The proneural factors Ascl1a and Ascl1b contribute to the terminal differentiation of dopaminergic GABAergic dual transmitter neurons in zebrafish.

The proneural factor Ascl1 is involved in several steps of neurogenesis, from neural progenitor maintenance to initiation of terminal differentiation and neuronal subtype specification. In neural progenitor cells, Ascl1 initiates the cell-cycle exit of progenitors, and contributes to their differentiation into mainly GABAergic neurons. Several catecholaminergic neuron groups in the forebrain of zebrafish use GABA as co-transmitter, but a potential role of the two paralogues Ascl1a and Ascl1b in their neurogenesis is not understood. Here, we show that ascl1a, ascl1b double mutant embryos develop a significantly reduced number of neurons in all GABAergic and catecholaminergic dual transmitter neuron anatomical clusters in the fore- and hindbrain, while glutamatergic catecholaminergic clusters develop normally. However, none of the affected catecholaminergic cell clusters are lost completely, suggesting an impairment in progenitor pools, or a requirement of Ascl1a/b for differentiation of a subset of neurons in each cluster. Early progenitors which are dlx2a+, fezf2 + or emx2 + are not reduced whereas late progenitors and differentiating neurons marked by the expression of dlx5a, isl1 and arxa are severely reduced in ascl1a, ascl1b double mutant embryos. This suggests that Ascl1a and Ascl1b play only a minor or no role in the maintenance of their progenitor pools, but rather contribute to the initiation of terminal differentiation of GABAergic catecholaminergic neurons.

Role of noradrenergic and dopaminergic systems in the antinociceptive effect of N-(3-(phenylselanyl)prop-2-yn-1-yl)benzamide in mice.

Pain has a negative impact on public health, reducing quality of life. Unfortunately, current treatments are not fully effective and have adverse effects. Therefore, there is a need to develop new analgesic compounds. Due to promising results regarding the antinociceptive effect of N-(3-(phenylselanyl)prop-2-in-1-yl)benzamide (SePB), this study aimed to evaluate the participation of the dopaminergic and noradrenergic systems in this effect in mice, as well as its toxicity. To this, the antagonists sulpiride (D2/D3 receptor antagonist, 5 mg/kg), SCH-23390 (D1 receptor antagonist, 0.05 mg/kg), prazosin (α1 adrenergic receptor antagonist, 0.15 mg/kg), yohimbine (α2-adrenergic receptors, 0.15 mg/kg) and propranolol (non-selective ß-adrenergic antagonist, 10 mg/kg) were administered intraperitoneally to mice 15 min before SePB (10 mg/kg, intragastrically), except for propranolol (20 min). After 26 min of SePB administration, the open field test was performed for 4 min to assess locomotor activity, followed by the tail immersion test to measure the nociceptive response. For the toxicity test, animals received a high dose of 300 mg/kg of SePB. SePB showed an increase in the latency for nociceptive response in the tail immersion test, and this effect was prevented by SCH-23390, yohimbine and propranolol, indicating the involvement of D1, α2 and ß-adrenergic receptors in the antinociceptive mechanism of the SePB effect. No changes were observed in the open field test, and the toxicity assessment suggested that SePB has low potential to induce toxicity. These findings contribute to understanding SePB's mechanism of action, with a focus on the development of new alternatives for pain treatment.

Effects on cerebral blood flow after single doses of the ß2 agonist, clenbuterol, in healthy volunteers and patients with mild cognitive impairment or Parkinson's disease.

