Marker Of Neuronal Activation Research Articles

Spectral graph modeling reveals global slowing of neurophysiological network transmission in Alzheimer’s disease

AbstractBackgroundAlzheimer’s disease (AD) is the most common form of dementia, progressively impairing memory and cognition. While various neuroimaging studies have revealed functional network abnormalities in patients with AD, how these relate to aberrant neuronal circuit mechanisms remains unclear. In order to answer these questions, we employed a spectral graph‐theory based model (SGM) to identify abnormal biophysical markers of neuronal activity in AD.MethodSGM is an analytic model that describes how the long‐range fiber projections in the brain mediate and couple the excitatory and inhibitory activity of local neuronal subpopulations. Unlike other coupled models, the SGM is linear, available in closed‐form, and parameterized by a small set of global parameters. This facilitates their rapid and unambiguous inference which we performed here on a well characterized clinical population of patients with AD (N = 88) and a cohort of age‐matched healthy controls (N = 88). We estimated SGM parameters that best captured the regional magnetoencephalography (MEG) frequency spectra of patients with AD and age‐matched controls.ResultSGM was able to capture the regional MEG frequency spectra of patients with AD and healthy controls, specifically, the abnormal slowing of neural oscillations in AD (Fig 1A). Patients with AD have significantly elevated long‐range excitatory neuronal time constant (tG) compared to controls (p < 0.001). Time constant tG is also the most important feature for accurate classification of patients with AD from controls (Area Under Curve = 0.85; Fig 1B). Lastly, higher tG is negatively correlated with global cognitive decline score (p = 0.02; Fig 1C).ConclusionThese results indicate that a global impairment in the long‐range excitatory neuronal activity is associated with abnormal spectral signatures and cognitive deficits in AD. Intriguingly, our work is able to recapitulate the spatial and spectral patterns of AD‐related functional activity without introducing any spatial heterogeneity whatsoever; indeed, the SGM model is entirely global and spatially‐invariant. This raises the possibility that a global increase in the long‐range excitatory time constant might be a sufficient factor underlying observed spatiotemporal alterations of neuronal activity in AD. Our findings provide new insights into potential mechanistic links between abnormal neural oscillations and their cellular correlates in AD.

Interneuron hyperexcitability in an APP/PS1 mouse model of Alzheimer’s disease

AbstractBackgroundNeuronal hyperexcitability is commonly observed in Alzheimer’s disease (AD) patients and in mouse models of AD. What is not clear yet is whether hyperexcitability occurs in all neurons or whether certain types of neurons are selectively vulnerable towards developing a hyperexcitable phenotype.MethodElectrophysiological recordings were performed in hippocampal slices from APP/PS1 mice to measure intrinsic and network properties of excitatory pyramidal neurons and of inhibitory parvalbumin (PV)‐positive interneurons. Cell type‐specific chemogenetic interventions were used to selectively reverse the hyperexcitable phenotype of these neurons. The outcome of these interventions was measured using hippocampal slice physiology, local field potential (LFP) recordings and behavioral assessment.ResultThe intrinsic excitability of hippocampal PV interneurons was significantly higher in APP/PS1 mice at 3‐4 months of age whereas pyramidal neurons were not affected at this age. Increased excitability of PV interneurons coincided with impaired learning and memory in the Morris water maze. Reducing the activity of PV neurons using chemogenetics resulted in a complete and long‐lasting rescue of PV cell excitability, network properties and learning and memory. LFP recordings revealed changes in oscillatory power and excitation/inhibition balance that could be related to early PV cell hyperexcitability and may translate to novel EEG biomarkers to detect AD at an early stage in humans.ConclusionHyperexcitability of hippocampal PV interneurons is an early cellular phenotype in APP/PS1 mice that is causally related to neuronal network and memory impairments, whereas pyramidal cells only become hyperexcitable at later disease stages. These findings are relevant for AD as they may help to identify neuronal activity markers that are specific for early disease stages as well as cell type‐specific ion channels or receptors that can be targeted to treat AD in its earliest stage.

