TY - JOUR
T1 - Transgenic archaerhodopsin-3 expression in hypocretin/orexin neurons engenders cellular dysfunction and features of type 2 narcolepsy
AU - Williams, Rhîannan H.
AU - Tsunematsu, Tomomi
AU - Thomas, Alexia M.
AU - Bogyo, Kelsie
AU - Yamanaka, Akihiro
AU - Kilduff, Thomas S.
N1 - Funding Information:
This work was supported by National Institutes of Health Grants R01NS077408 and R01NS098813 to T.S.K., ERCStG 715933 to R.H.W., and Ministry of Education, Culture, Sports, Science and Technology KAKENHI Grants 16H01271 and 15H01428 to A.Y. We thank C. Saito, K. Nishimura, Srikanta Chowdhury, Sarah Wurts-Black and Tsui-ming Chen for technical assistance.
Funding Information:
This work was supported by National Institutes of Health Grants R01NS077408 and R01NS098813 to T.S.K., ERCStG 715933 to R.H.W., and Ministry of Education, Culture, Sports, Science and Technology KAKENHI Grants
Publisher Copyright:
Copyright © 2019 the authors
PY - 2019/11
Y1 - 2019/11
N2 - Narcolepsy, characterized by excessive daytime sleepiness, is associated with dysfunction of the hypothalamic hypocretin/orexin (Hcrt) system, either due to extensive loss of Hcrt cells (Type 1, NT1) or hypothesized Hcrt signaling impairment (Type 2, NT2). Accordingly, efforts to recapitulate narcolepsy-like symptoms in mice have involved ablating these cells or interrupting Hcrt signaling. Here, we describe orexin/Arch mice, in which a modified archaerhodopsin-3 gene was inserted downstream of the prepro-orexin promoter, resulting in expression of the yellow light-sensitive Arch-3 proton pump specifically within Hcrt neurons. Histological examination along with ex vivo and in vivo electrophysiological recordings of male and female orexin/Arch mice demonstrated silencing of Hcrt neurons when these cells were photoilluminated. However, high expression of the Arch transgene affected cellular and physiological parameters independent of photoillumination. The excitability of Hcrt neurons was reduced, and both circadian and metabolic parameters were perturbed in a subset of orexin/Arch mice that exhibited high levels of Arch expression. Orexin/Arch mice also had increased REM sleep under baseline conditions but did not exhibit cataplexy, a sudden loss of muscle tone during wakefulness characteristic of NT1. These aberrations resembled some aspects of mouse models with Hcrt neuron ablation, yet the number of Hcrt neurons in orexin/Arch mice was not reduced. Thus, orexin/Arch mice may be useful to investigate Hcrt system dysfunction when these neurons are intact, as is thought to occur in narcolepsy without cataplexy (NT2). These results also demonstrate the utility of extended phenotypic screening of transgenic models when specific neural circuits have been manipulated.
AB - Narcolepsy, characterized by excessive daytime sleepiness, is associated with dysfunction of the hypothalamic hypocretin/orexin (Hcrt) system, either due to extensive loss of Hcrt cells (Type 1, NT1) or hypothesized Hcrt signaling impairment (Type 2, NT2). Accordingly, efforts to recapitulate narcolepsy-like symptoms in mice have involved ablating these cells or interrupting Hcrt signaling. Here, we describe orexin/Arch mice, in which a modified archaerhodopsin-3 gene was inserted downstream of the prepro-orexin promoter, resulting in expression of the yellow light-sensitive Arch-3 proton pump specifically within Hcrt neurons. Histological examination along with ex vivo and in vivo electrophysiological recordings of male and female orexin/Arch mice demonstrated silencing of Hcrt neurons when these cells were photoilluminated. However, high expression of the Arch transgene affected cellular and physiological parameters independent of photoillumination. The excitability of Hcrt neurons was reduced, and both circadian and metabolic parameters were perturbed in a subset of orexin/Arch mice that exhibited high levels of Arch expression. Orexin/Arch mice also had increased REM sleep under baseline conditions but did not exhibit cataplexy, a sudden loss of muscle tone during wakefulness characteristic of NT1. These aberrations resembled some aspects of mouse models with Hcrt neuron ablation, yet the number of Hcrt neurons in orexin/Arch mice was not reduced. Thus, orexin/Arch mice may be useful to investigate Hcrt system dysfunction when these neurons are intact, as is thought to occur in narcolepsy without cataplexy (NT2). These results also demonstrate the utility of extended phenotypic screening of transgenic models when specific neural circuits have been manipulated.
KW - Hypothalamus
KW - NREM sleep
KW - Narcolepsy
KW - Optogenetic
KW - REM sleep
KW - Wakefulness
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UR - http://www.scopus.com/inward/citedby.url?scp=85075813848&partnerID=8YFLogxK
U2 - 10.1523/JNEUROSCI.0311-19.2019
DO - 10.1523/JNEUROSCI.0311-19.2019
M3 - Article
C2 - 31628177
AN - SCOPUS:85075813848
VL - 39
SP - 9435
EP - 9452
JO - Journal of Neuroscience
JF - Journal of Neuroscience
SN - 0270-6474
IS - 47
ER -