Brainstem Areas Research Articles

Modulation of visual processing of food by transcutaneous vagus nerve stimulation (tVNS)

Present project is concerned with the possibility to modulate the neural regulation of food intake by non-invasive stimulation of the vagus nerve. This nerve carries viscero-afferent information from the gut and other internal organs and therefore serves an important role in ingestive behavior. The electrical stimulation of the vagus nerve (VNS) is a qualified procedure in the treatment of drug-resistant epilepsy and depression. Since weight loss is a known common side effect of VNS treatment in patients with implanted devices, VNS is evaluated as a treatment of obesity. To investigate potential VNS-related changes in the cognitive processing of food-related items, 21 healthy participants were recorded in a 3-Tesla scanner in two counterbalanced sessions. Participants were presented with 72 food pictures and asked to rate how much they liked that food. Before entering the scanner subjects received a 1-h sham or verum stimulation, which was implemented transcutanously with a Cerbomed NEMOS® device. We found significant activations in core areas of the vagal afferent pathway, including left brainstem, thalamus, temporal pole, amygdala, insula, hippocampus, and supplementary motor area for the interaction between ratings (high vs low) and session (verum vs sham stimulation). Significant activations were also found for the main effect of verum compared to sham stimulation in the left inferior and superior parietal cortex. These results demonstrate an effect of tVNS on food image processing even with a preceding short stimulation period. This is a necessary prerequisite for a therapeutic application of tVNS which has to be evaluated in longer-term studies.

Nucleobindin 2/nesfatin-1 expression and colocalisation with neuropeptide Y and cocaine- and amphetamine-regulated transcript in the human brainstem.

Feeding is a complex behaviour entailing elaborate interactions between forebrain, hypothalamic and brainstem neuronal circuits via multiple orexigenic and anorexigenic neuropeptides. Nucleobindin-2 (NUCB2)/nesfatin-1 is a negative regulator of food intake and body weight with a widespread distribution in rodent brainstem nuclei. However, its localisation pattern in the human brainstem is unknown. The present study aimed to explore NUCB2/nesfatin-1 immunoexpression in human brainstem nuclei and its possible correlation with body weight. Sections of human brainstem from 20 autopsy cases (13 males, seven females; eight normal weight, six overweight, six obese) were examined using immunohistochemistry and double immunofluorescence labelling. Strong immunoreactivity for NUCB2/nesfatin-1 was displayed in various brainstem areas, including the locus coeruleus, medial and lateral parabrachial nuclei, pontine nuclei, raphe nuclei, nucleus of the solitary tract, dorsal motor nucleus of vagus (10N), area postrema, hypoglossal nucleus, reticular formation, inferior olive, cuneate nucleus, and spinal trigeminal nucleus. NUCB2/nesfatin-1 was shown to extensively colocalise with neuropeptide Y and cocaine- and amphetamine-regulated transcript in the locus coeruleus, dorsal raphe nucleus and solitary tract. Interestingly, in the examined cases, NUCB2/nesfatin-1 protein expression was lower in obese than normal weight subjects in the solitary tract (P=0.020). The findings of the present study provide neuroanatomical support for a role for NUCB2/nesfatin-1 in feeding behaviour and energy balance. The widespread distribution of NUCB2/nesfatin-1 in the human brainstem nuclei may be indicative of its pleiotropic effects on autonomic, neuroendocrine and behavioural processes. In the solitary tract, a key integrator of energy status, altered neurochemistry may contribute to obesity. Further research is necessary to decipher human brainstem energy homeostasis circuitry, which, despite its importance, remains inadequately characterised.

Graphene-Based Nanoparticles as Potential Treatment Options for Parkinson's Disease: A Molecular Dynamics Study.

IntroductionThe study of abnormal aggregation of proteins in different tissues of the body has recently earned great attention from researchers in various fields of science. Concerning neurological diseases, for instance, the accumulation of amyloid fibrils can contribute to Parkinson’s disease, a progressively severe neurodegenerative disorder. The most prominent features of this disease are the degeneration of neurons in the substantia nigra and accumulation of α-synuclein aggregates, especially in the brainstem, spinal cord, and cortical areas. Dopamine replacement therapies and other medications have reduced motor impairment and had positive consequences on patients’ quality of life. However, if these medications are stopped, symptoms of the disease will recur even more severely. Therefore, the improvement of therapies targeting more basic mechanisms like prevention of amyloid formation seems to be critical. It has been shown that the interactions between monolayers like graphene and amyloids could prevent their fibrillation.MethodsFor the first time, the impact of four types of last-generation graphene-based nanostructures on the prevention of α-synuclein amyloid fibrillation was investigated in this study by using molecular dynamics simulation tools.ResultsAlthough all monolayers were shown to prevent amyloid fibrillation, nitrogen-doped graphene (N-Graphene) caused the most instability in the secondary structure of α-synuclein amyloids. Moreover, among the four monolayers, N-Graphene was shown to present the highest absolute value of interaction energy, the lowest contact level of amyloid particles, the highest number of hydrogen bonds between water and amyloid molecules, the highest instability caused in α-synuclein particles, and the most significant decrease in the compactness of α-synuclein protein.DiscussionUltimately, it was concluded that N-Graphene could be the most effective monolayer to disrupt amyloid fibrillation, and consequently, prevent the progression of Parkinson’s disease.

