Hepatic noradrenergic innervation acts via CREB/CRTC2 to activate gluconeogenesis during cold.

BACKGROUND AND AIM: Although it is well established that hormones like glucagon stimulates gluconeogenesis via the PKA-mediated phosphorylation of CREB and dephosphorylation of the cAMP-regulated CREB coactivators CRTC2, the role of neural signals in the regulation of gluconeogenesis remains uncertain. METHODS AND RESULTS: Here, we characterize the noradrenergic bundle architecture in mouse liver; we show that the sympathoexcitation induced by acute cold exposure promotes hyperglycemia and upregulation of gluconeogenesis via triggering of the CREB/CRTC2 pathway. Following its induction by dephosphorylation, CRTC2 translocates to the nucleus and drives the transcription of key gluconeogenic genes. Rodents submitted to different models of sympathectomy or knockout of CRTC2 do not activate gluconeogenesis in response to cold. Norepinephrine directly acts in hepatocytes mainly through a Ca2+-dependent pathway that stimulates CREB/CRTC2, leading to activation of the gluconeogenic program. CONCLUSION: Our data demonstrate the importance of the CREB/CRTC2 pathway in mediating effects of hepatic sympathetic inputs on glucose homeostasis, providing new insights into the role of norepinephrine in health and disease.

Selective Enhancement of REM Sleep in Male Rats through Activation of Melatonin MT1 Receptors Located in the Locus Ceruleus Norepinephrine Neurons.

Sleep disorders affect millions of people around the world and have a high comorbidity with psychiatric disorders. While current hypnotics mostly increase non-rapid eye movement sleep (NREMS), drugs acting selectively on enhancing rapid eye movement sleep (REMS) are lacking. This polysomnographic study in male rats showed that the first-in-class selective melatonin MT1 receptor partial agonist UCM871 increases the duration of REMS without affecting that of NREMS. The REMS-promoting effects of UCM871 occurred by inhibiting, in a dose-response manner, the firing activity of the locus ceruleus (LC) norepinephrine (NE) neurons, which express MT1 receptors. The increase of REMS duration and the inhibition of LC-NE neuronal activity by UCM871 were abolished by MT1 pharmacological antagonism and by an adeno-associated viral (AAV) vector, which selectively knocked down MT1 receptors in the LC-NE neurons. In conclusion, MT1 receptor agonism inhibits LC-NE neurons and triggers REMS, thus representing a novel mechanism and target for REMS disorders and/or psychiatric disorders associated with REMS impairments.

A noradrenergic pathway for the induction of pain by sleep loss.

An epidemic of sleep loss currently affects modern societies worldwide and is implicated in numerous physiological disorders, including pain sensitization, although few studies have explored the brain pathways affected by active sleep deprivation (ASD; e.g., due to recreation). Here, we describe a neural circuit responsible for pain sensitization in mice treated with 9-h non-stress ASD. Using a combination of advanced neuroscience methods, we found that ASD stimulates noradrenergic inputs from locus coeruleus (LCNA) to glutamatergic neurons of the hindlimb primary somatosensory cortex (S1HLGlu). Moreover, artificial inhibition of this LCNA→S1HLGlu pathway alleviates ASD-induced pain sensitization in mice, while chemogenetic activation of this pathway recapitulates the pain sensitization observed following ASD. Our study thus implicates activation of the LCNA→S1HLGlu pathway in ASD-induced pain sensitization, expanding our fundamental understanding of the multisystem interplay involved in pain processing.

Inputs to the locus coeruleus from the periaqueductal gray and rostroventral medulla shape opioid-mediated descending pain modulation.

The supraspinal descending pain modulatory system (DPMS) shapes pain perception via monoaminergic modulation of sensory information in the spinal cord. However, the role and synaptic mechanisms of descending noradrenergic signaling remain unclear. Here, we establish that noradrenergic neurons of the locus coeruleus (LC) are essential for supraspinal opioid antinociception. While much previous work has emphasized the role of descending serotonergic pathways, we find that opioid antinociception is primarily driven by excitatory output from the ventrolateral periaqueductal gray (vlPAG) to the LC. Furthermore, we identify a previously unknown opioid-sensitive inhibitory input from the rostroventromedial medulla (RVM), the suppression of which disinhibits LC neurons to drive spinal noradrenergic antinociception. We describe pain-related activity throughout this circuit and report the presence of prominent bifurcating outputs from the vlPAG to the LC and the RVM. Our findings substantially revise current models of the DPMS and establish a supraspinal antinociceptive pathway that may contribute to multiple forms of descending pain modulation.

