Measurement of biological activity of somatotropin in hypophysectomized rats

目的：建立测定生长激素（ＧＨ）在体生物活性的方法．方法：以去垂体大鼠体重增长（ＢＷＧ）和胫骨骺软骨板宽度（ＴＥＷ）为指标，观察动物性别、给药途径、次数和周期不同对效应的影响；同时进行４ｄＢＷＧ，６ｄＢＷＧ和６ｄＴＥＷ法，测定ＧＨ的效价（平行线３×３设计）．结果：♀和♂ｓｃ和ｉｍ给药以及每日给药１次和２次的ＢＷＧ和ＴＥＷ差异无显著意义．给药６ｄ比给药４ｄ引起较大的ＢＷＧ和ＴＥＷ（Ｐ＜００５）．４ｄＢＷＧ法和６ｄＢＷＧ法在００２０－０５００ＩＵ·ｄ－１有较好的λ值（００６６０和０１７４７）和ｒ值（０９０００和０９２３７）；４ｄＢＷＧ，６ｄＢＷＧ和６ｄＴＥＷ法测得ｒｈＧＨ的效价为４６１３２，３９８２９和４８０２３ＩＵ／ａｍｐ．６ｄＢＷＧ法有较小的λ值和较低的ＡＲＦＬ值．结论：可在同一组去垂体大鼠体内同时用４ｄＢＷＧ，６ｄＢＷＧ和６ｄＴＥＷ法测ＧＨ活性，以６ｄＢＷＧ法较好．

IM: To develop a method for measurement of biological activity of recombinant DNA derived somatotropin (rhGH). METHODS: The effects of varying the route, frequency and period of administration of GH, the sex of test animals on the biological responses, body weight gain (BWG), and tibial epiphyseal width (TEW), of hypophysectomized (Hypox) rats were compared, respectively. 4 d BWG, 6 d BWG, and 6 d TEW tests were carried out simultaneously in the same group of Hypox rats to determine the biopotency of GH preparations according to a parallel line bioassay (6 point assay). The final result was chosen from the test which had smaller values for the index of precision (λ) and the average rate of fiducial limits (ARFL) than other tests. RESULTS: No significant differences in the responses between male and female rats, between sc and im , once daily and twice daily injections of bGH were found. But the BWG and TEW of Hypox rats injected with 0 045 and 0 135 IU·d -1 of bGH for 6 d were significantly greater than that for 4 d. Both 4 d BWG test and 6 d BWG test in the range from 0 020 to 0 500 IU·d -1 had values for λ=0 0660 and 0 1747, and for r =0 9000 and 0 9237, respectively. Three estimates of rhGH preparation compared with the International Standard for somatotropin (IShGH), 4 6132, 3 9829, and 4 8023 IU/ampoule, were obtained separately from 4 d BWG test, 6 d BWG test and 6 d TEW test. And the result from 6 d BWG test was reported finally because it had smaller values for λ and ARFL (0 0608 and 37 907 %) than other two tests. CONCLUSION: Both BWG test and TEW test can be carried out simultaneously in the same group of Hypox rats. 6 d BWG test seemed to be more suitable for potency determination of GH preparations than 4 d BWG test and 6 d TEW test.