Nocturnal eye movements in patients with idiopathic rapid eye movement sleep behaviour disorder and patients with Parkinson's disease.

Patients with idiopathic rapid-eye-movement (REM) sleep behaviour disorder (iRBD) have a high risk of converting into manifest α-synucleinopathies. Eye movements (EMs) are controlled by neurons in the lower brainstem, midbrain and frontal areas, and may be affected by the early neurodegenerative process seen in iRBD. Studies have reported impairment of the oculomotor function in patients with Parkinson's disease (PD) during wakefulness, but no studies have investigated EMs during sleep. We aimed to evaluate nocturnal EMs in iRBD and PD, hypothesizing that these patients present abnormal EM distribution during sleep. Twenty-eight patients with periodic limb movement disorder (PLMD), 24 iRBD, 23 PD without RBD (PDwoRBD), 29 PD and RBD (PDwRBD) and 24 controls were included. A validated EM detector automatically identified EM periods between lights off and on. The EM coverage was computed as the percentage of time containing EMs during stable wake after lights off, N1, N2, N3 and REM sleep. Between-group comparisons revealed that PDwRBD had significantly less EM coverage during wake and significantly higher EM coverage during N2 compared to controls and PLMD patients. PDwoRBD showed significantly less EM coverage during wake compared to controls and higher EM coverage during N2 compared to controls and PLMD. Finally, iRBD showed less coverage of EM during wake compared to controls. The same trend was observed between iRBD and controls in N2 but was not significant. The different profiles of EM coverage in iRBD and PD with/without RBD may mirror different stages of central nervous system involvement across neurodegenerative disease progression.

NMDA receptor partial agonist GLYX-13 alleviates chronic stress-induced depression-like behavior through enhancement of AMPA receptor function in the periaqueductal gray

Depression is a common mental disorder affecting more than 300 million people worldwide and is one of the leading causes of disability among all medical illnesses. The accumulation of preclinical data has fueled the revival of interest in targeting glutamatergic neurotransmission for the treatment of major depressive disorder. GLYX-13, a glutamatergic compound that acts as an N-methyl-d-aspartate (NMDA) modulator with glycine-site partial agonist properties, produces rapid and long-lasting antidepressant effects in both animal models and patients. However, the mechanisms underlying the antidepressant actions of GLYX-13 have not been fully characterized, especially in the midbrain ventrolateral periaqueductal gray (vlPAG), a brain stem area that controls stress-associated depression-like behavior. Here, we use a combination of electrophysiological recordings, behavioral tests, and pharmacological manipulations to study the antidepressant actions of GLYX-13 in the vlPAG. A single intravenous injection of a GLYX-13 rapidly mitigated footshock stress (FS)-induced depression-like behavior in rats. The FS-induced diminished glutamatergic transmission in the vlPAG was also reversed by a single GLYX-13 intravenous injection. Moreover, intra-vlPAG GLYX-13 microinjection produced a long-lasting antidepressant effect; however, this effect was prevented by the intra-vlPAG microinjection of tropomyosin-related kinase B (TrkB) receptor antagonist ANA-12, a selective mammalian target of rapamycin complex 1 (mTORC1) inhibitor rapamycin, and CNQX, an AMPA receptor antagonist. Additionally, a bath application of GLYX-13 enhanced glutamatergic transmission in vlPAG neurons; however, this enhancement effect was blocked by the co-application of ANA-12 and rapamycin. These results demonstrate that BDNF-TrkB-mTORC1 signaling in the vlPAG is required for the sustained antidepressant effects of GLYX-13.

The Mammalian Diving Response: Inroads to Its Neural Control.

The mammalian diving response (DR) is a remarkable behavior that was first formally studied by Laurence Irving and Per Scholander in the late 1930s. The DR is called such because it is most prominent in marine mammals such as seals, whales, and dolphins, but nevertheless is found in all mammals studied. It consists generally of breathing cessation (apnea), a dramatic slowing of heart rate (bradycardia), and an increase in peripheral vasoconstriction. The DR is thought to conserve vital oxygen stores and thus maintain life by directing perfusion to the two organs most essential for life—the heart and the brain. The DR is important, not only for its dramatic power over autonomic function, but also because it alters normal homeostatic reflexes such as the baroreceptor reflex and respiratory chemoreceptor reflex. The neurons driving the reflex circuits for the DR are contained within the medulla and spinal cord since the response remains after the brainstem transection at the pontomedullary junction. Neuroanatomical and physiological data suggesting brainstem areas important for the apnea, bradycardia, and peripheral vasoconstriction induced by underwater submersion are reviewed. Defining the brainstem circuit for the DR may open broad avenues for understanding the mechanisms of suprabulbar control of autonomic function in general, as well as implicate its role in some clinical states. Knowledge of the proposed diving circuit should facilitate studies on elite human divers performing breath-holding dives as well as investigations on sudden infant death syndrome (SIDS), stroke, migraine headache, and arrhythmias. We have speculated that the DR is the most powerful autonomic reflex known.

SAT-LB102 Obesity Is Associated With Reduced Expression of the Anorexigenic Neuropeptide Nucleobindin-2/Nesfatin-1 in the Human Nucleus of the Solitary Tract

Introduction: Feeding is a complex behavior coordinated by interrelated forebrain, hypothalamic, and brainstem neuronal networks. Brainstem neurons constitute an important input for the neural circuitry integrating nutrient signals to control ingestive behavior. Orexigenic and anorexigenic neuropeptides act in concert to regulate energy balance. Data from animal models suggest that altered neuropeptidergic expression contributes to obesity. Nucleobindin-2/nesfatin-1, an appetite-suppressing neuropeptide and negative regulator of body weight, is reduced in the hypothalamus of mouse obesity models. In obese and overweight humans, we have recently reported decreased nucleobindin-2/nesfatin-1 immunoexpression in the lateral hypothalamic area, which is critically involved in appetite and metabolic regulation and has extensive connections with brainstem feeding circuits. Objective: The present study explored nucleobindin-2/nesfatin-1 localization pattern as well as the association between nucleobindin-2/nesfatin-1 protein expression and body weight in human brainstem nuclei. Methods: Sections of 20 human brainstems (13 males, 7 females; 8 normal weight, 6 overweight, 6 obese) were examined by means of immunohistochemistry and double immunofluorescence labeling. Results: Nucleobindin-2/nesfatin-1 widespread distribution was observed in various brainstem areas, including nuclei with well-defined roles in energy homeostasis and in autonomic and behavioral processes, such as the nucleus of the solitary tract, dorsal motor nucleus of vagus, area postrema, inferior olive, raphe nuclei, reticular formation, locus coeruleus, parabrachial nuclei, and pontine nuclei, and in Purkinje cells of the cerebellum. Interestingly, nucleobindin-2/nesfatin-1 immunofluorescence signal extensively localized in neuronal subpopulations expressing neuropeptide Y and cocaine- and amphetamine-regulated transcript (peptides known to exert potent actions on food intake and energy balance) in nucleus of the solitary tract, inferior olive, locus coeruleus, and dorsal raphe nucleus. Of note, nucleobindin-2/nesfatin-1 immunoexpression was significantly lower in obese than normal weight subjects in the nucleus of the solitary tract (p<0.05). Conclusions: These data provide for the first time neuroanatomical support for the potential role of nucleobindin-2/nesfatin-1 in human brainstem circuits controlling energy homeostasis. In nucleus of the solitary tract, a key integrator of nutrient state signals and a neural substrate of food reward-related processes, altered neurochemistry such as nucleobindin-2/nesfatin-1 deficiency may contribute to dysregulation of homeostatic and/or hedonic feeding behavior and ultimately to obesity.

Oxytocin Reduces Intravesical Pressure in Anesthetized Female Rats: Action on Oxytocin Receptors of the Urinary Bladder.

Urinary bladder dysfunction affects several people worldwide and shows higher prevalence in women. Micturition is dependent on the Barrington’s nucleus, pontine urine storage center and periaqueductal gray matter, but other brain stem areas are involved in the bladder regulation. Neurons in the medulla oblongata send projections to hypothalamic nuclei as the supraoptic nucleus, which synthetizes oxytocin and in its turn, this peptide is released in the circulation. We investigated the effects of intravenous injection of oxytocin (OT) on the urinary bladder in sham and ovariectomized rats. We also evaluated the topical (in situ) action of OT on intravesical pressure (IP) as well as the existence of oxytocin receptors in the urinary bladder. In sham female Wistar rats, anesthetized with isoflurane, intravenous infusion of OT (10 ng/kg) significantly decreased the IP (–47.5 ± 1.2%) compared to saline (3.4 ± 0.7%). Similar effect in IP was observed in ovariectomized rats after i.v. OT (–41.9 ± 2.9%) compared to saline (0.5 ± 0.6%). Topical administration (in situ) of 0.1 mL of OT (1.0 ng/mL) significantly reduced the IP (22.3.0 ± 0.6%) compared to saline (0.9 ± 0.7%). We also found by qPCR that the gene expression of oxytocin receptor is present in this tissue. Blockade of oxytocin receptors significantly attenuated the reduction in IP evoked by oxytocin i.v. or in situ. Therefore, the findings suggest that (1) intravenous oxytocin decreases IP due to bladder relaxation and (2) OT has local bladder effect, binding directly in receptors located in the bladder.

Activity-Dependent Neuroplastic Changes in Autonomic Circuitry Modulating Cardiovascular Control: The Essential Role of Baroreceptors and Chemoreceptors Signaling.

Aerobic exercise training improves the autonomic control of the circulation. Emerging evidence has shown that exercise induces neuroplastic adaptive changes in preautonomic circuitry controlling sympathetic/parasympathetic outflow to heart and vessels. The mechanisms underlying neuronal plasticity are, however, incompletely understood. Knowing that sinoaortic denervation blocks training-induced cardiovascular benefits, we investigate whether baroreceptors’ and chemoreceptors’ signaling are able to drive neuronal plasticity within medullary and supramedullary pathways controlling autonomic outflow. Male Wistar rats submitted to sinoaortic denervation (SAD) or dopamine β-hydroxylase-saporin lesion (DBHx) and respective controls (SHAM) were allocated to training (T) or sedentary (S) protocols for 8 weeks. After hemodynamic measurements at rest, rats were deeply anesthetized for brain harvesting. The density of DBH and oxytocin (OT) cell bodies and terminals were analyzed in brainstem and hypothalamic brain areas (double immunofluorescence reactions, optic and confocal microscopy). In SHAM rats training augmented the density of DBH+ neurons in the nucleus of solitary tract, increased the density of ascending NORergic projections and the number of DBH+ boutons contacting preautonomic OT+ neurons into paraventricular hypothalamic preautonomic nuclei, augmented the density of local OTergic neurons and enhanced the density of OT+ terminals targeting brainstem autonomic areas. These plastic changes occurred simultaneously with reduced sympathetic/increased parasympathetic activity, augmented baroreflex sensitivity and reduced resting heart rate. SAD reduced the density of both DBH+ fibers ascending from brainstem to paraventricular nucleus of hypothalamus and preautonomic OT+ neurons projecting to the brainstem, abrogated training-induced plastic changes and autonomic adaptive responses without changing the treadmill performance. Minor neuroplastic changes with preserved baroreflex sensitivity were observed in trained rats after partial selective disruption of ascending NORergic projections. Our data indicated that afferent inputs conveyed by arterial baroreceptors and chemoreceptors are the main stimuli to drive both inactivity-induced and activity-dependent neuroplasticity within the autonomic circuitry.

Inconsistent effects of surgical and chemical castration on arterial baroreceptor dysfunction and cardiac and brainstem inflammation in endotoxic rats

Impaired cardiac autonomic and arterial baroreflex activity has been implicated in cardiovascular derangements induced by endotoxemia. In this communication, we tested the hypothesis that androgenic hormones contribute to endotoxic manifestations of arterial baroreflex dysfunction and related cardiac and central neuroinflammatory pathways in male rats. Baroreflex curves relating changes in heart rate to increases or decreases in blood pressure evoked by phenylephrine (PE) and sodium nitroprusside (SNP), respectively, were constructed in conscious sham‐operated and castrated rats treated with or without lipopolysaccharide (LPS, 10 mg/kg i.v.). Slopes of baroreflex curves were used as measures of baroreflex sensitivity (BRS). In sham rats, LPS caused significant reductions in BRS and increases in the immunohistochemical expression of NFκB in cardiac tissues as well as in brainstem neurons of the nucleus tractus solitarius (NTS) and rostral ventrolateral medulla (RVLM). The baroreflex depressant effect of LPS was maintained in CAS rats despite significant attenuation of the inflammatory response in cardiac and brainstem areas. We also evaluated the effects of pharmacologic inhibition of androgenic biosynthetic pathways on LPS responses. Whereas none of the LPS effects were altered after prior exposure to formestane (aromatase inhibitor, 15 mg/kg s.c)‐pretreated rats, the LPS‐evoked BRSPE, but not BRSSNP, depression and cardiac and neuronal inflammation disappeared in intact rats pretreated with degarelix (gonadotropin‐releasing hormone receptor blocker, 1 mg/kg s.c.). On the other hand, the prior inhibition of 5α‐reductase by finasteride (20 mg/kg s.c) did not affect baroreflex dysfunction induced by LPS and reduced cardiac, but not neuronal, NFκB expression. The data highlight advantageous effects for the inhibition of hypothalamic‐pituitary‐gonadal axis in counteracting baroreflex dysfunction caused by endotoxemia and predisposing cardiac and neuroinflammatory signals.Support or Funding InformationSupported by the Science and Technology Development Fund, Egypt (STDF Grant No. 14895)