Short-term stimulations of the entopeduncular nucleus induce cerebellar changes of c-Fos expression in an animal model of paroxysmal dystonia

Deep brain stimulation (DBS) of the globus pallidus internus (entopeduncular nucleus, EPN, in rodents) is important for the treatment of drug-refractory dystonia. The pathophysiology of this movement disorder and the mechanisms of DBS are largely unknown. Insights into the mechanisms of DBS in animal models of dystonia can be helpful for optimization of DBS and add-on therapeutics. We recently found that short-term EPN-DBS with 130 Hz (50 µA, 60 µs) for 3 h improved dystonia in dtsz hamsters and reduced spontaneous excitatory cortico-striatal activity in brain slices of this model, indicating fast effects on synaptic plasticity. Therefore, in the present study, we examined if these effects are related to changes of c-Fos, a marker of neuronal activity, in brains derived from dtsz hamsters after these short-term DBS or sham stimulations. After DBS vs. sham, c-Fos intensity was increased around the electrode, but the number of c-Fos+ cells was not altered within the whole EPN and projection areas (habenula, thalamus). DBS did not induce changes in striatal and cortical c-Fos+ cells as GABAergic (GAD67+ and parvalbumin-reactive) neurons in motor cortex and striatum. Unexpectedly, c-Fos+ cells were decreased in deep cerebellar nuclei (DCN) after DBS, suggesting that cerebellar changes may be involved in antidystonic effects already during short-term DBS. However, the present results do not exclude functional changes within the basal ganglia–thalamo-cortical network, which will be further investigated by long-term EPN stimulations. The present study indicates that the cerebellum deserves attention in ongoing examinations on the mechanisms of DBS in dystonia.

Drug-detecting bioelectronic nose based on odor cue memory combined with a brain computer interface

The international drug situation is increasingly, various new drugs are hidden in public places through changing forms and packaging, which brings new challenges to drug enforcement. This study proposes a drug-detecting bioelectronic nose based on odor cue memory combined with brain-computer interface and optogenetic regulation technologies. First, the rats were trained to generate positive memories of drug odors through food reward training, and multichannel microelectrodes were implanted into the DG region of the hippocampus for responsible memory retrieval, the spike signals of individual neurons and the local field potential signals of population neurons in the brain region were collected for pattern recognition and analysis. Preliminary experimental results have shown that when low-dose drugs are buried in a hidden area, rats can find the location of the drugs in a very short time, and when close to the relevant area, there is a significant change in the energy value and time-frequency spectrum signal coupling of the returned data, which can be extracted to indicate that the rats have found the drugs. Second, we labled the neuronal activity marker c-fos and revealed more robust activation in the DG region following odor detection. We modulated these neurons through neuroregulatory technology, so that the rats could recognize drugs by retrieving memories more quickly. We conceive that the drug-detecting rat robot can detect trace amounts of various drugs in complex terrain and multiple scenes, which is of great significance for anti-drug work in the future.

SAT601 The Role Of The Melanocortin System In Ovine Puberty

Abstract Disclosure: E.G. Aerts: None. M.J. Griesgraber: None. A. Thomson: None. M. Brown: None. A. Seman: None. S.L. Hardy: None. R.L. Goodman: None. C. Nestor: None. S.M. Hileman: None. The neural mechanisms that regulate the timing of puberty onset are not completely known. In several species, including sheep, puberty onset relies on an increase in gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) secretion as a result of decreased sensitivity to estradiol (E2) inhibition. Additionally, it is unclear how E2 acts in the hypothalamus to inhibit GnRH/LH secretion, as GnRH neurons do not contain estrogen receptor alpha (ERα). Neurons within the arcuate nucleus (ARC) of the hypothalamus that contain kisspeptin, neurokinin B, and dynorphin (KNDy neurons) are critical for the generation of GnRH pulses and contain ERα. Data from our laboratory suggests that KNDy neurons, while critical, may be responding to other inputs that time puberty onset. Proopiomelanocortin (POMC) and Agouti-related peptide (AgRP) neurons in the ARC have been shown to contain ERα and provide input to KNDy neurons, which contain the melanocortin 3 and 4 receptor (MC3R, MC4R). The goal of this work was to assess POMC- and AgRP-positive cell numbers, input onto KNDy neurons, and neuronal activity changes in a puberty-specific manner. Female sheep were ovariectomized and given subcutaneous E2 implants at 5 months (prepubertal, n=4), 8 months (peripubertal, n=5), and 10 months (postpubertal, n=5) of age. Two weeks after surgery, blood samples were collected via jugular venipuncture every 12 minutes for 4 hours and assessed for LH. The sheep were then sacrificed and hypothalamic tissue was perfused, collected, and prepared for staining. The tissue was assessed via immunohistochemistry for POMC, AgRP, kisspeptin, NKB, and c-Fos, a known marker of neuronal activity. Pulsatile LH secretion was, as expected, reduced at 5 months and highest at 10 months. ARC POMC cell numbers did not significantly change over development (p>0.10). The number of ARC POMC close contacts onto ARC kisspeptin neurons increased significantly with development (p<0.05), as well as the percentage of ARC POMC neurons expressing c-Fos (p<0.05). ARC AgRP cell numbers and the percentage of AgRP cells colocalized with c-Fos decreased significantly over time (p<0.05). The number of AgRP close contacts onto ARC NKB cells is currently being analyzed. The percentage of NKB cells colocalizing c-Fos throughout pubertal development also increased significantly (p<0.05). This data supports the hypothesis that the ARC melanocortin system impacts KNDy neurons to regulate GnRH/LH secretion throughout pubertal development. Presentation: Saturday, June 17, 2023

