1
|
Ferrer-Acosta Y, Rodriguez-Massó S, Pérez D, Eterovic VA, Ferchmin PA, Martins AH. Memantine has a nicotinic neuroprotective pathway in acute hippocampal slices after an NMDA insult. Toxicol In Vitro 2022; 84:105453. [PMID: 35944748 PMCID: PMC10026604 DOI: 10.1016/j.tiv.2022.105453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/14/2022] [Accepted: 08/03/2022] [Indexed: 10/15/2022]
Abstract
Memantine is a non-competitive antagonist with a moderate affinity to the N-methyl-d-Aspartate (NMDA) receptor. The present study assessed memantine's neuroprotective activity using electrophysiology of ex-vivo hippocampal slices. Interestingly, a nicotinic component was necessary for memantine's neuroprotection (NP). Memantine demonstrated a bell-shaped dose-response curve of NP against NMDA. Memantine was neuroprotective at concentrations below 3 μM, but the NP declined at higher concentrations (>3 μM) when memantine inhibits the NMDA receptor. Additional evidence that memantine NP is mediated by an alternate mechanism independent of the inhibition of the NMDA receptor is supported by its ability to protect neurons when applied before or after the NMDA insult and in the presence of D(-)-2-Amino-5-phosphonopentanoic acid (APV), the standard NMDA receptor inhibitor. We found several similarities between the memantine NP mechanism and the neuroprotective nicotinic drug, the 4R cembranoid. Memantine's NP requires the release of acetylcholine, the activation of α4β2, and is independent of MEK/MAPK signaling. Both 4R and memantine require the activation of PI3K/AKT for NP against NMDA-mediated excitotoxicity, although at different concentrations. In conclusion, our studies show memantine is neuroprotective through a nicotinic pathway, similar to the nicotinic drug 4R. This information leads to a better understanding of memantine's mechanisms of action and explains its dose-dependent effectiveness in Alzheimer's and other neurological disorders.
Collapse
Affiliation(s)
- Yancy Ferrer-Acosta
- Department of Neuroscience, Universidad Central del Caribe, Laurel Avenue 2U6, Lomas Verdes, Bayamón 00956, Puerto Rico.
| | - Sergio Rodriguez-Massó
- Department of Pharmacology and Toxicology, University of Puerto Rico, Medical Sciences Campus, Los Paseos Avenue, Guillermo Arbona Building, San Juan 00935, Puerto Rico.
| | - Dinely Pérez
- Department of Biochemistry, Universidad Central del Caribe Laurel Avenue, #100, Santa Juanita, Bayamón 00956, Puerto Rico
| | - Vesna A Eterovic
- Neuroprotection for Life, 480 E Village Dr., Carmel, IN 46032, USA
| | - P A Ferchmin
- Neuroprotection for Life, 480 E Village Dr., Carmel, IN 46032, USA
| | - Antonio Henrique Martins
- Department of Pharmacology and Toxicology, University of Puerto Rico, Medical Sciences Campus, Los Paseos Avenue, Guillermo Arbona Building, San Juan 00935, Puerto Rico.
| |
Collapse
|
2
|
In Vivo Evaluation of the Acute Systemic Toxicity of (1S,2E,4R,6R,7E,11E)-Cembratriene-4,6-diol (4R) in Sprague Dawley Rats. NUTRACEUTICALS 2022; 2:60-70. [PMID: 35855209 PMCID: PMC9291268 DOI: 10.3390/nutraceuticals2020005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The tobacco cembranoid (1S,2E,4R,6R,7E,11E)-2,7,11-cembratriene-4,6-diol (4R) interacts with nicotinic acetylcholine receptors, which results in neuroprotection against organophosphate toxicity, brain ischemia, and Parkinson’s disease. The present study is a continuation of our previous research in which we applied a single dose of 4R 1 h before or 24 h after exposure to diisopropylfluorophosphate (DFP) (analog of the nerve agent sarin). The 4R dose robustly decreased neuroinflammation and neuronal death at both timepoints. Here, we investigated the toxicity of a single dose of 4R in male and female Sprague Dawley (SD) rats after a subcutaneous (s.c.) injection of 6, 24, or 98 mg/kg. Body weight was not affected by 4R during the 7-day observation period. No histopathologic changes in the organs were attributed to 4R. Minor hematological and blood composition variations were detected on Day 3 in the mid- and the high-dose males, but these were resolved by Day 8. At the area of the s.c. injection site, alopecia and dry skin were detected in both the 4R-treated males and females and in the female controls.