Sex-dimorphic hindbrain lactate regulation of ventromedial hypothalamic nucleus glucoregulatory neuron 5'-AMP-activated protein kinase activity and transmitter marker protein expression.

BACKGROUND: The oxidizable glycolytic end-product L-lactate is a gauge of nerve cell metabolic fuel stability that metabolic-sensory hindbrain A2 noradrenergic neurons impart to the brain glucose-regulatory network. Current research investigated the premise that hindbrain lactate deficiency exerts sex-specific control of energy sensor and transmitter marker protein responses to hypoglycemia in ventromedial hypothalamic nucleus (VMN) glucose-regulatory nitrergic and γ-aminobutyric acid (GABA) neurons. METHODS: Nitric oxide synthase (nNOS)- or glutamate decarboxylase65/67 (GAD)-immunoreactive neurons were laser-catapult-microdissected from male and female rat VMN after subcutaneous insulin injection and caudal fourth ventricular L-lactate or vehicle infusion for Western blot protein analysis. RESULTS: Hindbrain lactate repletion reversed hypoglycemia-associated augmentation (males) or inhibition (females) of nitrergic neuron nNOS expression, and prevented up-regulation of phosphorylated AMPK 5'-AMP-activated protein kinase (pAMPK) expression in those neurons. Hypoglycemic suppression of GABAergic neuron GAD protein was averted by exogenous lactate over the rostro-caudal length of the male VMN and in the middle region of the female VMN. Lactate normalized GABA neuron pAMPK profiles in hypoglycemic male (caudal VMN) and female (all VMN segments) rats. Hypoglycemic patterns of norepinephrine (NE) signaling were lactate-dependent throughout the male VMN, but confined to the rostral and middle female VMN. CONCLUSIONS: Results document, in each sex, regional VMN glucose-regulatory transmitter responses to hypoglycemia that are controlled by hindbrain lactate status. Hindbrain metabolic-sensory regulation of hypoglycemia-correlated nitric oxide or GABA release may entail AMPK-dependent mechanisms in specific VMN rostro-caudal segments in each sex. Additional effort is required to examine the role of hindbrain lactoprivic-sensitive VMN neurotransmitters in lactate-mediated attenuation of hypoglycemic hyperglucagonemia and hypercorticosteronemia in male and female rats.

Carbachol increases locus coeruleus activation by targeting noradrenergic neurons, inhibitory interneurons and inhibitory synaptic transmission.

The locus coeruleus (LC) consists of noradrenergic (NA) neurons and plays an important role in controlling behaviours. Although much of the knowledge regarding LC functions comes from studying behavioural outcomes upon administration of muscarinic acetylcholine receptor (mAChR) agonists into the nucleus, the exact mechanisms remain unclear. Here, we report that the application of carbachol (CCh), an mAChR agonist, increased the spontaneous action potentials (sAPs) of both LC-NA neurons and local inhibitory interneurons (LC I-INs) in acute brain slices by activating M1/M3 mAChRs (m1/3 AChRs). Optogenetic activation of LC I-INs evoked inhibitory postsynaptic currents (IPSCs) in LC-NA neurons that were mediated by γ-aminobutyric acid type A (GABAA ) and glycine receptors, and CCh application decreased the IPSC amplitude through a presynaptic mechanism by activating M4 mAChRs (m4 AChRs). LC-NA neurons also exhibited spontaneous phasic-like activity (sPLA); CCh application increased the incidence of this activity. This effect of CCh application was not observed with blockade of GABAA and glycine receptors, suggesting that the sPLA enhancement occurred likely because of the decreased synaptic transmission of LC I-INs onto LC-NA neurons by the m4 AChR activation and/or increased spiking rate of LC I-INs by the m1/3 AChR activation, which could lead to fatigue of the synaptic transmission. In conclusion, we report that CCh application, while inhibiting their synaptic transmission, increases sAP rates of LC-NA neurons and LC I-INs. Collectively, these effects provide insight into the cellular mechanisms underlying the behaviour modulations following the administration of muscarinic receptor agonists into the LC reported by the previous studies.

Brainstem noradrenergic neurons: Identifying a hub at the intersection of cognition, motility, and skeletal muscle regulation.

