Real-Time Monitoring of Neurotransmitters in the Brain of Living Animals

Abstract

Neurotransmitters, as important chemical small molecules, perform the function of neural signal transmission from cell to cell. Excess concentrations of neurotransmitters are often closely associated with brain diseases, such as Alzheimer's disease, depression, schizophrenia, and Parkinson's disease. On the other hand, the release of neurotransmitters under the induced stimulation indicates the occurrence of reward-related behaviors, including food and drug addiction. Therefore, to understand the physiological and pathological functions of neurotransmitters, especially in complex environments of the living brain, it is urgent to develop effective tools to monitor their dynamics with high sensitivity and specificity. Over the past 30 years, significant advances in electrochemical sensors and optical probes have brought new possibilities for studying neurons and neural circuits by monitoring the changes in neurotransmitters. This Review focuses on the progress in the construction of sensors for in vivo analysis of neurotransmitters in the brain and summarizes current attempts to address key issues in the development of sensors with high selectivity, sensitivity, and stability. Combined with the latest advances in technologies and methods, several strategies for sensor construction are provided for recording chemical signal changes in the complex environment of the brain.

Significance of an Electrochemical Sensor and Nanocomposites: Toward the Electrocatalytic Detection of Neurotransmitters and Their Importance within the Physiological System

“…The NTs are collected in investigations after the diffusion of NTs in the brain under the drive of the concentration gradient. 6 Equilibrium of molecular distribution is the fundamental nature of the sampling process, which is responsible for the long delay and limited resolution. In addition, the size of the exchange area of the semipermeable ACS Nanoscience Au membrane also bounds the spatial resolution microdialysis technique.…”

“…Consciousness and action of the human brain come from the activities of neurons, as the human brain comprises billions of neurons. Neurotransmitters (NTs) are chemical species which serve as messengers of information between neurons . Therefore, NTs are crucial for the proper functioning of the human brain and disease diagnosis.…”

Fentanyl Induces Novel Conditioned Place Preference in Adult Zebrafish, Disrupts Neurotransmitter Homeostasis, and Triggers Behavioral Changes

“…Drug addiction is associated with disruption in a large number of biomarkers in various areas of the brain, especially in the reward centers. For example, high neurotransmitter concentrations are often closely associated with brain diseases such as Alzheimer’s disease, depression, schizophrenia, and Parkinson’s disease [ 61 ]. Neurotransmitter levels in the central reward region of the brain can influence neurobehavior, with dopaminergic and serotonergic neurons associated with drug-seeking behavior in humans [ 62 ].…”

“…L-glutamine (Gln) is the most abundant amino acid in plasma and cerebrospinal fluid and is the precursor of the major central nervous system excitatory (L-glutamate) and inhibitory (gamma-aminobutyric acid) neurotransmitters. Increased glutamine increases formation of GABA, leading to excitotoxicity and impairment in spatial learning and memory [ 61 , 70 ]. In our experiments, major neurotransmitters (including Gln, GABA, DA, and 5-HT) and cortisol exhibited disturbed homeostasis.…”

Nano- and Microsensors for In Vivo Real-Time Electrochemical Analysis: Present and Future Perspectives

“…One of the first in vivo studies to measure catecholamines in brain tissue used a carbon paste electrode [ 46 ]. Nowadays, significant progress can be noted in the development of electrodes for neuromeasurements [ 11 , 22 , 23 , 24 , 47 , 48 , 49 , 50 , 51 , 52 ]. In particular, it is known that electrodes can be modified with graphene [ 53 ] to allow detection of dopamine (DA) without the influence of ascorbic acid (AA) and uric acid (UA).…”