FRI001 Tanycytic Thyroid-stimulating Hormone Receptor Activation Increases Blood-Hypothalamus Barrier Permeability And Induces Appetite In Female Mice

Abstract Disclosure: H.S. Kannangara: None. B. Jocoll: None. S. Miyashita: None. A. Gumerova: None. F. Korkmaz: None. R. Witztum: None. S. Sims: None. U. Cheliadinova: None. G. Pevnev: None. O. Moldavski: None. T. Frolinger: None. T. Yuen: None. V. Ryu: None. M. Zaidi: None. In addition to its well-known action to trigger thyroid hormone production, thyroid-stimulating hormone (TSH) is released in the brain, and its receptor (TSHR) has been found in brain sites, including the tanycytes of the third ventricle, that regulate ingestive behavior and convey metabolic information across the blood-hypothalamus barrier (BHB). Our recent work highlights largely undiscovered role for TSHRs in the tanycytes. Here, we tested the hypothesis that tanycytic TSHR activation triggers rapid remodeling of BHB vascular permeability inducing appetite. We compared hypothalamic vascular permeability of food deprived (FD) and ad libitum fed (AL) Tshr+/- and their wild type (WT) counterparts exploiting transmission electron microscopy studies and immunofluorescence for constitutive tight junction protein Claudin-1 and homodimer glycoprotein MECA-32, primarily expressed in tanycytes and endothelial cells, respectively. Fasting significantly increased the organization of tanycytic honeycomb pattern of Claudin-1 and fenestral MECA-32-associated diaphragms in the median eminence and arcuate nucleus implying decreased BHB vascular permeability in Tshr+/- mice. Transmission electron microscopy confirmed immunofluorescence results. In a separate gain-of-function experiment, TSHR activation by the small molecule MS438 increased BHB vascular permeability as evidenced by decreased Claudin-1 and MECA-32 immunostaining. Tanycytic TSHR activation significantly increased both food foraging and intake as during one-hour refeeding after FD. Surprisingly, refeeding restored neuronal activation marker c-Fos expression in the paraventricular nucleus of the hypothalamus, parabrachial nucleus and nucleus of the solitary tract, though failed to do so in the paraventricular nucleus and nucleus of the solitary tract of MS438-injected mice. Collectively, these data infer that modulation of tanycytic TSHRs plays an important role in BHB plasticity in relation with ingestive behavior. Presentation: Friday, June 16, 2023

Arc/Arg3.1 expression in the brain tissues during the learning process in Alzheimer's disease animal models

Introduction. Arc/Arg3.1 is a common marker of neuronal activation for learning and memorizing. Some experimental data show the Arc/Arg3.1 expression in the post-mitotic neurons of the neurogenic niches. At the same time, we still have to understand the importance of such an expression for neurogenesis induced by the learning or memorizing processes, in health and in disease.
 Objective: to evaluate the changes in Arc/Arg3.1 expression in the post-mitotic neurons and to assess the proliferative activity of the neurogenic niche cells in Alzheimer's disease animal models.
 Materials and methods. We divided the C57Bl/6В mice into 2 groups: experimental (n = 15) and control (n = 15). The experimental group were injected with the amyloid- oligomers 2535 in their CA1 hippocampal region while the control mice received normal saline injections in the same region. Passive Avoidance Test (PAT) was used to assess the cognitive functions from the day 9 after the intervention. One hour after each test session we collected the samples of brain tissues to immunohistochemically assess them for the Arc/Arg3.1 expression and PCNA cell proliferation marker.
 Results. At day 11 the count of Arc/Arg3.1+NeuN+ cells in the subgranular zone had significantly increased. In animal neurodegeneration models the 1st and 2nd PAT sessions were associated with a significant increase in Arc/Arg3.1+NeuN+ cells, although by the day 11 their count significantly decreased. The count of Arc/Arg3.1+ cells in the subventricular and subgranular zones had increased after the 3rd PAT session in the control group while in Alzheimer's disease animal models this was observed only after the 2nd PAT session. Preserved Arc/Arg3.1 expression in the subventricular zone is associated with the increased PCNA cell prolifera- tion marker expression. At the same time, the toxic effect of the amyloid- oligomers suppressed the cells' proliferative activity in the subgranular zone at day 9.
 Conclusions. Despite the toxic effect of the amyloid- oligomers 2535, the post-mitotic neurons of the neurogenic niches retained the ability to express Arc/Arg3.1 in vivo. The obtained results show a transient increase in sensitivity of the post-mitotic neurons of the neurogenic niches for the learning stimuli in the early stages of the Alzheimer-type neurodegeneration.

