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Sibomana I, Rohan JG, Mattie DR. 21-Day dermal exposure to aircraft engine oils: effects on esterase activities in brain and liver tissues, blood, plasma, and clinical chemistry parameters for Sprague Dawley rats. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2021; 84:357-388. [PMID: 33380269 DOI: 10.1080/15287394.2020.1867680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
This dermal study tested the potential toxicity of grade 3 (G3) and 4 (G4) organophosphate-containing aircraft engine oils in both new (G3-N, G4-N) and used states (G3-U, G4-U) to alter esterase activities in blood, brain and liver tissues, clinical chemistry parameters, and electrophysiology of hippocampal neurons. A 300 µl volume of undiluted oil was applied in Hill Top Chamber Systems®, then attached to fur-free test sites on backs of male and female Sprague Dawley rats for 6 hr/day, 5 days/week for 21 days. Recovery rats received similar treatments and kept for 14 days post-exposure to screen for reversibility, persistence, or delayed occurrence of toxicity. In brain, both versions of G3 and G4 significantly decreased (32-41%) female acetylcholinesterase (AChE) activity while in males only G3-N and G4-N reduced (33%) AChE activity. Oils did not markedly affect AChE in liver, regardless of gender. In whole blood, G3-U decreased female AChE (29%) which persisted during recovery (32%). G4-N significantly lowered (29%) butyrylcholinesterase (BChE) in male plasma, but this effect was resolved during recovery. For clinical chemistry indices, only globulin levels in female plasma significantly increased following G3-N or G4-N exposure. Preliminary electrophysiology data suggested that effects of both versions of G3 and G4 on hippocampal function may be gender dependent. Aircraft maintenance workers may be at risk if precautions are not taken to minimize long-term aircraft oil exposure.
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Affiliation(s)
- Isaie Sibomana
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright-Patterson Air Force Base, OH, USA
- Air Force Research Laboratory, 711 Human Performance Wing, Wright-Patterson Air Force Base, OH, USA
| | - Joyce G Rohan
- Environmental Health Effects Laboratory, Naval Medical Research Unit Dayton (NAMRU-D), Wright-Patterson Air Force Base, OH, USA
| | - David R Mattie
- Air Force Research Laboratory, 711 Human Performance Wing, Wright-Patterson Air Force Base, OH, USA
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2
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Stone TW. Does kynurenic acid act on nicotinic receptors? An assessment of the evidence. J Neurochem 2020; 152:627-649. [PMID: 31693759 PMCID: PMC7078985 DOI: 10.1111/jnc.14907] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/19/2019] [Accepted: 10/30/2019] [Indexed: 02/06/2023]
Abstract
As a major metabolite of kynurenine in the oxidative metabolism of tryptophan, kynurenic acid is of considerable biological and clinical importance as an endogenous antagonist of glutamate in the central nervous system. It is most active as an antagonist at receptors sensitive to N-methyl-D-aspartate (NMDA) which regulate neuronal excitability and plasticity, brain development and behaviour. It is also thought to play a causative role in hypo-glutamatergic conditions such as schizophrenia, and a protective role in several neurodegenerative disorders, notably Huntington's disease. An additional hypothesis, that kynurenic acid could block nicotinic receptors for acetylcholine in the central nervous system has been proposed as an alternative mechanism of action of kynurenate. However, the evidence for this alternative mechanism is highly controversial, partly because at least eight earlier studies concluded that kynurenic acid blocked NMDA receptors but not nicotinic receptors and five subsequent, independent studies designed to repeat the results have failed to do so. Many studies considered to support the alternative 'nicotinic' hypothesis have been based on the use of analogs of kynurenate such as 7-chloro-kynurenic acid, or putatively nicotinic modulators such as galantamine, but a detailed analysis of the pharmacology of these compounds suggests that the results have often been misinterpreted, especially since the pharmacology of galantamine itself has been disputed. This review examines the evidence in detail, with the conclusion that there is no confirmed, reliable evidence for an antagonist activity of kynurenic acid at nicotinic receptors. Therefore, since there is overwhelming evidence for kynurenate acting at ionotropic glutamate receptors, especially NMDAR glutamate and glycine sites, with some activity at GPR35 sites and Aryl Hydrocarbon Receptors, results with kynurenic acid should be interpreted only in terms of these confirmed sites of action.
