1
|
Pittaluga A. Presynaptic release-regulating NMDA receptors in isolated nerve terminals: A narrative review. Br J Pharmacol 2021; 178:1001-1017. [PMID: 33347605 PMCID: PMC9328659 DOI: 10.1111/bph.15349] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 11/10/2020] [Accepted: 12/03/2020] [Indexed: 02/02/2023] Open
Abstract
The existence of presynaptic, release‐regulating NMDA receptors in the CNS has been long matter of discussion. Most of the reviews dedicated to support this conclusion have preferentially focussed on the results from electrophysiological studies, paying little or no attention to the data obtained with purified synaptosomes, even though this experimental approach has been recognized as providing reliable information concerning the presence and the role of presynaptic release‐regulating receptors in the CNS. To fill the gap, this review is dedicated to summarising the results from studies with synaptosomes published during the last 40 years, which support the existence of auto and hetero NMDA receptors controlling the release of transmitters such as glutamate, GABA, dopamine, noradrenaline, 5‐HT, acetylcholine and peptides, in the CNS of mammals. The review also deals with the results from immunochemical studies in isolated nerve endings that confirm the functional observations.
Collapse
Affiliation(s)
- Anna Pittaluga
- Department of Pharmacology (DIFAR), School of Medical and Pharmaceutical Sciences, 3Rs Center, University of Genova, Italy.,San Martino Hospital IRCCS, Genova, Italy
| |
Collapse
|
2
|
Coccurello R, Caprioli A, Bellantuono S, D'Amato FR, Conti R, Giannessi F, Borsini F, Moles A. Effects of the increase in neuronal fatty acids availability on food intake and satiety in mice. Psychopharmacology (Berl) 2010; 210:85-95. [PMID: 20232053 DOI: 10.1007/s00213-010-1820-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 02/24/2010] [Indexed: 11/30/2022]
Abstract
RATIONALE Neurons detect free fatty acids (FFAs) availability and use this nutritional status to modulate feeding and control body weight. OBJECTIVES The work is designed to characterize the impact on feeding behavior of either oleic acid (OA) administration (experiment 1) or the inhibition (experiment 2) of the enzyme carnitine palmitoyltransferase-1 (CPT-1). The structure of feeding behavior and satiation time course were examined through the behavioral satiety sequence (BSS) paradigm. METHODS Adult male mice were initially habituated to a palatable diet, then subjected to intracerebroventricular (i.c.v.) infusion of different doses of OA or the CPT-1 inhibitor ST1326. Food intake at different time points, duration, and frequencies of feeding and non-feeding-related behaviors were continuously monitored over 40 min and satiety development profiled according to BSS. RESULTS Intra-i.c.v. infusion of oleic acid (300 nM) and ST1326 (50 and 75 pM) suppressed food intake. As indicated by the earlier leftward shifting of the normal transition from eating to resting, both strategies similarly accelerated the onset of satiety. The premature onset of satiety resulted in a dose-related fashion with 50 pM of ST1326 producing a marked premature onset than the lower dose. However, at the highest dose injected, the inhibition of CPT-1 disrupted the BSS profile. CONCLUSIONS The increased neuronal availability of FFAs mediates a significant anorectic response which is mirrored by an early occurrence of satiety onset. Besides supporting the role of central nutrient sensing in feeding, the present data demonstrate that the modulation of satiety enhancement can produce appetite suppressant effects within narrow range of neuronal FFAs availability.
Collapse
Affiliation(s)
- Roberto Coccurello
- Institute of Neuroscience, National Research Council, Via del Fosso di Fiorano, 64-00143 Rome, Italy
| | | | | | | | | | | | | | | |
Collapse
|
3
|
Thomas TC, Kruzich PJ, Joyce BM, Gash C, Suchland K, Surgener SP, Rutherford EC, Grandy DK, Gerhardt GA, Glaser PE. Dopamine D4 receptor knockout mice exhibit neurochemical changes consistent with decreased dopamine release. J Neurosci Methods 2007; 166:306-14. [PMID: 17449106 PMCID: PMC2699616 DOI: 10.1016/j.jneumeth.2007.03.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 03/08/2007] [Accepted: 03/14/2007] [Indexed: 11/17/2022]
Abstract
Dopamine D4 receptor (D4R) knockout mice (D4R-/-) provided for unique neurochemical studies designed to understand D4R contributions to dopamine (DA) regulation. In this study, post-mortem brain tissue content of DA did not differ between D4R+/+ and D4R-/- mice in the striatum (Str) or nucleus accumbens core (NAc). However, there was a significant decrease (82%) in the content of 3,4-dihydoxyphenylacetic acid (DOPAC), a major metabolite of DA, in the NAc of D4R-/- mice. Microdialysis studies performed in a region of brain spanning of the dorsal Str and NAc showed lower baseline levels of DA and a significant reduction in KCl-evoked overflow of DA in the D4R-/- mice. Baseline extracellular levels of DOPAC and homovanillic acid were also significantly lower in the D4R-/- mice. In vivo chronoamperometric recordings of KCl-evoked release of DA also showed decreased release of DA in the Str and NAc of the D4R-/- mice. These studies demonstrate a role of D4Rs in presynaptic DA regulation and support the hypothesis that alterations in D4Rs may lead to diminished DA function.