Astroglial Regulation of Caloric Intake Following Acute High‐Fat Diet Exposure

Obesity and long‐term exposure to high fat diet (HFD) are both associated with peripheral and central inflammation. Acute HFD exposure, however, is also associated with neuroinflammation in brainstem areas responsible for control of gastric functions and energy homeostasis prior to the development of obesity. Neuroinflammation and astroglial activation are known to modulate neuronal activity and physiological outcomes, such as gastric motility, emptying, and food intake. Following initial HFD exposure and a brief (24hr) period of hyperphagia, both humans and rodent models regulate their caloric intake within 3–5 days. The neuroinflammation observed within the brainstem during acute HFD exposure may, therefore, contribute to the homeostatic regulation of caloric intake. The aim of this study is to test the hypothesis that restoration of energy balance during acute HFD exposure requires brainstem astroglial activation.Sprague‐Dawley rats, 6–8 weeks of age, were fed a control or HFD (14% or 60% kcal from fat, respectively) throughout the study. Immunohistochemical techniques were used to examine astrocyte (GFAP and S100β) and microglia (Iba1 and CD11b) morphology and activity state within the dorsal vagal complex (DVC) after 1,3,5, and 14 days of HFD exposure. Confocal microscopy was used to quantify astrocyte and microglial density, staining intensity, and morphology. Chronic 4th ventricular cannulae were implanted for the administration the astrocyte metabolism inhibitor, fluoroacetate, the microglial activation inhibitor, minocycline (5 and 10mg/mL in 5μL, respectively), or vehicle (PBS) to assess the role of astrocytes and microglia in the regulation of caloric intake. Food intake and body weight were measured twice daily for 10 days prior to, and throughout, HFD exposure. The effects of 4th ventricular administration of fluoroacetate on gastric emptying rates were additionally assessed using the 13C octanoic acid breath test technique.Immunohistochemical characterization of DVC microglia and astrocytes demonstrated an increase in Iba1 and GFAP staining intensity on days 3 and 5 of HFD exposure, which recovered by day 14 (3 Day: 225%, 210%, 5 Day: 195%, 280%, 14 Day: 124%, 92% of control total fluorescence (CTF), respectively, N=2). 4th ventricular application of fluoroacetate and minocycline attenuated the homeostatic regulation of caloric intake observed following acute HFD exposure, compared to vehicle controls (AUC: 242±11.4 vs. 264±2.8 vs. 187±10.6, P&lt;0.05 F=10.35, N=3–5) and preliminary data suggest that fluoroacetate also attenuates the homeostatic delay in gastric emptying observed in control conditions (t1/2: 102.5% vs 150.3% of baseline, respectively, N=1–2).The results from this study indicate that astrocyte and microglial activation occurs within 3–5 days of HFD exposure and is required for the homeostatic regulation of caloric intake and gastric emptying following acute HFD exposure. Understanding the physiological mechanisms responsible for energy homeostasis, and importantly, how this mechanism is lost, is critically important for the development of novel therapeutic targets for the treatment of obesity.Support or Funding InformationAPS UGSRF to CSNIH DK111667 to KNB NIH F31 118833 to CC