KCNK3 channel is important for the ventilatory response to hypoxia in rats

To clarify the contribution of KCNK3/TASK-1 channel chemoreflex in response to hypoxia and hypercapnia, we used a unique Kcnk3-deficient rat. We assessed ventilatory variables using plethysmography in Kcnk3-deficient and wild-type rats at rest in response to hypoxia (10% O2) and hypercapnia (4% CO2). Immunostaining for C-Fos, a marker of neuronal activity, was performed to identify the regions of the respiratory neuronal network involved in the observed response.Under basal conditions, we observed increased minute ventilation in Kcnk3-deficient rats, which was associated with increased c-Fos positive cells in the ventrolateral region of the medulla oblongata. Kcnk3-deficient rats show an increase in ventilatory response to hypoxia without changes in response to hypercapnia. In Kcnk3-deficient rats, linked to an increased hypoxia response, we observed a greater increase in c-Fos-positive cells in the first central relay of peripheral chemoreceptors and Raphe Obscurus. This study reports that KCNK3/TASK-1 deficiency in rats induces an inadequate peripheral chemoreflex, alternating respiratory rhythmogenesis, and hypoxic chemoreflex.

Bidirectional synaptic changes in deep and superficial hippocampal neurons following in vivo activity

Neuronal activity during experience is thought to induce plastic changes within the hippocampal network that underlie memory formation, although the extent and details of such changes invivo remain unclear. Here, we employed a temporally precise marker of neuronal activity, CaMPARI2, to label active CA1 hippocampal neurons invivo, followed by immediate acute slice preparation and electrophysiological quantification of synaptic properties. Recently active neurons in the superficial sublayer of stratum pyramidale displayed larger post-synaptic responses at excitatory synapses from area CA3, with no change in pre-synaptic release probability. In contrast, invivo activity correlated with weaker pre- and post-synaptic excitatory weights onto pyramidal cells in the deep sublayer. Invivo activity of deep and superficial neurons within sharp-wave/ripples was bidirectionally changed across experience, consistent with the observed changes in synaptic weights. These findings reveal novel, fundamental mechanisms through which the hippocampal network is modified by experience to store information.

Altered Fear Behavior in Aeroallergen House Dust Mite Exposed C57Bl/6 Mice: A Model of Th2-skewed Airway Inflammation.

There is a growing interest for studying the impact of chronic inflammation, particularly lung inflammation, on the brain and behavior. This includes asthma, a chronic inflammatory condition, that has been associated with psychiatric conditions such as posttraumatic stress disorder (PTSD). Although asthma is driven by elevated production of Th2 cytokines (IL-4, IL-5 and IL-13), which drive asthma symptomology, recent work demonstrates that concomitant Th1 or Th17 cytokine production can worsen asthma severity. We previously demonstrated a detrimental link between PTSD-relevant fear behavior and allergen-induced lung inflammation associated with a mixed Th2/Th17-inflammatory profile in mice. However, the behavioral effects of Th2-skewed airway inflammation, typical to mild/moderate asthma, are unknown. Therefore, we investigated fear conditioning/extinction in allergen house dust mite (HDM)-exposed C57Bl/6 mice, a model of Th2-skewed allergic asthma. Behaviors relevant to panic, anxiety, and depression were also assessed. Furthermore, we investigated the accumulation of Th2/Th17-cytokine-expressing cells in lung and brain, and the neuronal activation marker, ΔFosB, in fear regulatory brain areas. HDM-exposed mice elicited lower freezing during fear extinction with no effects on acquisition and conditioned fear. No HDM effect on panic, anxiety or depression-relevant behaviors was observed. While HDM evoked a Th2-skewed immune response in lung tissue, no significant alterations in brain Th cell subsets were observed. Significantly reduced ΔFosB+ cells in the basolateral amygdala of HDM mice were observed post extinction. Our data indicate that allergen-driven Th2-skewed responses may induce fear extinction promoting effects, highlighting beneficial interactions of Th2-associated immune mediators with fear regulatory circuits.

