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Molecular Psychiatry Jun 2021Excessive alcohol drinking has been shown to modify brain circuitry to predispose individuals for future alcohol abuse. Previous studies have implicated the central...
Excessive alcohol drinking has been shown to modify brain circuitry to predispose individuals for future alcohol abuse. Previous studies have implicated the central nucleus of the amygdala (CeA) as an important site for mediating the somatic symptoms of withdrawal and for regulating alcohol intake. In addition, recent work has established a role for both the Kappa Opioid Receptor (KOR) and its endogenous ligand dynorphin in mediating these processes. However, it is unclear whether these effects are due to dynorphin or KOR arising from within the CeA itself or other input brain regions. To directly examine the role of preprodynorphin (PDYN) and KOR expression in CeA neurons, we performed region-specific conditional knockout of these genes and assessed the effects on the Drinking in the Dark (DID) and Intermittent Access (IA) paradigms. Conditional gene knockout resulted in sex-specific responses wherein PDYN knockout decreased alcohol drinking in both male and female mice, whereas KOR knockout decreased drinking in males only. We also found that neither PDYN nor KOR knockout protected against anxiety caused by alcohol drinking. Lastly, a history of alcohol drinking did not alter synaptic transmission in PDYN neurons in the CeA of either sex, but excitability of PDYN neurons was increased in male mice only. Taken together, our findings indicate that PDYN and KOR signaling in the CeA plays an important role in regulating excessive alcohol consumption and highlight the need for future studies to examine how this is mediated through downstream effector regions.
Topics: Alcohol Drinking; Alcoholism; Animals; Central Amygdaloid Nucleus; Dynorphins; Female; Male; Mice; Receptors, Opioid, kappa
PubMed: 32099099
DOI: 10.1038/s41380-020-0690-z -
Cell Reports Feb 2017Circuit-specific signaling of ventral tegmental area (VTA) dopamine neurons drives different aspects of motivated behavior, but the neuromodulatory control of these...
Circuit-specific signaling of ventral tegmental area (VTA) dopamine neurons drives different aspects of motivated behavior, but the neuromodulatory control of these circuits is unclear. We tested the actions of co-expressed lateral hypothalamic peptides, orexin A (oxA) and dynorphin (dyn), on projection-target-defined dopamine neurons in mice. We determined that VTA dopamine neurons that project to the nucleus accumbens lateral shell (lAcbSh), medial shell (mAcbSh), and basolateral amygdala (BLA) are largely non-overlapping cell populations with different electrophysiological properties. Moreover, the neuromodulatory effects of oxA and dyn on these three projections differed. OxA selectively increased firing in lAcbSh- and mAcbSh-projecting dopamine neurons. Dyn decreased firing in the majority of mAcbSh- and BLA-projecting dopamine neurons but reduced firing only in a small fraction of those that project to the lAcbSh. In conclusion, the oxA-dyn input to the VTA may drive reward-seeking behavior by tuning dopaminergic output in a projection-target-dependent manner.
Topics: Animals; Dopamine; Dopaminergic Neurons; Dynorphins; Female; Hypothalamus; Male; Mice; Neural Pathways; Neuropeptides; Nucleus Accumbens; Orexins; Reward; Ventral Tegmental Area
PubMed: 28178514
DOI: 10.1016/j.celrep.2017.01.030 -
Proceedings of the National Academy of... Mar 2020Acid-sensing ion channels (ASICs) are proton-gated cation channels that contribute to neurotransmission, as well as initiation of pain and neuronal death following...
Acid-sensing ion channels (ASICs) are proton-gated cation channels that contribute to neurotransmission, as well as initiation of pain and neuronal death following ischemic stroke. As such, there is a great interest in understanding the in vivo regulation of ASICs, especially by endogenous neuropeptides that potently modulate ASICs. The most potent endogenous ASIC modulator known to date is the opioid neuropeptide big dynorphin (BigDyn). BigDyn is up-regulated in chronic pain and increases ASIC-mediated neuronal death during acidosis. Understanding the mechanism and site of action of BigDyn on ASICs could thus enable the rational design of compounds potentially useful in the treatment of pain and ischemic stroke. To this end, we employ a combination of electrophysiology, voltage-clamp fluorometry, synthetic BigDyn analogs, and noncanonical amino acid-mediated photocrosslinking. We demonstrate that BigDyn binding results in an ASIC1a closed resting conformation that is distinct from open and desensitized states induced by protons. Using alanine-substituted BigDyn analogs, we find that the BigDyn modulation of ASIC1a is primarily mediated through electrostatic interactions of basic amino acids in the BigDyn N terminus. Furthermore, neutralizing acidic amino acids in the ASIC1a extracellular domain reduces BigDyn effects, suggesting a binding site at the acidic pocket. This is confirmed by photocrosslinking using the noncanonical amino acid azidophenylalanine. Overall, our data define the mechanism of how BigDyn modulates ASIC1a, identify the acidic pocket as the binding site for BigDyn, and thus highlight this cavity as an important site for the development of ASIC-targeting therapeutics.