Gene expression in the liver of the rat induced in synthetic torpor

Torpor/hibernation is a survival strategy used by several mammals in periods of unfavorable environmental conditions, such as food shortage and low ambient temperature. It is characterized by an active reduction in metabolic rate followed by a decrease in body temperature. The decrease of metabolism and therefore in oxygen demand could be beneficial in many clinical conditions, such as, but not only, transplant and stroke. Recently, rats (non‐hibernating mammals) were successfully induced in a torpor‐mimicking state called synthetic torpor (Cerri, Annu Rev Physiol., 2017) by central inhibition of Raphe Pallidus (RPa), a key brainstem area involved in thermoregulation (Cerri et al., J Neurosci., 2013). Even though this model is very promising, it is still not known how this condition of induced etherotermy acts on a cellular level on a non‐hibernating mammal.Eight male Sprague‐Dawley rats, adapted to a standard Light‐Dark cycle of 12h‐12h (Light: 07 AM–07 PM), were used. Under general anesthesia (Diazepam, 5mg/kg, i.m., Ketamine, 100 mg/kg, i.p.), animals were implanted with a hypothalamic thermistor and a microcannula within the RPa. After recovery from surgery, starting at 7 AM, rats were divided in two groups: i) animals induced in a state of synthetic torpor by the repeated microinjections of the GABA‐A agonist muscimol (1mM, 120nl), within the RPa for 9 hours (Synthetic torpor, n=4); ii) homeothermic animals, injected with artificial cerebrospinal fluid (aCSF) within the RPa (Control, n =4), for 9 hours. At 4 PM, rats were euthanized and the liver was dissected and processed for gene expression analysis by RNA‐Seq.Analysis of the Differential Expression (DE) shows that in synthetic torpor a total of 1107 mRNA sequences were significantly up‐regulated, among which genes involved in the metabolic switch to beta‐oxidation of free fatty acids (fatty acid binding proteins (FABP), Peroxisome proliferator‐activated receptor (PPAR) family, Pyruvate dehydrogenase lipoamide kinase isozyme 4 (PDK4), Carnitine Palmitoyltransferase 1α (CPT1α)) and 1337 significantly down‐regulated.In a preliminary analysis, we report that several upregulated genes in synthetic torpor are known to be upregulated in hibernation as well. These preliminary findings suggest that the specific adaptation observed in natural torpor may be replicated also in non hibernators. Significantly upregulated mRNA expression of genes involved in fatty acid metabolism, in rats induced in synthetic torpor (Synthetic torpor, n=4) vs normothermic ones (Control, n=4) expressed in values of log2FC (FC=fold change). On the right side, their corresponding known function, and a list of hibernating species where a significant upregulation of the genes has been observed in literature. mRNA log2FC Function Upregulated in Fatty‐acid binding proteins (FABP) Facilitation of β‐oxidation in mitochondria Myotis lucifugus (Eddy&amp; Storey, 2004) Ictidomys tridecemlineatus (Epperson et al., 2010) FABP5 1.05 FABP9 1.65 FABP12 1.42 Peroxisome proliferator‐activated receptor (PPAR) family Safe deposition and consumption of fatty acid, avoiding the associated inflammatory risks (Nunn et al. 2007). Linked to the integration of nutritional information and circadian rhythms (Kohsaka &amp; Bass, 2007; Green et al. 2008). Spermophilus tridecemlineatus (Eddy et al., 2004) Myotis lucifugus (Eddy&amp; Storey, 2004) PPARGC1a 3.40 PPARGC1b 1.80 Pyruvate dehydrogenase lipoamide kinase isozyme 4 Shift away from the oxidation of carbohydrates and toward the combustion of stored fatty acids as the primary source of energy during torpor (Buck et al., 2002) Ictidomys Tridecemlineatus (Buck et al., 2002) PDK4 4.03 Carnitine Palmitoyltransferase 1α Fatty acid catabolism Urocitellus parryii (Williams et al., 2011) CPT1α 1.08

Connection Input Mapping and 3D Reconstruction of the Brainstem and Spinal Cord Projections to the CSF-Contacting Nucleus.

ObjectiveTo investigate whether the CSF-contacting nucleus receives brainstem and spinal cord projections and to understand the functional significance of these connections.MethodsThe retrograde tracer cholera toxin B subunit (CB) was injected into the CSF-contacting nucleus in Sprague-Dawley rats according the previously reported stereotaxic coordinates. After 7–10 days, these rats were perfused and their brainstem and spinal cord were sliced (thickness, 40 μm) using a freezing microtome. All the sections were subjected to CB immunofluorescence staining. The distribution of CB-positive neuron in different brainstem and spinal cord areas was observed under fluorescence microscope.ResultsThe retrograde labeled CB-positive neurons were found in the midbrain, pons, medulla oblongata, and spinal cord. Four functional areas including one hundred and twelve sub-regions have projections to the CSF-contacting nucleus. However, the density of CB-positive neuron distribution ranged from sparse to dense.ConclusionBased on the connectivity patterns of the CSF-contacting nucleus receives anatomical inputs from the brainstem and spinal cord, we preliminarily conclude and summarize that the CSF-contacting nucleus participates in pain, visceral activity, sleep and arousal, emotion, and drug addiction. The present study firstly illustrates the broad projections of the CSF-contacting nucleus from the brainstem and spinal cord, which implies the complicated functions of the nucleus especially for the unique roles of coordination in neural and body fluids regulation.

Usefulness of diffusion tensor imaging findings as biomarkers for amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease. However, no reliable biomarkers have been identified to represent the clinical status. This study aimed to investigate whether diffusion tensor imaging (DTI) findings are useful imaging biomarkers to indicate the clinical status of ALS patients. Ninety-six probable or definite ALS cases and 47 age- and sex-matched, normal controls were enrolled. Demographic and clinical data were collected at the time of DTI. DTI data were acquired using a 3-Tesla magnetic resonance imaging scanner and analysed by voxel-wise statistical analyses for fractional anisotropy, axial diffusivity, radial diffusivity, mean diffusivity, and mode of anisotropy. Compared with the healthy control group, the ALS group had significant differences in DTI scalars in the diffuse tracts of the brain, which was predominant in the corticospinal tract at the brainstem and cerebellar peduncle area. Furthermore, the DTI values correlated with the ALS functional rating scale-revised (ALSFRS-R) scores and the delta ALSFRS-R score representing the rate of disease progression. The subgroup analysis revealed a more severe and widespread brain degeneration was observed in rapidly progressive ALS. Therefore, our results suggest that DTI findings are useful as imaging biomarkers for evaluating the clinical severity and rate of disease progression in ALS.

