title: From the Golgi-Cajal mapping to the transmitter-based characterization of the neuronal networks leading to two modes of brain communication: wiring and volume transmission.
abstract: After Golgi-Cajal mapped neural circuits, the discovery and mapping of the central monoamine neurons opened up for a new understanding of interneuronal communication by indicating that another form of communication exists. For instance, it was found that dopamine may be released as a prolactin inhibitory factor from the median eminence, indicating an alternative mode of dopamine communication in the brain. Subsequently, the analysis of the locus coeruleus noradrenaline neurons demonstrated a novel type of lower brainstem neuron that monosynaptically and globally innervated the entire CNS. Furthermore, the ascending raphe serotonin neuron systems were found to globally innervate the forebrain with few synapses, and where deficits in serotonergic function appeared to play a major role in depression. We propose that serotonin reuptake inhibitors may produce antidepressant effects through increasing serotonergic neurotrophism in serotonin nerve cells and their targets by transactivation of receptor tyrosine kinases (RTK), involving direct or indirect receptor/RTK interactions. Early chemical neuroanatomical work on the monoamine neurons, involving primitive nervous systems and analysis of peptide neurons, indicated the existence of alternative modes of communication apart from synaptic transmission. In 1986, Agnati and Fuxe introduced the theory of two main types of intercellular communication in the brain: wiring and volume transmission (WT and VT). Synchronization of phasic activity in the monoamine cell clusters through electrotonic coupling and synaptic transmission (WT) enables optimal VT of monoamines in the target regions. Experimental work suggests an integration of WT and VT signals via receptor-receptor interactions, and a new theory of receptor-connexin interactions in electrical and mixed synapses is introduced. Consequently, a new model of brain function must be built, in which communication includes both WT and VT and receptor-receptor interactions in the integration of signals. This will lead to the unified execution of information handling and trophism for optimal brain function and survival.
authors: Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden. Kjell.Fuxe@ki.se
authors: Kjell
authors: K
authors: Fuxe
authors: Annica
authors: A
authors: Dahlström
authors: Malin
authors: M
authors: Höistad
authors: Daniel
authors: D
authors: Marcellino
authors: Anders
authors: A
authors: Jansson
authors: Alicia
authors: A
authors: Rivera
authors: Zaida
authors: Z
authors: Diaz-Cabiale
authors: Kirsten
authors: K
authors: Jacobsen
authors: Barbro
authors: B
authors: Tinner-Staines
authors: Beth
authors: B
authors: Hagman
authors: Giuseppina
authors: G
authors: Leo
authors: William
authors: W
authors: Staines
authors: Diego
authors: D
authors: Guidolin
authors: Jan
authors: J
authors: Kehr
authors: Susanna
authors: S
authors: Genedani
authors: Natale
authors: N
authors: Belluardo
authors: Luigi F
authors: LF
authors: Agnati
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D008959:Models, Neurological; D009415:Nerve Net / Q000502:physiology / Q000648:ultrastructure; D009474:Neurons / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D018377:Neurotransmitter Agents / Q000378:metabolism*; D016622:Silver Staining / Q000379:methods*; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D018377:Neurotransmitter Agents