Connexin mRNA expression in single dopaminergic neurons of substantia nigra pars compacta.
Dopaminergic neurons of the substantia nigra pars compacta play a major role in goal-directed behavior and reinforcement learning. The study of their local interactions has revealed that they are connected by electrical synapses. Connexins, the molecular substrate of electrical synapses, constitute a multigenic family of 20 proteins in rodents. The permeability and regulation properties of electrical synapses depend on their connexin composition. Therefore, the knowledge of the molecular composition of electrical synapses is fundamental to the understanding of their specific functions. We have investigated the connexin mRNA expression pattern of dopaminergic neurons by single-cell RT-PCR analysis, during two periods in which dopaminergic neurons are electrically coupled in vitro (P7-P10 and P17-P21). Our results show that dopaminergic neurons express mRNAs of various connexins (Cx26, Cx30, Cx31.1, Cx32, Cx36 and Cx43) in a developmentally regulated manner. Furthermore, we have observed that dopaminergic neurons display different connexin expression patterns, and that multiple connexins can be expressed in a single dopaminergic neuron. These observations underline the importance of electrical coupling in the development of dopaminergic neurons and raise the question of the existence of functionally distinct electrically coupled networks in the substantia nigra pars compacta.
Vandecasteele
Marie
M
Laboratoire de Dynamique et Physiopathologie des Réseaux Neuronaux, Inserm, U667, Collège de France, Univ Pierre et Marie Curie, 11 place Marcelin Berthelot, Paris, France.
Glowinski
Jacques
J
Venance
Laurent
L
D000818:Animals; D017630:Connexins / Q000096:biosynthesis*; D004298:Dopamine / Q000502:physiology*; D004594:Electrophysiology; D005260:Female; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D018613:Microscopy, Confocal; D009415:Nerve Net / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013378:Substantia Nigra / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D017630:Connexins; D012333:RNA, Messenger; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine