Morphological features of pain- and itch-specific neurons in the lateral parabrachial nucleus

窦雪瑛 于劲 张文馨 王姗 袁婷 李创 王宣人 周楠 王璐 董玉琳

doi:10.16098/j.issn.0529-1356.2026.02.003

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Acta Anatomica Sinica ›› 2026, Vol. 57 ›› Issue (2) : 160-168. DOI: 10.16098/j.issn.0529-1356.2026.02.003

Morphological features of pain- and itch-specific neurons in the lateral parabrachial nucleus

DOU Xue-ying^1,2, YU Jin^2,3, ZHANG Wen-xin^2,4, WANG Shan², YUAN Ting^2,5, LI Chuang^2,5, WANG Xuan-ren^2,4, ZHOU Nan^2,4, WANG Lu^1*, DONG Yu-lin^2*

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Abstract

Objective To investigate the distribution patterns of pain- and itch-specific neurons within the lateral parabrachial nucleus (LPB), and to map their divergent downstream projection pathways. Methods The male C57BL/6 mice were used, the optimal induction window for the tetracycline-off gene expression system (Tet-off system) was determined to be seven days through preliminary experiment (n=24). We then employed the Tet-off system, in combination with c-Fos promoter-driven viral vectors and Fos immunofluorescence histochemistry, to specifically label LPB neurons activated by pain (LPB^pain) or itch (LPB^itch) and to analyze their co-localization within LPB subnuclei (n=7). Finally, using Tet-off-based viral anterograde tracing (n=6), we compared the downstream projection targets of these two neuronal populations. Results Sequential application of distinct noxious stimuli within defined time windows induced robust co-expression of viral vector-derived enhanced green fluorescent protein (EGFP) and Fos protein (labeled by red fluorescence) in the LPB. Microscopic analysis revealed that LPB^painand LPB^itch neurons were extensively co-localized in the external part of the lateral parabrachial nucleus (LPBE). The co-localization rate reached up to 72.9% for EGFP^＋ pain neurons with Fos^＋ itch neurons, and 79.5% for EGFP^＋ itch neurons with Fos^＋ pain neurons. Co-labelling rates in other subnuclei were relatively lower. Anterograde tracing results showed that both LPB^pain and LPB^itch neurons projected predominantly to overlapping regions, including the central amygdaloid nucleus (CeA), periaqueductal gray (PAG), zona incerta (ZI), revealing a highly similar overall projection pattern. Conclusion While the LPB is activated by both pain and itch stimuli, its subnuclei exhibit distinct response profiles to these stimuli. The largely overlapping downstream projections of LPB^pain and LPB^itch neurons suggest that differential central encoding of pain and itch may rely more on molecular or functional mechanisms than on strictly segregated anatomical pathways.

Key words

Lateral parabrachial nucleus

/ Pain / Itch;Tetracycline-off system / Brain stereotactic injection / Immunofluorescence / Mouse

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DOU Xue-ying, YU Jin, ZHANG Wen-xin, WANG Shan, YUAN Ting, LI Chuang, WANG Xuan-ren, ZHOU Nan, WANG Lu, DONG Yu-lin. Morphological features of pain- and itch-specific neurons in the lateral parabrachial nucleus[J]. Acta Anatomica Sinica. 2026, 57(2): 160-168 https://doi.org/10.16098/j.issn.0529-1356.2026.02.003

References

［1］ Yosipovitch G, Greaves MW, Schmelz M. Itch［J］. Lancet, 2003,361(9358):690-694.

［2］ Yamanoi Y, Kittaka H, Tominaga M. Cheek injection model for simultaneous measurement of pain and itch-related behaviors ［J］. Vis Exp, 2019,(151).doi: 10.3791/58943.

［3］ Sun L, Liu R, Guo F, et al. Parabrachial nucleus circuit governs neuropathic pain-like behavior［J］. Nat Commun, 2020,11(1): 5974.

［4］ Li JN, Ren JH, Zhao LJ, et al. Projecting neurons in spinal dorsal horn send collateral projections to dorsal midline/intralaminar thalamic complex and parabrachial nucleus［J］. Brain Res Bull, 2021,169: 184-195.