AIMS: Cerebral hypometabolism occurs years prior to a diagnosis of neurodegenerative diseases and coincides with reduced cerebral perfusion and declining noradrenergic transmission from the locus coeruleus. In pre-clinical models, ß-adrenoceptor (ß-AR) agonists increase cerebrocortical glucose metabolism, and may have therapeutic potential for neurodegenerative diseases. This study investigated the safety and effects on regional cerebral blood flow (rCBF) of the oral, brain-penetrant ß2-AR agonist, clenbuterol, in healthy volunteers (HV) and patients with mild cognitive impairment (MCI) or Parkinson's disease (PD). METHODS: This study evaluated the safety and effects on cerebral activity of the oral, brain-penetrant, ß2-AR agonist clenbuterol (20-160 µg) in healthy volunteers and patients with MCI or PD. Regional CBF, which is tightly coupled to glucose metabolism, was measured by arterial spin labelling MRI in 32 subjects (25 HV and 8 MCI or PD) across five cohorts. In some cohorts, low doses of nadolol (1-5 mg), a ß-AR antagonist with minimal brain penetration, were administered with clenbuterol to control peripheral ß2-AR responses. RESULTS: Significant, dose-dependent increases in rCBF were seen in multiple brain regions, including hippocampus, amygdala and thalamus, following the administration of clenbuterol to HVs (mean changes from baseline in hippocampal rCBF of -1.7%, 7.3%, 22.9%, 28.4% 3 h after 20, 40, 80 and 160 µg clenbuterol, respectively). In patients with MCI or PD, increases in rCBF following 80 µg clenbuterol were observed both without and with 5 mg nadolol (in hippocampus, 18.6%/13.7% without/with nadolol). Clenbuterol was safe and well-tolerated in all subjects; known side effects of ß2-agonists, including increased heart rate and tremor, were mild in intensity and were blocked by low-dose nadolol. CONCLUSIONS: The effects of clenbuterol on rCBF were evident both in the absence and presence of low-dose nadolol, suggesting central nervous system (CNS) involvement. Concomitant inhibition of the peripheral effects of clenbuterol by nadolol confirms that meaningful ß2-AR antagonism in the periphery was achieved without interrupting the central effects of clenbuterol on rCBF.

Obesity during preclinical Alzheimer's disease development exacerbates brain metabolic decline.

Alzheimer's disease (AD) is the most common form of dementia. Obesity in middle age increases AD risk and severity, which is alarming given that obesity prevalence peaks at middle age and obesity rates are accelerating worldwide. Midlife, but not late-life obesity increases AD risk, suggesting that this interaction is specific to preclinical AD. AD pathology begins in middle age, with accumulation of amyloid beta (Aß), hyperphosphorylated tau, metabolic decline, and neuroinflammation occurring decades before cognitive symptoms appear. We used a transcriptomic discovery approach in young adult (6.5 months old) male and female TgF344-AD rats that overexpress mutant human amyloid precursor protein and presenilin-1 and wild-type (WT) controls to determine whether inducing obesity with a high-fat/high-sugar "Western" diet during preclinical AD increases brain metabolic dysfunction in dorsal hippocampus (dHC), a brain region vulnerable to the effects of obesity and early AD. Analyses of dHC gene expression data showed dysregulated mitochondrial and neurotransmission pathways, and up-regulated genes involved in cholesterol synthesis. Western diet amplified the number of genes that were different between AD and WT rats and added pathways involved in noradrenergic signaling, dysregulated inhibition of cholesterol synthesis, and decreased intracellular lipid transporters. Importantly, the Western diet impaired dHC-dependent spatial working memory in AD but not WT rats, confirming that the dietary intervention accelerated cognitive decline. To examine later consequences of early transcriptional dysregulation, we measured dHC monoamine levels in older (13 months old) AD and WT rats of both sexes after long-term chow or Western diet consumption. Norepinephrine (NE) abundance was significantly decreased in AD rats, NE turnover was increased, and the Western diet attenuated the AD-induced increases in turnover. Collectively, these findings indicate obesity during prodromal AD impairs memory, potentiates AD-induced metabolic decline likely leading to an overproduction of cholesterol, and interferes with compensatory increases in NE transmission.

Rnf220/Zc4h2-mediated monoubiquitylation of Phox2 is required for noradrenergic neuron development.

Noradrenaline belongs to the monoamine system and is involved in cognition and emotional behaviors. Phox2a and Phox2b play essential but non-redundant roles during development of the locus coeruleus (LC), the main noradrenergic (NA) neuron center in the mammalian brain. The ubiquitin E3 ligase Rnf220 and its cofactor Zc4h2 participate in ventral neural tube patterning by modulating Shh/Gli signaling, and ZC4H2 mutation is associated with intellectual disability, although the mechanisms for this remain poorly understood. Here, we report that Zc4h2 and Rnf220 are required for the development of central NA neurons in the mouse brain. Both Zc4h2 and Rnf220 are expressed in developing LC-NA neurons. Although properly initiated at E10.5, the expression of genes associated with LC-NA neurons is not maintained at the later embryonic stages in mice with a deficiency of either Rnf220 or Zc4h2 In addition, we show that the Rnf220/Zc4h2 complex monoubiquitylates Phox2a/Phox2b, a process required for the full transcriptional activity of Phox2a/Phox2b. Our work reveals a role for Rnf220/Zc4h2 in regulating LC-NA neuron development, and this finding may be helpful for understanding the pathogenesis of ZC4H2 mutation-associated intellectual disability.

