title: Effects of inactivation and stimulation of locus coeruleus on respiratory activity of neonatal rat.
abstract: We examined the effects of pharmacological inactivation and electrical stimulation of the locus coeruleus (LC) on the respiratory rate (RR) in isolated brainstem-spinal cord preparations of the neonatal rat. The brainstem and spinal cord were isolated en bloc from neonatal (days 1-4) Sprague-Dawley rats and superfused with artificial cerebrospinal fluid (ACSF) equilibrated with a gas mixture containing 2% CO(2) (pH 7.8). Pharmacological inactivation of the bilateral LC by means of microinjection of tetrodotoxin or noradrenaline elicited a significant decrease in RR in preparations obtained from rats aged 3-4 days, but not in preparations of rats aged 1-2 days. Stimulation of the bilateral LC with a train of electrical pulses (25-50 microA, 30 ms, 0.5 Hz, 3-4 min) caused a marginal but significant increase in RR on days 3-4, but not on days 1-2. These results indicate that the LC exerts an excitatory effect on the medullary respiratory rhythm generator in an age-dependent manner.
authors.affiliation: Department of Medicine, School of Medicine, Keio University, 35 Shinano-machi, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Hakuno
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Oyamada
authors.forename: Michie
authors.initials: M
authors.lastname: Murai
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ito
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Yamaguchi
mesh_terms: D000367:Age Factors; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001933:Brain Stem / Q000166:cytology / Q000502:physiology; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology; D008125:Locus Coeruleus / Q000187:drug effects / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology; D009924:Organ Culture Techniques; D010507:Periodicity; D051381:Rats; D017207:Rats, Sprague-Dawley; D012125:Respiratory Center / Q000166:cytology / Q000502:physiology*; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D000779:Anesthetics, Local; D013779:Tetrodotoxin; D009638:Norepinephrine