Interventional Medication
The PDEIs dosages were determined from revious studies (Martorana, Beume, Lucattelli, Wollin & Lungarella, 2005; Sun, Li, Gong, Ren, Wan & Deng, 2012; Wang, Chen, Zhang, Hu & Peng, 2012), i.e., 5 mg·kg-1 for ROF, 10 mg·kg-1 for both PTX and THEO. Determination of the TRI dosage was done by converting the equivalent dose for human beings, i.e., 24 mg TRI for a 60 kg adult, based on body surface area and adapting it accordingly for the mice (Reagan-Shaw, Nihal & Ahmad, 2008). ROF was suspended in sterilized water and given intragastrically once a day, five days a week for 2 weeks, commencing from the 29thweek; PTX and THEO were dissolved in sterilized water and given intraperitoneally once a day, five days a week for 2 weeks, commencing from the 29th week; TRI (5 mg·kg-1) was administered intramuscularly through a single injection in the 29th week due to its long lasting effect. All the mice were humanely euthanized with an overdose of sodium pentobarbitone (50 mg·kg-1) at end of the 30 week course.