Brainstem noradrenergic neuron clusters form a node integrating efferents projecting to distinct areas such as those regulating cognition and skeletal muscle structure and function, and receive dissimilar afferents through established circuits to coordinate organismal responses to internal and environmental challenges. Genetic lineage tracing shows the remarkable heterogeneity of brainstem noradrenergic neurons, which may explain their varied functions. They project to the locus coeruleus, the primary source of noradrenaline in the brain, which supports learning and cognition. They also project to pre-ganglionic neurons, which lie within the spinal cord and form synapses onto post-ganglionic neurons. The synapse between descending brainstem noradrenergic neurons and pre-ganglionic spinal neurons, and these in turn with post-ganglionic noradrenergic neurons located at the paravertebral sympathetic ganglia, support an anatomical hierarchy that regulates skeletal muscle innervation, neuromuscular transmission, and muscle trophism. Whether any noradrenergic neuron subpopulation is more susceptible to damaged protein deposit and death with ageing and neurodegeneration is a relevant question that answer will help us to detect neurodegeneration at an early stage, establish prognosis, and anticipate disease progression. Loss of muscle mass and strength with ageing, termed sarcopenia, may predict impaired cognition with ageing and neurodegeneration and establish an early time to start interventions aimed at reducing central noradrenergic neurons hyperactivity. Complex multidisciplinary approaches, including genetic tracing, specific circuit labelling, optogenetics and chemogenetics, electrophysiology, and single-cell transcriptomics and proteomics, are required to test this hypothesis pre-clinical.

Activation of locus coeruleus-spinal cord noradrenergic neurons alleviates neuropathic pain in mice via reducing neuroinflammation from astrocytes and microglia in spinal dorsal horn.

BACKGROUND: The noradrenergic neurons of locus coeruleus (LC) project to the spinal dorsal horn (SDH), and release norepinephrine (NE) to inhibit pain transmission. However, its effect on pathological pain and the cellular mechanism in the SDH remains unclear. This study aimed to explore the analgesic effects and the anti-neuroinflammation mechanism of LC-spinal cord noradrenergic pathway (LC:SC) in neuropathic pain (NP) mice with sciatic chronic constriction injury. METHODS: The Designer Receptors Exclusively Activated by Designer Drugs (DREADD) was used to selectively activate LC:SC. Noradrenergic neuron-specific retro-adeno-associated virus was injected to the spinal cord. Pain threshold, LC and wide dynamic range (WDR) neuron firing, neuroinflammation (microglia and astrocyte activation, cytokine expression), and α2AR expression in SDH were evaluated. RESULTS: Activation of LC:SC with DREADD increased the mechanical and thermal nociceptive thresholds and reduced the WDR neuron firing. LC:SC activation (daily, 7 days) downregulated TNF-α and IL-1ß expression, upregulated IL-4 and IL-10 expression in SDH, and inhibited microglia and astrocytes activation in NP mice. Immunofluorescence double staining confirmed that LC:SC activation decreased the expression of cytokines in microglia of the SDH. In addition, the effects of LC:SC activation could be reversed by intrathecal injection of yohimbine. Immunofluorescence of SDH showed that NE receptor α2B-AR was highly expressed in microglia in CCI mice. CONCLUSION: These findings indicate that selective activation of LC:SC alleviates NP in mice by increasing the release of NE and reducing neuroinflammation of astrocytes and microglia in SDH.

Hindbrain lactate regulation of hypoglycemia-associated patterns of catecholamine and metabolic-sensory biomarker gene expression in A2 noradrenergic neurons innervating the male versus female ventromedial hypothalamic nucleus.