Collapse
|
3
|
Rojas-Colón LA, Dash PK, Morales-Vías FA, Lebrón-Dávila M, Ferchmin PA, Redell JB, Maldonado-Martínez G, Vélez-Torres WI. 4R-cembranoid confers neuroprotection against LPS-induced hippocampal inflammation in mice. J Neuroinflammation 2021; 18:95. [PMID: 33874954 PMCID: PMC8054431 DOI: 10.1186/s12974-021-02136-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 03/22/2021] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Chronic brain inflammation has been implicated in the pathogenesis of various neurodegenerative diseases and disorders. For example, overexpression of pro-inflammatory cytokines has been associated with impairments in hippocampal-dependent memory. Lipopolysaccharide (LPS) injection is a widely used model to explore the pathobiology of inflammation. LPS injection into mice causes systemic inflammation, neuronal damage, and poor memory outcomes if the inflammation is not controlled. Activation of the alpha-7 nicotinic receptor (α7) plays an anti-inflammatory role in the brain through vagal efferent nerve signaling. 4R-cembranoid (4R) is a natural compound that crosses the blood-brain barrier, induces neuronal survival, and has been shown to modulate the activity of nicotinic receptors. The purpose of this study is to determine whether 4R reduces the deleterious effects of LPS-induced neuroinflammation and whether the α7 receptor plays a role in mediating these beneficial effects. METHODS Ex vivo population spike recordings were performed in C57BL/6J wild-type (WT) and alpha-7-knockout (α7KO) mouse hippocampal slices in the presence of 4R and nicotinic receptor inhibitors. For in vivo studies, WT and α7KO mice were injected with LPS for 2 h, followed by 4R or vehicle for 22 h. Analyses of IL-1β, TNF-α, STAT3, CREB, Akt1, and the long-term novel object recognition test (NORT) were performed for both genotypes. In addition, RNA sequencing and RT-qPCR analyses were carried out for 12 mRNAs related to neuroinflammation and their modification by 4R. RESULTS 4R confers neuroprotection after NMDA-induced neurotoxicity in both WT and α7KO mice. Moreover, hippocampal TNF-α and IL-1β levels were decreased with 4R treatment following LPS exposure in both strains of mice. 4R restored LPS-induced cognitive decline in NORT. There was a significant increase in the phosphorylation of STAT3, CREB, and Akt1 with 4R treatment in the WT mouse hippocampus following LPS exposure. In α7KO mice, only pAkt levels were significantly elevated in the cortex. 4R significantly upregulated mRNA levels of ORM2, GDNF, and C3 following LPS exposure. These proteins are known to play a role in modulating microglial activation, neuronal survival, and memory. CONCLUSION Our results indicate that 4R decreases the levels of pro-inflammatory cytokines; improves memory function; activates STAT3, Akt1, and CREB phosphorylation; and upregulates the mRNA levels of ORM2, GDNF, and C3. These effects are independent of the α7 nicotinic receptor.
Collapse
Affiliation(s)
- Luis A Rojas-Colón
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Av. Sta. Juanita, Bayamón, 00960, Puerto Rico
| | - Pramod K Dash
- Department of Neurobiology and Anatomy, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Fabiola A Morales-Vías
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Av. Sta. Juanita, Bayamón, 00960, Puerto Rico
| | - Madeline Lebrón-Dávila
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Av. Sta. Juanita, Bayamón, 00960, Puerto Rico
| | - Pedro A Ferchmin
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Av. Sta. Juanita, Bayamón, 00960, Puerto Rico
| | - John B Redell
- Department of Neurobiology and Anatomy, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Geronimo Maldonado-Martínez
- University of Puerto Rico Molecular Science Research Center, Av. Juan Ponce de León, San Juan, 00926, Puerto Rico
| | - Wanda I Vélez-Torres
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Av. Sta. Juanita, Bayamón, 00960, Puerto Rico.