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Affiliation(s)
- Trevor W. Stone
- Institute for Neuroscience and PsychologyUniversity of GlasgowGlasgowG12 8QQUK
- Present address:
Kennedy InstituteNDORMSUniversity of OxfordOxfordOX3 7FYUK
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Oh MM, Disterhoft JF. Learning and aging affect neuronal excitability and learning. Neurobiol Learn Mem 2019; 167:107133. [PMID: 31786311 DOI: 10.1016/j.nlm.2019.107133] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 11/21/2019] [Accepted: 11/27/2019] [Indexed: 11/20/2022]
Abstract
The first study that demonstrated a change in intrinsic neuronal excitability after learning in ex vivo brain tissue slices from a mammal was published over thirty years ago. Numerous other manuscripts describing similar learning-related changes have followed over the years since the original paper demonstrating the postburst afterhyperpolarization (AHP) reduction in CA1 pyramidal neurons from rabbits that learned delay eyeblink conditioning was published. In addition to the learning-related changes, aging-related enlargement of the postburst AHP in CA1 pyramidal neurons have been reported. Extensive work has been done relating slow afterhyperpolarization enhancement in CA1 hippocampus to slowed learning in some aging animals. These reproducible findings strongly implicate modulation of the postburst AHP as an essential cellular mechanism necessary for successful learning, at least in learning tasks that engage CA1 hippocampal pyramidal neurons.
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Affiliation(s)
- M Matthew Oh
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611-3008, United States
| | - John F Disterhoft
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611-3008, United States.
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Agrawal M, Saraf S, Saraf S, Antimisiaris SG, Chougule MB, Shoyele SA, Alexander A. Nose-to-brain drug delivery: An update on clinical challenges and progress towards approval of anti-Alzheimer drugs. J Control Release 2018; 281:139-177. [DOI: 10.1016/j.jconrel.2018.05.011] [Citation(s) in RCA: 203] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 05/10/2018] [Accepted: 05/10/2018] [Indexed: 01/02/2023]
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5
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Yang CT, Leung YM, Hsu SF, MacDonald I, Wang ML, Lin JG, Hung SY, Chen YH. A comparison of the delayed outward potassium current between the nucleus ambiguus and hippocampus: sensitivity to paeonol. Eur J Pharmacol 2016; 784:49-60. [PMID: 27164420 DOI: 10.1016/j.ejphar.2016.04.057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2015] [Revised: 04/26/2016] [Accepted: 04/28/2016] [Indexed: 01/31/2023]
Abstract
Whole-cell patch-clamp recordings investigated the electrophysiological effects of 2'-hydroxy-4'-methoxyacetophenone (paeonol), one of the major components of Moutan Cortex, in hippocampal CA1 neurons and nucleus ambiguus (NA) neurons from neonatal rats as well as in lung epithelial H1355 cells expressing Kv2.1 or Kv1.2. Extracellular application of paeonol at 100μM did not significantly affect the spontaneous action potential frequency, whereas paeonol at 300μM increased the frequency of spontaneous action potentials in hippocampal CA1 neurons. Paeonol (300μM) significantly decreased the tetraethylammonium-sensitive outward current in hippocampal CA1 neurons, but had no effect upon the fast-inactivating potassium current (IA). Extracellular application of paeonol at 300μM did not affect action potentials or the delayed outward currents in NA neurons. Paeonol (100μM) reduced the Kv2.1 current in H1355 cells, but not the Kv1.2 current. The inhibitor of Kv2, guangxitoxin-1E, reduced the delayed outward potassium currents in hippocampal neurons, but had only minimal effects in NA neurons. We demonstrated that paeonol decreased the delayed outward current and increased excitability in hippocampal CA1 neurons, whereas these effects were not observed in NA neurons. These effects may be associated with the inhibitory effects on Kv2.1 currents.
