Pallet V, Azaïs-Braesco V, Enderlin V, Grolier P, Noël-Suberville C, Garcin H, Higueret P
Laboratoire de Nutrition, ISTAB, Université de Bordeaux I, Talence, France.
Mech Ageing Dev. 1997 Dec 15;99(2):123-36. doi: 10.1016/s0047-6374(97)00098-5.
The expression of nuclear receptors of retinoic acid (RAR) and triiodothyronine (TR) was analyzed in the liver of rats aged 2.5 (young), 6 (adult) and 24 (aged) months. In aged rats, decreased binding properties, binding capacity (Cmax) and affinity (Ka), of nuclear receptors were observed. This resulted, at least in part, from decreased transcription of receptor genes in that the amount of their mRNA also decreased. Moreover, the activity of malic enzyme (ME) and tissue transglutaminase (tTG), whose genes are TR and RAR responsive, respectively, was reduced in aged rats. These results are in agreement with the decreased binding capacity of these receptors. An inducer-related increase of RAR and TR expression was observed 24 h after a single dose of retinoic acid administration (5 mg/kg), while retinol administration (retinyl palmitate, 13 mg/kg) was without incidence on nuclear receptor expression in aged rats.
分析了2.5个月（幼年）、6个月（成年）和24个月（老年）大鼠肝脏中视黄酸（RAR）和三碘甲状腺原氨酸（TR）核受体的表达情况。在老年大鼠中，观察到核受体的结合特性、结合能力（Cmax）和亲和力（Ka）下降。这至少部分是由于受体基因转录减少，因为其mRNA的量也减少了。此外，苹果酸酶（ME）和组织转谷氨酰胺酶（tTG）的活性在老年大鼠中降低，其基因分别对TR和RAR有反应。这些结果与这些受体结合能力的下降一致。单次给予视黄酸（5mg/kg）24小时后，观察到RAR和TR表达与诱导剂相关的增加，而给予视黄醇（棕榈酸视黄酯，13mg/kg）对老年大鼠核受体表达无影响。