Collapse
Affiliation(s)
- Theresa Currier Thomas
- Department of Anatomy & Neurobiology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- Center for Sensor Technology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- University of Kentucky Morris K. Udall Parkinson’s Disease Research Center of Excellence, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
| | - Paul J. Kruzich
- Departments of Physiology & Pharmacology, Oregon Health and Science University; Portland, OR 97239, USA
- Department of Physiology, Medical College of Georgia, Augusta, GA 30912, USA
| | - B. Matthew Joyce
- Department of Anatomy & Neurobiology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- Center for Sensor Technology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- University of Kentucky Morris K. Udall Parkinson’s Disease Research Center of Excellence, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
| | - C.R. Gash
- Department of Psychiatry, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
| | - Katherine Suchland
- Departments of Physiology & Pharmacology, Oregon Health and Science University; Portland, OR 97239, USA
| | - Stewart P. Surgener
- Department of Anatomy & Neurobiology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- Center for Sensor Technology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- University of Kentucky Morris K. Udall Parkinson’s Disease Research Center of Excellence, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
| | - Erin C. Rutherford
- Department of Anatomy & Neurobiology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- Center for Sensor Technology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- University of Kentucky Morris K. Udall Parkinson’s Disease Research Center of Excellence, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
| | - David K. Grandy
- Departments of Physiology & Pharmacology, Oregon Health and Science University; Portland, OR 97239, USA
| | - Greg A. Gerhardt
- Department of Anatomy & Neurobiology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- Department of Psychiatry, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- Department of Neurology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- Center for Sensor Technology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- University of Kentucky Morris K. Udall Parkinson’s Disease Research Center of Excellence, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
| | - Paul E.A. Glaser
- Department of Anatomy & Neurobiology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- Department of Pediatrics, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- Department of Psychiatry, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- Center for Sensor Technology, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- University of Kentucky Morris K. Udall Parkinson’s Disease Research Center of Excellence, University of Kentucky Chandler Medical Center, Lexington, KY 40536, USA
- Address correspondence to: Paul E.A. Glaser M.D., Ph.D., University of Kentucky, 306 Whitney-Hendrickson Facility, Lexington, KY 40536, Tel.: (859) 323-4531, Fax: (859) 257-5310,
| |
Collapse
|
4
|
Yaksh TL, Kokotos G, Svensson CI, Stephens D, Kokotos CG, Fitzsimmons B, Hadjipavlou-Litina D, Hua XY, Dennis EA. Systemic and Intrathecal Effects of a Novel Series of Phospholipase A2 Inhibitors on Hyperalgesia and Spinal Prostaglandin E2 Release. J Pharmacol Exp Ther 2005; 316:466-75. [PMID: 16203828 DOI: 10.1124/jpet.105.091686] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Phospholipase A(2) (PLA(2)) forms are expressed in spinal cord, and inhibiting spinal PLA(2) induces a potent antihyperalgesia. Here, we examined the antihyperalgesic effects after systemic and i.t. delivery of four compounds constructed with a common motif consisting of a 2-oxoamide with a hydrocarbon tail and a four-carbon tether. These molecules were characterized for their ability to block group IVA calcium-dependent PLA(2) (cPLA(2)) and group VIA calcium-independent PLA(2) (iPLA(2)) in inhibition assays using human recombinant enzyme. The rank ordering of potency in blocking group IVA cPLA(2) was AX048 (ethyl 4-[(2-oxohexadecanoyl)amino]butanoate), AX006 (4-[(2-oxohexadecanoyl)amino]butanoic acid), and AX057 (tert-butyl 4-[(2-oxohexadecanoyl)amino]butanoate) > AX010 (methyl 4-[(2-oxohexadecanoyl)amino]butanoate) and for inhibiting group VIA iPLA(2) was AX048, AX057 > AX006, and AX010. No agent altered recombinant cyclooxygenase activity. In vivo, i.t. (30 mug) and systemic (0.2-3 mg/kg i.p.) AX048 blocked carrageenan hyperalgesia and after systemic delivery in a model of spinally mediated hyperalgesia induced by i.t. substance P (SP). The other agents were without activity. In rats prepared with lumbar i.t. loop dialysis catheters, SP evoked spinal prostaglandin E(2) (PGE(2)) release. AX048 alone inhibited PGE(2) release. Intrathecal SR141617, a cannabinoid CB1 inhibitor at doses that blocked the effects of i.t. anandamide had no effect upon i.t. AX048. These results suggest that AX048 is the first systemically bioavailable compound with a significant affinity for group IVA cPLA(2), which produces a potent antihyperalgesia. The other agents, although demonstrating enzymatic activity in cell-free assays, appear unable to gain access to the intracellular PLA(2) toward which their action is targeted.