| |
Collapse
|
4
|
Yan N, Du Y, Liu X, Zhang H, Liu Y, Zhang Z. A Review on Bioactivities of Tobacco Cembranoid Diterpenes. Biomolecules 2019; 9:E30. [PMID: 30654586 PMCID: PMC6359560 DOI: 10.3390/biom9010030] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 12/27/2018] [Accepted: 01/14/2019] [Indexed: 01/08/2023] Open
Abstract
Cembranoids are carbocyclic diterpenes comprising four isoprene units and are natural products with a parent skeleton consisting of a 14-membered ring. They have gained wide interest in recent years and are a major hotspot in the research of natural product chemistry. Since 1962, various tobacco cembranoid diterpenes have been identified. This review systematically discusses and summarises the excellent antimicrobial, insecticidal, cytotoxic and neuroprotective activities of tobacco cembranoid diterpenes. These compounds show potential to be developed as botanical fungicides, cytotoxic drugs and drugs for the treatment of human immunodeficiency virus, Alzheimer's disease, Parkinson's disease, and other neurodegenerative diseases. However, there are relatively few studies on the structure⁻activity relationship (SAR) of tobacco cembranoid diterpenes. Therefore, future studies should focus on their structural modification, SAR and biogenic relationships.
Collapse
Affiliation(s)
- Ning Yan
- Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao 266101, China.
| | - Yongmei Du
- Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao 266101, China.
| | - Xinmin Liu
- Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao 266101, China.
| | - Hongbo Zhang
- Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao 266101, China.
| | - Yanhua Liu
- Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao 266101, China.
| | - Zhongfeng Zhang
- Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao 266101, China.
| |
Collapse
|
5
|
Hu J, Ferchmin PA, Hemmerle AM, Seroogy KB, Eterovic VA, Hao J. 4R-Cembranoid Improves Outcomes after 6-Hydroxydopamine Challenge in Both In vitro and In vivo Models of Parkinson's Disease. Front Neurosci 2017; 11:272. [PMID: 28611572 PMCID: PMC5447022 DOI: 10.3389/fnins.2017.00272] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 04/28/2017] [Indexed: 11/13/2022] Open
Abstract
(1S, 2E, 4R, 6R,-7E, 11E)-2, 7, 11-cembratriene-4, 6-diol (4R) is one of the cembranoids found in tobacco leaves. Previous studies have found that 4R protected acute rat hippocampal slices against neurotoxicity induced by N-methyl-D-aspartate (NMDA) and against the toxic organophosphorus compounds paraoxon and diisopropylfluorophosphate (DFP). Furthermore, in vivo, 4R reduced the infarct size in a rodent ischemic stroke model and neurodegeneration caused by DFP. The present study expanded our previous study by focusing on the effect of 4R in Parkinson's disease (PD) and elucidating its underlying mechanisms using 6-hydroxydopamine (6-OHDA)-induced injury models. We found that 4R exhibited significant neuroprotective activity in the rat unilateral 6-OHDA-induced PD model in vivo. The therapeutic effect was evident both at morphological and behavioral levels. 4R (6 and 12 mg/kg) treatments significantly improved outcomes of 6-OHDA-induced PD in vivo as indicated by reducing forelimb asymmetry scores and corner test scores 4 weeks after injection of 6-OHDA (p < 0.05). The therapeutic effect of 4R was also reflected by decreased depletion of tyrosine hydroxylase (TH) in the striatum and substantia nigra (SN) on the side injected with 6-OHDA. TH expression was 70.3 and 62.8% of the contralateral side in striatum and SN, respectively, after 6 mg/kg 4R treatment; furthermore, it was 80.1 and 79.3% after treatment with 12 mg/kg of 4R. In the control group, it was 51.9 and 23.6% of the contralateral striatum and SN (p < 0.05). Moreover, 4R also protected differentiated neuro-2a cells from 6-OHDA-induced cytotoxicity in vitro. The activation of p-AKT and HAX-1, and inhibition of caspase-3 and endothelial inflammation, were involved in 4R-mediated protection against 6-OHDA-induced injury. In conclusion, the present study indicates that 4R shows a therapeutic effect in the rat 6-OHDA-induced PD model in vivo and in 6-OHDA-challenged neuro-2a cells in vitro.
