Abstract
一氧化氮 (NO) 可在一氧化氮合成酵素 (NOS) 將 L-arginine 轉變為 L- citrulline 時生成。 眾所皆知， NO 普遍存在於腦與周邊神經系統， 擔任神經傳導的工作。值得注意的是，不管是脊椎動物的還是無脊椎動物 的神經元，都有 NOS 存在。 近來發現腦下垂體前頁的某些特殊細胞中存 在有 NOS，並且藉由分泌 NO 來抑制本身釋放的促黃體激素和生長激素 。 雖然昆蟲的神經系統存在有 NO 已被廣泛證實， 但尚未有研究報告 指出昆蟲的內分泌器官內存在有 NOS。咽側腺體是昆蟲的重要內分泌器官 ，具有分泌青春激素的功能，對於昆蟲的生理就如同腦下腺前頁對脊椎動 物生理一會受到腦中的神經內分泌細胞分泌的多種 neuropeptides 所調 控， 以控制咽側腺細胞的青春激素分泌。而青春激素負責了昆蟲的生長 、變態與生殖。 本論文提出證據說明咽側腺細胞存在有 Constitutive NOS，並具有釋放 NO 之能力。 而這種存在於咽側腺內的 NOS 乃是 Ca2+ dependent，並且酵素活性可被連接在 CA上的神經 NCA-I 所抑制。 It is now well established that nitric oxide (NO) is a major inter- and intracellular neurotransmitter in the brain and peripheral nervous system. NO is formed from L-arginine by the enzyme NO synthase (NOS). Remarkable conservation of neuronal NOS has been noted between verterbrates and inverterbrates. Recently, NOS has also been identified in discrete subpopulations of anterior pituitary cells and NO may exert an inhibitory effect on release of luteinizing hormone and growth hormone. While there are ev idence showing production of NO from insect nervous system, nothing is known about the cellular localization of NOS in insect endocrine system. Insect corpora allate (CA) produce juvenile hormone (JH) and are considered the analogue of the anterior pituitary gland of verterbrates. While the CA have been shown to be the release site for several neuropeptides from brain neurosecretory cells, it is generally believed that JH is the only product synthesized and released from corpus allatum cells involving in the regulation of insect growth, metamorphosis and reproduction. We have now demonstrated that all corpus allatum cells contain a constitutive NOS which synthesize and release NO. The NOS is calcium dependent and inhibited by brain neurons terminating in the CA.