On the occurrence and enigmatic functions of mixed (chemical plus electrical) synapses in the mammalian CNS. (16th March 2019)

• Record Type: Journal Article
• Authors: Nagy, James I.; Pereda, Alberto E.; Rash, John E.
• Is Part Of: Neuroscience letters. Volume 695(2019)
• Page Start: 53
• Page End: 64
• Publication Date: 2019-03-16
• Subjects: Neuronal gap junctions -- Connexins -- Nerve terminals -- Dye coupling -- Electrical coupling; Neurology -- Periodicals; Neurology -- Periodicals; Research -- Periodicals; Neurologie -- Périodiques; Neuroanatomie -- Périodiques; Neuropharmacologie -- Périodiques; Neurophysiologie -- Périodiques; Neurology; Periodicals; Electronic journals; 617.48
• DOI: 10.1016/j.neulet.2017.09.021
• Languages: English
• ISSNs: 0304-3940

Abstract

Highlights: Gap junctions containing connexin36 occur at nerve terminals that form mixed synapses in the mammalian CNS. Mixed synapses are abundant in various brainstem and spinal cord regions of rat and mouse. So far, mixed synapses have been discovered only at excitatory / glutamatergic axon terminals. The possibility of electrical transmission at mixed synapses in mammalian brain warrents comprehensive electrophysiological investigation. Abstract: Electrical synapses with diverse configurations and functions occur at a variety of interneuronal appositions, thereby significantly expanding the physiological complexity of neuronal circuitry over that provided solely by chemical synapses. Gap junctions between apposed dendritic and somatic plasma membranes form "purely electrical" synapses that allow for electrical communication between coupled neurons. In addition, gap junctions at axon terminals synapsing on dendrites and somata allow for "mixed" (dual chemical + electrical) synaptic transmission. "Dual transmission" was first documented in the autonomic nervous system of birds, followed by its detection in the central nervous systems of fish, amphibia, and reptiles. Subsequently, mixed synapses have been detected in several locations in the mammalian CNS, where their properties and functional roles remain undetermined. Here, we review available evidence for the presence, complex structural composition, and emerging functional properties of mixed synapses in the mammalian CNS.