Collapse
Affiliation(s)
- Jing Hu
- Division of Pharmaceutical Sciences, James L. Winkle College of Pharmacy, University of CincinnatiCincinnati, OH, United States
| | - P A Ferchmin
- Department of Neurosciences, School of Medicine, Universidad Central del CaribeBayamón, Puerto Rico
| | - Ann M Hemmerle
- Department of Neurology and Rehabilitation Medicine, University of CincinnatiCincinnati, OH, United States
| | - Kim B Seroogy
- Department of Neurology and Rehabilitation Medicine, University of CincinnatiCincinnati, OH, United States
| | - Vesna A Eterovic
- Department of Neurosciences, School of Medicine, Universidad Central del CaribeBayamón, Puerto Rico
| | - Jiukuan Hao
- Division of Pharmaceutical Sciences, James L. Winkle College of Pharmacy, University of CincinnatiCincinnati, OH, United States
| |
Collapse
|
6
|
Vélez-Carrasco W, Green CE, Catz P, Furimsky A, O’Loughlin K, Eterović VA, Ferchmin PA. Pharmacokinetics and Metabolism of 4R-Cembranoid. PLoS One 2015; 10:e0121540. [PMID: 25811857 PMCID: PMC4374761 DOI: 10.1371/journal.pone.0121540] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 02/03/2015] [Indexed: 11/18/2022] Open
Abstract
4R-cembranoid (4R) is a natural cyclic diterpenoid found in tobacco leaves that displays neuroprotective activity. 4R protects against NMDA, paraoxon (POX), and diisopropylfluorophosphate (DFP) damage in rat hippocampal slices and against DFP in rats in vivo. The purpose of this study was to examine the metabolism and pharmacokinetics of 4R as part of its preclinical development as a neuroprotective drug. 10 µM 4R was found to be very stable in plasma for up to 1 hr incubation. 4R metabolism in human microsomes was faster than in the rat. Ten metabolites of 4R were detected in the microsomal samples; 6 dihydroxy and 4 monohydroxy forms of 4R. Male rats received a single dose of 4R at 6 mg/kg i.v., i.m., or s.c. The i.v. group had the highest plasma concentration of 1017 ng/mL. The t1/2 was 36 min and reached the brain within 10 min. The brain peak concentration was 6516 ng/g. The peak plasma concentration in the i.m. group was 163 ng/mL compared to 138 ng/mL in the s.c. group. The t1/2 of 4R after i.m. and s.c. administration was approximately 1.5 hr. The brain peak concentration was 329 ng/g in the i.m. group and 323 ng/g for the s.c. group. The brain to plasma ratio in the i.v. group was 6.4, reached 10 min after dose, whereas in the i.m. and s.c. groups was 2.49 and 2.48, respectively, at 90 min after dose. Our data show that 4R crosses the BBB and concentrates in the brain where it exerts its neuroprotective effect.
