in the latter three groups were made into models of long-term spleen asthenia. Rats in the normal control group were fed with normal chow, intragastric administered with saline (3 mL), once every other day for 34 weeks. Rats in the spleen asthenia group were intragastricly administered with Xiao Cheng-Qi decoction (3 mL) and fed every other day for 34 weeks, the rats in the natural convalescence group were fed with normal chow for 8 weeks after being treated as those in the spleen asthenia group for 26 weeks, and those in the SJZD-treated group were treated as those in the spleen asthenia group for 26 weeks, and then intragastricly administered with SJZD (4 mL, once a day) and fed with normal chow for 8 weeks. At the end of the 34th week,the rats were decapitated under anesthesia, and the skeletal muscle, liver,gastric mucosa and myocardium were taken out rapidly. The protein amounts in mitochondrial suspension were detected with the biuret method,the content of mitochondria in I g tissue was calculated according to the tissue mass, and the mitochondrial ultrastructures were observed under transmission electron microscope.MAIN OUTCOME MEASURES: The contents and ultrastructures of mitochondria in skeletal muscle, liver, gastric mucosa and myocardium were observed.RESULTS: All the 40 rats were involved in the analysis of results without deletion. ① At the end of the 34th week, the mitochondrial contents of skeletal muscle, liver, myocardium and gastric mucosa were all significantly lower in the spleen asthenia group than in the normal control group (P＜ 0.01), and markedly higher in the natural convalescence group than in the spleen asthenia group (P ＜ 0.05-0.01). The mitochondrial contents of the tissues were the highest in the SJZD-treated group, which were significantly higher than those in the spleen asthenia group and natural convalescence group (P ＜ 0.05-0.01), as well as the normal control group (P＜ 0.01). ② Comparison of mitochondrial ultrastructures in skeletal muscle,liver, gastric mucosa and myocardium at the end of the 34th week: In the spleen asthenia group, the mitochondria of myocardial cells were seriously swollen, the compact substance of hepatocellular mitochondria were decreased or disappeared and the crest disrupted; the mitochondria of skeletal muscle were shrunk and decreased, mitochondrial membranes were disorganized and crest disappeared, mitochondrial membranes were disorganized and crest disappeared; For gastric parietal cell of spleen asthenia,the amount of mitochondria reduced, inner structure confused, mitochondrial crestae of gastric chief cell was broken. In the natural convalescence group, the changes of the mitochondrial morphology were slight. The mitochondrial morphology in the SJZD group was close to those in the normal control group.CONCLUSION: SJZD has the effects of increasing the contents of mitochondria in skeletal muscle, liver, myocardium and gastric mucosa and repairing the damaged structure of mitochondria because of spleen asthenia.