The amygdaloid body of the family Delphinidae: a morphological study of its central nucleus through calbindin-D28k.

Introduction: The amygdala is a noticeable bilateral structure in the medial temporal lobe and it is composed of at least 13 different nuclei and cortical areas, subdivided into the deep nuclei, the superficial nuclei, and the remaining nuclei which contain the central nucleus (CeA). CeA mediates the behavioral and physiological responses associated with fear and anxiety through pituitary-adrenal responses by modulating the liberation of the hypothalamic Corticotropin Releasing Factor/Hormone. Methods: Five dolphins of three different species, belonging to the family Delphinidae (three striped dolphins, one common dolphin, and one Atlantic spotted dolphin), were used for this study. For a precise overview of the CeA's structure, thionine staining and the immunoperoxidase method using calbindin D-28k were employed. Results: CeA extended mainly dorsal to the lateral nucleus and ventral to the striatum. It was medial to the internal capsule and lateral to the optic tract and the medial nucleus of the amygdala. Discussion: The dolphin amygdaloid complex resembles that of primates, including the subdivision, volume, and location of the CeA.

Dysfunction of Small-Conductance Ca2+-Activated Potassium (SK) Channels Drives Amygdala Hyperexcitability and Neuropathic Pain Behaviors: Involvement of Epigenetic Mechanisms.

Neuroplasticity in the amygdala and its central nucleus (CeA) is linked to pain modulation and pain behaviors, but cellular mechanisms are not well understood. Here, we addressed the role of small-conductance Ca2+-activated potassium (SK) channels in pain-related amygdala plasticity. The facilitatory effects of the intra-CeA application of an SK channel blocker (apamin) on the pain behaviors of control rats were lost in a neuropathic pain model, whereas an SK channel activator (NS309) inhibited pain behaviors in neuropathic rats but not in sham controls, suggesting the loss of the inhibitory behavioral effects of amygdala SK channels. Brain slice electrophysiology found hyperexcitability of CeA neurons in the neuropathic pain condition due to the loss of SK channel-mediated medium afterhyperpolarization (mAHP), which was accompanied by decreased SK2 channel protein and mRNA expression, consistent with a pretranscriptional mechanisms. The underlying mechanisms involved the epigenetic silencing of the SK2 gene due to the increased DNA methylation of the CpG island of the SK2 promoter region and the change in methylated CpG sites in the CeA in neuropathic pain. This study identified the epigenetic dysregulation of SK channels in the amygdala (CeA) as a novel mechanism of neuropathic pain-related plasticity and behavior that could be targeted to control abnormally enhanced amygdala activity and chronic neuropathic pain.

Review on current status of Bonga, Afar, Menz, and Horro sheep breeds genetic improvement: Breeding program and progress.

This working paper reviews the research and development in genetic improvement and breeding strategies of Bonga, Menz, Afar and Horro sheep in Ethiopia. This review aims to provide structured information regarding the Ethiopian indigenous sheep breeds (Bonga, Afar, Menz, and Horro) breeding programs and its progress. Genetic diversity is an essential element for genetic improvement, preserving populations, evaluation and adapting to variable environmental situations. Sustainable breeding techniques and sensible use of indigenous breed have been developed as result of recent research approaches to the conservation of sheep genetic resources. However, there is still growing interest of the government and of farmers in different breeding program to improve indigenous sheep breeds. There is no comprehensive study showing the performance of indigenous sheep breeds (Bonga, Afar, Menz, and Horro) genetic improvement under different breeding program and its progress, both biological and economic, to substantiate the argument on the benefit of different breeding programs for smallholders farmers. Programs for the sheep breeds Menz, Afar, Horro, and Bonga have now been developed at the community level. The idea behind the nucleus breeding program is to develop elite breeding animals by gathering the finest male and female breeding participants from the population in one central location. The first stage in creating a breeding program is defining the breeding goals. Planning breeding programs requires a thorough grasp of the farmers' (beneficiaries') breeding goals and production objectives. Therefore, this review makes it evident that numerous instruments and techniques, including choice experiments, participatory rural assessment procedures, and rating animals from flocks, have been used to define and ascertain the breeding aim of Afar, Horro, Bonga and Menz sheep breeds in Ethiopia.

Multiple metabolic signals in the CeA regulate feeding: The role of AMPK.

