| Abstrakt: |
The effect of age on the responsiveness of rat thymocytes to 3,5,3′-tri-iodothyronine (T3) was studied. It has been demonstrated previously that the plasma membrane-mediated effect of T3to increase sugar uptake by rat thymocytes is influenced by age and sex. In both sexes, T3given in vitrostimulated sugar uptake in cells from animals of 15 days of age, had no effect at 21 days and was again effective at 26 days. In the male, thymocytes from animals of 40 days of age and older were refractory to T3. However, in the female, T3, although less effective than in cells from 26-day-old animals, remained stimulatory in cells from 40- and 60-day-old rats. T3had no effect in cells from animals of 90 days of age and older. In in-vivo studies in which female rats of 26, 60 and 90 days of age were first injected with T3and 1 h later with [3H]2-deoxyglucose, the responsiveness of thymocytes to T3also declined progressively with advancing age; T3was most effective in cells from 26-day-old animals, less stimulatory in 60-day-old and essentially without effect in cells from 90-day-old animals. From these observations we have concluded that in both male and female rats the responsiveness of thymocytes to T3declines progressively with age, and that this decline occurs at an earlier age in cells obtained from males.J. Endocr.(1986) 110,511–515 |
