Institute for Zoology, University of Göttingen, 37073 Göttingen, Germany.
J Insect Physiol. 2011 Jan;57(1):94-107. doi: 10.1016/j.jinsphys.2010.09.010. Epub 2010 Oct 14.
The corpora allata (CA) of various insects express enzymes with fixation resistant NADPHdiaphorase activity. In female grasshoppers, juvenile hormone (JH) released from the CA is necessary to establish reproductive readiness, including sound production. Previous studies demonstrated that female sound production is also promoted by systemic inhibition of nitric oxide (NO) formation. In addition, allatotropin and allatostatin expressing central brain neurons were located in close vicinity of NO generating cells. It was therefore speculated that NO signaling may contribute to the control of juvenile hormone release from the CA. This study demonstrates the presence of NO/cGMP signaling in the CA of female Chorthippus biguttulus. CA parenchymal cells exhibit NADPHdiaphorase activity, express anti NOS immunoreactivity and accumulate citrulline, which is generated as a byproduct of NO generation. Varicose terminals from brain neurons in the dorsal pars intercerebralis and pars lateralis that accumulate cGMP upon stimulation with NO donors serve as intrinsic targets of NO in the CA. Both accumulation of citrulline and cyclic GMP were inhibited by the NOS inhibitor aminoguanidine, suggesting that NO in CA is produced by NOS. These results suggest that NO is a retrograde transmitter that provides feedback to projection neurons controlling JH production. Combined immunostainings and backfill experiments detected CA cells with processes extending into the CC and the protocerebrum that expressed immunoreactivity against the pan-neural marker anti-HRP. Allatostatin and allatotropin immunopositive brain neurons do not express NOS but subpopulations accumulate cGMP upon NO-formation. Direct innervation of CA by these peptidergic neurons was not observed.
各种昆虫的前胸腺（CA）表达具有固定抗性 NADPH 黄递酶活性的酶。在雌性蚱蜢中，来自 CA 的保幼激素（JH）的释放对于建立生殖准备状态是必要的，包括发声。先前的研究表明，雌性发声也受到全身抑制一氧化氮（NO）形成的促进。此外，表达前胸腺激素和前胸腺抑制素的中枢脑神经元位于产生 NO 的细胞附近。因此，推测 NO 信号可能有助于控制 CA 中保幼激素的释放。本研究证明了雌性 Chorthippus biguttulus 的 CA 中存在 NO/cGMP 信号。CA 实质细胞表现出 NADPH 黄递酶活性，表达抗 NOS 免疫反应性，并积累瓜氨酸，瓜氨酸是 NO 生成的副产物。刺激 NO 供体后，来自背侧脑前叶和脑外侧叶的神经元中的静脉曲张末端会积累 cGMP，作为 CA 中 NO 的内在靶点。NOS 抑制剂氨基胍抑制瓜氨酸和环鸟苷酸的积累，表明 CA 中的 NO 由 NOS 产生。这些结果表明，NO 是一种逆行递质，为控制 JH 产生的投射神经元提供反馈。联合免疫染色和回溯实验检测到具有伸向 CC 和protocerebrum 的过程的 CA 细胞，这些细胞表达针对泛神经标志物抗 HRP 的免疫反应性。表达 allatostatin 和 allatotropin 的脑神经元不表达 NOS，但亚群在形成 NO 时积累 cGMP。这些肽能神经元没有观察到对 CA 的直接神经支配。