BACKGROUND: The central nucleus of the amygdala (CeA) is part of the dopaminergic reward system and controls energy balance. Recently, a cluster of neurons was identified as responsive to the orexigenic effect of ghrelin and fasting. However, the signaling pathway by which ghrelin and fasting induce feeding is unknown. AMP-activated protein kinase (AMPK) is a cellular energy sensor, and its Thr172 phosphorylation (AMPKThr172) in the mediobasal hypothalamus regulates food intake. However, whether the expression and activation of AMPK in CeA could be one of the intracellular signaling activated in response to ghrelin and fasting eliciting food intake is unknown. AIM: To evaluate the activation of AMPK into CeA in response to ghrelin, fasting, and 2-deoxy-D-glucose (2DG) and whether feeding accompanied these changes. In addition, to investigate whether the inhibition of AMPK into CeA could decrease food intake. METHODS: On a chow diet, eight-week-old Wistar male rats were stereotaxically implanted with a cannula in the CeA to inject several modulators of AMPKα1/2Thr172 phosphorylation, and we performed physiological and molecular assays. KEY FINDINGS: Fasting increased, and refeeding reduced AMPKThr172 in the CeA. Intra-CeA glucose injection decreased feeding, whereas injection of 2DG, a glucoprivation inductor, in the CeA, increased food intake and blood glucose, despite faint increases in AMPKThr172. Intra-CeA ghrelin injection increased food intake and AMPKThr172. To further confirm the role of AMPK in the CeA, chronic injection of Melanotan II (MTII) in CeA reduced body mass and food intake over seven days together with a slight decrease in AMPKThr172. SIGNIFICANCE: Our findings identified that AMPK might be part of the signaling machinery in the CeA, which responds to nutrients and hormones contributing to feeding control. The results can contribute to understanding the pathophysiological mechanisms of altered feeding behavior/consumption, such as binge eating of caloric-dense, palatable food.

Investigations into the anatomical location, physiological function, clinical implications, and significance of the nucleus of Perlia.

BACKGROUND: The article discusses the investigations into the nucleus of Perlia (NP), a spindle-shaped nucleus located in the dorsal aspect of the oculomotor complex. However, there is still debate over its exact location and function, with conflicting findings in nonhuman primates. Therefore, the current study aimed the describe the location, function, clinical and surgical implications of NP. METHODS: A systematic review was conducted to identify studies related to the following MeSH terms: "perlia nucleus" OR "nucleus of "perlia" OR "convergence nucleus" OR "nucleus of convergence" OR "Perlia's nucleus". The search was conducted until September 2022. RESULTS: The location of the NP has been consistently reported in various studies, with most describing it as situated ventral to the Edinger-Westphal nucleus (EW) and dorsomedial to the oculomotor complex. The incidence of the NP in humans has been reported to range from 9 to 40%. In primates, it was observed to be absent in 77% of midbrains, while well developed in 9%. It is also noted that the NP is not a single nucleus, but rather a group of nuclei that are interconnected and involved in the coordination of eye movements that contain parasympathetic neurons. CONCLUSIONS: The study of the NP holds clinical implications for understanding the neural mechanisms underlying the irregularities in the pupillary light reflex, such as anisocoria or abnormal responses to light, diagnosis, and treatment of neurological disorders like Horner's syndrome, and management of eye movement disorders including one-and-a-half syndrome, vertical gaze palsy, skew deviation and ptosis. The current study also highlighted the limitations of previous studies, including variations in the reported prevalence of the NP, limitations of the histological techniques, and inconsistent findings across human and animal studies.

Alteration of serotonin release response in the central nucleus of the amygdala to noxious and non-noxious mechanical stimulation in a neuropathic pain model rat.

Previously, we found that serotonin (5-HT) release in the central nucleus of the amygdala (CeA) of anesthetized rats decreases in response to innocuous stroking of the skin, irrespective of stimulus laterality, but increases in response to noxious pinching applied to a hindlimb contralateral to the 5-HT measurement site. The aim of the present study was to determine whether intra-CeA 5-HT release responses to cutaneous stimulation were altered in an animal model of neuropathic pain induced by ligation of the left L5 spinal nerve. In anesthetized neuropathic pain model rats, stroking of the left hindlimb increased 5-HT release in the CeA, whereas stroking of the right hindlimb decreased it. Meanwhile, pinching of the left hindlimb increased intra-CeA 5-HT release irrespective of stimulus laterality. In conclusion, the present study demonstrated that intra-CeA 5-HT release responses to cutaneous stimulation are altered in an animal model of neuropathic pain.