Caudal hindbrain A2 noradrenergic neurons provide critical metabolic-sensory input to the brain glucostatic circuitry. In males, insulin-induced hypoglycemia (IIH)-associated patterns of A2 cell dopamine-beta-hydroxylase (DßH) protein expression reflect diminution of the oxidizable fuel L-lactate, yet DßH exhibits sex-dimorphic responses to IIH. Here, retrograde tracing and combinatory single-cell laser-microdissection/multiplex qPCR techniques were used to examine whether lactate imposes sex-specific control of hypoglycemia-associated metabolic-sensory function and noradrenergic neurotransmission in A2 neurons that innervate the ventromedial hypothalamic nucleus (VMN), a key glucose-regulatory structure. VMN-projecting A2 neurons from each sex were characterized by presence or absence of nuclear glucokinase regulatory protein (nGKRP) immunoreactivity (-ir). IIH caused lactate-reversible up- or down-regulation of DßH mRNA in male and female nGKRP-ir-positive A2 neurons, respectively, and stimulated glucokinase (GCK) and sulfonylurea receptor-1 (SUR-1) gene expression in these cells in each sex. Hypoglycemia did not alter DßH, GCK, and SUR-1 transcript profiles in nGKRP-ir-negative male or female A2 neurons innervating the VMN. Estrogen receptor (ER) gene profiles in nGKRP-ir-positive neurons showed sex-specific [ER-alpha; G-protein-coupled estrogen-receptor-1 (GPER)] or sex-monomorphic (ER-beta) transcriptional responses to IIH. Fewer ER gene profiles were affected by IIH in nGKRP-ir-negative A2 neurons from male or female rats. Results show that during IIH, VMN-projecting A2 neurons may deliver altered, sex-dependent (nGKRP-positive) or unaffected (nGKRP-negative) noradrenergic input to the VMN. In each sex, metabolic-sensory gene profiles were reactive to hypoglycemia in nGKRP-ir-positive, not -negative A2 cells. Further studies are needed to elucidate the role of GKRP in transduction of metabolic imbalance into noradrenergic signaling, and to determine if input by one or more ER variants establishes sex differences in DßH transcriptional sensitivity to IIH.

A5 noradrenergic-projecting C1 neurons activate sympathetic and breathing outputs in anaesthetized rats.

NEW FINDINGS: What is the central question of this study? C1 neurons innervate pontine noradrenergic cell groups, including the A5 region: do A5 noradrenergic neurons contribute to the activation of sympathetic and respiratory responses produced by selective activation of the C1 group of neurons. What is the main finding and its importance? The increase in sympathetic and respiratory activities elicited by selective stimulation of C1 neurons is reduced after blockade of excitatory amino acid within the A5 region, suggesting that the C1-A5 pathway might be important for sympathetic-respiratory control. ABSTRACT: Adrenergic C1 neurons innervate and excite pontine noradrenergic cell groups, including the ventrolateral pontine noradrenergic region (A5). Here, we tested the hypothesis that C1 activates A5 neurons through the release of glutamate and this effect is important for sympathetic and respiratory control. Using selective tools, we restricted the expression of channelrhodopsin2 under the control of the artificial promoter PRSx8 to C1 neurons (69%). Transduced catecholaminergic terminals within the A5 region are in contact with noradrenergic A5 neurons and the C1 terminals within the A5 region are predominantly glutamatergic. In a different group of animals, we performed retrograde lesion of C1 adrenergic neurons projecting to the A5 region with unilateral injection of the immunotoxin anti-dopamine ß-hydroxylase-saporin (anti-DßH-SAP) directly into the A5 region during the hypoxic condition. As expected, hypoxia (8% O2 , 3 h) induced a robust increase in fos expression within the catecholaminergic C1 and A5 regions of the brainstem. Depletion of C1 cells projecting to the A5 regions reduced fos immunoreactivity induced by hypoxia within the C1 region. Physiological experiments showed that bilateral injection of kynurenic acid (100 mM) into the A5 region reduced the rise in mean arterial pressure, and sympathetic and phrenic nerve activities produced by optogenetic stimulation of C1 cells. In conclusion, the C1 neurons activate the ventrolateral pontine noradrenergic neurons (A5 region) possibly via the release of glutamate and might be important for sympathetic and respiratory outputs in anaesthetized rats.

The Influence of an Adrenergic Antagonist Guanethidine (GUA) on the Distribution Pattern and Chemical Coding of Dorsal Root Ganglia (DRG) Neurons Supplying the Porcine Urinary Bladder.