Collapse
Affiliation(s)
- Wanda Vélez-Carrasco
- Department of Biochemistry, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
| | - Carol E. Green
- SRI International Biosciences Division, Menlo Park, California, United States of America
| | - Paul Catz
- SRI International Biosciences Division, Menlo Park, California, United States of America
| | - Anna Furimsky
- SRI International Biosciences Division, Menlo Park, California, United States of America
| | - Kathleen O’Loughlin
- SRI International Biosciences Division, Menlo Park, California, United States of America
| | - Vesna A. Eterović
- Department of Biochemistry, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
| | - P. A. Ferchmin
- Department of Biochemistry, Universidad Central del Caribe, Bayamon, Puerto Rico, United States of America
- * E-mail:
| |
Collapse
|
7
|
Ferchmin PA, Andino M, Reyes Salaman R, Alves J, Velez-Roman J, Cuadrado B, Carrasco M, Torres-Rivera W, Segarra A, Martins AH, Lee JE, Eterovic VA. 4R-cembranoid protects against diisopropylfluorophosphate-mediated neurodegeneration. Neurotoxicology 2014; 44:80-90. [PMID: 24928201 DOI: 10.1016/j.neuro.2014.06.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Revised: 06/01/2014] [Accepted: 06/01/2014] [Indexed: 11/26/2022]
Abstract
Many organophosphorous esters synthesized for applications in industry, agriculture, or warfare irreversibly inhibit acetylcholinesterase, and acute poisoning with these compounds causes life-threatening cholinergic overstimulation. Following classical emergency treatment with atropine, an oxime, and a benzodiazepine, surviving victims often suffer brain neurodegeneration. Currently, there is no pharmacological treatment to prevent this brain injury. Here we show that a cyclic diterpenoid, (1S,2E,4R,6R,7E,11E)-cembra-2,7,11-triene-4,6-diol (4R) ameliorates the damage caused by diisopropylfluorophosphate (DFP) in the hippocampal area CA1. DFP has been frequently used as a surrogate for the warfare nerve agent sarin. In rats, DFP is lethal at the dose used to cause brain damage. Therefore, to observe brain damage in survivors, the death rate was reduced by pre-administration of the peripherally acting antidotes pyridostigmine and methyl atropine or its analog ipratropium. Pyridostigmine bromide, methyl atropine nitrate, and ipratropium bromide were dissolved in saline and injected intramuscularly at 0.1mg/kg, 20mg/kg, and 23mg/kg, respectively. DFP (9mg/kg) dissolved in cold water was injected intraperitoneally. 4R (6mg/kg) dissolved in DMSO was injected subcutaneously, either 1h before or 5 or 24h after DFP. Neurodegeneration was assessed with Fluoro-Jade B and amino cupric silver staining; neuroinflammation was measured by the expression of nestin, a marker of activated astrocytes. Forty-eight hours after DFP administration, 4R decreased the number of dead neurons by half when injected before or after DFP. 4R also significantly decreased the number of activated astrocytes. These data suggest that 4R is a promising new drug that could change the therapeutic paradigm for acute poisoning with organophosphorous compounds by the implementation of a second-stage intervention after the classical countermeasure treatment.
Collapse
Affiliation(s)
- P A Ferchmin
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Bayamón, PR 00960, USA.
| | - Myrna Andino
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Bayamón, PR 00960, USA
| | - Rebeca Reyes Salaman
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Bayamón, PR 00960, USA
| | - Janaina Alves
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Bayamón, PR 00960, USA
| | - Joyce Velez-Roman
- Department of Pharmacology, University of Puerto Rico Medical Sciences Campus, San Juan, PR 00936, USA
| | - Brenda Cuadrado
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Bayamón, PR 00960, USA
| | - Marimeé Carrasco
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Bayamón, PR 00960, USA
| | - Wilmarie Torres-Rivera
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Bayamón, PR 00960, USA
| | - Annabell Segarra
- Department of Pharmacology, University of Puerto Rico Medical Sciences Campus, San Juan, PR 00936, USA
| | - Antonio Henrique Martins
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Bayamón, PR 00960, USA
| | - Jae Eun Lee
- RTRN Data Coordinating Center, Jackson State University, Jackson, MI 39204, USA
| | - Vesna A Eterovic
- Department of Biochemistry, Universidad Central del Caribe School of Medicine, Bayamón, PR 00960, USA
| |
Collapse
|
8
|
Arias HR, López JJ, Feuerbach D, Fierro A, Ortells MO, Pérez EG. Novel 2-(substituted benzyl)quinuclidines inhibit human α7 and α4β2 nicotinic receptors by different mechanisms. Int J Biochem Cell Biol 2013; 45:2420-30. [DOI: 10.1016/j.biocel.2013.08.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 07/11/2013] [Accepted: 08/06/2013] [Indexed: 01/12/2023]
