Tactile mechanisms and afferents underlying the rat pup transport response.

Juvenile rodents and other altricial mammals react with calming, immobility, and postural modifications to parental pickup, a set of behaviors referred to as the transport response. Here, we investigate sensory mechanisms underlying the rat transport response. Grasping rat pups in anterior neck positions evokes strong immobility and folding up of feet, whereas more posterior grasping has lesser effects on immobility and foot position.

Drug-induced change in transmitter identity is a shared mechanism generating cognitive deficits.

Cognitive deficits are long-lasting consequences of drug use, yet the convergent mechanism by which classes of drugs with different pharmacological properties cause similar deficits is unclear. We find that both phencyclidine and methamphetamine, despite differing in their targets in the brain, cause the same glutamatergic neurons in the medial prefrontal cortex of male mice to gain a GABAergic phenotype and decrease expression of their glutamatergic phenotype. Suppressing drug-induced gain of GABA with RNA-interference prevents appearance of memory deficits.

Tactile Mechanisms and Afferents Underlying the Rat Pup Transport Response.

Juvenile rodents and other altricial mammals react with calming, immobility and folding up of feet to parental pickup, a set of behaviors referred to as transport response. Here we investigate sensory mechanisms underlying the rat transport response. Grasping rat pups in anterior neck positions evokes strong immobility and folding up of feet, whereas more posterior grasping positions have lesser effects on immobility and foot position.

Postsynaptic receptors regulate presynaptic transmitter stability through transsynaptic bridges.

Stable matching of neurotransmitters with their receptors is fundamental to synapse function and reliable communication in neural circuits. Presynaptic neurotransmitters regulate the stabilization of postsynaptic transmitter receptors. Whether postsynaptic receptors regulate stabilization of presynaptic transmitters has received less attention.

Generalized fear after acute stress is caused by change in neuronal cotransmitter identity.

Overgeneralization of fear to harmless situations is a core feature of anxiety disorders resulting from acute stress, yet the mechanisms by which fear becomes generalized are poorly understood. In this study, we show that generalized fear in mice results from a transmitter switch from glutamate to γ-aminobutyric acid (GABA) in serotonergic neurons of the lateral wings of the dorsal raphe. Similar change in transmitter identity was found in the postmortem brains of individuals with posttraumatic stress disorder (PTSD).

Bioelectronic Medicine: a multidisciplinary roadmap from biophysics to precision therapies.

Bioelectronic Medicine stands as an emerging field that rapidly evolves and offers distinctive clinical benefits, alongside unique challenges. It consists of the modulation of the nervous system by precise delivery of electrical current for the treatment of clinical conditions, such as post-stroke movement recovery or drug-resistant disorders. The unquestionable clinical impact of Bioelectronic Medicine is underscored by the successful translation to humans in the last decades, and the long list of preclinical studies.

Drug-induced change in transmitter identity is a shared mechanism generating cognitive deficits.

Cognitive deficits are a long-lasting consequence of drug use, yet the convergent mechanism by which classes of drugs with different pharmacological properties cause similar deficits is unclear. We find that both phencyclidine and methamphetamine, despite differing in their targets in the brain, cause the same glutamatergic neurons in the medial prefrontal cortex to gain a GABAergic phenotype and decrease their expression of the vesicular glutamate transporter. Suppressing the drug-induced gain of GABA with RNA-interference prevents the appearance of memory deficits.

Viral vector-mediated transgene delivery with novel recombinase systems for targeting neuronal populations defined by multiple features.

A comprehensive understanding of neuronal diversity and connectivity is essential for understanding the anatomical and cellular mechanisms that underlie functional contributions. With the advent of single-cell analysis, growing information regarding molecular profiles leads to the identification of more heterogeneous cell types. Therefore, the need for additional orthogonal recombinase systems is increasingly apparent, as heterogeneous tissues can be further partitioned into increasing numbers of specific cell types defined by multiple features.

Generalized fear following acute stress is caused by change in co-transmitter identity of serotonergic neurons.

Overgeneralization of fear to harmless situations is a core feature of anxiety disorders resulting from acute stress, yet the mechanisms by which fear becomes generalized are poorly understood. Here we show that generalized fear in mice in response to footshock results from a transmitter switch from glutamate to GABA in serotonergic neurons of the lateral wings of the dorsal raphe. We observe a similar change in transmitter identity in the postmortem brains of PTSD patients.

Decoding Neurotransmitter Switching: The Road Forward.