Locus Coeruleus-Noradrenergic Neurons Regulate Stress Coping During Subchronic Exposure to Social Threats: A Characteristic Feature in Postpartum Female Mice.

Stress-coping strategies have been implicated in depression. The control of stress coping may improve the symptom and higher prevalence of depression during the postpartum period in women. However, the neuronal mechanisms underlying stress coping remain to be fully elucidated in postpartum women. In this study, we examined how locus coeruleus-noradrenergic (LC-NA) neurons, which have been associated with both stress coping and depression, regulate changes in coping style induced by subchronic exposure to unfamiliar male mice as a social threat in postpartum female mice. In contrast to virgin females, dams exposed to unfamiliar males daily for four consecutive days showed reduced immobility duration in the forced swim test, indicating that exposure to unfamiliar males decreased passive stress coping in dams. Exposure to unfamiliar males also decreased sucrose palatability in the sucrose preference test and suppressed the crouching behavior in the maternal care test but did not affect anxiety-like behavior in the hole-board test in dams. In fiber photometry analyses, LC-NA neurons showed differential activity between dams and virgin females in response to unfamiliar males. Chemogenetic inhibition of LC-NA neurons during exposure to unfamiliar males prevented the social threat-induced decrease in immobility duration in the forced swim test in dams. Furthermore, inhibition or activation of LC-NA neurons exacerbated crouching behavior in dams. These results indicate that LC-NA neurons regulate the social threat-induced decrease in passive stress coping and relieve social threat-induced inhibition of maternal care in postpartum female mice.

Rostral-middle locus coeruleus integrity and subjective cognitive decline in early old age.

OBJECTIVES: Abnormal tau, a hallmark Alzheimer's disease (AD) pathology, may appear in the locus coeruleus (LC) decades before AD symptom onset. Reports of subjective cognitive decline are also often present prior to formal diagnosis. Yet, the relationship between LC structural integrity and subjective cognitive decline has remained unexplored. Here, we aimed to explore these potential associations. METHODS: We examined 381 community-dwelling men (mean age = 67.58; SD = 2.62) in the Vietnam Era Twin Study of Aging who underwent LC-sensitive magnetic resonance imaging and completed the Everyday Cognition scale to measure subjective cognitive decline along with their selected informants. Mixed models examined the associations between rostral-middle and caudal LC integrity and subjective cognitive decline after adjusting for depressive symptoms, physical morbidities, and family. Models also adjusted for current objective cognitive performance and objective cognitive decline to explore attenuation. RESULTS: For participant ratings, lower rostral-middle LC contrast to noise ratio (LCCNR) was associated with significantly greater subjective decline in memory, executive function, and visuospatial abilities. For informant ratings, lower rostral-middle LCCNR was associated with significantly greater subjective decline in memory only. Associations remained after adjusting for current objective cognition and objective cognitive decline in respective domains. CONCLUSIONS: Lower rostral-middle LC integrity is associated with greater subjective cognitive decline. Although not explained by objective cognitive performance, such a relationship may explain increased AD risk in people with subjective cognitive decline as the LC is an important neural substrate important for higher order cognitive processing, attention, and arousal and one of the first sites of AD pathology.

Randomized controlled pilot trial of prazosin for prophylaxis of posttraumatic headaches in active-duty service members and veterans.

