A parallel cholinergic brainstem pathway for enhancing locomotor drive.
The brainstem locomotor system is believed to be organized serially from the mesencephalic locomotor region (MLR) to reticulospinal neurons, which in turn project to locomotor neurons in the spinal cord. We identified brainstem muscarinoceptive neurons in lampreys (Petromyzon marinus) that received parallel inputs from the MLR and projected back to reticulospinal cells to amplify and extend the duration of locomotor output. These cells responded to muscarine with extended periods of excitation, received direct muscarinic excitation from the MLR and projected glutamatergic excitation to reticulospinal neurons. Targeted blockade of muscarine receptors over these neurons profoundly reduced MLR-induced excitation of reticulospinal neurons and markedly slowed MLR-evoked locomotion. The presence of these neurons forces us to rethink the organization of supraspinal locomotor control, to include a sustained feedforward loop that boosts locomotor output.
Smetana
Roy
R
Department of Biological Sciences and Laboratory in Neurobiology, University of Illinois at Chicago, Chicago, Illinois, USA.
Juvin
Laurent
L
Dubuc
Réjean
R
Alford
Simon
S
D000200:Action Potentials; D000818:Animals; D001933:Brain Stem / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D004525:Efferent Pathways / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials; D018698:Glutamic Acid / Q000378:metabolism; D066298:In Vitro Techniques; D007798:Lampreys; D008124:Locomotion / Q000187:drug effects / Q000502:physiology*; D008636:Mesencephalon / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology; D056325:Neuronal Tract-Tracers; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011976:Receptors, Muscarinic / Q000378:metabolism*; D013116:Spinal Cord / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology; D013550:Swimming / Q000502:physiology; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D056325:Neuronal Tract-Tracers; D011976:Receptors, Muscarinic; D018698:Glutamic Acid
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