Gender- and age-related changes in 6-phosphogluconate dehydrogenase gene expression in white adipose tissue of rats (Rattus norvegicus) are not related to serum testosterone concentration

Abstract Previously, we have shown that the age-related changes in 6-phosphogluconate dehydrogenase (6PGDH) activity depend on sex, and that oestradiol is playing a crucial role in the regulation of 6PGDH gene expression in rat liver, but not in other tissues [Pankiewicz, A., Sledzinski, T., Nogalska, A., Swierczynski, J., 2003. Tissue specific, sex and age-related differences in the 6-phosphogluconate dehydrogenase gene expression. Int. J. Biochem. Cell Biol. 35, 235–245.]. To complete the knowledge on the influence of sex hormones on 6PGDH activity, experiments have been performed on the effect of testosterone on 6PGDH gene expression in rat white adipose tissue and liver. The results presented here disclosed that in young male rats high serum testosterone concentration was associated with high white adipose tissue 6PGDH activity. After orchidectomy, a decrease in serum testosterone concentration (both in young and old rats) was observed. In contrast, no changes in white adipose tissue and liver 6PGDH activity were found. In female rats, both young and old, serum testosterone concentration was below the limit of detection, whereas 6PGDH activity was much higher in young than in old animals. Moreover, the testosterone administration to 9-month old male rats (which displayed much lower serum testosterone concentration that young animals) resulted in no effect on 6PGDH activity either in WAT or in the liver. In conclusion, the results presented in this paper indicate that testosterone does not play any role in the age- and gender-related differences in 6PGDH gene expression in white adipose tissue.