1
|
Kajita Y, Fukuda Y, Kawamatsu R, Oyanagi T, Mushiake H. Pentylenetetrazole kindling induces dynamic changes in GAD65 expression in hippocampal somatostatin interneurons. Pharmacol Biochem Behav 2024; 239:173755. [PMID: 38527654 DOI: 10.1016/j.pbb.2024.173755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/01/2024] [Accepted: 03/22/2024] [Indexed: 03/27/2024]
Abstract
INTRODUCTION One of the mechanisms of epileptgenesis is impairment of inhibitory neural circuits. Several studies have compared neural changes among subtypes of gamma-aminobutyric acid-related (GABAergic) neurons after acquired epileptic seizure. However, it is unclear that GABAergic neural modifications that occur during acquisition process of epileptic seizure. METHODS Male rats were injected with pentylenetetrazole (PTZ kindling: n = 30) or saline (control: n = 15) every other day to observe the development of epileptic seizure stages. Two time points were identified: the point at which seizures were most difficult to induce, and the point at which seizures were most easy to induce. The expression of GABAergic neuron-related proteins in the hippocampus was immunohistochemically compared among GABAergic subtypes at each of these time points. RESULTS Bimodal changes in seizure stages were observed in response to PTZ kindling. The increase of seizure stage was transiently suppressed after 8 or 10 injections, and then progressed again by the 16th injection. Based on these results, we defined 10 injections as a short-term injection period during which seizures are less likely to occur, and 20 injections as a long-term injection period during which continuous seizures are likely to occur. The immunohistochemical analysis showed that hippocampal glutamic acid decarboxylase 65 (GAD65) expression was increased after short-term kindling but unchanged after long-term kindling. Increased GAD65 expression was limited to somatostatin-positive (SOM+) cells among several GABAergic subtypes. By contrast, GAD, GABA, GABAAR α1, GABABR1, and VGAT cells showed no change following short- or long-term PTZ kindling. CONCLUSION PTZ kindling induces bimodal changes in the epileptic seizure stage. Seizure stage is transiently suppressed after short-term PTZ injection with GAD65 upregulation in SOM+ cells. The seizure stage is progressed again after long-term PTZ injection with GAD65 reduction to baseline level.
Collapse
Affiliation(s)
- Yuki Kajita
- Department of Physiology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan.
| | - Yuki Fukuda
- Department of Physiology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Riho Kawamatsu
- Department of Physiology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Takanori Oyanagi
- Department of Physiology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| | - Hajime Mushiake
- Department of Physiology, Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai 980-8575, Japan
| |
Collapse
|
2
|
Rosen JB, Schulkin J. Hyperexcitability: From Normal Fear to Pathological Anxiety and Trauma. Front Syst Neurosci 2022; 16:727054. [PMID: 35993088 PMCID: PMC9387392 DOI: 10.3389/fnsys.2022.727054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 06/20/2022] [Indexed: 11/16/2022] Open
Abstract
Hyperexcitability in fear circuits is suggested to be important for development of pathological anxiety and trauma from adaptive mechanisms of fear. Hyperexcitability is proposed to be due to acquired sensitization in fear circuits that progressively becomes more severe over time causing changing symptoms in early and late pathology. We use the metaphor and mechanisms of kindling to examine gains and losses in function of one excitatory and one inhibitory neuropeptide, corticotrophin releasing factor and somatostatin, respectively, to explore this sensitization hypothesis. We suggest amygdala kindling induced hyperexcitability, hyper-inhibition and loss of inhibition provide clues to mechanisms for hyperexcitability and progressive changes in function initiated by stress and trauma.
