title: Grafting of fetal brainstem 5-HT neurons into the sublesional spinal cord of paraplegic rats restores coordinated hindlimb locomotion.
abstract: In rodent models of spinal cord injury, there is increasing evidence that activation of the locomotor central pattern generator (CPG) below the site of injury with 5-hydroxytryptamine (5-HT) agonists improves locomotor recovery and restores coordination. A promising means of replacing 5-HT control of locomotion is to graft brainstem 5-HT neurons into the spinal cord below the level of the spinal cord injury. However, it is not known whether this approach improves limb coordination because recovery of coordinated stepping has not been documented in detail in previous studies employing this transplantation strategy. Here, adult rats with complete spinal cord transections at the T9/10 level were grafted with E14 fetal neurons from the medulla at the T10/11 vertebra level one month after injury. The B1, B2 and B3 fetal anlagen of brainstem 5-HT neurons, a grouping that included the presumed precursors of recently described 5-HT locomotor command neurons, were used in these grafts. EMG and video recordings of treadmill locomotion evoked by tail stimulation showed full recovery of inter- and intralimb coordination in the grafted rats. We showed, using systemically applied antagonists, that 5-HT₂ and 5-HT₇ receptors mediate the improved locomotion after grafting, but through actions on different populations of spinal locomotor neurons. Specifically, 5-HT₂ receptors control CPG activation as well as motoneuron output, while 5-HT₇ receptors contribute primarily to activity of the locomotor CPG. These results are consistent with the roles for these receptors during locomotion in intact rodents and in rodent brainstem-spinal cord in vitro preparations.
authors.affiliation: Laboratory of Neuromuscular Plasticity, Department of Neurophysiology, Nencki Institute of Experimental Biology PAS, Warsaw, Poland. u.slawinska@nencki.gov.pl
authors.forename: Urszula
authors.initials: U
authors.lastname: Sławińska
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Miazga
authors.forename: Anna M
authors.initials: AM
authors.lastname: Cabaj
authors.forename: Anna N
authors.initials: AN
authors.lastname: Leszczyńska
authors.forename: Henryk
authors.initials: H
authors.lastname: Majczyński
authors.forename: James I
authors.initials: JI
authors.lastname: Nagy
authors.forename: Larry M
authors.initials: LM
authors.lastname: Jordan
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000637:transplantation*; D004195:Disease Models, Animal; D004576:Electromyography; D004622:Embryo, Mammalian; D005260:Female; D016332:Fetal Tissue Transplantation / Q000379:methods*; D006614:Hindlimb / Q000503:physiopathology*; D008124:Locomotion / Q000187:drug effects; D010264:Paraplegia / Q000209:etiology / Q000473:pathology / Q000601:surgery; D010636:Phenols / Q000494:pharmacology; D011597:Psychomotor Performance / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D044348:Receptors, Serotonin, 5-HT2 / Q000378:metabolism; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology; D012701:Serotonin / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000494:pharmacology; D013119:Spinal Cord Injuries / Q000150:complications*; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: D010636:Phenols; D044348:Receptors, Serotonin, 5-HT2; C404922:SB 269970; D012702:Serotonin Antagonists; D013449:Sulfonamides; D012701:Serotonin
keywords: Locomotor movement; Serotonin; Spinal cord injury; Transplantation