Attenuated baroreflex in a Parkinson's disease animal model coincides with impaired activation of non-C1 neurons.

Orthostatic hypotension is one of the most common symptoms observed in Parkinson's disease (PD), a neurodegenerative disease caused by death of dopaminergic neurons in the substantia nigra pars compacta (SNc), and it is associated with denervation of the heart and impairment of the baroreflex. Here, we aimed to investigate if the impaired baroreflex was associated with lower activation of cardiovascular brainstem areas in a 6-hydroxydopamine (6-OHDA) animal model of PD. The PD model was generated with male Wistar rats by injection of 6-OHDA or vehicle into the striatum. After 20 or 60days, the femoral vein and artery were cannulated to assess cardiovascular parameters during injection of sodium nitroprusside (SNP) or phenylephrine (Phe). Brainstem slices were submitted to immunohistochemistry and immunofluorescence. After 6-OHDA injection, 75% of the dopaminergic neurons in the SNc were absent, confirming establishment of the PD model. Intravenous (iv) injection of SNP generated reduced hypotension and tachycardia response, and the noncatecholaminergic (nonC1) neurons of the rostral ventrolateral medulla (RVLM) were less activated. Additionally, iv injection of Phe increased blood pressure and bradycardia to the same extent and activated equivalent numbers of neurons in the nucleus of the solitary tract and the caudal ventrolateral medulla as well as cholinergic neurons of the dorsal motor nucleus of the vagus and the nucleus ambiguus between control and PD animals. In summary, these data showed that in the PD model, impairment of cardiovascular autonomic control was observed only during deactivation of the baroreflex, which could be related to reduced activation of non-C1 neurons within the RVLM.

Auditory Dysfunction in Parkinson's Disease.

PD is a progressive and complex neurological disorder with heterogeneous symptomatology. PD is characterized by classical motor features of parkinsonism and nonmotor symptoms and involves extensive regions of the nervous system, various neurotransmitters, and protein aggregates. Extensive evidence supports auditory dysfunction as an additional nonmotor feature of PD. Studies indicate a broad range of auditory impairments in PD, from the peripheral hearing system to the auditory brainstem and cortical areas. For instance, research demonstrates a higher occurrence of hearing loss in early-onset PD and evidence of abnormal auditory evoked potentials, event-related potentials, and habituation to novel stimuli. Electrophysiological data, such as auditory P3a, also is suggested as a sensitive measure of illness duration and severity. Improvement in auditory responses following dopaminergic therapies also indicates the presence of similar neurotransmitters (i.e., glutamate and dopamine) in the auditory system and basal ganglia. Nonetheless, hearing impairments in PD have received little attention in clinical practice so far. This review summarizes evidence of peripheral and central auditory impairments in PD and provides conclusions and directions for future empirical and clinical research. © 2020 International Parkinson and Movement Disorder Society.

Disrupted functional connectivity of the locus coeruleus in healthy adults with parental history of Alzheimer's disease

Prevention and early treatment strategies for Alzheimer's disease (AD) are hampered by the lack of research biomarkers. Neuropathological changes in the Locus Coeruleus (LC) are detected early in AD, and noradrenaline plays a neuroprotective role in LC projecting areas. We assessed functional connectivity (FC) of the brainstem in asymptomatic individuals at familial risk for AD hypothesizing that FC of the LC will be decreased in relation to not-at-risk individuals. Thirty-one offspring of patients with late-onset AD (O-LOAD) (22 females; mean age ± SD = 50.36 ± 8.32) and 28 healthy controls (HC) (20 females; mean age ± SD = 53.90 ± 8.44) underwent a neurocognitive evaluation and a resting-state functional magnetic resonance imaging acquisition. In FC analyses we evaluated whole-brain global connectivity of the brainstem area, and subsequently assessed seed-to-voxel FC patterns from regions showing between-group differences. O-LOAD individuals scored worse in neurocognitive measures of memory and overall functioning (pFDR<0.05). In imaging analyses, we observed that O-LOAD individuals showed decreased global connectivity in a cluster encompassing the left LC (peak = −4, −34, −32, pTFCE<0.05). Seed-to-voxel analyses revealed that this finding was largely explained by decreased connectivity between the LC and the cerebellar cortex. Moreover, FC between the LC and the left cerebellum correlated positively with delayed recall scores. FC between the LC and the cerebellar cortex is decreased in the healthy offspring of patients with LOAD, such connectivity measurements being associated with delayed memory scores. The assessment of FC between the LC and the cerebellum may serve as a biomarker of AD vulnerability.

