Peptidergic activation of locomotor pattern generators in the neonatal spinal cord.
The development of motor networks in the spinal cord is partly activity-dependent. We have observed receptor-mediated excitatory effects of two peptides, arginine vasopressin (AVP) and oxytocin (OXT), on motor network activity in the neonate. With the use of an en bloc in vitro preparation of mouse spinal cord (2-3 d old), which either was isolated completely or had muscles of the hindlimb left intact, we show that the bath application of AVP or OXT can evoke an increase in population bursting of motoneurons recorded from the lumbar ventral roots. By using antagonists for AVP and OXT, we found that these peptides were binding primarily to V1a and OXT receptors, respectively. Western blot analysis revealed a 48 kDa V1a and a 55 kDa OXT receptor immunoreactive band that was expressed in tissue obtained from L1-L6 sections of spinal cord. AVP, but not OXT, could, on occasion, evoke sustained periods of locomotor-like activity. In addition, when we applied AVP or OXT in combination with a 5-HT2 agonist, bouts of locomotor-like activity could be observed in a majority of preparations. Collectively, these data point to a novel role for AVP and OXT in the activation of spinal motor networks.
Pearson
Selina A
SA
Neuroscience Research Group, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
Mouihate
Abdeslam
A
Pittman
Quentin J
QJ
Whelan
Patrick J
PJ
D000818:Animals; D000831:Animals, Newborn; D001127:Arginine Vasopressin / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004576:Electromyography; D006614:Hindlimb; D066298:In Vitro Techniques; D008161:Lumbosacral Region; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology; D009415:Nerve Net / Q000187:drug effects / Q000502:physiology*; D010121:Oxytocin / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D013126:Spinal Nerve Roots / Q000187:drug effects / Q000502:physiology
D017366:Serotonin Receptor Agonists; D001127:Arginine Vasopressin; D010121:Oxytocin