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Affiliation(s)
- Chin-Tsang Yang
- School of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Yuk-Man Leung
- Department of Physiology, China Medical University, Taichung, Taiwan
| | - Sheng-Feng Hsu
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan
| | - Iona MacDonald
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan
| | - Mei-Ling Wang
- Department of Physiology, China Medical University, Taichung, Taiwan
| | - Jaung-Geng Lin
- School of Chinese Medicine, China Medical University, Taichung, Taiwan
| | - Shih-Ya Hung
- Division of Colorectal Surgery, China Medical University Hospital, Taichung, Taiwan; Graduate Institute of Integrated Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan.
| | - Yi-Hung Chen
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, Taiwan; Department of Photonics and Communication Engineering, Asia University, Taiwan.
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Eckart C, Woźniak-Kwaśniewska A, Herweg NA, Fuentemilla L, Bunzeck N. Acetylcholine modulates human working memory and subsequent familiarity based recognition via alpha oscillations. Neuroimage 2016; 137:61-69. [PMID: 27222217 DOI: 10.1016/j.neuroimage.2016.05.049] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 05/18/2016] [Accepted: 05/18/2016] [Indexed: 12/26/2022] Open
Abstract
Working memory (WM) can be defined as the ability to maintain and process physically absent information for a short period of time. This vital cognitive function has been related to cholinergic neuromodulation and, in independent work, to theta (4-8Hz) and alpha (9-14Hz) band oscillations. However, the relationship between both aspects remains unclear. To fill this apparent gap, we used electroencephalography (EEG) and a within-subject design in healthy humans who either received the acetylcholinesterase inhibitor galantamine (8mg) or a placebo before they performed a Sternberg WM paradigm. Here, sequences of sample images were memorized for a delay of 5s in three different load conditions (two, four or six items). On the next day, long-term memory (LTM) for the images was tested according to a remember/know paradigm. As a main finding, we can show that both theta and alpha oscillations scale during WM maintenance as a function of WM load; this resembles the typical performance decrease. Importantly, cholinergic stimulation via galantamine administration slowed down retrieval speed during WM and reduced associated alpha but not theta power, suggesting a functional relationship between alpha oscillations and WM performance. At LTM, this pattern was accompanied by impaired familiarity based recognition. These findings show that stimulating the healthy cholinergic system impairs WM and subsequent recognition, which is in line with the notion of a quadratic relationship between acetylcholine levels and cognitive functions. Moreover, our data provide empirical evidence for a specific role of alpha oscillations in acetylcholine dependent WM and associated LTM formation.
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Affiliation(s)
- Cindy Eckart
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; Department of Psychology, Goethe University Frankfurt, Frankfurt am Main, Germany
| | | | - Nora A Herweg
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany
| | - Lluis Fuentemilla
- Cognition and Brain Plasticity Group, [Bellvitge Biomedical Research Institute] IDIBELL, L'Hospitalet de Llobregat, Barcelona 08097, Spain; Department of Cognition, Development and Educational Psychology, Faculty of Psychology, and Institute of Neuroscience, University of Barcelona, Barcelona 08035, Spain
| | - Nico Bunzeck
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; Department of Psychology, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany.
