Egawa M, Inoue S, Sato S, Takamura Y, Murakami N, Takahashi K
Third Department of Internal Medicine, Yokohama City University, Medical School, Tokyo, Japan.
Neuroendocrinology. 1991 Jun;53(6):543-8. doi: 10.1159/000125772.
The effects of ventromedial hypothalamic (VMH) lesions on the circadian periodicity of blood corticosterone were studied in female rats. The rats were kept on a 12-hour light/12-hour dark illumination regimen and fed ad libitum. Three, 10 and 12 weeks after the VMH lesions, the concentrations of blood corticosterone were measured every 4 h for 48 h in the same unanesthetized rats. Three weeks after the operation, the circadian rhythm in VMH-lesioned rats was disturbed and disappeared. The corticosterone levels at 03:00, 07:00, and 11:00 were significantly higher than those in sham-operated rats. 10 and 12 weeks after the operation, the circadian rhythm, however, was notable (p less than 0.05, p less than 0.05). The elevated mean corticosterone levels over 48 h at 3 weeks after the operation decreased at 10 and 12 weeks. The sham-operated rats showed a significant circadian rhythm at 3, 10 and 12 weeks after the operation (p less than 0.001 in each period) with a peak concentration at 19:00 and through at 07:00. These findings show that the corticosterone circadian rhythms which were disturbed in the dynamic phase after VMH lesions recovered in the static phase of obesity, suggesting that the ventromedial hypothalamus is not an essential biological clock of circadian corticosterone rhythm.
研究了腹内侧下丘脑（VMH）损伤对雌性大鼠血液皮质酮昼夜节律的影响。将大鼠置于12小时光照/12小时黑暗的光照方案下，并随意进食。在VMH损伤后的3周、10周和12周，对同一未麻醉的大鼠每4小时测量一次血液皮质酮浓度，持续48小时。手术后3周，VMH损伤大鼠的昼夜节律受到干扰并消失。在03:00、07:00和11:00时的皮质酮水平显著高于假手术大鼠。然而，在手术后10周和12周，昼夜节律明显（p<0.05，p<0.05）。手术后3周时48小时内升高的平均皮质酮水平在10周和12周时下降。假手术大鼠在手术后3周、10周和12周表现出显著的昼夜节律（各时期p<0.001），峰值浓度出现在19:00，谷值出现在07:00。这些发现表明，VMH损伤后动态期受到干扰的皮质酮昼夜节律在肥胖静止期恢复，提示腹内侧下丘脑不是皮质酮昼夜节律的基本生物钟。