Collapse
Affiliation(s)
- Tony L Yaksh
- Department of Anesthesiology, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0818, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
5
|
|
6
|
Kang JH, Park IS, Oh WY, Lim HK, Wang SY, Lee SY, Choi KH, Kim JI, Jung SY, Suh CK, Kim DS. Inhibition of aroclor 1254-induced depletion of stored calcium prevents the cell death in catecholaminergic cells. Toxicology 2004; 200:93-101. [PMID: 15212806 DOI: 10.1016/j.tox.2004.03.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2003] [Revised: 03/01/2004] [Accepted: 03/01/2004] [Indexed: 11/27/2022]
Abstract
The relationship between depleting effects of polychlorinated biphenyls (PCBs) on the intracellular calcium store and PCBs-induced cell death in dopaminergic cells has not been fully evaluated. Here, we evaluated the effects of inhibitors of the release of ER-stored calcium on the cytotoxicities induced by 10 microg/ml of Aroclor 1254 (A1254; polychlorinated biphenyl mixture) in a catecholaminergic cell-line, CATH.a cells. Exposure to A1254 produced an elevation in free calcium ([Ca2+]i) in the presence or absence of extracellular calcium and decreased in cell viability. From our results, we deduced that the A1254-induced elevation of [Ca2+]i resulted from the depletion of ER-stored calcium. The [Ca2+)]i elevation was dramatically inhibited by an inositol 1,4,5-triphosphate receptor (IP3R) antagonist, and slightly inhibited by a ryanodine receptor (RyR) blocker. IP3R blockers conferred significant protection against A1254-induced cell death, as did RyR blockers, but calcium chelators or NMDA blockers did not. However, none of these reagents inhibited the depletion of intracellular dopamine by A1254 indicating that the mechanism of PCB-induced dopamine depletion may be independent of calcium alterations. Taken together, these data suggest that agents inhibiting the receptor-mediated depletion of stored calcium can prevent the A1254-induced cell death, but not modulate the A1254-induced intracellular dopamine depletion in CATH.a cells.
Collapse
Affiliation(s)
- Ju-Hee Kang
- Department of Pharmacology and Toxicology, College of Medicine, Inha University, Incheon 402-751, South Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Melis MR, Succu S, Mascia MS, Cortis L, Argiolas A. Extracellular excitatory amino acids increase in the paraventricular nucleus of male rats during sexual activity: main role of N-methyl-d-aspartic acid receptors in erectile function. Eur J Neurosci 2004; 19:2569-75. [PMID: 15128410 DOI: 10.1111/j.0953-816x.2004.03362.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The concentrations of glutamic and aspartic acids were measured in the dialysate obtained with vertical microdialysis probes implanted into the paraventricular nucleus of the hypothalamus of sexually potent male rats during sexual activity. Animals showed noncontact erections when put in the presence of, and copulated with, a receptive (ovarietomized oestrogen- and progesterone-primed) female rat. The concentrations of glutamic and aspartic acids in the paraventricular dialysate increased by 37 and 80%, respectively, above baseline values during exposure to the receptive female rat and by 55 and 127%, respectively, during copulation. No changes in the concentrations of glutamic and aspartic acids were detected in the paraventricular dialysate when sexually potent male rats were exposed to nonreceptive (ovariectomized not oestrogen- and progesterone-primed) female rats or when impotent male rats were used. The injection into the paraventricular nucleus of the excitatory amino acid receptor antagonist dizocilpine (5 micro g), a noncompetitive N-methyl-d-aspartic acid receptor antagonist, reduced noncontact erections and significantly impaired copulatory activity. The alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist 6-cyano-7-nitro-quinoxaline-2,3-dione (5 micro g) was also able to impair copulatory activity, but to a much lower extent than dizocilpine. In contrast, (+/-)-2-amino-4-phosphono-butanoic acid, a metabotropic receptor antagonist (5 micro g), was found to be ineffective. These results confirm the involvement of the paraventricular nucleus in the control of erectile function and copulatory behaviour and show that excitatory amino acid concentration increases in the paraventricular nucleus when penile erection occurs in physiological contexts.
