Study of sex differences in the expression of β-actin gene in various tissues of the rat

Introduction: Beta-actin is a housekeeping gene, which is used as an internal standard in various biological studies. Recently, it was reported that the expression of commonly used housekeeping genes including ß–actin changes in disease states or under certain experimental conditions. Based on the reports about the effects of sex hormones on the expression of the ß- actin gene, in this study, we examined the sex differences in the expression levels of ß- actin gene in different tissues of the rat. Methods: Total RNA was extracted from the brain, spinal cord, heart, kidney and liver tissues in male and female rats as well as uterus in females. The RT-PCR method was used to measure the levels of ß-actin gene expression in all tissues. Results: The expression of ß-actin gene in the brain and spinal cord of male rats was significantly higher than its expression in female animals (P<0.05). It was also found that the expression of ß-actin gene in the heart and uterus of females were significantly higher in comparison with other tissues (P<0.001 and P<0.05 respectively). Similarly, ßactin gene expression in the heart tissue of male rats was significantly higher than other tissues (P<0.001). Conclusion: It is suggested to validate the constancy of ß-actin gene expression under the experimental condition, before using this house keeping gene as an internal standard in molecular biology studies.