Fear conditioning and extinction distinctively alter bidirectional synaptic plasticity within the amygdala of an animal model of post-traumatic stress disorder.

Synaptic plasticity in the amygdala plays an essential role in the formation and inhibition of fear memory; however, this plasticity has mainly been studied in the lateral amygdala, making it largely uninvestigated in other subnuclei. Here, we investigated long-term potentiation (LTP) and long-term depression (LTD) in the basolateral amygdala (BLA) to the medial division of the central amygdala (CEm) synapses of juvenile C57BL/6N (B6) and 129S1/SvImJ (S1) mice. We found that in naïve B6 and S1 mice, LTP was not induced at the BLA to CEm synapses, whereas fear conditioning lowered the threshold for LTP induction in these synapses of both B6 and S1 mice. Interestingly, fear extinction disrupted the induction of LTP at the BLA to CEm synapses of B6 mice, whereas LTP was left intact in S1 mice. Both low-frequency stimulation (LFS) and modest LFS (mLFS) induced LTD in naïve B6 and S1 mice, suggesting that the BLA to CEm synapses express bidirectional plasticity. Fear conditioning disrupted both types of LTD induction selectively in S1 mice and LFS-LTD, presumably NMDAR-dependent LTD was partially recovered by fear extinction. However, mLFS-LTD which has been known to be endocannabinoid receptor 1 (CB1R)-dependent was not induced after fear extinction in both mouse strains. Our observations suggest that fear conditioning enhances LTP while fear extinction diminishes LTP at the BLA to the CEm synapses of B6 mice with successful extinction. Considering that S1 mice showed strong fear conditioning and impaired extinction, strong fear conditioning in the S1 strain may be related to disrupted LTD, and impaired extinction may be due to constant LTP and weak LFS-LTD at the BLA to CEm synapses. Our study contributes to the further understanding of the dynamics of synaptic potentiation and depression between the subnuclei of the amygdala in juvenile mice after fear conditioning and extinction.

Pharmacological activation of the amygdala, but not single prolonged footshock-induced acute stress, interferes with cue-induced motivation toward food rewards in rats.

In the face of threats, animals adapt their behaviors to cope with the situation. Under such circumstances, irrelevant behaviors are usually suppressed. In this study, we examined whether food-seeking motivation would decrease under activation of the amygdala, an important nucleus in the regulation of stress response in the central nervous system, or after a physical acute stress session. In Experiment 1, we pharmacologically activated the basolateral nucleus (BLA) or the central nucleus of the amygdala (CeA) before a cue-induced reinstatement test in rats. Our results showed that activation of the BLA or the CeA abolished cue-induced motivation toward food rewards, while locomotor activity and free food intake were not affected. In Experiments 2 and 3, we further assessed anxiety and despair levels, as well as cue-induced reinstatement, after a single prolonged footshock-induced acute stress in rats. Behaviorally, acute stress did not affect anxiety level, despair level, or cue-induced motivation toward food rewards. Physiologically, there was no difference in cellular activities of the amygdala immediately after acute stress. To conclude, our results suggested that pharmacological activation of the amygdala decreased cue-induced motivation toward food reward. However, physiological acute stress did not immediately interfere with the negative emotions, motivation, or amygdala activities of the animals.

Possible involvement of GABAergic system on central amygdala Mediated anxiolytic effect of agmatine in rats.

OBJECTIVES: To study the pharmacological interactions between agmatine and gamma aminobutyric acid (GABA) modulatory agents in the regulation of anxiety-like behavior in rats. MATERIALS AND METHODS: Male Wistar rats were treated drugs per se or in combination and 15 min after last injection were subjected to elevated plus-maze (EPM) test. Anxiety-like behavior was evaluated by measuring behavioral conventional readout, open arm activity (duration and/or entries) for 5-minute duration. RESULTS: Acute intra-central amygdala (CeA) injection of agmatine (0.1-0.6 µmol/site/rat), muscimol (0.25-1 nmol/site/rat), diazepam (5-20 µg/site/rat) and allopregnanolone (2-8 µg/site/rat) increased open arm entries of the rats in EPM suggesting anxiolytic effect in dose dependent manner. Moreover, the anxiolytic effect at subeffective dose of agmatine (0.1 µmol/site/rat) was potentiated by subeffective dose of muscimol (0.25 nmol/site/rat), diazepam (5 µg/site/rat) and allopregnanolone (4 µg/site/rat). Whereas, pretreatment with GABAA receptor antagonist, bicuculline (10 ng/site/rat) blocked the anxiolytic effect of agmatine and its synergistic effect of agmatine plus muscimol. Similarly, benzodiazepine (BZD) receptor antagonist, flumazenil (15 µg/site/rat) and GABA allosteric modulator antagonist, RO 15-45 13 (10 µg/site/rat) reduced the anxiolytic effect of agmatine, given alone and with diazepam and allopregnanolone, respectively. CONCLUSION: These results indicated that anxiolytic effect of agmatine is medicated via GABAergic mechanisms, probably conciliated by the GABAA receptor subtypes. Modulation of interplay between agmatine and GABAA receptor activity might be a pertinent solution for the regulation of anxiety.