Collapse
Affiliation(s)
- Jeffrey B. Rosen
- Department of Psychological and Brain Sciences, University of Delaware, Newark, DE, United States
- *Correspondence: Jeffrey B. Rosen,
| | - Jay Schulkin
- School of Medicine, University of Washington, Seattle, WA, United States
| |
Collapse
|
3
|
Leibowitz JA, Natarajan G, Zhou J, Carney PR, Ormerod BK. Sustained somatostatin gene expression reverses kindling-induced increases in the number of dividing Type-1 neural stem cells in the hippocampi of behaviorally responsive rats. Epilepsy Res 2019; 150:78-94. [PMID: 30735971 DOI: 10.1016/j.eplepsyres.2019.01.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 12/18/2018] [Accepted: 01/10/2019] [Indexed: 12/13/2022]
Abstract
Neurogenesis persists throughout life in the hippocampi of all mammals, including humans. In the healthy hippocampus, relatively quiescent Type-1 neural stem cells (NSCs) can give rise to more proliferative Type-2a neural progenitor cells (NPCs), which generate neuronal-committed Type-2b NPCs that mature into Type-3 neuroblasts. Many Type-3 neuroblasts survive and mature into functionally integrated granule neurons over several weeks. In kindling models of epilepsy, neurogenesis is drastically upregulated and many new neurons form aberrant connections that could support epileptogenesis and/or seizures. We have shown that sustained vector-mediated hippocampal somatostatin (SST) expression can both block epileptogenesis and reverse seizure susceptibility in fully kindled rats. Here we test whether adeno-associated virus (AAV) vector-mediated sustained SST expression modulates hippocampal neurogenesis and microglial activation in fully kindled rats. We found significantly more dividing Type-1 NSCs and a corresponding increased number of surviving new neurons in the hippocampi of kindled versus sham-kindled rats. Increased numbers of activated microglia were found in the granule cell layer and hilus of kindled rats at both time points. After intrahippocampal injection with either eGFP or SST-eGFP vector, we found similar numbers of dividing Type-1 NSCs and -2 NPCs and surviving BrdU+ neurons and glia in the hippocampi of kindled rats. Upon observed variability in responses to SST-eGFP (2/4 rats exhibited Grade 0 seizures in the test session), we conducted an additional experiment. We found significantly fewer dividing Type-1 NSCs in the hippocampi of SST-eGFP vector-treated responder rats (5/13 rats) relative to SST-eGFP vector-treated non-responders and eGFP vector-treated controls that exhibited high-grade seizures on the test session. The number of activated microglia was upregulated in the GCL and hilus of kindled rats, regardless of vector treatment. These data support the hypothesis that sustained SST expression exerts antiepileptic effects potentially through normalization of neurogenesis and suggests that abnormally high proliferating Type-1 NSC numbers may be a cellular mechanism of epilepsy.
Collapse
Affiliation(s)
| | - Gowri Natarajan
- Department of Neurology and Pediatrics, USA; Neuroscience Program, USA
| | - Junli Zhou
- Department of Neurology and Pediatrics, USA; Neuroscience Program, USA
| | - Paul R Carney
- Department of Neurology and Pediatrics, USA; Neuroscience Program, USA; Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Brandi K Ormerod
- J. Crayton Pruitt Family Department of Biomedical Engineering, USA; Department of Neuroscience, USA; McKnight Brain Institute, USA.
| |
Collapse
|
4
|
Natarajan G, Leibowitz JA, Zhou J, Zhao Y, McElroy JA, King MA, Ormerod BK, Carney PR. Adeno-associated viral vector-mediated preprosomatostatin expression suppresses induced seizures in kindled rats. Epilepsy Res 2017; 130:81-92. [PMID: 28167431 DOI: 10.1016/j.eplepsyres.2017.01.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 12/04/2016] [Accepted: 01/04/2017] [Indexed: 01/29/2023]
Abstract
Somatostatin is expressed widely in the hippocampus and notably in hilar GABAergic neurons that are vulnerable to seizure neuropathology in chronic temporal lobe epilepsy. We previously demonstrated that sustained bilateral preprosomatostatin (preproSST) expression in the hippocampus prevents the development of generalized seizures in the amygdala kindling model of temporal lobe epilepsy. Here we tested whether sustained preproSST expression is anticonvulsant in rats already kindled to high-grade seizures. Rats were kindled until they exhibited 3 consecutive Racine Grade 5 seizures before adeno-associated virus serotype 5 (AAV5) vector driving either eGFP (AAV5-CBa-eGFP) or preproSST and eGFP (AAV5-CBa-preproSST-eGFP) expression was injected bilaterally into the hippocampal dentate gyrus and CA1 region. Retested 3 weeks later, rats that received control vector (AAV5-CBa-eGFP) continued to exhibit high-grade seizures whereas 6/13 rats that received preproSST vector (AAV5-CBa-preproSST-eGFP) were seizure-free. Of these rats, 5/6 remained seizure-free after repeated stimulation sessions and when the stimulation current was increased. These results suggest that vector-mediated expression of preproSST may be a viable therapeutic strategy for temporal lobe epilepsy.