［5］ Ren X, Liu S, Virlogeux A, et al. Identification of an essential spinoparabrachial pathway for mechanical itch［J］. Neuron, 2023,111(11): 1812-1829.e6.

［6］ Chen, ZF. A neuropeptide code for itch［J］. Nat Rev Neurosci, 2021,22(12): 758-776.

［7］ Gautam M, Prasoon P, Kumar R, et al. Role of neurokinin type 1 receptor in nociception at the periphery and the spinal level in the rat［J］. Spinal Cord, 2016,54(3): 172-182.

［8］ Li JN, Wu XM, Zhao LJ, et al. Central medial thalamic nucleus dynamically participates in acute itch sensation and chronic itch-induced anxiety-like behavior in male mice［J］. Nat Commun, 2023,14(1): 2539.

［9］ Weng HJ, Pham QTT, Chang CW, et al. Druggable targets and compounds with both antinociceptive and antipruritic effects［J］. Pharmaceuticals (Basel), 2022,15(7):892.

［10］ Moullan N, Mouchiroud L, Wang X, et al. Tetracyclines disturb mitochondrial function across eukaryotic models: a call for caution in biomedical research［J］. Cell Rep, 2015,10(10): 1681-1691.

［11］ Pan Q, Guo SS, Chen M, et al. Representation and control of pain and itch by distinct prefrontal neural ensembles［J］. Neuron, 2023,111(15): 2414-2431.e7.

［12］ Deng J, Zhou H, Lin JK, et al. The parabrachial nucleus directly channels spinal nociceptive signals to the intralaminar thalamic nuclei, but not the amygdala［J］. Neuron, 2020,107(5): 909-923.e6.

［13］ Gao F, Ma J, Yu YQ, et al. A non-canonical retina-ipRGCs-SCN-PVT visual pathway for mediating contagious itch behavior［J］. Cell Rep, 2022,41(1): 111444.

［14］ Sun Y, Wang J, Liang SH, et al. Involvement of the ventrolateral periaqueductal gray matter-central medial thalamic nucleus-basolateral amygdala pathway in neuropathic pain regulation of rats［J］. Front Neuroanat, 2020,14: 32.

［15］ Cui M, Ji R, Song L, et al. Neuronal and molecular mechanisms underlying chronic pain and depression comorbidity in the paraventricular thalamus［J］. J Neurosci, 2024,44(13):e1752232024.

［16］ Campos CA, Bowen AJ, Roman CW, et al. Encoding of danger by parabrachial CGRP neurons［J］. Nature, 2018,555(7698): 617-622.

［17］ Hakim M, Battle AR, Belmer A, et al. Pavlovian olfactory fear conditioning: its neural circuity and importance for understanding clinical fear-based disorders［J］. Front Mol Neurosci, 2019,12: 221.

［18］ Pavlenko D, Ishida H, Markan A, et al. A subpopulation of projections from the parabrachial nucleus to the central amygdala mediates itch［J］. Sci Rep, 2025,15(1): 26432.

［19］ Phua SC, Tan YL, Kok AMY, et al. A distinct parabrachial-to-lateral hypothalamus circuit for motivational suppression of feeding by nociception［J］. Sci Adv, 2021,7(19): eabe4323.

［20］ Mochizuki H, Sadato N, Saito DN, et al. Neural correlates of perceptual difference between itching and pain: a human fMRI study［J］. Neuroimage, 2007,36(3): 706-717.

［21］ Yosipovitch G, Carstens E, McGlone F. Chronic itch and chronic pain: analogous mechanisms［J］. Pain, 2007,131(1-2): 4-7.

［22］ Yang H, de Jong JW, Cerniauskas I, et al. Pain modulates dopamine neurons via a spinal-parabrachial-mesencephalic circuit［J］. Nat Neurosci, 2021,24(10): 1402-1413.

［23］ Li JN, Ren JH, He CB, et al. Projections from the lateral parabrachial nucleus to the lateral and ventral lateral periaqueductal gray subregions mediate the itching sensation［J］. Pain, 2021,162(6): 1848-1863.