The development of synaptic transmission is time-locked to early social behaviors in rats

• Published in: Nature communications 2019-03, Vol.10 (1), p.1195-1195, Article 1195
• Main Authors: Naskar, Shovan, Narducci, Roberto, Balzani, Edoardo, Cwetsch, Andrzej W., Tucci, Valter, Cancedda, Laura
• Format: Article
• Language: English
• Subjects: 42/109; 631/136/334/1874/486; 631/378; 631/378/2571; 631/378/340; 64/86; 9/74; Animals; Animals, Newborn; Behavior; Behavior, Animal - drug effects; Behavior, Animal - physiology; Brain; Citalopram - pharmacology; GABAergic Neurons - metabolism; Glutamatergic transmission; Glutamic Acid - metabolism; Huddling; Humanities and Social Sciences; Models, Animal; Motors; multidisciplinary; Neocortex; Neocortex - cytology; Neocortex - drug effects; Neocortex - growth & development; Neocortex - metabolism; Neurodevelopment; Neuromodulation; Neurotransmission; Patch-Clamp Techniques; Rats; Rats, Sprague-Dawley; Science; Science (multidisciplinary); Serotonin; Serotonin - metabolism; Serotonin Uptake Inhibitors - pharmacology; Social Behavior; Somatosensory Cortex - drug effects; Somatosensory Cortex - physiology; Synapses; Synapses - drug effects; Synapses - physiology; Synaptic transmission; Synaptic Transmission - drug effects; Synaptic Transmission - physiology; Synaptogenesis; Time Factors; γ-Aminobutyric acid
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-09156-3

The development of functional synapses is a sequential process preserved across many brain areas. Here, we show that glutamatergic postsynaptic currents anticipated GABAergic currents in Layer II/III of the rat neocortex, in contrast to the pattern described for other brain areas. The frequencies of both glutamatergic and GABAergic currents increased abruptly at the beginning of the second postnatal week, supported by a serotonin upsurge. Integrative behaviors arose on postnatal day (P)9, while most motor and sensory behaviors, which are fundamental for pup survival, were already in place at approximately P7. A reduction in serotonin reuptake accelerated the development of functional synapses and integrative huddling behavior, while sparing motor and sensory function development. A decrease in synaptic transmission in Layer II/III induced by a chemogenetic approach only inhibited huddling. Thus, precise developmental sequences mediate early, socially directed behaviors for which neurotransmission and its modulation in supragranular cortical layers play key roles. The development of functional synapses is a key milestone in neurodevelopment. Here, the authors show how serotonin signalling coordinates development of glutamatergic and GABAergic currents and triggers the emergence of integrative behavior (huddling) in rat pups.