Topics: Acid Sensing Ion Channels; Animals; Animals, Genetically Modified; Binding Sites; Dynorphins; HEK293 Cells; Humans; Hydrogen-Ion Concentration; Neurons; Neuropeptides; Oocytes; Protons; Xenopus laevis
PubMed: 32165542
DOI: 10.1073/pnas.1919323117 -
Endocrinology Aug 2010Recently, a subset of neurons was identified in the arcuate nucleus of the hypothalamus that colocalize three neuropeptides, kisspeptin, neurokinin B, and dynorphin,... (Review)
Review
Recently, a subset of neurons was identified in the arcuate nucleus of the hypothalamus that colocalize three neuropeptides, kisspeptin, neurokinin B, and dynorphin, each of which has been shown to play a critical role in the central control of reproduction. Growing evidence suggests that these neurons, abbreviated as the KNDy subpopulation, are strongly conserved across a range of species from rodents to humans and play a key role in the physiological regulation of GnRH neurons. KNDy cells are a major target for steroid hormones, form a reciprocally interconnected network, and have direct projections to GnRH cell bodies and terminals, features that position them well to convey steroid feedback control to GnRH neurons and potentially serve as a component of the GnRH pulse generator. In addition, recent work suggests that alterations in KNDy cell peptides may underlie neuroendocrine defects seen in clinical reproductive disorders such as polycystic ovarian syndrome. Taken together, this evidence suggests a key role for the KNDy subpopulation as a focal point in the control of reproductive function in health and disease.
Topics: Animals; Arcuate Nucleus of Hypothalamus; Dynorphins; Feedback, Physiological; Gonadal Steroid Hormones; Gonadotropin-Releasing Hormone; Humans; Kisspeptins; Models, Biological; Neurokinin B; Periodicity; Tumor Suppressor Proteins
PubMed: 20501670
DOI: 10.1210/en.2010-0022 -
Journal of Innate Immunity 2019Bacterial biofilms constitute a critical problem in hospitals, especially in resuscitation units or for immunocompromised patients, since bacteria embedded in their own... (Review)
Review
Bacterial biofilms constitute a critical problem in hospitals, especially in resuscitation units or for immunocompromised patients, since bacteria embedded in their own matrix are not only protected against antibiotics but also develop resistant variant strains. In the last decade, an original approach to prevent biofilm formation has consisted of studying the antibacterial potential of host communication molecules. Thus, some of these compounds have been identified for their ability to modify the biofilm formation of both Gram-negative and Gram-positive bacteria. In addition to their effect on biofilm production, a detailed study of the mechanism of action of these human hormones on bacterial physiology has allowed the identification of new bacterial pathways involved in biofilm formation. In this review, we focus on the impact of neuropeptidic hormones on bacteria, address some future therapeutic issues, and provide a new view of inter-kingdom communication.
Topics: Biofilms; Calcitonin Gene-Related Peptide; Dynorphins; Gram-Negative Bacteria; Gram-Positive Bacteria; Humans; Natriuretic Peptides; Neuropeptides; Peptide Hormones; Somatostatin; Virulence
PubMed: 30396172
DOI: 10.1159/000493926 -
Journal of Neuroendocrinology Jun 2022Undernutrition limits reproduction through inhibition of gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) secretion. Because KNDy neurons coexpress...
Undernutrition limits reproduction through inhibition of gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) secretion. Because KNDy neurons coexpress neuropeptides that play stimulatory (kisspeptin and neurokinin B [NKB]) and inhibitory (dynorphin) roles in pulsatile GnRH/LH release, we hypothesized that undernutrition would inhibit kisspeptin and NKB expression at the same time as increasing dynorphin expression. Fifteen ovariectomized lambs were either fed to maintain pre-study body weight (controls) or feed-restricted to lose 20% of pre-study body weight (FR) over 13 weeks. Blood samples were collected and plasma from weeks 0 and 13 were assessed for LH by radioimmunoassay. At week 13, animals were killed, and brain tissue was processed for assessment of KNDy peptide mRNA or protein expression. Mean LH and LH pulse amplitude were lower in FR lambs compared to controls. We observed lower mRNA abundance for kisspeptin within KNDy neurons of FR lambs compared to controls with no significant change in mRNA for NKB or dynorphin. We also observed that FR lambs had fewer numbers of arcuate nucleus kisspeptin and NKB perikarya compared to controls. These findings support the idea that KNDy neurons are important for regulating reproduction during undernutrition in female sheep.