Developing a 3-D computational model of neurons in the central amygdala to understand pharmacological targets for pain.

Neuropathic and nociplastic pain are major causes of pain and involve brain areas such as the central nucleus of the amygdala (CeA). Within the CeA, neurons expressing protein kinase c-delta (PKCδ) or somatostatin (SST) have opposing roles in pain-like modulation. In this manuscript, we describe our progress towards developing a 3-D computational model of PKCδ and SST neurons in the CeA and the use of this model to explore the pharmacological targeting of these two neural populations in modulating nociception. Our 3-D model expands upon our existing 2-D computational framework by including a realistic 3-D spatial representation of the CeA and its subnuclei and a network of directed links that preserves morphological properties of PKCδ and SST neurons. The model consists of 13,000 neurons with cell-type specific properties and behaviors estimated from laboratory data. During each model time step, neuron firing rates are updated based on an external stimulus, inhibitory signals are transmitted between neurons via the network, and a measure of nociceptive output from the CeA is calculated as the difference in firing rates of pro-nociceptive PKCδ neurons and anti-nociceptive SST neurons. Model simulations were conducted to explore differences in output for three different spatial distributions of PKCδ and SST neurons. Our results show that the localization of these neuron populations within CeA subnuclei is a key parameter in identifying spatial and cell-type pharmacological targets for pain.

Increased pituitary adenylate cyclase-activating polypeptide in the central bed nucleus of the stria terminalis in mood disorders in men.

The mood disorders major depressive disorder (MDD) and bipolar disorder (BD) are highly prevalent worldwide. Women are more vulnerable to these psychopathologies than men. The bed nucleus of the stria terminalis (BNST), the amygdala, and the hypothalamus are the crucial interconnected structures involved in the stress response. In mood disorders, stress systems in the brain are put into a higher gear. The BNST is implicated in mood, anxiety, and depression. The stress-related neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) is highly abundant in the central BNST (cBNST). In this study, we investigated alterations in PACAP in the cBNST of patients with mood disorders. Immunohistochemical (IHC) staining of PACAP and in situ hybridization (ISH) of PACAP mRNA were performed on the cBNST of post-mortem human brain samples. Quantitative IHC revealed elevated PACAP levels in the cBNST in both mood disorders, MDD and BD, but only in men, not in women. The PACAP ISH was negative, indicating that PACAP is not produced in the cBNST. The results support the possibility that PACAP innervation of the cBNST plays a role in mood disorder pathophysiology in men.

Somatostatin signaling modulates binge drinking behavior via the central nucleus of the amygdala.

Somatostatin (SST) is a neuropeptide widely expressed in the central nervous system with dense expression in limbic regions such as the extended amygdala. It has recently gained attention for playing a role in modulating alcohol use disorders and co-morbid neuropsychiatric disorders. However, the role of SST in the central nucleus of the amygdala (CeA), a key region for neuropeptide regulation of alcohol and anxiety related behaviors, in alcohol consumption has not been assessed. In this work we perform an initial examination of the interaction between the CeA SST system and binge ethanol intake. Binge intake is a dangerous pattern of excessive ethanol consumption associated with health complications and the transition into alcohol dependence. We use the Drinking in the Dark (DID) model of binge intake in C57BL/6J male and female mice to examine: 1) the impact of 3 DID cycles on CeA SST expression; 2) the effect of intra-CeA SST injection on binge-like ethanol consumption; and 3) if the SST receptor 2 or 4 (SST2R or SST4R) mediate any effect on consumption. Our results show binge-like ethanol intake decreases SST expression in the CeA, but not neighboring basolateral amygdala. We further found intra-SST CeA administration reduces binge ethanol intake. This decrease was replicated by the administration of an SST4R agonist. These effects were not sex-dependent. Overall, this work lends further support for SST playing a role in alcohol related behaviors and as a potential therapeutic target.

