Immunocytochemical localization of some aminergic and peptidergic neurosubstances in the cephalic neurosecretory system of the dragonfly, Tramea virginia (Rambur) (Anisoptera: Libellulidae)

An immunocytochemical study showed the presence of 7 neurosubstance-like materials: FMRFamide, neuropeptide-Y (NPY), substance-P, serotonin, gastrin, cholecystokinin (CCK) and vasoactive intestinal peptide (VIP) in the median, lateral, ventral and optic neurosecretory cells groups (MNC, LNC, VNC and ONC, respectively) in the brain and in the corpora cardiaca (CC) of the adult, T. virginia. In the MNC cell type A showed NPY- and serotonin- while B and C cell types showed NPY-, serotonin-, substance P- and CCK-like positive immunoreaction. The B cell type in LNC showed FMRFamide-, NPY- and serotonin- and the C cell type showed only NPY and serotonin-like positive immunoreaction. In VNC group, the B cell type showed substance P- and gastrin-, while the C cell type showed substance P- and gastrin- and VIP- like positive immunoreaction. B and C cell types of ONC group showed substance P- and serotonin-like positive immunoreaction. The CC showed only NPY-like positive immunoreactive intrinsic neurosecretory cells. The functional significance of these myotropic and vertebrate gastrointestinal hormone-like substances in the cephalic neurosecretory system of T. Virginia is discussed.