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7
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Li WZ, Hao XL, Zhao N, Han WX, Zhai XF, Zhao Q, Wang YE, Zhou YQ, Cheng YC, Yue YH, Fu LN, Zhou JL, Wu HY, Dong CJ. Propylene glycol-embodying deformable liposomes as a novel drug delivery carrier for vaginal fibrauretine delivery applications. J Control Release 2016; 226:107-14. [PMID: 26883754 DOI: 10.1016/j.jconrel.2016.02.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 01/30/2016] [Accepted: 02/13/2016] [Indexed: 01/17/2023]
Abstract
The purpose of this work was to develop and characterize the fibrauretine (FN) loaded propylene glycol-embodying deformable liposomes (FDL), and evaluate the pharmacokinetic behavior and safety of FDL for vaginal drug delivery applications. FDL was characterized for structure, particle size, zeta potential, deformability and encapsulation efficiency; the ability of FDL to deliver FN across vagina tissue in vitro and the distribution behavior of FN in rat by vaginal drug delivery were investigated, the safety of FDL to the vagina of rabbits and rats as well as human vaginal epithelial cells (VK2/E6E7) were also evaluated. Results revealed that: (i) the FDL have a closed spherical shape and lamellar structure with a homogeneous size of 185±19nm, and exhibited a negative charge of -53±2.7mV, FDL also have a good flexibility with a deformability of 92±5.6 (%phospholipids/min); (ii) the dissolving capacity of inner water phase and hydrophilicity of phospholipid bilayers of deformable liposomes were increased by the presence of propylene glycol, this may be elucidated by the fluorescent probes both lipophilic Nile red and hydrophilic calcein that were filled up the entire volume of the FDL uniformly, so the FDL with a high entrapment capacity (were calculated as percentages of total drug) for FN was 78±2.14%; (iii) the permeability of FN through vaginal mucosa was obviously improved by propylene glycol-embodying deformable liposomes, no matter whether the FN loaded in liposomes or not, although FN loaded in liposomes caused the highest permeability and drug reservoir in vagina; (iv) the FN mainly aggregated in the vagina and uterus, then the blood, spleen, liver, kidney, heart and lungs for vaginal drug delivery, this indicating vaginal delivery of FDL have a better 'vaginal local targeting effect'; and (v) the results of safety evaluation illustrate that the FDL is non-irritant and well tolerated in vivo, thereby establishing its vaginal drug delivery potential. These results indicate that the propylene glycol-embodying deformable liposomes may be a promising drug delivery carrier for vaginal delivery of fibrauretine.
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Affiliation(s)
- Wei-Ze Li
- College of Pharmacy, Xi'an Medical University, Xi'an 710021, PR China; Center of Drug Research and Development, Yantai Weitenarui Pharmaceutical Technology Co. Ltd., Yantai 264000, PR China
| | - Xu-Liang Hao
- Shanxi Research Institute of Traditional Chinese Medicine, Taiyuan 034000, PR China
| | - Ning Zhao
- College of Pharmacy, Xi'an Medical University, Xi'an 710021, PR China
| | - Wen-Xia Han
- College of Pharmacy, Xi'an Medical University, Xi'an 710021, PR China
| | - Xi-Feng Zhai
- College of Pharmacy, Xi'an Medical University, Xi'an 710021, PR China
| | - Qian Zhao
- School of Life Science, China Pharmaceutical University, Nanjing 211198, PR China
| | - Yu-E Wang
- Shanxi Research Institute of Traditional Chinese Medicine, Taiyuan 034000, PR China
| | - Yong-Qiang Zhou
- Center of Drug Research and Development, Yantai Weitenarui Pharmaceutical Technology Co. Ltd., Yantai 264000, PR China.
