Japan Camponotus Gaba And 5-ht Immunoreactive Neuron Distribution In The Brain A Comparative Study

Using CP (Colophony-Paraffin) embedding tissue section technique and immunocytochemical method (Streptavidin-Peroxidase, SP), we have investigated the distribution of GABA and 5-HT immunoreactive neurons in the brain of female and male ants, Camponotus Japonicus. Special attention has been paid to the comparative research on the differences between female and male ants. We also try to give possible interpretations leading to these differences in the behavioral aspects.Here we show that in the brain of female and male C. Japonicus, all the GABA and 5-HT immunoreactive neurons are distributed symmetrically on the left and right hemisphere and grouped into clusters. The GABA and 5-HT positive neurons in the male are less than that in the female ant. All main neuropil regions of brain in the two ant castes are innervated by extensive arborizations of GABA and 5-HT immunoreactive fibers. The protocerebrum shows obvious immunoreactivity. The three optic neuropils in the optic lobes are layered and stained brown. There are totally three kind of neurons in the optic lobes: amacrine neurons, columnar neurons and tangential neurons, part of which are GABA immunoreactive and only several tangential neurons are 5-HT immunoreactive. The lateral and median calyces of mushroom bodies show GABA and 5-HT immunoreactivity. The staining in α-lobe is stronger than that in β-lobe. Kenyon cells are devoid of both immunoreactivities. The upper central body shows stronger GABA immunoreactivity than that in the lower central body. However, 5-HT immunoreactivity in both units shows no obvious difference. In the antennal lobes, olfactory glomeruli show intense GABA staining and fainter 5-HT staining. The dorsal lobes show fainter GABA staining and stronger 5-HT staining than that in the antennal lobes. The tritocerebrum and suboesophageal ganglion show obvious GABA and 5-HT immunoreactivity. In general, GABA densely exists in the brain and it is more important in mediating local neural interactions, while 5-HT play roles in mediating distant neural interactions.