The Construction Of DA And 5-HT System In The Brain And Suboesophageal Ganglion Of Drosophila Melanogaster

Drosophila melanogaster as a classic model of biological, is widely used in morphology, medicine and pathology research. However, due to the technical constraints, the researches about the functional system of Drosophila which used optical microscope are rarely reported. Using CP(Colophony- Paraffin) embedding method, the adjacent section technique, combined with immuno-colocalization method, and rabbit anti-TH(Tyrosine hydroxylase) polyclonal antibody, we revealed the DA-ergic system distribution in the brain and suboesophageal ganglion of Drosophila in this paper. Then compared with the 5-HT-ergic neurons in the brain and suboesophageal ganglion. The results show that a large number of TH positive neurons distributed in the brain and suboesophageal ganglion of Drosophila. These neurons mainly distributed in the lateral posterior protocerebral, in the medial posterior protocerebral, in the anterior protocerebral and in the suboesophageal ganglion. Most of these neurons were located in bilateral clusters; some were distributed as bilateral pairs. According to their location these neurons can be divided into 26 groups of positive cells, respectively PPM1, PPM2, PPM3, PPM4, PPL1, PPL2, PPL3, DP1, DP2, SA1, SA2, SA3, PAL1, PAL2, SM, DM, SL, SP1, SP2, VUM1, VUM2, AL1, AL2, AL3, AL4 and T1. Some of the positive clusters contains nearly 100 positive cell bodies, such as PAM cluster. Many DA-gic neurons located between lamina and medulla and the edge of lobula(more than 1000 cell bodies each side). Immunoreactive processes were found in all compartments of the mushroom bodies, in all divisions of the central body complex, in the optic lobe, and in non-glomerular neuropil of protocerebrum, tritocerebrum and the subesophageal ganglion. For comparison, sheep anti-TPH polyclonal antibody was used to locate the 5-HT neurons in the brain of Drosophila and suboesophageal ganglion. About 80 positive neurons were found in per hemisphere, belong to LP1, LP2 a LP2b, DP, SP1, SP2, IP, PLP, SLP, AMP, ALP, AVP, PAL, DLS, SE1, SE2 and SE3 clusters. 5-HT immunoreactive processes projected in the medulla, lobula and lobula plate of the optic lobe and layered in medulla. By comparison, we found that 5-HT-gic and DA-gic systems had differences in the number of the cell body, distribution and spatial position. There was no intracellular coexistence. But some postive neurons of these two systems had the similar distribution area and some positive fibers had the same projection area, so they may have a close contact on some physiological function. The morphology of the extensively arborizing aminergic neurons described suggests that they have modulatory functions in the brain and subesophageal ganglion.