CB1R chronic intermittent pharmacological activation facilitates amphetamine seeking and self-administration and changes in CB1R/CRFR1 expression in the amygdala and nucleus accumbens in rats.

Patterns of drug ingestion may have a dissimilar impact on the brain, and therefore also the development of drug addiction. One pattern is binge intoxication that refers to the ingestion of a high amount of drug on a single occasion followed by an abstinence period of variable duration. In this study, our goal was to contrast the effect of continuous low amounts with intermittent higher amounts of Arachidonyl-chloro-ethylamide (ACEA), a CB1R agonist, on amphetamine seeking and ingestion, and describe the effects on the expression of CB1R and CRFR1 in the central nucleus of the amygdala (CeA) and in the nucleus accumbens shell (NAcS). Adult male Wistar rats were treated with a daily administration of vehicle or 20 µg of ACEA, or four days of vehicle followed by 100 µg of ACEA on the fifth day, for a total of 30 days. Upon completion of this treatment, the CB1R and CRFR1 expression in the CeA and NAcS was evaluated by immunofluorescence. Additional groups of rats were evaluated for their anxiety levels (elevated plus maze, EPM), amphetamine (AMPH) self-administration (ASA) and breakpoint (A-BP), as well as AMPH-induced conditioned place preference (A-CPP). Results indicated that ACEA induced changes in the CB1R and CRFR1 expression in both the NAcS and CeA. An increase in anxiety-like behavior, ASA, A-BP and A-CPP was also observed. Since the intermittent administration of 100 µg of ACEA induced the most evident changes in most of the parameters studied, we concluded that binge-like ingestion of drugs induces changes in the brain that may make the subject more vulnerable to developing drug addiction.

Paraventricular nucleus-central amygdala oxytocinergic projection modulates pain-related anxiety-like behaviors in mice.

AIMS: Anxiety disorders associated with pain are a common health problem. However, the underlying mechanisms remain poorly understood. We aimed to investigate the role of paraventricular nucleus (PVN)-central nucleus of the amygdala (CeA) oxytocinergic projections in anxiety-like behaviors induced by inflammatory pain. METHODS: After inflammatory pain induction by complete Freund's adjuvant (CFA), mice underwent elevated plus maze, light-dark transition test, and marble burying test to examine the anxiety-like behaviors. Chemogenetic, optogenetic, and fiber photometry recordings were used to modulate and record the activity of the oxytocinergic projections of the PVN-CeA. RESULTS: The key results are as follows: inflammatory pain-induced anxiety-like behaviors in mice accompanied by decreased activity of PVN oxytocin neurons. Chemogenetic activation of PVN oxytocin neurons prevented pain-related anxiety-like behaviors, whereas inhibition of PVN oxytocin neurons induced anxiety-like behaviors in naïve mice. PVN oxytocin neurons projected directly to the CeA, and microinjection of oxytocin into the CeA blocked anxiety-like behaviors. Inflammatory pain also decreased the activity of CeA neurons, and optogenetic activation of PVNoxytocin -CeA circuit prevented anxiety-like behavior in response to inflammatory pain. CONCLUSION: The results of our study suggest that oxytocin has anti-anxiety effects and provide novel insights into the role of PVNoxytocin -CeA projections in the regulation of anxiety-like behaviors induced by inflammatory pain.

Corticotropin-releasing hormone neurons in the central nucleus of amygdala are required for chronic stress-induced hypertension.

