Meeting Abstract

P3.102  Thursday, Jan. 6  THE CELLULAR AND MOLECULAR BIOLOGY OF OCTOPAMINERGIC NEURONS LEHMAN, Herman K.; Hamilton College, Clinton, NY hlehman@hamilton.edu

Biogenic amines are among the most important modulators of vertebrate and invertebrate nervous system function and behavior. Changes in the amount of a neuromodulator released by a neuron can have profound effects on behavior and is a key mechanism in the neurochemical regulation of behavioral plasticity. Thus, understanding the regulation of neuromodulator biosynthesis is an important element in the analysis of neuromodulation. Octopamine (OA) is one of the most widely studied biogenic amines in the arthropod nervous system, and the rich background knowledge of OA provides a unique opportunity to address important questions regarding the synthesis of this neuromodulator. Tyramine beta-hydroxylase (TBh) is the pivotal enzyme that that mediates octopamine synthesis; it is a catalyst for the hydroxylation of tyramine to form OA, and it is found exclusively in octopaminergic neurons. Recent studies have suggested that the substrates and co-factors necessary for TBh function (tyramine, copper, ascorbate, and oxygen) can have profound effects on TBh rate functions. Therefore, substrate transport and metabolism (tyrosine, tyramine, and octopamine), co-substrate transport and metabolism (pyridoxal 5′-phosphate, copper, and ascorbic acid) and oxygen availability may all potentially influence octopamine levels and the amount of OA release in the insect nervous system. I describe how and where these processes occur within OA cells and illuminate novel regulatory mechanisms. Thus, to clearly understand how this multipotent neuromodulator regulates behavior it is vital to fully understand the cellular and molecular processes that underlie its synthesis.