title: Novel axonal projection from the caudal end of the ventrolateral medulla to the intermediolateral cell column.
abstract: We used an optical imaging technique to investigate whether axons of neurons in the caudal end of the ventrolateral medulla (CeVLM), as well as axons of neurons in the rostral ventrolateral medulla (RVLM), project to neurons in the intermediolateral cell column (IML) of the spinal cord. Brain stem-spinal cord preparations from neonatal normotensive Wistar-Kyoto and spontaneously hypertensive rats were stained with a voltage-sensitive dye, and responses to electrical stimulation of the IML at the Th2 level were detected as changes in fluorescence intensity with an optical imaging apparatus (MiCAM-01). The results were as follows: 1) depolarizing responses to IML stimulation during low-Ca high-Mg superfusion were detected on the ventral surface of the medulla at the level of the CeVLM, as well as at the level of the RVLM, 2) depolarizing responses were also detected on cross sections at the level of the CeVLM, and they had a latency of 24.0 +/- 5.5 (SD) ms, 3) antidromic action potentials in response to IML stimulation were demonstrated in the CeVLM neurons where optical images were detected, and 4) glutamate application to the CeVLM increased the frequency of excitatory postsynaptic potentials (EPSPs) and induced depolarization of the IML neurons. The optical imaging findings suggested a novel axonal and functional projection from neurons in the CeVLM to the IML. The increase in EPSPs of the IML neurons in response to glutamate application suggests that the CeVLM participates in the regulation of sympathetic nerve activity and blood pressure and may correspond to the caudal pressor area.
authors.affiliation: Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Kamon
authors.initials: K
authors.lastname: Iigaya
authors.forename: Hiroo
authors.initials: H
authors.lastname: Kumagai
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Onimaru
authors.forename: Akira
authors.initials: A
authors.lastname: Kawai
authors.forename: Naoki
authors.initials: N
authors.lastname: Oshima
authors.forename: Toshiko
authors.initials: T
authors.lastname: Onami
authors.forename: Chie
authors.initials: C
authors.lastname: Takimoto
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kamayachi
authors.forename: Koichi
authors.initials: K
authors.lastname: Hayashi
authors.forename: Takao
authors.initials: T
authors.lastname: Saruta
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Itoh
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D001369:Axons / Q000502:physiology*; D001933:Brain Stem / Q000166:cytology / Q000502:physiology; D002118:Calcium; D004558:Electric Stimulation; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D018698:Glutamic Acid / Q000494:pharmacology; D007091:Image Processing, Computer-Assisted; D008274:Magnesium; D008526:Medulla Oblongata / Q000166:cytology / Q000502:physiology*; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
chemical_list: D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D008274:Magnesium; D002118:Calcium