Although guanethidine (GUA) was used in the past as a drug to suppress hyperactivity of the sympathetic nerve fibers, there are no available data concerning the possible action of this substance on the sensory component of the peripheral nervous system supplying the urinary bladder. Thus, the present study was aimed at disclosing the influence of intravesically instilled GUA on the distribution, relative frequency, and chemical coding of dorsal root ganglion neurons associated with the porcine urinary bladder. The investigated sensory neurons were visualized with a retrograde tracing method using Fast Blue (FB), while their chemical profile was disclosed with single-labeling immunohistochemistry using antibodies against substance P (SP), calcitonin gene-related peptide (CGRP), pituitary adenylate cyclase activating polypeptide (PACAP), galanin (GAL), neuronal nitric oxide synthase (nNOS), somatostatin (SOM), and calbindin (CB). After GUA treatment, a slight decrease in the number of FB+ neurons containing SP was observed when compared with untreated animals (34.6 ± 6.5% vs. 45.6 ± 1.3%), while the number of retrogradely traced cells immunolabeled for GAL, nNOS, and CB distinctly increased (12.3 ± 1.0% vs. 7.4 ± 0.6%, 11.9 ± 0.6% vs. 5.4 ± 0.5% and 8.6 ± 0.5% vs. 2.7 ± 0.4%, respectively). However, administration of GUA did not change the number of FB+ neurons containing CGRP, PACAP, or SOM. The present study provides evidence that GUA significantly modifies the sensory innervation of the porcine urinary bladder wall and thus may be considered a potential tool for studying the plasticity of this subdivision of the bladder innervation.

The Role of the Noradrenergic System in Eating Disorders: A Systematic Review.

Noradrenaline (NE) is a catecholamine acting as both a neurotransmitter and a hormone, with relevant effects in modulating feeding behavior and satiety. Several studies have assessed the relationship between the noradrenergic system and Eating Disorders (EDs). This systematic review aims to report the existing literature on the role of the noradrenergic system in the development and treatment of EDs. A total of 35 studies were included. Preclinical studies demonstrated an involvement of the noradrenergic pathways in binge-like behaviors. Genetic studies on polymorphisms in genes coding for NE transporters and regulating enzymes have shown conflicting evidence. Clinical studies have reported non-unanimous evidence for the existence of absolute alterations in plasma NE values in patients with Anorexia Nervosa (AN) and Bulimia Nervosa (BN). Pharmacological studies have documented the efficacy of noradrenaline-modulating therapies in the treatment of BN and Binge Eating Disorder (BED). Insufficient evidence was found concerning the noradrenergic-mediated genetics of BED and BN, and psychopharmacological treatments targeting the noradrenergic system in AN. According to these data, further studies are required to expand the existing knowledge on the noradrenergic system as a potential target for treatments of EDs.

Neural dynamics underlying birdsong practice and performance.

Musical and athletic skills are learned and maintained through intensive practice to enable precise and reliable performance for an audience. Consequently, understanding such complex behaviours requires insight into how the brain functions during both practice and performance. Male zebra finches learn to produce courtship songs that are more varied when alone and more stereotyped in the presence of females1. These differences are thought to reflect song practice and performance, respectively2,3, providing a useful system in which to explore how neurons encode and regulate motor variability in these two states. Here we show that calcium signals in ensembles of spiny neurons (SNs) in the basal ganglia are highly variable relative to their cortical afferents during song practice. By contrast, SN calcium signals are strongly suppressed during female-directed performance, and optogenetically suppressing SNs during practice strongly reduces vocal variability. Unsupervised learning methods4,5 show that specific SN activity patterns map onto distinct song practice variants. Finally, we establish that noradrenergic signalling reduces vocal variability by directly suppressing SN activity. Thus, SN ensembles encode and drive vocal exploration during practice, and the noradrenergic suppression of SN activity promotes stereotyped and precise song performance for an audience.

Noradrenaline modulates neuronal and perceptual visual detectability via ß-adrenergic receptor.

RATIONALE: Noradrenaline (NA) is a neuromodulator secreted from noradrenergic neurons in the locus coeruleus to the whole brain depending on the physiological state and behavioral context. It regulates various brain functions including vision via three major adrenergic receptor (AR) subtypes. Previous studies investigating the noradrenergic modulations on vision reported different effects, including improvement and impairment of perceptual visual sensitivity in rodents via ß-AR, an AR subtype. Therefore, it remains unknown how NA affects perceptual visual sensitivity via ß-AR and what neuronal mechanisms underlie it. OBJECTIVES: The current study investigated the noradrenergic modulation of perceptual and neuronal visual sensitivity via ß-AR in the primary visual cortex (V1). METHODS: We performed extracellular multi-point recordings from V1 of rats performing a go/no-go visual detection task under the head-fixed condition. A ß-AR blocker, propranolol (10 mM), was topically administered onto the V1 surface, and the drug effect on behavioral and neuronal activities was quantified by comparing pre-and post-drug administration. RESULTS: The topical administration of propranolol onto the V1 surface significantly improved the task performance. An analysis of the multi-unit activity in V1 showed that propranolol significantly suppressed spontaneous activity and facilitated the visual response of the recording sites in V1. We further calculated the signal-to-noise ratio (SNR), finding that the SNR was significantly improved after propranolol administration. CONCLUSIONS: Pharmacological blockade of ß-AR in V1 improves perceptual visual detectability by modifying the SNR of neuronal activity.