Collapse
Affiliation(s)
- Maria Rosaria Melis
- Bernard B. Brodie Department of Neuroscience and Center of Excellence for the Neurobiology of Addictions, University of Cagliari, Cittadella Universitaria, S.P. Monserrato-Sestu, Km 0.700, 09042 Monserrato (CA), Italy.
| | | | | | | | | |
Collapse
|
8
|
Chen N, Appell M, Berfield JL, Reith MEA. Inhibition by arachidonic acid and other fatty acids of dopamine uptake at the human dopamine transporter. Eur J Pharmacol 2003; 478:89-95. [PMID: 14575792 DOI: 10.1016/j.ejphar.2003.08.045] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
It is known that arachidonic acid, in addition to promoting release of dopamine, can inhibit its transport. The present study provides preliminary information on structure-activity relationships for uptake inhibition by rotating disk voltammetry in human embryonic kidney-293 cells expressing the human dopamine transporter. Except for anandamide, all other fatty acids studied at a pretreatment concentration of 80 microM caused significant reductions in Vmax but not Km. Increasing saturation of the hydrocarbon tails (partial saturation: oleic acid, linoleic acid; full saturation: arachidic acid, stearic acid, stearic acid ethyl ester) removed inhibitory activity incrementally, suggesting a role for cis-unsaturation (folding/bending of hydrocarbon tails). The relative lack of effect of 5,8,11,14-eicosatetraynoic acid also supports the idea that less linear structures are less inhibitory on dopamine uptake. Esterification of the free carboxylic group (arachidonic acid ethyl ester) prevented most of the inhibitory activity, arguing against mere membrane lipid disruption. Finally, the endogenous cannabinoid anandamide greatly reduced uptake Vmax accompanied by a small decrease in Km, a potentially important effect on dopaminergic neurotransmission.
Collapse
Affiliation(s)
- Nianhang Chen
- Department of Biomedical and Therapeutic Sciences, University of Illinois College of Medicine, Box 1649, Peoria, IL 61656-1649, USA
| | | | | | | |
Collapse
|
9
|
Abstract
Amphetamine stimulates particulate protein kinase C (PKC) activity that is associated with the outward-transport of dopamine (DA) (Giambalvo [2003] Synapse 49:125-133). This stimulatory effect requires intracellular calcium ([Ca](i)) and endogenous DA and when DA release is diminished, the inward-transport of amphetamine inhibits PKC activity. This study examines the mechanisms involved. It was found that synaptoneurosomes incubated with amphetamine showed a dose-dependent increase in phospholipase C and A(2) activities. Furthermore, pretreatments with the phospholipase C inhibitor D609 or the phospholipase A(2) inhibitors quinacrine or p-bromophenacylbromide attenuated the amphetamine-induced increase in PKC activity. This suggests that both phospholipases were essential for the amphetamine-induced increase in PKC activity. The Na/Ca antiporter was also involved, since pretreatment with amiloride or benzamil attenuated the amphetamine-induced increase in PKC activity. Since these drugs by themselves increased PKC activity, the return to basal activity after addition of amphetamine suggests that, in the absence of Na/Ca exchange, amphetamine had an inhibitory effect on PKC activity. This inhibitory effect might be due to the activation of phospholipase A(2) through an increase in intracellular pH induced by amphetamine. This was supported by the finding that pretreatment with dimethylamiloride, an inhibitor of the Na/H antiporter that increases intracellular [H(+)], attenuated the effects of amphetamine on PKC activity. Other drugs that decrease intracellular [H(+)] (ammonia, monensin) also inhibited PKC activity without Ca. In contrast to amphetamine, monensin had no effect on PKC activity with Ca. This could be related to its large differential effects on phospholipase A(2) vs. phospholipase C activity. Thus, the monensin-mediated decrease in PKC activity seen without Ca was partially attenuated by pretreatment with quinacrine. Furthermore, when Na/Ca antiporter was inhibited with benzamil, monensin inhibited PKC activity. These results suggest that amphetamine, as well as monensin, may have dual effects on PKC activity, a Ca-dependent stimulatory effect via phospholipase C, and an inhibitory effect via phospholipase A(2).