Gestational intermittent hypoxia increases FosB-immunoreactive perikaryas in the paraventricular nucleus of the hypothalamus of adult male (but not female) rats.

Sleep-disordered breathing is a respiratory disorder commonly experienced by pregnant women. The recurrent hypoxaemic events associated with sleep-disordered breathing have deleterious consequences for the mother and fetus. Adult male (but not female) rats born to dams subjected to gestational intermittent hypoxia (GIH) have a higher resting blood pressure than control animals and show behavioural/neurodevelopmental disorders. The origin of this persistent, sex-specific effect of GIH in offspring is unknown, but disruption of the neuroendocrine stress pathways is a key mechanism by which gestational stress increases disease risk in progeny. Using FosB immunolabelling as a chronic marker of neuronal activation, we determined whether GIH augments basal expression of FosB in the perikaryas of cells in the paraventricular nucleus of the hypothalamus (PVN), a key structure in the regulation of the stress response and blood pressure. From gestational day 10, female rats were subjected to GIH for 8h/day (light phase) until the day before delivery (gestational day 21); GIH consisted of 2min hypoxic bouts (10.5% O2 ) alternating with normoxia. Control rats were exposed to intermittent normoxia over the same period (GNX). At adulthood (10-15weeks), the brains of male and female rats were harvested for FosB immunohistochemistry. In males, GIH augmented PVN FosB labelling density by 30%. Conversely, PVN FosB density in GIH females was 28% lower than that of GNX females. We conclude that GIH has persistent and sex-specific impacts on the development of stress pathways, thereby offering a plausible mechanism by which GIH can disturb neural development and blood pressure homeostasis in adulthood. NEW FINDINGS: What is the central question of this study? In pregnant women, sleep apnoea increases the risk of disease for the offspring at various life stages. Given that gestational stress disrupts the programming of the stress pathways, we determined whether exposing female rats to gestational intermittent hypoxia (GIH) activates hypothalamic neurons regulating the stress response in adult rats. What is the main finding and its importance? Using FosB immunolabelling as a marker of marker of neuronal activation, we showed that GIH augmented basal activation of the paraventricular nucleus of the hypothalamus in males, but not females. Disruption of the stress pathways is a new hypothesis to explain the persistent and sex-specific impacts of GIH on offspring health.

The parabrachial to central amygdala pathway is critical to injury-induced pain sensitization in mice

The spino-ponto-amygdaloid pathway is a major ascending circuit relaying nociceptive information from the spinal cord to the brain. Potentiation of excitatory synaptic transmission in the parabrachial nucleus (PBN) to central amygdala (CeA) pathway has been reported in rodent models of persistent pain. However, the functional significance of this pathway in the modulation of the somatosensory component of pain was recently challenged by studies showing that spinal nociceptive neurons do not target CeA-projecting PBN cells and that manipulations of this pathway have no effect on reflexive-defensive somatosensory responses to peripheral noxious stimulation. Here, we showed that activation of CeA-projecting PBN neurons is critical to increase both stimulus-evoked and spontaneous nociceptive responses following an injury in male and female mice. Using optogenetic-assisted circuit mapping, we confirmed a functional excitatory projection from PBN→CeA that is independent of the genetic or firing identity of CeA cells. We then showed that peripheral noxious stimulation increased the expression of the neuronal activity marker Fos in CeA-projecting PBN neurons and that chemogenetic inactivation of these cells decreased behavioral hypersensitivity in models of neuropathic and inflammatory pain without affecting baseline nociception. Lastly, we showed that chemogenetic activation of CeA-projecting PBN neurons is sufficient to induced bilateral hypersensitivity without injury. Together, our results indicate that the PBN→CeA pathway is a key modulator of pain-related behaviors that can increase reflexive-defensive and affective-motivational responses to somatosensory stimulation in injured states without affecting nociception under normal physiological conditions.