Topics: Animals; Arcuate Nucleus of Hypothalamus; Body Weight; Dynorphins; Female; Gonadotropin-Releasing Hormone; Kisspeptins; Malnutrition; Neurokinin B; Neurons; RNA, Messenger; Sheep
PubMed: 35579068
DOI: 10.1111/jne.13135 -
The Journal of Neuroscience : the... Sep 2000The nonopioid actions of spinal dynorphin may promote aspects of abnormal pain after nerve injury. Mechanistic similarities have been suggested between opioid tolerance...
The nonopioid actions of spinal dynorphin may promote aspects of abnormal pain after nerve injury. Mechanistic similarities have been suggested between opioid tolerance and neuropathic pain. Here, the hypothesis that spinal dynorphin might mediate effects of sustained spinal opioids was explored. Possible abnormal pain and spinal antinociceptive tolerance were evaluated after intrathecal administration of [D-Ala(2), N-Me-Phe(4), Gly-ol(5)]enkephalin (DAMGO), an opioid mu agonist. Rats infused with DAMGO, but not saline, demonstrated tactile allodynia and thermal hyperalgesia of the hindpaws (during the DAMGO infusion) and a decrease in antinociceptive potency and efficacy of spinal opioids (tolerance), signs also characteristic of nerve injury. Spinal DAMGO elicited an increase in lumbar dynorphin content and a decrease in the mu receptor immunoreactivity in the spinal dorsal horn, signs also seen in the postnerve-injury state. Intrathecal administration of dynorphin A(1-17) antiserum blocked tactile allodynia and reversed thermal hyperalgesia to above baseline levels (i.e., antinociception). Spinal dynorphin antiserum, but not control serum, also reestablished the antinociceptive potency and efficacy of spinal morphine. Neither dynorphin antiserum nor control serum administration altered baseline non-noxious or noxious thresholds or affected the intrathecal morphine antinociceptive response in saline-infused rats. These data suggest that spinal dynorphin promotes abnormal pain and acts to reduce the antinociceptive efficacy of spinal opioids (i.e., tolerance). The data also identify a possible mechanism for previously unexplained clinical observations and offer a novel approach for the development of strategies that could improve the long-term use of opioids for pain.
Topics: Analgesics; Analgesics, Opioid; Animals; Drug Tolerance; Dynorphins; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Hindlimb; Hot Temperature; Hyperalgesia; Immune Sera; Immunohistochemistry; Injections, Spinal; Male; Morphine; Pain Measurement; Precipitin Tests; Rats; Rats, Sprague-Dawley; Reaction Time; Receptors, Opioid, mu; Sensory Thresholds; Spinal Cord; Touch
PubMed: 10995854
DOI: 10.1523/JNEUROSCI.20-18-07074.2000 -
ENeuro 2021Neuropeptides within the central nucleus of the amygdala (CeA) potently modulate neuronal excitability and have been shown to regulate conditioned threat discrimination...
Neuropeptides within the central nucleus of the amygdala (CeA) potently modulate neuronal excitability and have been shown to regulate conditioned threat discrimination and anxiety. Here, we investigated the role of κ opioid receptor (KOR) and its endogenous ligand dynorphin in the CeA for regulation of conditioned threat discrimination and anxiety-like behavior in mice. We demonstrate that reduced KOR expression through genetic inactivation of the KOR encoding gene, , in the CeA results in increased anxiety-like behavior and impaired conditioned threat discrimination. In contrast, reduction of dynorphin through genetic inactivation of the dynorphin encoding gene, , in the CeA has no effect on anxiety or conditioned threat discrimination. However, inactivation of from multiple sources, intrinsic and extrinsic to the CeA phenocopies inactivation. These findings suggest that dynorphin inputs to the CeA signal through KOR to promote threat discrimination and dampen anxiety.
Topics: Animals; Anxiety; Central Amygdaloid Nucleus; Dynorphins; Mice; Receptors, Opioid, kappa; Signal Transduction
PubMed: 33323398
DOI: 10.1523/ENEURO.0370-20.2020 -
Proceedings of the National Academy of... Feb 1983A specific antiserum was prepared against dynorphin B, an endogenous opioid peptide contained in a recently isolated 4,000-dalton dynorphin. The antiserum did not...
