Optogenetic induction of hibernation-like state with modified human Opsin4 in mice

• Published in: Cell reports methods 2022-11, Vol.2 (11), p.100336-100336, Article 100336
• Main Authors: Takahashi, Tohru M., Hirano, Arisa, Kanda, Takeshi, Saito, Viviane M., Ashitomi, Hiroto, Tanaka, Kazumasa Z., Yokoshiki, Yasufumi, Masuda, Kosaku, Yanagisawa, Masashi, Vogt, Kaspar E., Tokuda, Takashi, Sakurai, Takeshi
• Format: Article
• Language: English
• ISSN: 2667-2375; 2667-2375
• DOI: 10.1016/j.crmeth.2022.100336

We recently determined that the excitatory manipulation of Qrfp -expressing neurons in the preoptic area of the hypothalamus (quiescence-inducing neurons [Q neurons]) induced a hibernation-like hypothermic/hypometabolic state (QIH) in mice. To control the QIH with a higher time resolution, we develop an optogenetic method using modified human opsin4 (OPN4; also known as melanopsin), a G protein-coupled-receptor-type blue-light photoreceptor. C-terminally truncated OPN4 (OPN4dC) stably and reproducibly induces QIH for at least 24 h by illumination with low-power light (3 μW, 473 nm laser) with high temporal resolution. The high sensitivity of OPN4dC allows us to transcranially stimulate Q neurons with blue-light-emitting diodes and non-invasively induce the QIH. OPN4dC-mediated QIH recapitulates the kinetics of the physiological changes observed in natural hibernation, revealing that Q neurons concurrently contribute to thermoregulation and cardiovascular function. This optogenetic method may facilitate identification of the neural mechanisms underlying long-term dormancy states such as sleep, daily torpor, and hibernation. • We developed a GPCR(Gq)-based optogenetic tool using modified human OPN4 (OPN4dC) • OPN4dC optogenetics exhibited a high degree of sustainability and reproducibility • OPN4dC is useful for 24 h neuronal excitation and non-invasive stimulation • OPN4dC induces a hibernation-like state similar to natural hibernation Optogenetics is used to manipulate neurons at a high temporal resolution to understand the neuronal mechanisms of many physiologies. Increasing evidence suggests that current tools are effective for short-term manipulation (seconds to minutes); however, the effects of manipulating neurons are difficult to examine for a longer period (hours to days) on long-term behavioral and physiological responses, such as hibernation. This study aimed to establish a method that allows stable and long-lasting (∼24 h) neuronal manipulation with high reproducibility using a modified OPN4 (melanopsin), a highly photosensitive G protein-coupled-receptor-type photosensor. To control the induced hibernation-like state with higher time resolution in mice, Takahashi et al. develop an optogenetic method using human opsin4 (OPN4), a G protein-coupled-receptor-type blue-light photoreceptor. Modified OPN4 stably induces hypothermia for 24 h via extremely low-power light illumination.