In order to investigate the effects of Shuanghuanglian on the expression of
platelet derived growth factor BB(PDGF BB)in
the lung tissue from rats repeatedly infected with mycoplasma pneumoniae(MP),the authors made a rat MP infection model by infecting rats with MP for 9 times during a period of 24 weeks with a technique of ultrasonic nebulizing inhalation and treated the rats with Shuanghuanglian by peritoneal injection.Then immunohistochemical stain was performed with PDGF BB monoclone antibody and the results were quantitatively analyzed. The results showed that(1) MP polymerase chain reaction(PCR)tests indicated positive effectiveness in the bronchoalveolar lavage fluid(BALF)from all of the MP infected rats(n=4)while they were all negative in BALF from the control animals(n=4,P<0 05)and in BALF from those rats both infected with MP,and at the same time,treated with Shuanghuanglian (n=4,P<0 05).Bacterial cultures of the bronchial and lung tissue were negative in all three groups. The observation with transmission electron microscope found that the interalveolar septa were widened with increased amount of collagen in the MP infected rats while there were no obvious abnormalities in the other two groups.(2)Strong positive stain of PDGF BB protein was found in the interstitial connective tissue,the airway wall and the wall of blood vessels in the lung tissue from the MP infected animals with the integral optical densities being 23 26±3 87(n=4)which was significantly higher than the values of control group(1 52±0 61,n=4,P<0 05)and of the group with MP infection plus Shuanghuanglian treatment(3 49±0 63,n=4,P<0 05).These results suggest that Shuanghuanlian can inhibit the overexpression of PDGF BB in the lung tissue of rats with MP infection,which may be helpful for the prevention and treatment of
pulmonary interstitial fibrosis caused by the repeated MP infection.