| Popis: |
Neurobiologie des Signaux Intercellulaires, Centre National de la Recherche ScientifiqueUMR 7101, Universite´ Pierre et Marie Curie, 75252 Paris Cedex 05, FranceABSTRACTThe5-HT5Areceptorisaseven-transmembranereceptornegativelycoupledtoadenylatecyclase, whose activation opens K channels. The 5-HT5A receptor may thus exert aninhibitory effect on neuronal activity. However, the function of this receptor is still largelyunknown, in particular at the spinal level, and this is partly due to lack of specific ligands.Immunocytochemistry using specific anti-5-HT5A antibodies reveals a particularly denselabeling in the two superficial layers of the dorsal horn, suggesting that the 5-HT5A receptormay be involved in the spinal modulation of pain. In addition, a very intense staining in thelumbar dorsolateral nucleus (Onuf nucleus) in both males and females suggests that the5-HT5A receptor is also involved in micturition through the control of urethral sphinctermuscles. Colchicine pretreatment allows the staining of numerous cell bodies in lamina II.Fewer labeled cell bodies are seen in laminae I and III–VI, in the lateral spinal nucleus, andinlaminaX.Electronmicroscopeexaminationof5-HT5Areceptorimmunoreactivityinspinalcords from untreated animals confirmed the postsynaptic labeling in all regions studied(dorsal horn, dorsolateral nucleus, and lamina X). The morphological heterogeneity of labeleddorsal horn cell bodies suggests that they belong to functionally distinct neurons (projectionneurons and interneurons). In the lumbar dorsolateral nucleus, the labeling is preferentiallylocalized on dendrites, suggesting that in this nucleus 5-HT preferentially acts at thedendritic level. Finally, the dense labeling of postsynaptic specializations suggests that thereceptor may be in stock before being addressed to the synaptic differentiation. J. Comp.Neurol. 476:316–329, 2004. |
Plný text