OBJECTIVE: Evaluate the efficacy and tolerability of prazosin for prophylaxis of headaches following mild traumatic brain injury in active-duty service members and military veterans. BACKGROUND: Prazosin is an alpha-1 adrenoreceptor antagonist that reduces noradrenergic signaling. An open-label trial in which prazosin reduced headache frequency in veterans following mild traumatic brain injury provided the rationale for this pilot study. METHODS: A 22-week parallel-group randomized controlled trial  which included 48 military veterans and active-duty service members with mild traumatic brain injury-related headaches was performed. The study design was based on International Headache Society consensus guidelines for randomized controlled trials for chronic migraine. Following a pre-treatment baseline phase, participants with at least eight qualifying headache days per 4 weeks were randomized 2:1 to prazosin or placebo. After a 5-week titration to a maximum possible dose of 5 mg (morning) and 20 mg (evening), participants were maintained on the achieved dose for 12 weeks. Outcome measures were evaluated in 4-week blocks during the maintenance dose phase. The primary outcome measure was change in 4-week frequency of qualifying headache days. Secondary outcome measures were percent participants achieving at least 50% reduction in qualifying headache days and change in Headache Impact Test-6 scores. RESULTS: Intent-to-treat analysis of randomized study participants (prazosin N = 32; placebo N = 16) demonstrated greater benefit over time in the prazosin group for all three outcome measures. In prazosin versus placebo participants, reductions from baseline to the final rating period for 4-week headache frequency were -11.9 ± 1.0 (mean ± standard error) versus -6.7 ± 1.5, a prazosin minus placebo difference of -5.2 (-8.8, -1.6 [95% confidence interval]), p = 0.005 and for Headache Impact Test-6 scores were -6.0 ± 1.3 versus +0.6 ± 1.8, a difference of -6.6 (-11.0, -2.2), p = 0.004. The mean predicted percent of participants at 12 weeks with ≥50% reduction in headache days/4 weeks, baseline to final rating, was 70 ± 8% for prazosin (21/30) versus 29 ± 12% for placebo (4/14), odds ratio 5.8 (1.44, 23.6), p = 0.013. The trial completion rate of 94% in the prazosin group (30/32) and 88% in the placebo group (14/16) indicated that prazosin was generally well tolerated at the administered dose regimen. Morning drowsiness/lethargy was the only adverse effect that differed significantly between groups, affecting 69% of the prazosin group (22/32) versus 19% of the placebo group (3/16), p = 0.002. CONCLUSIONS: This pilot study provides a clinically meaningful efficacy signal for prazosin prophylaxis of posttraumatic headaches. A larger randomized controlled trial is needed to confirm and extend these promising results.

Mifepristone as a pharmacological intervention for stress-induced alcohol craving: A human laboratory study.

Preclinical and clinical work suggests that mifepristone may be a viable treatment for alcohol use disorder (AUD). This was a Phase 1/2, outpatient, cross-over, randomized, double-blind, placebo-controlled trial with non-treatment-seeking individuals with AUD (N = 32). We assessed safety, alcohol craving and consumption, after 1-week mifepristone 600 mg/day administration, in a human laboratory study comprised of a single oral yohimbine administration (32.4 mg), a cue-reactivity procedure and alcohol self-administration. Safety was monitored by adverse events and hemodynamic parameters, alcohol craving by alcohol craving questionnaire and cue-induced saliva output. During the alcohol self-administration, we assessed alcohol pharmacokinetics, subjective effects and consumption. Outcomes were assessed using Generalized Estimating Equations and mediation analysis. Mild-moderate adverse events were reported in both conditions. There was no statistically significant difference between mifepristone and placebo in alcohol pharmacokinetics and subjective effects. Furthermore, blood pressure increased only in the placebo condition after the stress-induced laboratory procedures. Mifepristone, compared to placebo, significantly reduced alcohol craving and increased cortisol levels. Mifepristone-induced cortisol increase was not a mediator of alcohol craving. Mifepristone, compared to placebo, did not reduce alcohol consumption in the laboratory or in a naturalistic setting. This study successfully translated a developed preclinical procedure to a human laboratory study, confirming the safety of mifepristone in people with AUD and providing evidence to its role in reducing alcohol craving under stress procedures. The lack of effects on alcohol drinking may be related to the selection of non-treatment seekers and suggests future treatment-oriented trials should investigate mifepristone in people with AUD.

Exposure to Benzo[a]pyrene Decreases Noradrenergic and Serotonergic Axons in Hippocampus of Mouse Brain.