Collapse
Affiliation(s)
- Cecilia T Giambalvo
- Rhode Island Psychiatric Research Center, Eleanor Slater Hospital, Cranston, Rhode Island 02920, USA
| |
Collapse
|
10
|
Svensson CI, Yaksh TL. The spinal phospholipase-cyclooxygenase-prostanoid cascade in nociceptive processing. Annu Rev Pharmacol Toxicol 2002; 42:553-83. [PMID: 11807183 DOI: 10.1146/annurev.pharmtox.42.092401.143905] [Citation(s) in RCA: 212] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Intrathecal phospholipase A2 (PLA2) and cyclooxygenase-2 (COX-2), but not COX-1, inhibitors attenuate facilitated pain states generated by peripheral injury/inflammation and by direct activation of spinal glutamate and substance P receptors. These results are consistent with the constitutive expression of PLA2 and COX-2 in spinal cord, the spinal release of prostaglandins by persistent afferent input, and the effects of prostaglandins on spinal excitability. Whereas the acute actions of COX-2 inhibitors are clearly mediated by constitutively expressed spinal COX-2, studies of spinal COX-2 expression indicate that it is upregulated by neural input and circulating cytokines. Given the intrathecal potency of COX-2 inhibitors, the comparable efficacy of intrathecal versus systemic COX-2 inhibitors in hyperalgesic states not associated with inflammation, and the onset of antihyperalgesic activity prior to COX-2 upregulation, it is argued that a principal antihyperalgesic mechanism of COX-2 inhibitors lies with modulation of constitutive COX-2 present at the spinal level.
Collapse
Affiliation(s)
- Camilla I Svensson
- Department of Anesthesiology, University of California, San Diego, La Jolla, California 92093-0818, USA.
| | | |
Collapse
|
11
|
Mariussen E, Myhre O, Reistad T, Fonnum F. The polychlorinated biphenyl mixture aroclor 1254 induces death of rat cerebellar granule cells: the involvement of the N-methyl-D-aspartate receptor and reactive oxygen species. Toxicol Appl Pharmacol 2002; 179:137-44. [PMID: 11906243 DOI: 10.1006/taap.2002.9353] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Polychlorinated biphenyls (PCBs) are widespread persistent environmental contaminants that display a complex spectrum of toxicological properties, including neurotoxicity. The present study investigates the effects of the PCB mixtures Aroclor 1242 (A1242) and Aroclor 1254 (A1254), and the PCB congeners 126 (3,3',4,4',5,-PeCB) and 153 (2,2',4,4',5,5'-HxCB) on formation of reactive oxygen species (ROS) and cell death in cultured rat cerebellar granule cells. The increase of ROS and induction of cell death were assayed using the fluorescent probe 2,7-dichlorofluorescin diacetate (DCFH-DA) and the trypan blue exclusion assay, respectively. A1242 and A1254 and PCB 153 induced a concentration-dependent increase in cell death and ROS formation. A1254 was selected for mechanistic studies. When the cerebellar granule cells were exposed to 15 microM A1254 for 12 h, 95% of the cells died. Both PCB-mediated cell death and the increase of the ROS formation were inhibited by MK-801, demonstrating the importance of the N-methyl-D-aspartate receptor. Inhibitors of nitric oxide synthase and phospholipase A2 led to a significant reduction of the DCF fluorescence and cell death. The mitochondrial permeability transition pore blocker cyclosporin A and the antioxidant vitamin E also increased survival and reduced ROS formation. The results show a connection between cell death and free radical formation.