A specific antiserum was prepared against dynorphin B, an endogenous opioid peptide contained in a recently isolated 4,000-dalton dynorphin. The antiserum did not crossreact with dynorphin A, alpha-neo-endorphin, beta-neo-endorphin, dynorphin-(1-8), or [Leu]enkephalin. In immunohistochemical staining experiments on frozen sections through rat brains from normal and colchicine-treated animals, the antiserum labeled the same neuronal fiber systems previously described as containing both dynorphin A and alpha-neo-endorphin immunoreactive material. The alpha-neo-endorphin/dynorphin A immunoreactive perikarya in the hypothalamic magnocellular nuclei also were labeled by the dynorphin B antiserum. In addition, the dynorphin B antiserum revealed groups of immunoreactive neuronal cell bodies in several other hypothalamic and extrahypothalamic areas, including brain-stem, midbrain, central nucleus of amygdala, and in the dorsomedial, lateral, and anterior nuclei of hypothalamus. These perikarya had not been detected in previous studies that used dynorphin A and alpha-neo-endorphin antisera. The findings are in agreement with recent studies demonstrating a common precursor for dynorphin A, dynorphin B, and alpha-neo-endorphin. The apparently wider distribution of dynorphin B immunoreactive cell bodies compared to alpha-neo-endorphin/dynorphin A immunoreactive perikarya may be a reflection of differential processing of the precursor in different brain regions.
Topics: Animals; Brain; Brain Chemistry; Brain Mapping; Dynorphins; Endorphins; Fluorescent Antibody Technique; Neurons; Rats
PubMed: 6133279
DOI: 10.1073/pnas.80.4.1125 -
The Journal of Neuroscience : the... Nov 2015We employ transgenic mice with selective expression of tdTomato or cre recombinase together with optogenetics to investigate whether hypothalamic arcuate (ARC)...
Dopamine/Tyrosine Hydroxylase Neurons of the Hypothalamic Arcuate Nucleus Release GABA, Communicate with Dopaminergic and Other Arcuate Neurons, and Respond to Dynorphin, Met-Enkephalin, and Oxytocin.
UNLABELLED
We employ transgenic mice with selective expression of tdTomato or cre recombinase together with optogenetics to investigate whether hypothalamic arcuate (ARC) dopamine/tyrosine hydroxylase (TH) neurons interact with other ARC neurons, how they respond to hypothalamic neuropeptides, and to test whether these cells constitute a single homogeneous population. Immunostaining with dopamine and TH antisera was used to corroborate targeted transgene expression. Using whole-cell recording on a large number of neurons (n = 483), two types of neurons with different electrophysiological properties were identified in the dorsomedial ARC where 94% of TH neurons contained immunoreactive dopamine: bursting and nonbursting neurons. In contrast to rat, the regular oscillations of mouse bursting neurons depend on a mechanism involving both T-type calcium and A-type potassium channel activation, but are independent of gap junction coupling. Optogenetic stimulation using cre recombinase-dependent ChIEF-AAV-DJ expressed in ARC TH neurons evoked postsynaptic GABA currents in the majority of neighboring dopamine and nondopamine neurons, suggesting for the first time substantial synaptic projections from ARC TH cells to other ARC neurons. Numerous met-enkephalin (mENK) and dynorphin-immunoreactive boutons appeared to contact ARC TH neurons. mENK inhibited both types of TH neuron through G-protein coupled inwardly rectifying potassium currents mediated by δ and μ opioid receptors. Dynorphin-A inhibited both bursting and nonbursting TH neurons by activating κ receptors. Oxytocin excited both bursting and nonbursting neurons. These results reveal a complexity of TH neurons that communicate extensively with neurons within the ARC.
SIGNIFICANCE STATEMENT
Here, we show that the great majority of mouse hypothalamic arcuate nucleus (ARC) neurons that synthesize TH in the dorsomedial ARC also contain immunoreactive dopamine, and show either bursting or nonbursting electrical activity. Unlike rats, the mechanism underlying bursting was not dependent on gap junctions but required T-type calcium and A-type potassium channel activation. Neuropeptides dynorphin and met-enkephalin inhibited dopamine neurons, whereas oxytocin excited them. Most ventrolateral ARC TH cells did not contain dopamine and did not show bursting electrical activity. TH-containing neurons appeared to release synaptic GABA within the ARC onto dopamine neurons and unidentified neurons, suggesting that the cells not only control pituitary hormones but also may modulate nearby neurons.
Topics: Animals; Arcuate Nucleus of Hypothalamus; Cell Communication; Dopaminergic Neurons; Dynorphins; Enkephalin, Methionine; Female; Humans; Male; Mice; Mice, Transgenic; Organ Culture Techniques; Oxytocin; Rats; Swine; Tyrosine 3-Monooxygenase; gamma-Aminobutyric Acid
PubMed: 26558770
DOI: 10.1523/JNEUROSCI.0293-15.2015