Effect of maternal phenobarbital consumption on muscle development in mice

The effect of prenatal exposure to phenobarbital on muscle development was determined in 4 muscles (biceps brachii, triceps brachii, soleus and cranial tibial) of 34 mice (16 males, 18 females) at 12 weeks of age. The control group received unadulterated food ad libitum throughout the period of study. The phenobarbital-exposed group received 3 g of phenobarbital per kilogram of food from gestation day 7 to 18 as the only source of food. Outside this period they received unadulterated food and water ad libitum. Each mouse was killed at 12 weeks of age. The muscle mass of control mice was significantly larger than that of the phenobarbital-exposed group in both sexes. The smaller muscle mass of the phenobarbital-exposed group as observed from the analysis of the soleus muscle was due to a smaller number of muscle fibres being present than in the control group, since the muscle fibre sizes were similar in both groups. This indicated that prenatal administration of phenobarbital inhibits normal hyperplasia of muscle fibres.