Collapse
|
12
|
Mitrovic I, Napier TC. Mu and kappa opioid agonists modulate ventral tegmental area input to the ventral pallidum. Eur J Neurosci 2002; 15:257-68. [PMID: 11849293 DOI: 10.1046/j.0953-816x.2001.01860.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The ventral pallidum (VP) is situated at the convergence of midbrain dopamine and accumbal opioid efferent projections. Using in vivo electrophysiological procedures in chloral hydrate-anaesthetized rats, we examined whether discrete application of mu- [D-Ala2,N-Me-Phe4,Gly-ol5 (DAMGO)] or kappa- (U50488) opioid receptor agonists could alter VP responses to electrical stimulation of ventral tegmental area. Rate suppressions occurred frequently following ventral tegmental area stimulation. Consistent with an involvement of dopamine in this effect, none of the 12 spontaneously active ventral pallidal neurons recorded in rats that had monoamines depleted by reserpine responded to electrical stimulation of ventral tegmental area. Moreover, in intact rats, the dopamine antagonist flupenthixol attenuated evoked suppression in 100% of the neurons tested; however, the GABAA antagonist bicuculline was able to slightly attenuate the response in 50% of the neurons tested. These observations concur with our previous studies in indicating that ventral tegmental area stimulation releases dopamine (and sometimes GABA) onto ventral pallidal neurons. Both DAMGO and U50488 decreased the inhibitory effects of ventral tegmental area stimulation. These effects on the endogenously released transmitter differed from those seen with exogenously applied dopamine, for DAMGO did not alter the efficacy or potency of microiontophoretically applied dopamine. Taken together, these observations suggest that the interaction between DAMGO and dopamine does not occur at a site that is immediately postsynaptic to the dopaminergic input within the VP, but rather that opioid modulation involves mechanisms governing presynaptically released dopamine. These modulatory processes would enable ventral pallidal opioids to gate the influence of ventral tegmental area dopamine transmission on limbic system outputs at the level of the VP.
Collapse
MESH Headings
- 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer/pharmacology
- Analgesics, Non-Narcotic/pharmacology
- Analgesics, Opioid/pharmacology
- Animals
- Dopamine/metabolism
- Electric Stimulation
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Evoked Potentials/drug effects
- Evoked Potentials/physiology
- Globus Pallidus/cytology
- Iontophoresis
- Male
- Neural Pathways
- Nucleus Accumbens/cytology
- Nucleus Accumbens/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid, kappa/agonists
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/metabolism
- Ventral Tegmental Area/cytology
- Ventral Tegmental Area/drug effects
- Ventral Tegmental Area/metabolism
- gamma-Aminobutyric Acid/metabolism
Collapse
Affiliation(s)
- Igor Mitrovic
- Department of Pharmacology and Experimental Therapeutics, Loyola University Chicago Stritch School of Medicine, Building 102, 2160 South First Avenue, Maywood, IL 60153, USA
| | | |
Collapse
|
13
|
Contestabile A. Roles of NMDA receptor activity and nitric oxide production in brain development. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2000; 32:476-509. [PMID: 10760552 DOI: 10.1016/s0165-0173(00)00018-7] [Citation(s) in RCA: 281] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The concept that neural activity is important for brain maturation has focused much research interest on the developmental role of the NMDA receptor, a key mediator of experience-dependent synaptic plasticity. However, a mechanism able to link spatial and temporal parameters of synaptic activity during development emerged as a necessary condition to explain how axons segregate into a common brain region and make specific synapses on neuronal sub-populations. To comply with this developmental constraint, it was proposed that nitric oxide (NO), or other substances having similar chemical and biological characteristics, could act as short-lived, activity-dependent spatial signals, able to stabilize active synapses by diffusing through a local volume of tissue. The present article addresses this issue, by reviewing the experimental evidence for a correlated role of the activity of the NMDA receptor and the production of NO in key steps of neural development. Evidence for such a functional coupling emerges not only concerning synaptogenesis and formation of neural maps, for which it was originally proposed, but also for some earlier phases of neurogenesis, such as neural cell proliferation and migration. Regarding synaptogenesis and neural map formation in some cases, there is so far no conclusive experimental evidence for a coupled functional role of NMDA receptor activation and NO production. Some technical problems related to the use of inhibitors of NO formation and of gene knockout animals are discussed. It is also suggested that other substances, known to act as spatial signals in adult synaptic plasticity, could have a role in developmental plasticity. Concerning the crucial developmental phase of neuronal survival or elimination through programmed cell death, the well-documented survival role related to NMDA receptor activation also starts to find evidence for a concomitant requirement of downstream NO production. On the basis of the reviewed literature, some of the major controversial issues are addressed and, in some cases, suggestions for possible future experiments are proposed.
Collapse
Affiliation(s)
- A Contestabile
- Department of Biology, University of Bologna, Via Selmi 3, 40126, Bologna, Italy.
| |
Collapse
|