title: Direct projection from the lateral habenula to the trigeminal mesencephalic nucleus in rats.
abstract: Trigeminal mesencephalic nucleus (Vmes) neurons are primary afferents conveying deep sensation from the masticatory muscle spindles or the periodontal mechanoreceptors, and are crucial for controlling jaw movements. Their cell bodies exist in the brain and receive descending commands from a variety of cortical and subcortical structures involved in limbic (emotional) systems. However, it remains unclear how the lateral habenula (LHb), a center of negative emotions (e.g., pain, stress and anxiety), can influence the control of jaw movements. To address this issue, we examined whether and how the LHb directly projects to the Vmes by means of neuronal tract tracing techniques in rats. After injections of a retrograde tracer Fluorogold in the rostral and caudal Vmes, a number of neurons were labeled in the lateral division of LHb (LHbl) bilaterally, whereas a few neurons were labeled in the medial division of LHb (LHbm) bilaterally. After injections of an anterograde tracer, biotinylated dextranamine (BDA) in the LHbl, a small number of labeled axons were distributed bilaterally in the rostral and caudal levels of Vmes, where some labeled axonal boutons contacted the cell body of rostral and caudal levels of Vmes neurons bilaterally. After the BDA injection into the LHbm, however, no axons were labeled bilaterally in the rostral and caudal levels of Vmes. Therefore, the present study for the first time demonstrated the direct projection from the LHbl to the Vmes and the detailed projection patterns, suggesting that jaw movements are modulated by negative emotions that are signaled by LHbl neurons.
authors.affiliation: Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan; Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
authors.forename: Haruka
authors.initials: H
authors.lastname: Ohara
authors.affiliation: Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Tachibana
authors.affiliation: Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujio
authors.affiliation: Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan; Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
authors.forename: Rieko
authors.initials: R
authors.lastname: Takeda-Ikeda
authors.affiliation: Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Sato
authors.affiliation: Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan; Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Oka
authors.affiliation: Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
authors.forename: Etsuko
authors.initials: E
authors.lastname: Ikenoue
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamashiro
authors.affiliation: Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan. Electronic address: yoshida@dent.osaka-u.ac.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yoshida
mesh_terms: D000344:Afferent Pathways / Q000033:anatomy & histology / Q000502:physiology; D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives; D003911:Dextrans; D019262:Habenula / Q000033:anatomy & histology* / Q000502:physiology; D007568:Jaw / Q000294:innervation / Q000502:physiology; D008297:Male; D009043:Motor Activity / Q000502:physiology; D056347:Neuroanatomical Tract-Tracing Techniques; D056325:Neuronal Tract-Tracers; D009474:Neurons / Q000166:cytology / Q000502:physiology; D010784:Photomicrography; D017208:Rats, Wistar / Q000033:anatomy & histology* / Q000502:physiology; D013266:Stilbamidines; D013681:Tegmentum Mesencephali / Q000033:anatomy & histology* / Q000502:physiology; D014278:Trigeminal Nuclei / Q000033:anatomy & histology* / Q000502:physiology
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D003911:Dextrans; D056325:Neuronal Tract-Tracers; D013266:Stilbamidines; C076397:biotinylated dextran amine; D001710:Biotin
keywords: Jaw movement; Mastication; Muscle spindle; Negative emotion; Pain; Stress