Cannabidiol modulates chronic neuropathic pain aversion behavior by attenuation of neuroinflammation markers and neuronal activity in the corticolimbic circuit in male Wistar rats

Chronic neuropathic pain (CNP) is a vast world health problem often associated with the somatosensory domain. This conceptualization is problematic because, unlike most other sensations that are usually affectively neutral and may present emotional, affective, and cognitive impairments. Neuronal circuits that modulate pain can increase or decrease painful sensitivity based on several factors, including context and expectation. The objective of this study was to evaluate whether subchronic treatment with Cannabidiol (CBD; 0.3, 3, and 10 mg/kg intraperitoneal route - i.p., once a day for 3 days) could promote pain-conditioned reversal, in the conditioned place preference (CPP) test, in male Wistar rats submitted to chronic constriction injury (CCI) of the sciatic nerve. Then, we evaluated the expression of astrocytes and microglia in animals treated with CBD through the immunofluorescence technique. Our results demonstrated that CBD promoted the reversal of CPP at 3 and 10 mg/kg. In CCI animals, CBD was able to attenuate the increase in neuronal hyperactivity, measured by FosB protein expression, in the regions of the corticolimbic circuit: anterior cingulate cortex (ACC), complex basolateral amygdala (BLA), granular layer of the dentate gyrus (GrDG), and dorsal hippocampus (DH) - adjacent to subiculum (CA1). CBD also prevented the increased expression of GFAP and IBA-1 in CCI animals. We concluded that CBD effects on CNP are linked to the modulation of the aversive component of pain. These effects decrease chronic neuronal activation and inflammatory markers in regions of the corticolimbic circuit.

Aged mice are less susceptible to motion sickness and show decreased efferent vestibular activity compared to young adults.

The efferent vestibular system (EVS) is a feedback circuit thought to modulate vestibular afferent activity by inhibiting type II hair cells and exciting calyx-bearing afferents in the peripheral vestibular organs. In a previous study, we suggested EVS activity may contribute to the effects of motion sickness. To determine an association between motion sickness and EVS activity, we examined the effects of provocative motion (PM) on c-Fos expression in brainstem efferent vestibular nucleus (EVN) neurons that are the source of efferent innervation in the peripheral vestibular organs. c-Fos is an immediate early gene product expressed in stimulated neurons and is a well-established marker of neuronal activation. To study the effects of PM, young adult C57/BL6 wild-type (WT), aged WT, and young adult transgenic Chat-gCaMP6f mice were exposed to PM, and tail temperature (Ttail ) was monitored using infrared imaging. After PM, we used immunohistochemistry to label EVN neurons to determine any changes in c-Fos expression. All tissue was imaged using laser scanning confocal microscopy. Infrared recording of Ttail during PM indicated that young adult WT and transgenic mice displayed a typical motion sickness response (tail warming), but not in aged WT mice. Similarly, brainstem EVN neurons showed increased expression of c-Fos protein after PM in young adult WT and transgenic mice but not in aged cohorts. We present evidence that motion sickness symptoms and increased activation of EVN neurons occur in young adult WT and transgenic mice in response to PM. In contrast, aged WT mice showed no signs of motion sickness and no change in c-Fos expression when exposed to the same provocative stimulus.

Behavioral dissection of hunger states in Drosophila

Hunger is a motivational drive that promotes feeding, and it can be generated by the physiological need to consume nutrients as well as the hedonic properties of food. Brain circuits and mechanisms that regulate feeding have been described, but which of these contribute to the generation of motive forces that drive feeding is unclear. Here, we describe our first efforts at behaviorally and neuronally distinguishing hedonic from homeostatic hunger states in Drosophila melanogaster and propose that this system can be used as a model to dissect the molecular mechanisms that underlie feeding motivation. We visually identify and quantify behaviors exhibited by hungry flies and find that increased feeding duration is a behavioral signature of hedonic feeding motivation. Using a genetically encoded marker of neuronal activity, we find that the mushroom body (MB) lobes are activated by hedonic food environments, and we use optogenetic inhibition to implicate a dopaminergic neuron cluster (protocerebral anterior medial [PAM]) to α’/β’ MB circuit in hedonic feeding motivation. The identification of discrete hunger states in flies and the development of behavioral assays to measure them offers a framework to begin dissecting the molecular and circuit mechanisms that generate motivational states in the brain.

Behavioral dissection of hunger states in Drosophila.