Seizures induce obstructive apnea in DBA/2J audiogenic seizure-prone mice: Lifesaving impact of tracheal implants.

The mechanism(s) for sudden death in epilepsy (SUDEP) remain(s) unknown, but seizure spread to brainstem areas serving autonomic and respiratory function is critical. In a rat model, we established a mechanism for SUDEP that involves seizure-induced laryngospasm and obstructive apnea lasting until respiratory arrest. We hypothesized that DBA/2J mice, which display lethal audiogenic seizures, would be protected from death by implanting a tracheal T-tube as a surrogate airway. In a 2×2 design, mice were implanted with either open or closed tracheal T-tubes and treated with either low-dose ketamine/xylazine to moderate thoracic spasm during the tonic seizure phase or no drug. Animals receiving both treatments had the highest survival rate, followed by animals receiving the open tube without ketamine/xylazine. The odds ratio for survival was >20 higher with an open T-tube (odds ratio=24.14). The impact of open tracheal tubes indicates that the mechanism of death in DBA/2J mice involves seizure-induced upper airway obstruction until respiratory arrest. These results, our rat work, and our demonstration of inspiratory effort-based electromyographic signals and electrocardiographic abnormalities in rats and humans suggest that seizure-induced laryngospasm and obstructive apnea directly link seizure activity to respiratory arrest in these sudden death examples.

Impaired endothelium-mediated cerebrovascular reactivity promotes anxiety and respiration disorders in mice

Carbon dioxide (CO2), the major product of metabolism, has a strong impact on cerebral blood vessels, a phenomenon known as cerebrovascular reactivity. Several vascular risk factors such as hypertension or diabetes dampen this response, making cerebrovascular reactivity a useful diagnostic marker for incipient vascular pathology, but its functional relevance, if any, is still unclear. Here, we found that GPR4, an endothelial H+ receptor, and endothelial Gαq/11 proteins mediate the CO2/H+ effect on cerebrovascular reactivity in mice. CO2/H+ leads to constriction of vessels in the brainstem area that controls respiration. The consequential washout of CO2, if cerebrovascular reactivity is impaired, reduces respiration. In contrast, CO2 dilates vessels in other brain areas such as the amygdala. Hence, an impaired cerebrovascular reactivity amplifies the CO2 effect on anxiety. Even at atmospheric CO2 concentrations, impaired cerebrovascular reactivity caused longer apneic episodes and more anxiety, indicating that cerebrovascular reactivity is essential for normal brain function. The site-specific reactivity of vessels to CO2 is reflected by regional differences in their gene expression and the release of vasoactive factors from endothelial cells. Our data suggest the central nervous system (CNS) endothelium as a target to treat respiratory and affective disorders associated with vascular diseases.

MiR-22 and cerebral microbleeds in brainstem and deep area are associated with depression one month after ischemic stroke.

In this study, we aimed to explore the relationship among miR-22, deep cerebral microbleeds (CMBs), and post-stroke depression (PSD) 1 month after ischemic stroke. We consecutively recruited 257 patients with first-ever and recurrent acute cerebral infarction and performed PSD diagnosis in accordance with the Diagnostic and Statistical Manual IV criteria for depression. Clinical information, assessments of stroke severity, and imaging data were recorded on admission. We further detected plasma miR-22 using quantitative PCR and analyzed the relationship among miR-22, clinical data, and PSD using SPSS 23.0 software. Logistic regression showed that deep (OR=1.845, 95%CI: 1.006-3.386, P=0.047) and brain stem CMBs (OR=2.652, 95%CI: 1.110–6.921, P=0.040), as well as plasma miR-22 levels (OR=2.094, 95%CI: 1.066–4.115, P=0.032) were independent risk factors for PSD. In addition, there were significant differences in baseline National Institutes of Health Stroke Scale scores (OR=1.881, 95%CI: 1.180–3.011, P=0.007) and Widowhood scores (OR=1.903, 95%CI: 1.182–3.063, P=0.012). Analysis of the receiver operating curve (AUC=0.723, 95%CI: 0.562–0.883, P=0.016) revealed that miR-22 could predict PSD one month after ischemic stroke. Furthermore, plasma miR-22 levels in brainstem and deep CMBs patients showed an upward trend (P=0.028) relative to the others. Patients with acute ischemic stroke, having brainstem and deep cerebral microbleeds, or a higher plasma miR-22 were more likely to develop PSD. These findings indicate that miR-22 might be involved in cerebral microvascular impairment and post-stroke depression.