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Yusuke Izuta, Michiko Shibuya, Erina Onishi, Imada Toshihiro, Shigeru Nakamura, Ayano Katagiri, Akihiro Yamanaka, Kazuo Tsubota; Pharmacogenetic manipulation of neuronal activity reveals a role of brain spinal trigeminal nucleus in reflex tearing.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1012.
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© ARVO (1962-2015); The Authors (2016-present)
Reflex tearing, marked transient secretion, is physiological reaction against sensory stimuli to cornea from external. Vc/C1 region of spinal trigeminal nucleus of brain (Vc/C1) is known to relay region of corneal sensation. Designer Receptors Excusively Activated by Designer Drugs (DREADD) technology enable to manipulate specific neuronal activity in a freely moving animal. In this study, using DREADD system, we investigate the role of the Vc/C1 in reflex tearing.
Eight weeks, female C57Bl/6J mice were used. Surgeries for Adeno associated virus (AAV) injections were conducted under pentobarbital anesthesia (50 mg/kg, i.p.) using stereotaxic instrument with a glass micropipette and an air pressure injector system. AAV-CMV-hM3Dq-mCherry (600nl/injection) were unilaterally injected into Vc/C1 (according to mouse brain atlas). Two weeks over after the surgery, the changes in tear secretion and eye scratching behavior were analyzed after the fiting of hM3Dq expressed neurons by administration of hM3Dq agonist clozapine-N-oxide (CNO) (1mg/kg, i.p.). Saline was used as control.
Increase in tear secretion along with eye scratching behavior were specifically observed in ipsilateral to the AAV injected side Increasing ratio were peaked at 30min after the CNO injection, approximately 200% (tear secretion) and 3000% (eye scratching) to before CNO injection (n=5). These increase were sustained up to 240minutes. Administration of saline did not altered these responses. In all mice, the expresiion of hM3Dq-mCherry were confirmed in Vc/C1 region.
Our results indicate that activation of Vc/C1 region involves in reflex tearing.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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