桑蚕促前胸腺激素的作用与前胸腺分泌活动的某些特点

本工作以前胸腺的体外器官培养技术和蜕皮激素的放射免疫分析法(MH-RIA)相结合,研究了桑蚕(Bombyx mori)促前胸腺激素(PTTH)的作用与前胸腺分泌的某些特点。结果表明,被PTTH激活后的前胸腺,在一定的时相过程内合成并分泌脱皮甾类激素;前胸腺本体不积累蜕皮甾类激素;PTTH对前胸腺的作用是积累性的;五龄不同天数的前胸腺合成分泌脱皮甾类激素的能力不同,并有不同的剂量反应。

THE ACTION OF PROTHOHACICOTROPIC HORMONE AND SOME CHARACTERISTICS OF PROTHORACIC GLAND ACTIVITY IN BOMBYX MORI

The action of the prothoracicotropic hormone (PTTH) and the secretory activity of the prothoracic gland (PG) of the silkworm Bombyx mori were studied by combining the methods of in vitro culture of PG from the last instar larva and from newly formed pupa under the influence of PTTH extracted from the brain of newly formed pupa and raclioimmunoassay (RIA) of the ecdysteroid hormone secreted from PG. The objective of this study is to eluci-date the action of PTTH and the secretory activity of PG in more detail. The results show that under the experimental condition the brain extraction of newly formed pupa contains enough PTTH to activate the PG of the larva in the last instar and of the newly formed pupa. The secretory activity of PG is characterized by the following respects: 1. The activated PG displays a time course of its own activity in ecdysteroid hormone synthesis and secretion. 2. The hormone synthesized would not accumulate in the PG. 3. The action of PTTH on PG is accumulative in the sense that a threshold titer of PTTH is required for activating the PG. 4. The PG's of larva on different days of the last instar are different in their sensitivity to the influence of PTTH and the capacity of hormone synthesis. PG of the 6th day larva is most easily to be activated and to reach the upper limit of secretion, that of the 2nd day larva is least to do so, and that of the 5th day larva or of the newly formed pupa remains in the intermediary condition.