AIMS: Chronic stress is a well-known risk factor for the development of hypertension. However, the underlying mechanisms remain unclear. Corticotropin-releasing hormone (CRH) neurons in the central nucleus of the amygdala (CeA) are involved in the autonomic responses to chronic stress. Here, we determined the role of CeA-CRH neurons in chronic stress-induced hypertension. METHODS AND RESULTS: Borderline hypertensive rats (BHRs) and Wistar-Kyoto (WKY) rats were subjected to chronic unpredictable stress (CUS). Firing activity and M-currents of CeA-CRH neurons were assessed, and a CRH-Cre-directed chemogenetic approach was used to suppress CeA-CRH neurons. CUS induced a sustained elevation of arterial blood pressure (ABP) and heart rate (HR) in BHRs, while in WKY rats, CUS-induced increases in ABP and HR quickly returned to baseline levels after CUS ended. CeA-CRH neurons displayed significantly higher firing activities in CUS-treated BHRs than unstressed BHRs. Selectively suppressing CeA-CRH neurons by chemogenetic approach attenuated CUS-induced hypertension and decreased elevated sympathetic outflow in CUS-treated BHRs. Also, CUS significantly decreased protein and mRNA levels of Kv7.2 and Kv7.3 channels in the CeA of BHRs. M-currents in CeA-CRH neurons were significantly decreased in CUS-treated BHRs compared with unstressed BHRs. Blocking Kv7 channel with its blocker XE-991 increased the excitability of CeA-CRH neurons in unstressed BHRs but not in CUS-treated BHRs. Microinjection of XE-991 into the CeA increased sympathetic outflow and ABP in unstressed BHRs but not in CUS-treated BHRs. CONCLUSIONS: CeA-CRH neurons are required for chronic stress-induced sustained hypertension. The hyperactivity of CeA-CRH neurons may be due to impaired Kv7 channel activity, which represents a new mechanism involved in chronic stress-induced hypertension.

A critical review of effects on ethanol intake of the dynorphin/kappa opioid receptor system in the extended amygdala: From inhibition to stimulation.

The dynorphin (DYN)/kappa opioid receptor (KOR) system has increasingly been investigated as a possible pharmacotherapeutic target for alcohol use disorder, but findings on the direction of its effects have been mixed. Activation of KORs by DYN has been shown to elicit dysphoric effects, and the DYN/KOR system has canonically been considered particularly important in driving alcohol intake through negative reinforcement in dependent states. However, this review also highlights its activity in opposing the positive reinforcement that drives alcohol intake at earlier stages. Both DYN and KORs are concentrated in the extended amygdala, a set of interconnected regions that includes the bed nucleus of the stria terminalis, central nucleus of the amygdala, and nucleus accumbens shell. This review focuses on the role of the DYN/KOR system in the extended amygdala in ethanol use. It begins by examining the effects of ethanol on the expression of DYN/KOR in the extended amygdala, expression of DYN/KOR in alcohol-preferring and alcohol-avoiding animals, and the effects of knocking out DYN/KOR genes on ethanol intake. Then, it examines the effects on ethanol use in both dependent and nondependent states from systemic pharmacological manipulations of DYN/KOR and from specific manipulation of this system in regions of the extended amygdala. We propose that greater expression and binding of DYN/KOR, by reducing the positive reinforcement that drives early stages of intake, initially acts to prevent the escalation of ethanol drinking. However, prolonged, binge-like, or intermittent ethanol intake enhances levels of DYN/KOR in the extended amygdala such that the system ultimately facilitates the negative reinforcement that drives later stages of ethanol drinking. This review highlights the potential of the DYN/KOR system as a target that can affect different outcomes across different stages of ethanol drinking and the development of alcohol use disorder.

Ethanol Metabolite, Acetate, Increases Excitability of the Central Nucleus of Amygdala Neurons through Activation of NMDA Receptors.

The central nucleus of the amygdala (CeA) is a key brain region involved in emotional and stressor responses due to its many projections to autonomic regulatory centers. It is also a primary site of action from ethanol consumption. However, the influence of active metabolites of ethanol such as acetate on the CeA neural circuitry has yet to be elucidated. Here, we investigated the effect of acetate on CeA neurons with the axon projecting to the rostral ventrolateral medulla (CeA-RVLM), as well as quantified cytosolic calcium responses in primary neuronal cultures. Whole-cell patch-clamp recordings in brain slices containing autonomic CeA-RVLM neurons revealed a dose-dependent increase in neuronal excitability in response to acetate. N-Methyl-d-aspartate receptor (NMDAR) antagonists suppressed the acetate-induced increase in CeA-RVLM neuronal excitability and memantine suppressed the direct activation of NMDAR-dependent inward currents by acetate in brain slices. We observed that acetate increased cytosolic Ca2+ in a time-dependent manner in primary neuronal cell cultures. The acetate enhancement of calcium signaling was abolished by memantine. Computational modeling of acetic acid at NMDAR/NR1 glutamatergic and glycinergic sites suggests potential active site interactions. These findings suggest that within the CeA, acetate is excitatory at least partially through activation of NMDAR, which may underlie the impact of ethanol consumption on autonomic circuitry.

