title: Control of lamprey locomotor neurons by colocalized monoamine transmitters.
abstract: Neurons in the central nervous system (CNS) often store more than one neurotransmitter, but as yet the functional significance of this type of coexistence is poorly understood. 5-Hydroxytryptamine (5-HT) modulates calcium-dependent K+ channels (KCa) responsible for the postspike afterhyperpolarization in different regions of the CNS. In lamprey, 5-HT neurons control apamine-sensitive KCa channels in spinal locomotor network interneurons, thereby in addition regulating the duration of locomotor bursts. We report here that these spinal 5-HT neurons also contain dopamine. Like 5-HT, dopamine causes a reduction of the afterhyperpolarization, but in this case it is due to a reduction of calcium entry during the action potential, which results in a reduced activation of KCa. 5-HT and dopamine are both released from these midline neurons, and both reduce the afterhyperpolarization through two distinctly different, but complementary cellular mechanisms. The net effect of dopamine (10-100 microM) on the locomotor network is similar to that of 5-HT, and the effects of dopamine and 5-HT are additive at the network level.
authors.affiliation: Nobel Institute for Neurophysiology, Department of Neuroscience, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Schotland
authors.forename: O
authors.initials: O
authors.lastname: Shupliakov
authors.forename: M
authors.initials: M
authors.lastname: Wikström
authors.forename: L
authors.initials: L
authors.lastname: Brodin
authors.forename: M
authors.initials: M
authors.lastname: Srinivasan
authors.forename: Z B
authors.initials: ZB
authors.lastname: You
authors.forename: M
authors.initials: M
authors.lastname: Herrera-Marschitz
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.forename: T
authors.initials: T
authors.lastname: Hökfelt
authors.forename: S
authors.initials: S
authors.lastname: Grillner
mesh_terms: D000200:Action Potentials; D000818:Animals; D015283:Citalopram / Q000494:pharmacology; D004298:Dopamine / Q000502:physiology*; D013006:Growth Hormone / Q000502:physiology*; D066298:In Vitro Techniques; D007395:Interneurons / Q000187:drug effects / Q000502:physiology*; D007798:Lampreys; D008124:Locomotion / Q000502:physiology; D013131:Spine / Q000166:cytology
chemical_list: D015283:Citalopram; D013006:Growth Hormone; D004298:Dopamine