The influence of castration on intramural neurons of the urinary bladder trigone in male pigs.

The present study investigated the influence of castration performed at neonatal age on neuronal elements in the intramural ganglia of the urinary bladder trigone (UBT) in male pigs using double-labeling immunohistochemistry. The ganglia were examined in intact (IP) 7-day-old (castration day) pigs, and at 3 and 6 months after surgery. In IP and control (3- and 6-month-old noncastrated pigs) groups, virtually, all neurons were adrenergic (68%) or cholinergic (32%) in nature. Many of them (32%, 51%, and 81%, respectively; 56%, 75%, and 85% adrenergic; and 32%, 52%, and 65% cholinergic, respectively) stained for the androgen receptor (AR), and only a small number of nerve cells were caspase-3 (CASP-3)-positive. In 3- and 6-month-old castrated pigs, an excessive loss (87.6% and 87.5%, respectively) of neurons and intraganglionic nerve fibers was observed. The majority of the surviving adrenergic (61% and 72%, respectively) and many cholinergic (41% and 31%, respectively) neurons expressed CASP-3 and were also AR-positive (61% and 66%, and 40% and 36%, respectively). This study revealed for the first time the excessive loss of intramural UBT neurons following castration, which could have resulted from apoptosis induced by androgen deprivation.

Restoration of Noradrenergic Function in Parkinson's Disease Model Mice.

Dysfunction of the central noradrenergic and dopaminergic systems is the primary neurobiological characteristic of Parkinson's disease (PD). Importantly, neuronal loss in the locus coeruleus (LC) that occurs in early stages of PD may accelerate progressive loss of dopaminergic neurons. Therefore, restoring the activity and function of the deficient noradrenergic system may be an important therapeutic strategy for early PD. In the present study, the lentiviral constructions of transcription factors Phox2a/2b, Hand2 and Gata3, either alone or in combination, were microinjected into the LC region of the PD model VMAT2 Lo mice at 12 and 18 month age. Biochemical analysis showed that microinjection of lentiviral expression cassettes into the LC significantly increased mRNA levels of Phox2a, and Phox2b, which were accompanied by parallel increases of mRNA and proteins of dopamine ß-hydroxylase (DBH) and tyrosine hydroxylase (TH) in the LC. Furthermore, there was considerable enhancement of DBH protein levels in the frontal cortex and hippocampus, as well as enhanced TH protein levels in the striatum and substantia nigra. Moreover, these manipulations profoundly increased norepinephrine and dopamine concentrations in the striatum, which was followed by a remarkable improvement of the spatial memory and locomotor behavior. These results reveal that over-expression of these transcription factors in the LC improves noradrenergic and dopaminergic activities and functions in this rodent model of PD. It provides the necessary groundwork for the development of gene therapies of PD, and expands our understanding of the link between the LC-norepinephrine and dopamine systems during the progression of PD.

Post-traumatic stress disorder increases pain sensitivity by reducing descending noradrenergic and serotoninergic modulation.

Exposure to stress might influence pain sensitivity; however, little is known about whether post-traumatic stress disorder (PTSD)-like symptoms alter pain sensitivity and how it can happen. Male rats were exposed to the inescapable footshock paired with either social isolation or a control condition (not exposed to footshock but subjected to social isolation). After 7, 14, or 21 days, memory retention was evaluated. In the following three days, animals underwent the following tests: open-field, social interaction and formalin tests. Another group of animals were subjected to the object recognition test and to von Frey filaments. In other cohorts of animals, saline, fluoxetine, or desipramine were injected intrathecally and immunohistochemistry was performed to investigate whether PTSD-like symptoms alter the expression of c-Fos in serotonergic and noradrenergic neurons. Inescapable footshock induced the development of PTSD-like symptoms. Animals with PTSD-like symptoms showed an increase in the number of flinches in the formalin test and a reduction in mechanical threshold in the von Frey test at both retention intervals. The social interaction was negatively correlated with the nociceptive response in the formalin test. Fluoxetine or desipramine prevented the nociceptive response to chemical stimulus in the formalin test. In addition, in animals with PTSD-like symptoms, there was a reduction in c-Fos expression in serotonergic and noradrenergic neurons. Our results are important for the association of increased sensitivity to pain as one of the clinical manifestations that are present in the development of PTSD, and a possible treatment for increased pain sensitivity in male individuals with PTSD.