Olfactory Stimulation Successfully Modulates the Neurochemical, Biochemical and Behavioral Phenotypes of the Visceral Pain.

Visceral pain (VP) is the organ-derived nociception in which increased inflammatory reaction and exaggerated activation of the central nucleus of the amygdala (CeA) may contribute to this deficiency. Considering the amygdala also serves as the integration center for olfaction, the present study aimed to determine whether olfactory stimulation (OS) would effectively depress over-activation and inflammatory reaction in CeA, and successfully relieve VP-induced abnormalities. Adult rats subjected to intraperitoneal injection of acetic acid inhaled lavender essential oil for 2 or 4 h. The potential benefits of OS were determined by measuring the pro-inflammatory cytokine level, intracellular potassium and the upstream small-conductance calcium-activated potassium (SK) channel expression, together with detecting the stress transmitters that participated in the modulation of CeA activity. Results indicated that in VP rats, strong potassium intensity, reduced SK channel protein level, and increased corticotropin-releasing factor, c-fos, and substance P immuno-reactivities were detected in CeA. Enhanced CeA activation corresponded well with increased inflammatory reaction and decreased locomotion, respectively. However, in rats subjected to VP and received OS, all above parameters were significantly returned to normal levels with higher change detected in treating OS of 4h. As OS successfully depresses inflammation and CeA over-activation, application of OS may serve as an alternative and effective strategy to efficiently relieve VP-induced deficiency.

Dynorphin/kappa opioid receptor system regulation on amygdaloid circuitry: Implications for neuropsychiatric disorders.

Amygdaloid circuits are involved in a variety of emotional and motivation-related behaviors and are impacted by stress. The amygdala expresses several neuromodulatory systems, including opioid peptides and their receptors. The Dynorphin (Dyn)/kappa opioid receptor (KOR) system has been implicated in the processing of emotional and stress-related information and is expressed in brain areas involved in stress and motivation. Dysregulation of the Dyn/KOR system has also been implicated in various neuropsychiatric disorders. However, there is limited information about the role of the Dyn/KOR system in regulating amygdala circuitry. Here, we review the literature on the (1) basic anatomy of the amygdala, (2) functional regulation of synaptic transmission by the Dyn/KOR system, (3) anatomical architecture and function of the Dyn/KOR system in the amygdala, (4) regulation of amygdala-dependent behaviors by the Dyn/KOR system, and (5) future directions for the field. Future work investigating how the Dyn/KOR system shapes a wide range of amygdala-related behaviors will be required to increase our understanding of underlying circuitry modulation by the Dyn/KOR system. We anticipate that continued focus on the amygdala Dyn/KOR system will also elucidate novel ways to target the Dyn/KOR system to treat neuropsychiatric disorders.

A novel cholinergic projection from the lateral parabrachial nucleus and its role in methamphetamine-primed conditioned place preference.

Drug relapse is a big clinical challenge in the treatment of addiction, but its neural circuit mechanism is far from being fully understood. Here, we identified a novel cholinergic pathway from choline acetyltransferase-positive neurons in the external lateral parabrachial nucleus (eLPBChAT) to the GABAergic neurons in the central nucleus of the amygdala (CeAGABA) and explored its role in methamphetamine priming-induced reinstatement of conditioned place preference. The anatomical structure and functional innervation of the eLPBChAT-CeAGABA pathway were investigated by various methods such as fluorescent micro-optical sectioning tomography, virus-based neural tracing, fibre photometry, patch-clamp and designer receptor exclusively activated by a designer drug. The role of the eLPBChAT-CeAGABA pathway in methamphetamine relapse was assessed using methamphetamine priming-induced reinstatement of conditioned place preference behaviours in male mice. We found that the eLPBChAT neurons mainly projected to the central nucleus of the amygdala. A chemogenetic activation of the eLPBChAT neurons in vitro or in vivo triggered the excitabilities of the CeAGABA neurons, which is at least in part mediated via the cholinergic receptor system. Most importantly, the chemogenetic activation of either the eLPBChAT neurons or the eLPBChAT neurons that project onto the central nucleus of the amygdala decreased the methamphetamine priming-induced reinstatement of conditioned place preference in mice. Our findings revealed a previously undiscovered cholinergic pathway of the eLPBChAT-CeAGABA and showed that the activation of this pathway decreased the methamphetamine priming-induced reinstatement of conditioned place preference.