|
9
|
Torres-Rivera W, Pérez D, Park KY, Carrasco M, Platt MO, Eterović VA, Ferchmin PA, Ulrich H, Martins AH. Kinin-B2 receptor exerted neuroprotection after diisopropylfluorophosphate-induced neuronal damage. Neuroscience 2013; 247:273-9. [PMID: 23735753 DOI: 10.1016/j.neuroscience.2013.05.054] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 05/23/2013] [Accepted: 05/24/2013] [Indexed: 02/06/2023]
Abstract
The kinin-B2 receptor (B2BKR) activated by its endogenous ligand bradykinin participates in various metabolic processes including the control of arterial pressure and inflammation. Recently, functions for this receptor in brain development and protection against glutamate-provoked excitotoxicity have been proposed. Here, we report neuroprotective properties for bradykinin against organophosphate poisoning using acute hippocampal slices as an in vitro model. Following slice perfusion for 10min with diisopropylfluorophosphate (DFP) to initiate the noxious stimulus, responses of pyramidal neurons upon an electric impulse were reduced to less than 30% of control amplitudes. Effects on synaptic-elicited population spikes were reverted when preparations had been exposed to bradykinin 30min after challenging with DFP. Accordingly, bradykinin-induced population spike recovery was abolished by HOE-140, a B2BKR antagonist. However, the kinin-B1 receptor (B1BKR) agonist Lys-des-Arg(9)-bradykinin, inducing the phosphorylation of mitogen-activated protein kinase (MEK/MAPK) and cell death, abolished bradykinin-mediated neuroprotection, an effect, which was reverted by the ERK inhibitor PD98059. In agreement with pivotal B1BKR functions in this process, antagonism of endogenous B1BKR activity alone was enough for restoring population spike activity. On the other hand pralidoxime, an oxime, reactivating acetylcholinesterase (AChE) after organophosphate poisoning, induced population spike recovery after DFP exposure in the presence of bradykinin and Lys-des-Arg(9)-bradykinin. Lys-des-Arg(9)-bradykinin did not revert protection exerted by pralidoxime, however when instead bradykinin and Ly-des-Arg(9)-bradykinin were superfused together, recovery of population spikes diminished. These findings again confirm the neuroprotective feature of bradykinin, which is, diminished by its endogenous metabolites, stimulating the B1BKR, providing a novel understanding of the physiological roles of these receptors.
Collapse
Affiliation(s)
- W Torres-Rivera
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR 00956, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Protective activity of (1S,2E,4R,6R,7E,11E)-2,7,11-cembratriene-4,6-diol analogues against diisopropylfluorophosphate neurotoxicity: preliminary structure-activity relationship and pharmacophore modeling. Bioorg Med Chem 2013; 21:4678-86. [PMID: 23769165 DOI: 10.1016/j.bmc.2013.05.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 05/03/2013] [Accepted: 05/10/2013] [Indexed: 01/09/2023]
Abstract
Diisopropylfluorophosphate (DFP) is an organophosphorous insecticide used as a surrogate for the more toxic chemical warfare nerve agent sarin. DFP produces neurotoxicity in vivo and irreversibly decreases the area of population spikes recorded from the CA1 region of acute hippocampal slices. (1S,2E,4R,6R,7E,11E)-2,7,11-Cembratriene-4,6-diol (1) is a neuroprotective natural cembranoid that reverses DFP-induced damage both in vivo and in the hippocampal slice. Cembranoid 1 acts by noncompetitive inhibition of the α7 nicotinic acetylcholine receptor. This study aims at establishing a preliminary structure-activity relationship to define the neuroprotective cembranoid pharmacophores using the hippocampal slice assay and pharmacophore modeling. Fourteen natural, semisynthetic, or biocatalytic cembranoid analogues 2-15 related to 1 were tested for their capacity to protect the population spikes from DFP-induced damage and intrinsic toxicity. Twelve cembranoids caused significant reversal of DFP toxicity; only 3 active analogues displayed minor intrinsic toxicity at 10 μM. The C-4 epimer of 1 (2) and the 4-O-methyl ether analogue of 1 (3), were totally devoid of neuroprotective activity. The results suggested a model for cembranoid binding where the hydrophobic ring surface binds to a hydrophobic (Hbic) patch on the receptor molecule and an electronegative atom (oxygen or sulfur) in proper spatial relationship to the ring surface interacts with an electropositive group in the receptor binding site. A pharmacophore model consisting of 1 hydrogen bond acceptor (HBA), 2 Hbic, and 10 exclusion spheres was established using HipHop-REFINE and supported the above mentioned pharmacophoric hypothesis.
Collapse
|