Abdelsalam Salaheldin, Uemura Hiroyuki, Umezaki Yujiro, Saifullah A S M, Shimohigashi Miki, Tomioka Kenji
Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
J Insect Physiol. 2008 Jul;54(7):1205-12. doi: 10.1016/j.jinsphys.2008.05.001. Epub 2008 Jun 26.
Pigment-dispersing factor (PDF) is a neuropeptide playing important roles in insect circadian systems. In this study, we morphologically and physiologically characterized PDF-immunoreactive neurons in the optic lobe and the brain of the cricket Gryllus bimaculatus. PDF-immunoreactivity was detected in cells located in the proximal medulla (PDFMe cells) and those in the dorsal and ventral regions of the outer chiasma (PDFLa cells). The PDFMe cells had varicose processes spread over the frontal surface of the medulla and the PDFLa cells had varicose mesh-like innervations in almost whole lamina, suggesting their modulatory role in the optic lobe. Some of PDFMe cells had a hairpin-shaped axonal process running toward the lamina then turning back to project into the brain where they terminated at various protocerebral areas. The PDFMe cells had a low frequency spontaneous spike activity that was higher during the night and was often slightly increased by light pulses. Six pairs of PDF-immunoreactive neurons were also found in the frontal ganglion. Competitive ELISA with anti-PDF antibodies revealed daily cycling of PDF both in the optic lobe and cerebral lobe with an increase during the night that persisted in constant darkness. The physiological role of PDF is discussed based on these results.
色素分散因子（PDF）是一种在昆虫昼夜节律系统中发挥重要作用的神经肽。在本研究中，我们对双斑蟋视叶和脑中PDF免疫反应性神经元进行了形态学和生理学特征分析。在位于近端髓质的细胞（PDFMe细胞）以及外交叉的背侧和腹侧区域的细胞（PDFLa细胞）中检测到PDF免疫反应性。PDFMe细胞具有分布于髓质前表面的曲张突，而PDFLa细胞在几乎整个神经层中具有曲张网状神经支配，表明它们在视叶中具有调节作用。一些PDFMe细胞有一个发夹状轴突，向神经层延伸然后折返，投射到脑中并在不同的原脑区域终止。PDFMe细胞具有低频自发放电活动，夜间较高，且常因光脉冲而略有增加。在额神经节中也发现了六对PDF免疫反应性神经元。用抗PDF抗体进行的竞争性ELISA显示，视叶和脑叶中PDF均有日周期变化，夜间增加且在持续黑暗中持续存在。基于这些结果讨论了PDF的生理作用。