Epidemiological studies showed the association between air pollution and dementia. A soluble fraction of particulate matters including polycyclic aromatic hydrocarbons (PAHs) is suspected to be involved with the adverse effects of air pollution on the central nervous system of humans. It is also reported that exposure to benzopyrene (B[a]P), which is one of the PAHs, caused deterioration of neurobehavioral performance in workers. The present study investigated the effect of B[a]P on noradrenergic and serotonergic axons in mouse brains. In total, 48 wild-type male mice (10 weeks of age) were allocated into 4 groups and exposed to B[a]P at 0, 2.88, 8.67 or 26.00 µg/mice, which is approximately equivalent to 0.12, 0.37 and 1.12 mg/kg bw, respectively, by pharyngeal aspiration once/week for 4 weeks. The density of noradrenergic and serotonergic axons was evaluated by immunohistochemistry in the hippocampal CA1 and CA3 areas. Exposure to B[a]P at 2.88 µg/mice or more decreased the density of noradrenergic or serotonergic axons in the CA1 area and the density of noradrenergic axons in the CA3 area in the hippocampus of mice. Furthermore, exposure to B[a]P dose-dependently upregulated Tnfα at 8.67 µg/mice or more, as well as upregulating Il-1ß at 26 µg/mice, Il-18 at 2.88 and 26 µg/mice and Nlrp3 at 2.88 µg/mice. The results demonstrate that exposure to B[a]P induces degeneration of noradrenergic or serotonergic axons and suggest the involvement of proinflammatory or inflammation-related genes with B[a]P-induced neurodegeneration.

Age differences in diffusivity in the locus coeruleus and its ascending noradrenergic tract.

The noradrenergic locus coeruleus (LC) is a small brainstem nucleus that promotes arousal and attention. Recent studies have examined the microstructural properties of the LC using diffusion-weighted magnetic resonance imaging and found unexpected age-related differences in fractional anisotropy - a measure of white matter integrity. Here, we used two datasets (Berlin Aging Study-II, N = 301, the Leipzig Study for Mind-Body-Emotion Interactions, N = 220), to replicate published findings and expand them by investigating diffusivity in the LC's ascending noradrenergic bundle. In younger adults, LC fractional anisotropy was significantly lower, compared to older adults. However, in the LC's ascending noradrenergic bundle, we observed significantly higher fractional anisotropy in younger adults, relative to older adults. These findings indicate that diffusivity in the LC versus the ascending noradrenergic bundle are both susceptible to structural changes in aging that have opposing effects on fractional anisotropy.

Examining the effect of stress on the flexible updating of avoidance responses.

Acute stress has been found to impair the flexible updating of stimulus - outcome associations. However, there is a lack of studies investigating the effect of acute stress on the flexible updating of stimulus-response associations, like active avoidance responses. The current study used an avoidance reversal learning paradigm to address this question. Sixty-one participants learned that a red dot was associated with an aversive sound, whereas a green dot was not (Pavlovian Acquisition phase). Next, they were trained to avoid the aversive stimulus by selectively pressing a button in response to the red, but not the green, dot (Avoidance Acquisition phase). Subsequently, participants either underwent a stress induction task or a no-stress control task. The flexible updating of expectancies of the US and avoidance responses were assessed after reversal of the original contingencies (Reversal Test). Acute stress did not impair the flexible updating of avoidance responses during the Reversal Test. In contrast, results showed that in the stress group the expectancies of the aversive sound were more in accordance with the reversed contingencies compared to the ratings of control participants. Additionally, cortisol responders avoided less often in comparison to cortisol non-responders. Increased noradrenergic activity in stressed participants was related to impairments in the flexible updating of avoidance responses after contingency reversal, while this association was absent in the control participants. In conclusion, our results suggest that the autonomic response might account for shifting the balance toward inflexible updating of stimulus-outcome awareness while stress does not impair flexible updating of avoidance responses.

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.

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.

Dexmedetomidine Ameliorated Cognitive Dysfunction Induced by Intestinal Ischemia Reperfusion in Mice with Possible Relation to the Anti-inflammatory Effect Through the Locus Coeruleus Norepinephrine System.