Hunger is a motivational drive that promotes feeding, and it can be generated by the physiological need to consume nutrients as well as the hedonic properties of food. Brain circuits and mechanisms that regulate feeding have been described, but which of these contribute to the generation of motive forces that drive feeding is unclear. Here, we describe our first efforts at behaviorally and neuronally distinguishing hedonic from homeostatic hunger states in Drosophila melanogaster and propose that this system can be used as a model to dissect the molecular mechanisms that underlie feeding motivation. We visually identify and quantify behaviors exhibited by hungry flies and find that increased feeding duration is a behavioral signature of hedonic feeding motivation. Using a genetically encoded marker of neuronal activity, we find that the mushroom body (MB) lobes are activated by hedonic food environments, and we use optogenetic inhibition to implicate a dopaminergic neuron cluster (protocerebral anterior medial [PAM]) to α'/β' MB circuit in hedonic feeding motivation. The identification of discrete hunger states in flies and the development of behavioral assays to measure them offers a framework to begin dissecting the molecular and circuit mechanisms that generate motivational states in the brain.

2'-Fucosyllactose Alleviates Early Weaning-Induced Anxiety-Like Behavior, Amygdala Hyperactivity, and Gut Microbiota Changes.

Early life stress has a significant impact on development of the central nervous system (CNS), with lasting rather than transient consequences; therefore, it is important to alleviate these effects. In recent years, functional communication between the CNS and gut microbiota through the so-called brain-gut-microbiota axis has been examined, and it is likely that prebiotics contribute to development of the CNS through the gut microbiota. In this study, we performed behavioral, neurohistological, and fecal microbiota analyses in early-weaned mice to examine the effects of 2'-fucosyllactose (2'-FL), a human milk oligosaccharide, on anxiety induced by early life stress. Mice weaned at 17 d old (17-d mice) showed anxiety-like behaviors, such as decreased time in the open arms in the elevated plus maze test, compared to mice weaned at 24 d old (24-d mice). The number of cells that were positive for the neuronal activity marker c-Fos in the amygdala was also higher in 17-d mice. The behavioral and neural abnormalities caused by early weaning were alleviated by post-weaning ingestion of 2'-FL. The composition of the fecal microbiota differed among control diet-fed 24-d and 17-d mice, and 2'-FL diet-fed 17-d mice. These findings indicate that human milk oligosaccharides 2'-FL alleviate early stress-induced anxiety, amygdala hyperactivity, and gut microbiota changes.

Effect of Tiaoshen Changzhi acupuncture on behavior and striatum ΔFosB in rats with levodopa-induced dyskinesias

ABSTRACT This study aims to study the effffects of Tiaoshen Changzhi acupuncture on behavior and striatum ΔFosB in rats with Levodopa-induced Dyskinesias (LIDs). In this experimental study, Levodopa-induced Dyskinesia (LID) rat models were established by 6-OHDA double-target injection and randomly assigned to six groups, with ten rats in each group. The rats were subjected to difffferent interventions for 28 days, and their behavior was observed. Additionally, the content of ΔFosB, a marker of neuronal activation, in the rat striatum was detected by immunohistochemistry and qRT-PCR. In contrallateral rotation behavior experiment and AIM experiment, the score of the model group was significantly increased, compared with the model group, the score of the Western medicine group, the ordinary acupuncture group and the Tiaoshen Changzhi group was significantly decreased (P < 0.01), the score of the Western medicine group and the Tiaoshen Changzhi group was significantly lower than the ordinary acupuncture group (P < 0.01), there was no statistical significance between the Western medicine group and the Tiaoshen Changzhi group (P>0.05). In the left forelimb function test, the score of the model group was significantly decreased, and compared with the model group, the left forelimb function score of the Western medicine group, the ordinary acupuncture group and the Tiaoshen Changzhi group were significantly increased (P < 0.01). The left forelimb function score of the Western medicine group and the Tiaoshen Changzhi group was higher than the ordinary acupuncture group (P < 0.05, P < 0.01). There was no statistical significance between Western medicine group and Tiaoshen Changzhi group (P > 0.05). After treatment, the content of ΔFosB in the striatum of the Western medicine group, the ordinary acupuncture group and the Tiaoshen Changzhi acupuncture group all decreased, the Western medicine group was better than the ordinary acupuncture group (P < 0.01), and the Tiaoshen Changzhi acupuncture group was better than the ordinary acupuncture group (P < 0.05). Tiaoshen Changzhi acupuncture can improve the behavioral performance of LID rats, reduce abnormal involuntary movement and contralateral rotation behavior and enhance the motor function of the left forelimb of rats. One of its therapeutic mechanisms for LID may be to reduce the expression level of ΔFosB in the striatum of LID rats, thereby reducing the symptoms of LID rats.

