5-HT1A receptors are involved in short- and long-term processes responsible for 5-HT-induced locomotor function recovery in chronic spinal rat.
After thoracic spinal cord transection, a paraplegic syndrome occurs. Previous data showed that an acute administration of a 5-HT2 agonist (quipazine) could promote motor function recovery in spinal rats. However, continuous subdural perfusion of quipazine via an osmotic pump over 1 month proved to be more effective. The present study was designed to investigate the possible involvement of 5-HT1A receptors in such recovery. Motor performances and locomotor parameters were analysed in spinal animals receiving daily, for 1 month, a dose of the 5-HT1A agonist 8-OHDPAT. The results were compared to those obtained in spinal rats receiving either a placebo or quipazine in the same conditions. Using daily injections instead of continuous perfusion of either receptor agonist to spinal animals allowed characterization of short- and long-term consequences of pharmacological stimulation of 5-HT1A and 5-HT2 receptors on motor function recovery. Our data demonstrate that daily injections of a 5-HT1A agonist induce long-term, cumulative, positive effects on motor function recovery, as assessed by the improvement in the walking parameters observed before the 'day-test' injection. This might involve use-dependent processes depending on a chronic and/or repetitive stimulation of the spinal network for locomotion in relation to 5-HT receptor activation. A further improvement in the motor parameters, transiently observed following the injection, suggests a more direct action of 5-HT1A and 5-HT2 receptor activation on spinal neurons involved in motor pattern generation.
Antri
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Neurobiologie des Signaux Intercellulaires, CNRS UMR 7101, Institut de Biologie Intégrative (IFR 83), Université Pierre et Marie Curie, 7, quai Saint Bernard Boite 002, F-75252 Paris, France.
Mouffle
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C
Orsal
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Barthe
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JY
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal; D001696:Biomechanical Phenomena; D004576:Electromyography / Q000379:methods; D005260:Female; D006614:Hindlimb / Q000503:physiopathology; D008124:Locomotion / Q000187:drug effects* / Q000502:physiology; D009043:Motor Activity / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects / Q000503:physiopathology; D011814:Quipazine / Q000494:pharmacology; D051381:Rats; D044282:Receptor, Serotonin, 5-HT1A / Q000502:physiology*; D020127:Recovery of Function / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013119:Spinal Cord Injuries / Q000188:drug therapy / Q000503:physiopathology*; D013997:Time Factors; D014743:Videotape Recording
D017366:Serotonin Receptor Agonists; D044282:Receptor, Serotonin, 5-HT1A; D012701:Serotonin; D011814:Quipazine; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin