Quigley K, Goya R, Nachreiner R, Meites J
Department of Physiology, Michigan State University, East Lansing 48824-1101.
Exp Gerontol. 1990;25(5):447-57. doi: 10.1016/0531-5565(90)90033-x.
The effects of a 50% reduction in normal food intake for a period of 10 weeks were measured on secretion of growth hormone (GH), thyroxine (T4), and triiodothyronine (T3) in 5 1/2-6 1/2-month old, 13 1/2-month-old, and 17 1/2-18 1/2-month-old male rats. In full-fed controls, GH, T3, and T4 were lower in the old and middle-aged than in the young rats. By the 10th week of underfeeding, GH, T3, and T4 were reduced in all age groups, but the decrease in T3 and T4 in the middle-aged and old rats was greater than in the young rats. Pulses of GH ceased in all the underfed groups. Upon refeeding for 5 days, pulses of GH and levels of GH returned to full-fed control values in the young and middle-aged but not in the old rats. T3 values in the young and middle-aged rats returned to full-fed control levels, but remained below control levels in the old rats. T4 values reached control levels in all age groups upon refeeding. The differences in the response to underfeeding and refeeding by the middle-aged and old rats as compared to the young rats may be due to their initially lower secretion of GH and thyroid hormones and to the age-related decrease in neuroendocrine function.
研究测量了5只5个半月至6个半月大、13个半月大以及17个半月至18个半月大的雄性大鼠，在正常食物摄入量减少50%持续10周的情况下，生长激素（GH）、甲状腺素（T4）和三碘甲状腺原氨酸（T3）的分泌情况。在正常喂食的对照组中，老年和中年大鼠的GH、T3和T4水平低于年轻大鼠。到限食第10周时，所有年龄组的GH、T3和T4均下降，但中年和老年大鼠的T3和T4下降幅度大于年轻大鼠。所有限食组的GH脉冲均停止。重新喂食5天后，年轻和中年大鼠的GH脉冲及GH水平恢复到正常喂食对照组的值，但老年大鼠未恢复。年轻和中年大鼠的T3值恢复到正常喂食对照组水平，但老年大鼠仍低于对照组水平。重新喂食后，所有年龄组的T4值均达到对照组水平。与年轻大鼠相比，中年和老年大鼠对限食和重新喂食的反应差异，可能是由于它们最初较低的GH和甲状腺激素分泌，以及与年龄相关的神经内分泌功能下降。