Characteristics of MK-801-induced locomotor sensitization

Repeated administration of drugs of abuse leads to progressively greater behavioral responses; this phenomenon is referred to as behavioral sensitization. MK-801 blocks the N-methyl-d-aspartate (NMDA) receptor and elicits behavioral sensitization. Ketamine and phencyclidine, are also NMDA antagonists and have well-documented abuse potential. This study investigated the characteristics of MK-801-induced behavioral sensitization and found that it induced sensitization rapidly; only five consecutive treatments were required. The optimal dose for robust sensitization was also identified, which corresponded to the typical doses of abused NMDA antagonists (i.e., between the doses inducing antidepressant and anesthetic effects). Following MK-801-induced behavioral sensitization, changes were observed in the expression and/or phosphorylation of NMDA receptor subunits. While the expression of early growth response protein 1, which serves as a marker of neuronal activation, was affected by MK-801 sensitization, extracellular signal-regulated kinase phosphorylation was not associated with MK-801 treatment.

Input from afferent renal nerves is involved in progression of hypertensive heart failure through central vasopressin-mediated sympathoexcitation

Introduction: Paraventricular nucleus of hypothalamus (PVN), a control center of sympathetic outflow, receives the input from afferent renal nerves. Although acute stimulation of afferent renal nerves increases central sympathetic outflow, it remains unclear if the renal afferents contribute to progression of heart failure. Acute stimulation of afferent renal nerves was reported to increase plasma vasopressin concentration. In addition, central dendritic release of vasopressin by activation of vasopressin-expressing neurons located in the PVN may cause sympathoexcitation via stimulation of neighboring presympathetic neurons in the PVN. Therefore, we hypothesized that the chronic input from afferent renal nerves contributes to sympathoexcitation and hypertensive cardiac dysfunction along with activation of vasopressin-expressing neurons and presympathetic neurons in the PVN. Methods: Male Dahl salt-sensitive rats were fed low salt diet (LS) or 8% high salt diet from 6 weeks of age, and the high salt-fed rats were allocated to selective afferent renal denervation (HS-ARDN) or sham surgery (HS-Sham) at 9 weeks. The effect of ARDN on central sympathetic regulation was investigated at 12 weeks (pre-heart failure phase). In another cohort, its effect on cardiac phenotypes was evaluated at 16 weeks (heart failure phase). Results: At 12 weeks, plasma norepinephrine level was increased in HS-Sham compared to LS and was attenuated by ARDN (LS 188.7±16.5 pg/ml, HS-Sham 563.8±82.7 pg/ml, HS-ARDN 327.4±50.2 pg/ml; n=15, 12, 14; p&lt;0.05). The c-Fos expression, a marker of neuronal activity, in presympathetic neurons in the PVN was also increased in HS-Sham and attenuated in HS-ARDN, which was in parallel with the c-Fos expression in vasopressin-expressing neurons in the PVN. At 16 weeks, the decrease of left ventricular (LV) fractional shortening (HS-Sham 25.9±1.7 % vs LS 46.7±0.6 %, n=9, 9; p&lt;0.01) was improved in HS-ARDN (42.2±1.2 %, n=7; p&lt;0.01 vs HS-Sham). LV weight and lung weight were significantly increased in HS-Sham compared to LS (LV weight/body weight: 4.39±0.19 mg/g vs 2.53±0.03 mg/g; lung weight/body weight: 5.29±0.37 mg/g vs 3.55±0.05 mg/g; p&lt;0.05), and these changes were attenuated in HS-ARDN (LV weight/body weight: 3.73±0.14 mg/g; lung weight/body weight: 4.17±0.11 mg/g; p&lt;0.05 vs HS-Sham). Histological LV fibrosis and fibrosis marker expression, such as connective tissue growth factor, in LV were significantly attenuated in HS-ARDN compared to HS-Sham. ARDN did not significantly impact the high salt-induced blood pressure elevation in both cohorts. Conclusion: The input from afferent renal nerves contributes to cardiac dysfunction, probably via the central vasopressin-mediated sympathoexcitation even without blood pressure changes in hypertensive heart failure model. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.