| | - Yu-Chuan Cheng
- Shanxi Research Institute of Traditional Chinese Medicine, Taiyuan 034000, PR China
| | - Yong-Hua Yue
- Shanxi Research Institute of Traditional Chinese Medicine, Taiyuan 034000, PR China
| | - Li-Na Fu
- College of Pharmacy, Xi'an Medical University, Xi'an 710021, PR China
| | - Ji-Lei Zhou
- Center of Drug Research and Development, Yantai Weitenarui Pharmaceutical Technology Co. Ltd., Yantai 264000, PR China
| | - Hong-Yu Wu
- Center of Drug Research and Development, Yantai Weitenarui Pharmaceutical Technology Co. Ltd., Yantai 264000, PR China
| | - Chun-Jing Dong
- Center of Drug Research and Development, Yantai Weitenarui Pharmaceutical Technology Co. Ltd., Yantai 264000, PR China
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8
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Weiss C, Disterhoft JF. The impact of hippocampal lesions on trace-eyeblink conditioning and forebrain-cerebellar interactions. Behav Neurosci 2015; 129:512-22. [PMID: 26214216 PMCID: PMC4518454 DOI: 10.1037/bne0000061] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Behavioral Neuroscience published a pivotal paper by Moyer, Deyo, and Disterhoft (1990) 25 years ago that described the impaired acquisition of trace-eyeblink conditioning in rabbits with complete removal of the hippocampus. As part of the Behavioral Neuroscience celebration commemorating the 30th anniversary of the journal, we reflect upon the impact of that study on understanding the role of the hippocampus, forebrain, and forebrain-cerebellar interactions that mediate acquisition and retention of trace-conditioned responses, and of declarative memory more globally. We discuss the expansion of the conditioning paradigm to species other than the rabbit, the heterogeneity of responses among hippocampal neurons during trace conditioning, the responsivity of hippocampal neurons following consolidation of conditioning, the role of awareness in conditioning, how blink conditioning can be used as a translational tool by assaying potential therapeutics for cognitive enhancement, how trace and delay classical conditioning may be used to investigate neurological disorders including Alzheimer's disease and schizophrenia, and how the 2 paradigms may be used to understand the relationship between declarative (explicit) and nondeclarative (implicit) memory systems.
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Affiliation(s)
- Craig Weiss
- Northwestern University Feinberg School of Medicine
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9
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Bunzeck N, Guitart-Masip M, Dolan RJ, Duzel E. Pharmacological dissociation of novelty responses in the human brain. ACTA ACUST UNITED AC 2013; 24:1351-60. [PMID: 23307638 PMCID: PMC3977623 DOI: 10.1093/cercor/bhs420] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Repeated processing of the same information is associated with decreased neuronal responses, termed repetition suppression (RS). Although RS effects (i.e., the difference in activity between novel and repeated stimuli) have been demonstrated within several brain regions, such as the medial temporal lobe, their precise neural mechanisms still remain unclear. Here, we used functional magnetic resonance imaging together with psychopharmacology in 48 healthy human subjects, demonstrating that RS effects within the mesolimbic system are differentially modulated by cholinergic and dopaminergic stimulation. The dopamine precursor levodopa (100 mg) attenuated RS within the hippocampus, parahippocampal cortex, and substantia nigra/ventral tegmental area, and the degree of this reduction correlated with recognition memory performance 24 h later. The acetylcholinesterase inhibitor galantamine (8 mg), in contrast, reversed RS into repetition enhancement, showing no relationship to subsequent recognition memory. This suggests that novelty sensitive neural populations of the mesolimbic system can dynamically shift their responses depending on the balance of cholinergic and dopaminergic neurotransmission, and these shifts can influence memory retention.
