Neurotrophic factors and target-specific retrograde signaling interactions define the specificity of classical and neuropeptide cotransmitter release at identified Lymnaea synapses

• Published in: Scientific reports 2020-08, Vol.10 (1), p.13526-13526, Article 13526
• Main Authors: Getz, Angela M., Janes, Tara A., Visser, Frank, Zaidi, Wali, Syed, Naweed I.
• Format: Article
• Language: English
• Subjects: 631/378/1686; 631/378/548; 631/378/87; 631/443/376; Acetylcholine; Animals; Arachidonic acid; Cells, Cultured; FMRFamide; Glycogen; Glycogen synthase kinase 3; Heterogeneity; Humanities and Social Sciences; Lymnaea; Lymnaea - genetics; Lymnaea - metabolism; Molecular modelling; multidisciplinary; Nerve Growth Factors - genetics; Nerve Growth Factors - metabolism; Neuromodulation; Neurons - metabolism; Neuropeptides; Neuropeptides - metabolism; Neurotransmitter Agents - metabolism; Neurotransmitter release; Neurotrophic factors; Peptides; Plasticity; Presynaptic plasticity; Presynaptic Terminals - physiology; Receptors, Nicotinic - metabolism; Retrograde transport; Science; Science (multidisciplinary); Synapses - physiology; Synaptic plasticity; Synaptic Transmission; Synaptophysin
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-70322-5

Many neurons concurrently and/or differentially release multiple neurotransmitter substances to selectively modulate the activity of distinct postsynaptic targets within a network. However, the molecular mechanisms that produce synaptic heterogeneity by regulating the cotransmitter release characteristics of individual presynaptic terminals remain poorly defined. In particular, we know little about the regulation of neuropeptide corelease, despite the fact that they mediate synaptic transmission, plasticity and neuromodulation. Here, we report that an identified Lymnaea neuron selectively releases its classical small molecule and peptide neurotransmitters, acetylcholine and FMRFamide-derived neuropeptides, to differentially influence the activity of distinct postsynaptic targets that coordinate cardiorespiratory behaviour. Using a combination of electrophysiological, molecular, and pharmacological approaches, we found that neuropeptide cotransmitter release was regulated by cross-talk between extrinsic neurotrophic factor signaling and target-specific retrograde arachidonic acid signaling, which converged on modulation of glycogen synthase kinase 3. In this context, we identified a novel role for the Lymnaea synaptophysin homologue as a specific and synapse-delimited inhibitory regulator of peptide neurotransmitter release. This study is among the first to define the cellular and molecular mechanisms underlying the differential release of cotransmitter substances from individual presynaptic terminals, which allow for context-dependent tuning and plasticity of the synaptic networks underlying patterned motor behaviour.