Neurotransmitters are naturally occurring chemical messengers that allow nerve cells to talk to one another. Catecholamine (CA) neurotransmitters affect cognition, mood, memory, motor control, and the reward system. Neurological malfunctions related to imbalances in CAs include depression, Parkinson’s disease, schizophrenia and substance addiction. Mental and neurological disorders in general afflict as many as a billion people worldwide.¹ Major depression, for example, is one of the most common mental disorders in the U.S.  Seven out of every 100 adults have had at least one major depressive episode,^1,2,3 where almost twice as many women are afflicted than men.³ It is a complex problem and in need of new approaches to study and understand it.

Tracking multiple neurotransmitters in brain requires high spatial and temporal resolution, exquisite sensitivity, and minimal tissue disruption. Existing methods only quantify fast, single-neurotransmitter changes at microscopic dimensions. We propose departures from the status quo, namely an electrochemical redox-cycling method on a microprobe that separates time and space for simultaneous multi-neurotransmitter measurements and without significant damage when inserted into tissue for biological studies. In the absence of such methods, the potential to develop new evidence-based intervention to treat or prevent a variety of psychiatric and neurological disorders will likely remain limited.

We have published preliminary data for detection of catecholamines–dopamine (DA), epinephrine (EP), and norepinephrine (NE)–to demonstrate our approach.^4-6 The chemical structures of the catecholamines are similar, and therefore, prior to our redox-cycling method, had been difficult to measure electrochemically when they coexist together.  The function of dopamine and norepinephrine, specifically, in the cause and treatment of depressive disorders is currently an area of intense research. Antidepressants that target them with other neurotransmitters like serotonin simultaneously could represent preferred therapies in the future. Thus, to be able to quantify and distinguish them from each other is especially of interest.