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Affiliation(s)
- Nico Bunzeck
- Department of Systems Neuroscience, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
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10
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Li W, Zhou Y, Zhao N, Hao B, Wang X, Kong P. Pharmacokinetic behavior and efficiency of acetylcholinesterase inhibition in rat brain after intranasal administration of galanthamine hydrobromide loaded flexible liposomes. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2012; 34:272-279. [PMID: 22613079 DOI: 10.1016/j.etap.2012.04.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2011] [Revised: 04/22/2012] [Accepted: 04/25/2012] [Indexed: 06/01/2023]
Abstract
Galanthamine hydrobromide (GH) has been approved for symptomatic treatment of Alzheimer's disease (AD) and vascular dementia. Hence, the effects of intranasal administration of GH loaded flexible liposomes have been investigated for the first time on the efficiency of acetylcholinesterase inhibition, as well as the pharmacokinetic behavior of GH in rat brain. The GH loaded flexible liposomes were characterized for shape, entrapment capacity, size distribution and zeta potential by transmission electron microscopy (TEM), ultracentrifugation and dynamic light scattering (DLS), respectively. The inhibition of acetylcholinesterase was investigated using rat brain homogenates as an enzyme resource and microdialysis was used to determine the pharmacokinetic behavior of GH in rats brain. The rat pheochromocytoma PC-12 cell line was used to evaluate the cytotoxicity of GH loaded flexible liposomes. The results revealed that: (i) the efficiency of acetylcholinesterase inhibition of GH was greatly enhanced by intranasal administration compared with oral administration, especially GH loaded in flexible liposomes; (ii) the C(max) and AUC(0→10) for intranasal administration of GH loaded flexible liposomes were 3.52 and 3.36 times higher than those of orally administered GH, moreover, the T(max) was greatly shortened from 1.5h for oral administration to 0.75h for intranasal administration of GH loaded flexible liposomes; and (iii) PC-12 cells viability tests showed that the flexible liposome carrier is not toxic to the cultured cells and the cytotoxicity of GH to cells was clearly decreased by loading in flexible liposomes. These results indicate that intranasal administration of GH loaded flexible liposomes could readily transport GH into brain tissues, suggesting some promise for this approach in successful brain-drug targeting in AD treatment.
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Affiliation(s)
- Weize Li
- College of Pharmacy, Xi'an Medical University, Xi'an 710021, PR China; Institute of Drug Research and Development, Fengyuan Pharmaceutical Limited Company, Ruicheng 044600, PR China
| | - Yongqiang Zhou
- Center of Nanjing Hailing R&D for Chinese Traditional Medicine Pharmaceutical Technology, Nanjing 210049, PR China.
| | - Ning Zhao
- College of Pharmacy, Xi'an Medical University, Xi'an 710021, PR China
| | - Baohua Hao
- School of Science and Life, Northwest University, Xi'an 710069, PR China
| | - Xiaoning Wang
- College of Pharmacy, Xi'an Medical University, Xi'an 710021, PR China
| | - Peng Kong
- Institute of Drug Research and Development, Fengyuan Pharmaceutical Limited Company, Ruicheng 044600, PR China
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McKay BM, Oh MM, Galvez R, Burgdorf J, Kroes RA, Weiss C, Adelman JP, Moskal JR, Disterhoft JF. Increasing SK2 channel activity impairs associative learning. J Neurophysiol 2012; 108:863-70. [PMID: 22552186 DOI: 10.1152/jn.00025.2012] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Enhanced intrinsic neuronal excitability of hippocampal pyramidal neurons via reductions in the postburst afterhyperpolarization (AHP) has been hypothesized to be a biomarker of successful learning. This is supported by considerable evidence that pharmacologic enhancement of neuronal excitability facilitates learning. However, it has yet to be demonstrated that pharmacologic reduction of neuronal excitability restricted to the hippocampus can retard acquisition of a hippocampus-dependent task. Thus, the present study was designed to address this latter point using a small conductance potassium (SK) channel activator NS309 focally applied to the dorsal hippocampus. SK channels are important contributors to intrinsic excitability, as measured by the medium postburst AHP. NS309 increased the medium AHP and reduced excitatory postsynaptic potential width of CA1 neurons in vitro. In vivo, NS309 reduced the spontaneous firing rate of CA1 pyramidal neurons and impaired trace eyeblink conditioning in rats. Conversely, trace eyeblink conditioning reduced levels of SK2 channel mRNA and protein in the hippocampus. Therefore, the present findings indicate that modulation of SK channels is an important cellular mechanism for associative learning and further support postburst AHP reductions in hippocampal pyramidal neurons as a biomarker of successful learning.