Cognitive impairment is a common central nervous system complication that occurs following surgery or organs damage outside the nervous system. Neuroinflammation plays a key role in the molecular mechanisms of cognitive impairment. Dexmedetomidine alleviates neuroinflammation and reduces cognitive dysfunction incidence; however, the mechanism by which dexmedetomidine alleviates cognitive dysfunction remains unclear. This study evaluated the effect of dexmedetomidine on attenuation of early cognitive impairment induced by intestinal ischemia-reperfusion in mice and examined whether the locus coeruleus norepinephrine (LCNE) system participates in the anti-inflammatory effect of dexmedetomidine. The superior mesenteric artery was clamped for 45 min to induce intestinal ischemia reperfusion injury. Dexmedetomidine alone or combined with DSP-4, a selective locus coeruleus noradrenergic neurotoxin, was used for pretreatment. Postoperative cognition was assessed using the Morris water maze. Serum and hippocampal levels of IL-1ß, TNF-α, norepinephrine (NE), and malondialdehyde (MDA) were assessed by enzyme-linked immunosorbent assay. Immunofluorescence, immunohistochemistry, and hematoxylin and eosin staining were used to evaluate the expression of tyrosine hydroxylase (TH) in the locus coeruleus, hippocampal microglia, and intestinal injury. Pretreatment with dexmedetomidine alleviated intestinal injury and decreased the serum and hippocampal levels of NE, IL-1ß, TNF-α, and MDA at 24 h after intestinal ischemia reperfusion, decreased TH-positive neurons in the locus coeruleus, and ameliorated cognitive impairment. Similarly, DSP-4 pre-treatment alleviated neuroinflammation and improved cognitive function. Furthermore, α2-adrenergic receptor antagonist atipamezole or yohimbine administration diminished the neuroprotective effects and improved cognitive function with dexmedetomidine. Therefore, dexmedetomidine attenuated early cognitive dysfunction induced by intestinal ischemia-reperfusion injury in mice, which may be related to its anti-inflammatory effects through the LCNE system.

Distribution of the Noradrenaline Innervation and Adrenoceptors in the Macaque Monkey Thalamus.

Noradrenaline (NA) in the thalamus has important roles in physiological, pharmacological, and pathological neuromodulation. In this work, a complete characterization of NA axons and Alpha adrenoceptors distributions is provided. NA axons, revealed by immunohistochemistry against the synthesizing enzyme and the NA transporter, are present in all thalamic nuclei. The most densely innervated ones are the midline nuclei, intralaminar nuclei (paracentral and parafascicular), and the medial sector of the mediodorsal nucleus (MDm). The ventral motor nuclei and most somatosensory relay nuclei receive a moderate NA innervation. The pulvinar complex receives a heterogeneous innervation. The lateral geniculate nucleus (GL) has the lowest NA innervation. Alpha adrenoceptors were analyzed by in vitro quantitative autoradiography. Alpha-1 receptor densities are higher than Alpha-2 densities. Overall, axonal densities and Alpha adrenoceptor densities coincide; although some mismatches were identified. The nuclei with the highest Alpha-1 values are MDm, the parvocellular part of the ventral posterior medial nucleus, medial pulvinar, and midline nuclei. The nucleus with the lowest Alpha-1 receptor density is GL. Alpha-2 receptor densities are highest in the lateral dorsal, centromedian, medial and inferior pulvinar, and midline nuclei. These results suggest a role for NA in modulating thalamic involvement in consciousness, limbic, cognitive, and executive functions.

Impact of transdermal trigeminal electrical neuromodulation on subjective and objective sleep parameters in patients with insomnia: a pilot study.

PURPOSE: Transcutaneous trigeminal electrical neuromodulation (TTEN) is a new treatment modality that has a potential to improve sleep through the suppression of noradrenergic activity. This study aimed to explore the changes of subjective and objective sleep parameters after 4-weeks of daily session of transcutaneous trigeminal electrical neuromodulation in a group of patients with insomnia. METHODS: In a group of patients with insomnia, TTEN targeting the ophthalmic division of the trigeminal nerve was utilized to test the effects of transcutaneous trigeminal electrical neuromodulation. Patients went through daily 20-min sessions of TTEN for 4 weeks. Polysomnography parameters, Pittsburgh sleep quality index, insomnia severity index, and Epworth sleepiness scale were obtained pre- and post-intervention. Changes in these parameters were compared and analyzed. RESULTS: Among 13 patients with insomnia there was a statistically significant reduction in Pittsburgh sleep quality index, insomnia severity index, and Epworth sleepiness scale scores after 4-week daily sessions of TTEN. There were no differences in polysomnography parameters pre- and post-intervention. CONCLUSION: This is the first study to demonstrate the effects of TTEN in a group of insomnia patients. TTEN may improve subjective parameters in patients with insomnia. Further replication studies are needed to support this finding. TRIAL REGISTRATION: The data presented in the study are from a study exploring the effect of TTEN on insomnia ( www. CLINICALTRIALS: gov , registration number: NCT04838067, date of registration: April 8, 2021, "retrospectively registered").

Pain Modulation from the Locus Coeruleus in a Model of Hydrocephalus: Searching for Oxidative Stress-Induced Noradrenergic Neuroprotection.

