Study of 5-HT release with a chronically implanted microdialysis probe in the ventral horn of the spinal cord of unrestrained rats during exercise on a treadmill.
The ventral horn of the spinal cord is profusely innervated by serotonin (5-hydroxytryptamine, 5-HT) which presumably modulates locomotor activity through motoneurons. However, direct evidence of correlation between 5-HT release and activation of motoneurons is still lacking. In order to appreciate the functional characteristics of this innervation, we have used microdialysis to monitor the release of 5-HT in the spinal cord of rats spontaneously running on a treadmill. For this purpose, we developed an original surgical procedure adapted for the chronic implantation of a microdialysis probe in the lumbar spinal cord. The probe was kept in place for 40 days, and microdialysis experiments were carried out at days 8, 16, 20 and 32. 5-HT was detected with HPLC coupled to electrochemistry. This technique demonstrated that release of 5-HT is not increased during exercise. However, a significant decrease was measured during postexercise rest. 5-HT could still be detected 32 days after probe implantation. Detailed histological and immunocytochemical analysis based on glial fibrillary acidic protein and 5-HT immunocytochemistry showed minimal gliosis and the presence of serotonergic varicose fibers, respectively, at the probe contact. It thus appears that microdialysis can be performed through a probe implanted chronically in the spinal cord of unrestrained rat during an endurance running exercise.
DPVSN, INSERM U-336, Montpellier, France.
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Gerin
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Legrand
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Privat
D000818:Animals; D000870:Anterior Horn Cells / Q000378:metabolism*; D008161:Lumbosacral Region; D008297:Male; D017551:Microdialysis / Q000295:instrumentation; D009043:Motor Activity / Q000502:physiology*; D009994:Osmolar Concentration; D019736:Prostheses and Implants; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism* / Q000473:pathology; D013997:Time Factors
D012701:Serotonin