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Affiliation(s)
- Bridget M McKay
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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Uteshev VV. α7 nicotinic ACh receptors as a ligand-gated source of Ca(2+) ions: the search for a Ca(2+) optimum. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:603-38. [PMID: 22453962 DOI: 10.1007/978-94-007-2888-2_27] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The spatiotemporal distribution of cytosolic Ca(2+) ions is a key determinant of neuronal behavior and survival. Distinct sources of Ca(2+) ions including ligand- and voltage-gated Ca(2+) channels contribute to intracellular Ca(2+) homeostasis. Many normal physiological and therapeutic neuronal functions are Ca(2+)-dependent, however an excess of cytosolic Ca(2+) or a lack of the appropriate balance between Ca(2+) entry and clearance may destroy cellular integrity and cause cellular death. Therefore, the existence of optimal spatiotemporal patterns of cytosolic Ca(2+) elevations and thus, optimal activation of ligand- and voltage-gated Ca(2+) ion channels are postulated to benefit neuronal function and survival. Alpha7 nicotinic -acetylcholine receptors (nAChRs) are highly permeable to Ca(2+) ions and play an important role in modulation of neurotransmitter release, gene expression and neuroprotection in a variety of neuronal and non-neuronal cells. In this review, the focus is placed on α7 nAChR-mediated currents and Ca(2+) influx and how this source of Ca(2+) entry compares to NMDA receptors in supporting cytosolic Ca(2+) homeostasis, neuronal function and survival.
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Affiliation(s)
- Victor V Uteshev
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, USA.
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Vicente MI, Costa PF, Lima PA. Galantamine inhibits slowly inactivating K+ currents with a dual dose–response relationship in differentiated N1E-115 cells and in CA1 neurones. Eur J Pharmacol 2010; 634:16-25. [DOI: 10.1016/j.ejphar.2010.02.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 01/26/2010] [Accepted: 02/13/2010] [Indexed: 11/15/2022]
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14
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Park E, Lee Y, Kim Y, Lee CJ. Cholinergic modulation of neural activity in the telencephalon of the zebrafish. Neurosci Lett 2008; 439:79-83. [DOI: 10.1016/j.neulet.2008.04.064] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 04/06/2008] [Accepted: 04/20/2008] [Indexed: 10/22/2022]
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15
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Villarroya M, García AG, Marco-Contelles J, López MG. An update on the pharmacology of galantamine. Expert Opin Investig Drugs 2007; 16:1987-98. [DOI: 10.1517/13543784.16.12.1987] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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16
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Oswald BB, Maddox SA, Powell DA. Impairments in trace EB conditioning by knife-cut lesions to the fornix in rabbits: Reversal by galantamine. Neurobiol Learn Mem 2007; 88:369-80. [PMID: 17613252 DOI: 10.1016/j.nlm.2007.05.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 05/08/2007] [Accepted: 05/18/2007] [Indexed: 10/23/2022]
Abstract
Previous work in our laboratory demonstrated that galantamine, a cholinesterase inhibitor and weak cholinergic agonist, facilitated classical trace eyeblink conditioning in healthy, young rabbits [Simon, B. B., Knuckley, B., & Powell, D. A. (2004). Galantamine facilitates acquisition of a trace-conditioned eyeblink response in healthy, young rabbits. Learning & Memory, 11(1), 116-122.]. The current study investigated the effects of galantamine (0.0 or 3.0mg/kg) in rabbits sustaining knife-cut lesions to the fimbria-fornix, a major projection pathway connecting the hippocampus to cortical and subcortical brain structures involved in the formation of long-term memories. Two experiments were conducted. Experiment one assessed the effects of knife-cut lesions to the fornix or sham surgeries on trace eyeblink (EB) conditioning. Results indicate that fornix lesions significantly retarded EB conditioning when trace parameters were employed. Experiment 2 assessed whether treatment with galantamine would reverse the deficits caused by fornix damage. Results indicate that 3.0mg/kg GAL reversed trace EB conditioning deficits in animals with fornix knife-cut lesions. These findings suggest that galantamine may provide benefit in the reversal of cognitive dysfunction following certain types of brain damage, especially damage involving hippocampal structures.