A5 noradrenergic neurons and breathing control in neonate rats.

The pontine A5 noradrenergic group contributes to the maturation of the respiratory system before birth in rats. These neurons are connected to the neural network responsible for respiratory rhythmogenesis. In the present study, we investigated the participation of A5 noradrenergic neurons in neonates (P7-8 and P14-15) in the control of ventilation during hypoxia and hypercapnia in in vivo experiments using conjugated saporin anti-dopamine beta-hydroxylase (DßH-SAP) to specifically ablate noradrenergic neurons. Thus, DßH-SAP (420 ng/µL) or saporin (SAP, control) was injected into the A5 region of neonatal male Wistar rats. Hypoxia reduced respiratory variability in control animals; however, A5 lesion prevented this effect in P7-8 rats. Our data suggest that noradrenergic neurons of the A5 region in neonate rats do not participate in the control of ventilation under baseline and hypercapnic conditions, but exert an inhibitory modulation on breathing variability under hypoxic challenge in early life (P7-8).

Co-released norepinephrine and galanin act on different timescales to promote stress-induced anxiety-like behavior.

Both the noradrenergic and galaninergic systems have been implicated in stress-related neuropsychiatric disorders, and these two neuromodulators are co-released from the stress-responsive locus coeruleus (LC); however, the individual contributions of LC-derived norepinephrine (NE) and galanin to behavioral stress responses are unclear. Here we aimed to disentangle the functional roles of co-released NE and galanin in stress-induced behavior. We used foot shock, optogenetics, and behavioral pharmacology in wild-type (WT) mice and mice lacking either NE (Dbh-/-) or galanin (GalcKO-Dbh) specifically in noradrenergic neurons to isolate the roles of these co-transmitters in regulating anxiety-like behavior in the elevated zero maze (EZM) either immediately or 24 h following stress. Foot shock and optogenetic LC stimulation produced immediate anxiety-like behavior in WT mice, and the effects of foot shock persisted for 24 h. NE-deficient mice were resistant to the anxiogenic effects of acute stress and optogenetic LC stimulation, while mice lacking noradrenergic-derived galanin displayed typical increases in anxiety-like behavior. However, when tested 24 h after foot shock, both Dbh-/- and GalcKO-Dbh mice lacked normal expression of anxiety-like behavior. Pharmacological rescue of NE, but not galanin, in knockout mice during EZM testing was anxiogenic. In contrast, restoring galanin, but not NE, signaling during foot shock normalized stress-induced anxiety-like behavior 24 h later. These results indicate that NE and noradrenergic-derived galanin play complementary, but distinguishable roles in behavioral responses to stress. NE is required for the expression of acute stress-induced anxiety, while noradrenergic-derived galanin mediates the development of more persistent responses following a stressor.

Kalirin-RAC controls nucleokinetic migration in ADRN-type neuroblastoma.

The migrational propensity of neuroblastoma is affected by cell identity, but the mechanisms behind the divergence remain unknown. Using RNAi and time-lapse imaging, we show that ADRN-type NB cells exhibit RAC1- and kalirin-dependent nucleokinetic (NUC) migration that relies on several integral components of neuronal migration. Inhibition of NUC migration by RAC1 and kalirin-GEF1 inhibitors occurs without hampering cell proliferation and ADRN identity. Using three clinically relevant expression dichotomies, we reveal that most of up-regulated mRNAs in RAC1- and kalirin-GEF1-suppressed ADRN-type NB cells are associated with low-risk characteristics. The computational analysis shows that, in a context of overall gene set poverty, the upregulomes in RAC1- and kalirin-GEF1-suppressed ADRN-type cells are a batch of AU-rich element-containing mRNAs, which suggests a link between NUC migration and mRNA stability. Gene set enrichment analysis-based search for vulnerabilities reveals prospective weak points in RAC1- and kalirin-GEF1-suppressed ADRN-type NB cells, including activities of H3K27- and DNA methyltransferases. Altogether, these data support the introduction of NUC inhibitors into cancer treatment research.