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Exp Neurobiol 2023; 32(6): 387-394
Published online December 31, 2023
https://doi.org/10.5607/en23018
© The Korean Society for Brain and Neural Sciences
Sanggeon Park1,2, Jeiwon Cho1,2* and Yeowool Huh3,4*
1Department of Brain and Cognitive Sciences, Scranton College, Ewha Womans University, Seoul 03760, 2Brain Disease Research Institute, Ewha Brain Institute, Ewha Womans University, Seoul 03760, 3Department of Medical Science, College of Medicine, Catholic Kwandong University, Gangneung 25601, 4Translational Brain Research Center, International St. Mary’s Hospital, Catholic Kwandong University, Incheon 22711, Korea
Correspondence to: *To whom correspondence should be addressed.
Jeiwon Cho, TEL: 82-2-3277-4226, FAX: 82-2-3277-6595
e-mail: jelectro21@ewha.ac.kr
Yeowool Huh, TEL: 82-32-290-2773, FAX: 82-2-3277-6595
e-mail: huh06@cku.ac.kr
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Loss of inhibition is suggested to cause pathological pain symptoms. Indeed, some human case reports suggest that lesions including the thalamic reticular nucleus (TRN) which provides major inhibitory inputs to other thalamic nuclei, may induce thalamic pain, a type of neuropathic pain. In support, recent studies demonstrated that activation of GABAergic neurons in the TRN reduces nociceptive responses in mice, reiterating the importance of the TRN in gating nociception. However, whether biochemically distinct neuronal types in the TRN differentially contribute to gating nociception has not been investigated. We, therefore, investigated whether the activity of parvalbumin (PV) and somatostatin (SOM) expressing neurons in the somatosensory TRN differentially modulate nociceptive behaviors using optogenetics and immunostaining techniques. We found that activation of PV neurons in the somatosensory TRN significantly reduced nociceptive behaviors, while activation of SOM neurons in the TRN had no such effect. Also, selective activation of PV neurons, but not SOM neurons, in the TRN activated relatively more PV neurons in the primary somatosensory cortex, which delivers inhibitory effect in the cortex, when measured with cFos and PV double staining. Results of our study suggest that PV neurons in the somatosensory TRN have a stronger influence in regulating nociception and that their activations may provide further inhibition in the somatosensory cortex by activating cortical PV neurons.
Keywords: Thalamus reticulate nucleus, Interneurons, Parvalbumin, Somatostatin, Optogenetics, Mice