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Affiliation(s)
- Barbara B Oswald
- Shirley L. Buchanan Neuroscience Laboratory (151A), WJB Dorn VA Medical Center, 6439 Garners Ferry Road, Columbia, SC 29209, USA
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Abstract
A great number of natural products, especially alkaloids, which exhibit a range of biological activities including acetylcholinesterase inhibition and antineoplastic, cardiovascular and immunostimulatory activities, have been isolated from the plants of the Amaryllidaceae family. this review summarizes isolation, biological activity, and synthetic studies of these alkaloids. The primary biosynthetic pathways of each type of alkaloids are also proposed.
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Affiliation(s)
- Zhong Jin
- State Key Laboratory and Institute of Elemento-organic Chemistry, Nankai University, Tianjin 300071, P. R. China.
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Bajgar J, Bartosova L, Fusek J, Svoboda Z, Herink J, Kvetina J, Palicka V, Zivny P, Blaha V. Changes of cholinesterase activities in the plasma and some tissues following administration of L-carnitine and galanthamine to rats. Neurosci Lett 2006; 411:212-6. [PMID: 17125927 DOI: 10.1016/j.neulet.2006.09.087] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Revised: 09/14/2006] [Accepted: 09/14/2006] [Indexed: 11/26/2022]
Abstract
Changes of acetylcholinesterase (AChE) activities in the hypophysis and brain (frontal cortex, hippocampus, medial septum and basal ganglia), and butyrylcholinesterase in plasma and liver following galanthamine (GAL) administration were studied in rats pretreated with L-carnitine (CAR). Following only GAL administration (10 mg/kg, i.m.), both cholinesterases (without clinical symptoms of GAL overdosage) were significantly inhibited. Pretreatment with CAR (3 consecutive days, 250 mg/kg, p.o.) followed by GAL administration showed higher AChE inhibition in comparison with single GAL administration. However, a statistically significant difference was observed for AChE in the hippocampus only. The activity of peripheral cholinesterases was not influenced by CAR pretreatment. Thus, pretreatment with CAR enhanced AChE inhibition in some brain parts of the rat following GAL administration.
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Affiliation(s)
- Jiri Bajgar
- Faculty of Military Health Sciences, University of Defence, and Institute of Clinical Biochemistry and Diagnostic, Faculty Hospital, Hradec Kralove, Czech Republic.
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19
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Disterhoft JF, Oh MM. Learning, aging and intrinsic neuronal plasticity. Trends Neurosci 2006; 29:587-99. [PMID: 16942805 DOI: 10.1016/j.tins.2006.08.005] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 06/14/2006] [Accepted: 08/17/2006] [Indexed: 11/28/2022]
Abstract
In vitro experiments indicate that intrinsic neuronal excitability, as evidenced by changes in the post-burst afterhyperpolarization (AHP) and spike-frequency accommodation, is altered during learning and normal aging in the brain. Here we review these studies, highlighting two consistent findings: (i) that AHP and accommodation are reduced in pyramidal neurons from animals that have learned a task; and (ii) that AHP and accommodation are enhanced in pyramidal neurons from aging subjects, a cellular change that might contribute to age-related learning impairments. Findings from in vivo single-neuron recording studies complement the in vitro data. From these consistently reproduced findings, we propose that the intrinsic AHP level might determine the degree of synaptic plasticity and learning. Furthermore, it seems that reductions in the AHP must occur before learning if young and aging subjects are to learn a task successfully.
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Affiliation(s)
- John F Disterhoft
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611-3008, USA.
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