Pain transmission at the spinal cord is modulated by noradrenaline (NA)-mediated actions that arise from supraspinal areas. We studied the locus coeruleus (LC) to evaluate the expression of the cathecolamine-synthetizing enzyme tyrosine hydroxylase (TH) and search for local oxidative stress and possible consequences in descending pain modulation in a model of hydrocephalus, a disease characterized by enlargement of the cerebral ventricular system usually due to the obstruction of cerebrospinal fluid flow. Four weeks after kaolin injection into the cisterna magna, immunodetection of the catecholamine-synthetizing enzymes TH and dopamine-ß-hydroxylase (DBH) was performed in the LC and spinal cord. Colocalization of the oxidative stress marker 8-OHdG (8-hydroxyguanosine; 8-OHdG), with TH in the LC was performed. Formalin was injected in the hindpaw both for behavioral nociceptive evaluation and the immunodetection of Fos expression in the spinal cord. Hydrocephalic rats presented with a higher expression of TH at the LC, of TH and DBH at the spinal dorsal horn along with decreased nociceptive behavioral responses in the second (inflammatory) phase of the formalin test, and formalin-evoked Fos expression at the spinal dorsal horn. The expression of 8-OHdG was increased in the LC neurons, with higher co-localization in TH-immunoreactive neurons. Collectively, the results indicate increased noradrenergic expression at the LC during hydrocephalus. The strong oxidative stress damage at the LC neurons may lead to local neuroprotective-mediated increases in NA levels. The increased expression of catecholamine-synthetizing enzymes along with the decreased nociception-induced neuronal activation of dorsal horn neurons and behavioral pain signs may indicate that hydrocephalus is associated with alterations in descending pain modulation.

Protective Effects of Currants (Vitis vinifera) on Corticolimbic Serotoninergic Alterations and Anxiety-like Comorbidity in a Rat Model of Parkinson's Disease.

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of nigral dopaminergic neurons. Increasing evidence supports that PD is not simply a motor disorder but a systemic disease leading to motor and non-motor symptoms, including memory loss and neuropsychiatric conditions, with poor management of the non-motor deficits by the existing dopaminergic medication. Oxidative stress is considered a contributing factor for nigrostriatal degeneration, while antioxidant/anti-inflammatory properties of natural phyto-polyphenols have been suggested to have beneficial effects. The present study aimed to determine the contribution of monoaminergic neurotransmission on the anxiety-like phenotype in a rat rotenone PD model and evaluate the possible neuroprotective effects of black Corinthian currant, Vitis vinifera, consisting of antioxidant polyphenols. Rotenone-treated rats showed anxiety-like behavior and exploratory deficits, accompanied by changes in 5-HT, SERT and ß2-ARs expression in the prefrontal cortices, hippocampus and basolateral amygdala. Importantly, the motor and non-motor behavior, as well as 5-HT, SERT and ß2-ARs expression patterns of the PD-like phenotype were partially recovered by a supplementary diet with currants. Overall, our results suggest that the neuroprotective effects of Corinthian currants in rotenone-induced anxiety-like behavior may be mediated via corticolimbic serotonergic transmission.

Locus Coeruleus Neurons' Firing Pattern Is Regulated by ERG Voltage-Gated K+ Channels.

Locus coeruleus (LC) neurons, with their extensive innervations throughout the brain, control a broad range of physiological processes. Several ion channels have been characterized in LC neurons that control intrinsic membrane properties and excitability. However, ERG (ether-à-go-go-related gene) K+ channels that are particularly important in setting neuronal firing rhythms and automaticity have not as yet been discovered in the LC. Moreover, the neurophysiological and pathophysiological roles of ERG channels in the brain remain unclear despite their expression in several structures. By performing immunohistochemical investigations, we found that ERG-1A, ERG-1B, ERG-2 and ERG-3 are highly expressed in the LC neurons of mice. To examine the functional role of ERG channels, current-clamp recordings were performed on mouse LC neurons in brain slices under visual control. ERG channel blockade by WAY-123,398, a class III anti-arrhythmic agent, increased the spontaneous firing activity and discharge irregularity of LC neurons. Here, we have shown the presence of distinct ERG channel subunits in the LC which play an imperative role in modulating neuronal discharge patterns. Thus, we propose that ERG channels are important players behind the changes in, and/or maintenance of, LC firing patterns that are implicated in the generation of different behaviors and in several disorders.