The regulatory mechanism of dopamine system involved in itch inglisal information processing is revealed.

On September 28, the journal Neuroscience published an online paper entitled "The Activity and Function of Dopamine Neurons in Itchy Processing in the Midbrain's Abdominal Area", completed by sun Yangang Research Group of the Institute of Neuroscience of the Chinese Academy of Sciences, the Center for Excellence in Brain Science and Intelligent Technology, and the National Key Laboratory of Neuroscience.
by using technical techniques such as in-body fiber recording, multi-channel electrophysiological recording, and photogenetic manipulation, the study found that dopamine neurons in the covered area of the mid-brain were mainly excited to increase after scratching, and that the excitatory response was necessary for the continuation of the scratching action.
this study reveals the regulatory mechanism of dopamine system involved in itch information processing, which provides a new perspective for the further study of the treatment and intervention methods of chronic itch.
itching can cause scratching, while excessive scratching in chronic itching patients can lead to severe skin damage.
understanding the brain mechanism of itch control is important for the treatment of chronic itching.
neuromodulation system plays an important regulatory role in the processing of many sensory information, including itching.
previous studies have shown that pharmacological methods systematically manipulate dopamine's type 1 or 2 receptors, affecting the scratching behavior of rodents and primates.
However, the specific changes and functions of dopamine neurons during scratching are not clear.
In order to monitor the changes in the activity of dopamine neurons in the mid-brain area covered in the abdominal part of the brain during the scratching process in real time, Sun Yangang's research team simultaneously recorded the group activity of dopamine-enabled neurons by recording itching behavior in mice.
researchers found that the dopamine-enabled neuronal population was significantly excited after scratching.
To further determine the response of individual dopamine neurons, the researchers identified a single dopamine neuron by combining electrophysiological records and optogenetic activation, and simultaneously recorded their activity and animal scratching behavior.
results showed that most dopamine-enabled neurons showed an exhilarating response, while some neurons were inhibited.
to test the role of the excitability changes in dopamine neurons in maintaining scratching, the researchers used optogenetics to specifically suppress dopamine neurons after the scratching action began.
this led to a significant reduction in the duration of the scratching action, and the results showed that increased excitability of dopamine neurons was necessary for the continuation of scratching action.
To further explore the neural loop saline basis for dopamine neurons to regulate itching, the researchers simultaneously recorded the activity and scratching behavior of dopamine-enabled fibers in the downstream volt-proof nucleus.
study found that the activation of dopamine fibers in the outer shell of the volt-proof nucleus was the largest, suggesting that dopamine projection in the region may have been involved in the regulation of itchinformation information.
: (A) Virus injection, fiber implantation (left) and synchronous recording of dopamine-enabled neuronal activity and scratch behavior graph (right).
marked area: VTA, covered area of the midbrain. The gCaMP6s fluorescence brightness of GCaMP6s expressed by dopamine neurons in VTA after the arrest of
(B) chloroquine began, while the eYFP brightness did not change, indicating that the neuronal activity of dopamine was increased after scratching began.
(C) the light-activated dopamine neurons identified in the body record are similar to the light-induced action potential waveforms.
(D) dopamine neurons change their activity after scratching.
(E) itching action began to inhibit dopamine neurons significantly shorten scratching time.
the study, Sun's research team successfully revealed the changes in the activity of dopamine neurons in the geyptic region of the middle brain, revealing the need for the continuation of the scratching action.
work deepens people's understanding of the mechanism of itching information in the neuromodulation system, and lays the foundation for the in-depth study of the treatment of chronic itch.
this work was mainly done by Yuan Lei, a doctoral student in Sun's research group, in which Liang Yu and Deng Wei played an important role.
the research was supported by the National Natural Science Foundation of China (3177158, 31371122) and the Chinese Academy of Sciences Strategic Pilot Science and Technology Special (XDBS0100000).
Source: Shanghai Institute of Life Sciences.