Rice F A, McCurdy J D, Newby M, Carlyn C, Stack J
Can J Physiol Pharmacol. 1984 Jan;62(1):53-8. doi: 10.1139/y84-008.
The reports of early investigators that growth is delayed by thymectomy of immature animals have been confirmed. Although growth is delayed by thymectomy, thymectomized animals approach asymptotically with age the same final weight as corresponding intact animals. Treatment with leucogenenol, a thymothyroid hormone, accelerates the rate of growth of immature neonatally thymectomized rats to that of normal rats. However, treatment with leucogenenol does not increase the rate of growth of normal rats. Treatment with leucogenenol does not change levels of growth hormone (GH) or thyroxine (T4) in the serum of either thymectomized or intact immature and adult rats. Neither is the depression in levels of serum leucogenenol that follows thymectomy associated with a change in serum levels of GH or T4. Thus it is apparent that levels of serum leucogenenol do not affect the rate of growth of immature animals by increasing serum levels of GH or T4. By analogy with the finding that treatment with leucogenenol increases the rate at which committed cells of the bone marrow and cells involved in the immune response develop into functional cells, it is suggested that the levels of serum leucogenenol are one of the factors that determine the rate at which types of body cells that make up bone and other body tissues develop from committed precursors.
早期研究者关于未成熟动物胸腺切除会延迟生长的报告已得到证实。尽管胸腺切除会延迟生长，但经胸腺切除的动物随着年龄增长会渐近地达到与相应完整动物相同的最终体重。用胸腺甲状腺激素亮氨醇治疗可使新生期胸腺切除的未成熟大鼠的生长速度加快至正常大鼠的水平。然而，用亮氨醇治疗并不会提高正常大鼠的生长速度。亮氨醇治疗不会改变胸腺切除或完整的未成熟及成年大鼠血清中生长激素（GH）或甲状腺素（T4）的水平。胸腺切除后血清亮氨醇水平的降低也与血清GH或T4水平的变化无关。因此，很明显血清亮氨醇水平不会通过提高血清GH或T4水平来影响未成熟动物的生长速度。鉴于用亮氨醇治疗会提高骨髓定向细胞和参与免疫反应的细胞发育为功能细胞的速度这一发现，有人提出血清亮氨醇水平是决定构成骨骼和其他身体组织的身体细胞类型从定向前体发育速度的因素之一。
