Immunohistochemical Localization Of Two Synthesizing Enzyme TPH And TH In The Brain Of Silk Moth

Antheraea pernyi is a classic species for studying insect brain nerves system because of its large size, relatively intact structure of brain and obvious cytodifferentiation. 5-HT and DA, the amine neurotransmitters, function as very important mediators in the insect brain. Meanwhile, in the vertebrate, they are closely correlated with nerves diseases, and their synthesis, transport and metabolism have been more and more concerned. The discovery of specific rate-limiting enzyme TPH responsible for synthesis of 5-HT made people look insight into the evolution of AAAH and synthesis of amine neurotransmitter, providing a novel pathway for studying amine neurotransmitter in the insect brain. The Colophony-Paraffin embedded section combining the adjacent section technique, can provide the view of the distribution of two kinds of neurons more obviously. In this paper, anti-TPH and anti-TH antisera were applied on the brain adjacent section of Antheraea pernyi, using the Streptavidin-Peroxidase immunohistochemical method and the Colophony-Paraffin embedded section technique. Results revealed that, there were TPH positive cell bodies, which located between the optic lobe and lateral protocerebrum, dosal protocerebrum, deutocerebrum and suboesophageal ganglion respectively. the pattern of TPH immunoreactivity of cell body is extreme similar to that of 5-HT. It implies that the PAH-TPH duplication may have occurred before the emergence of arthropods. The number of TPH positive neurons in the optic lobe and lateral protocerebrum is the largest among other insects we studied, and most of them are tangential neurons. TPH immunoreactive neurons in the dorsal protocerebrum interconnected with optic lobes and mushroom bodies. There was only one pair of TPH immunoreactive neurons in deutocerebrum,which interconnected with olfactory nerves. TPH immunoreactive neurons and fibers were present in tritocerebrum and suboesophageal ganglion, in which there was a group of neurons located in interior tritocerebrum that invaded the tritocerebrum by their dendrites. There were two giant isomorphic neurons located antero-ventral to the SOG neuropil in each hemisphere displayed strong TPH immunoreactivity, however, the somata of these two neurons were weakly labeled by anti-5-HT antiserum.. With regard to the immunohistochemical studies of DA and TH, we had not found the similar pattern to that of 5-HT and TPH. We had identified the purchased antibody with western blotting and analyzed the protocol of the experiments, raising the possibility that specificity of the antibody and some factors in the experiments affected the labeling of this neurotransmitter and its rate-limiting enzyme.