Neurotransmitter switching is a form of brain plasticity in which an environmental stimulus causes neurons to replace one neurotransmitter with another, often resulting in changes in behavior. This raises the possibility of applying a specific environmental stimulus to induce a switch that can enhance a desirable behavior or ameliorate symptoms of a specific pathology. For example, a stimulus inducing an increase in the number of neurons expressing dopamine could treat Parkinson's disease, or one affecting the number expressing serotonin could alleviate depression.

Fluoxetine Induces Morphological Rearrangements of Serotonergic Fibers in the Hippocampus.

Serotonin (5-HT)-releasing fibers show substantial structural plasticity in response to genetically induced changes in 5-HT content. However, whether 5-HT fibers appear malleable also following clinically relevant variations in 5-HT levels that may occur throughout an individual's life has not been investigated. Here, using confocal imaging and 3D modeling analysis in knock-in mice, we show that chronic administration of the antidepressant fluoxetine dramatically affects the morphology of 5-HT fibers innervating the dorsal and ventral hippocampus resulting in a reduced density of fibers.

Serotonergic neurotransmission manipulation for the understanding of brain development and function: Learning from Tph2 genetic models.

Serotonin (5-hydroxytriptamine; 5-HT) is a fascinating neurotransmitter that thanks to an extensive axonal network is released throughout the entire central nervous system (CNS) and exerts its action on the modulation of a countless number of physiological, behavioral and cognitive processes. In addition, cumulating evidences have linked alteration in 5-HT neurotransmission with the onset of psychiatric and neurodevelopmental disorders, such as depression, autisms and schizophrenia. Nevertheless only 5% of the total body content of serotonin exerts its action in the CNS, while the rest is synthetized and stored in peripheral tissues where it acts as an autacoid.

Development of Serotonergic Fibers in the Post-Natal Mouse Brain.

Serotonin (5-HT)-synthetizing neurons, which are confined in the nuclei of the rhombencephalon, provide a pervasive innervation of the central nervous system (CNS) and are involved in the modulation of a plethora of functions in both developing and adult brain. Classical studies have described the post-natal development of serotonergic axons as a linear process of terminal field innervation. However, technical limitations have hampered a fine morphological characterization.

Perturbation of Serotonin Homeostasis during Adulthood Affects Serotonergic Neuronal Circuitry.

Growing evidence shows that the neurotransmitter serotonin (5-HT) modulates the fine-tuning of neuron development and the establishment of wiring patterns in the brain. However, whether serotonin is involved in the maintenance of neuronal circuitry in the adult brain remains elusive. Here, we use a conditional knockout (cKO) mouse line to assess the impact of serotonin depletion during adulthood on serotonergic system organization.

A Tph2 Reporter Stem Cell Line To Model in Vitro and in Vivo Serotonergic Neuron Development and Function.

Modeling biological systems in vitro has contributed to clarification of complex mechanisms in simplified and controlled experimental conditions. Mouse embryonic stem (mES) cells can be successfully differentiated toward specific neuronal cell fates, thus representing an attractive tool to dissect, in vitro, mechanisms that underlie complex neuronal features. In this study, we generated and characterized a reporter mES cell line, called Tph2, in which the vital reporter GFP replaces the tryptophan hydroxylase 2 (Tph2) gene.

Generation of a Tph2 Conditional Knockout Mouse Line for Time- and Tissue-Specific Depletion of Brain Serotonin.

Serotonin has been gaining increasing attention during the last two decades due to the dual function of this monoamine as key regulator during critical developmental events and as neurotransmitter. Importantly, unbalanced serotonergic levels during critical temporal phases might contribute to the onset of neuropsychiatric disorders, such as schizophrenia and autism. Despite increasing evidences from both animal models and human genetic studies have underpinned the importance of serotonin homeostasis maintenance during central nervous system development and adulthood, the precise role of this molecule in time-specific activities is only beginning to be elucidated.

Generation of Pet1210-Cre transgenic mouse line reveals non-serotonergic expression domains of Pet1 both in CNS and periphery.

Neurons producing serotonin (5-hydroxytryptamine, 5-HT) constitute one of the most widely distributed neuronal networks in the mammalian central nervous system (CNS) and exhibit a profuse innervation throughout the CNS already at early stages of development. Serotonergic neuron specification is controlled by a combination of secreted molecules and transcription factors such as Shh, Fgf4/8, Nkx2.2, Lmx1b and Pet1.