Collapse
Affiliation(s)
- Gowri Natarajan
- Wilder Center of Excellence for Epilepsy Research, University of Florida, Gainesville, FL 32611, USA; J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA; Department of Pediatrics, University of Florida, Gainesville, FL 32611, USA; Department of Neurology, University of Florida, Gainesville, FL 32611, USA; Department of Neuroscience, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Jeffrey A Leibowitz
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA
| | - Junli Zhou
- Wilder Center of Excellence for Epilepsy Research, University of Florida, Gainesville, FL 32611, USA; Department of Pediatrics, University of Florida, Gainesville, FL 32611, USA; Department of Neurology, University of Florida, Gainesville, FL 32611, USA
| | - Yang Zhao
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32611, USA
| | - Jessica A McElroy
- Wilder Center of Excellence for Epilepsy Research, University of Florida, Gainesville, FL 32611, USA; Department of Pediatrics, University of Florida, Gainesville, FL 32611, USA
| | - Michael A King
- McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA; Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL 32611, USA; NF/SG VA Medical Center, University of Florida, Gainesville, FL 32611, USA
| | - Brandi K Ormerod
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA; Department of Neuroscience, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Paul R Carney
- Wilder Center of Excellence for Epilepsy Research, University of Florida, Gainesville, FL 32611, USA; J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611, USA; Department of Pediatrics, University of Florida, Gainesville, FL 32611, USA; Department of Neurology, University of Florida, Gainesville, FL 32611, USA; Department of Neuroscience, University of Florida, Gainesville, FL 32611, USA; McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA.
| |
Collapse
|
5
|
Buffel I, Meurs A, Portelli J, Raedt R, De Herdt V, Poppe L, De Meulenaere V, Wadman W, Bihel F, Schmitt M, Vonck K, Bourguignon JJ, Simonin F, Smolders I, Boon P. The effect of neuropeptide FF in the amygdala kindling model. Acta Neurol Scand 2016; 134:181-8. [PMID: 26503695 DOI: 10.1111/ane.12526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/29/2015] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Neuropeptide FF (NPFF) and its receptors (NPFF1 R and NPFF2 R) are differentially distributed throughout the central nervous system. NPFF reduces cortical excitability in rats when administered intracerebroventricularly (i.c.v.), and both NPFF and NPFF1 R antagonists attenuate pilocarpine-induced limbic seizures. In this study, our aim was to determine whether NPFF exerts anticonvulsant or anti-epileptogenic effects in the rat amygdala kindling model for temporal lobe seizures. METHODS Male Wistar rats were implanted with a recording/stimulation electrode in the right amygdala and a cannula in the left lateral ventricle. In a first group of animals, the afterdischarge threshold (ADT) was determined after a single i.c.v. infusion of saline (n = 8) or NPFF (1 nmol/h for 2 h; n = 10). Subsequently, daily infusion of saline (n = 8) or NPFF (1 nmol/h for 2 h; i.c.v.; n = 9) was performed, followed by a kindling stimulus (ADT+200 μA). Afterdischarge duration and seizure severity were evaluated after every kindling stimulus. A second group of rats (n = 7) were fully kindled, and the effect of saline or a high dose of NPFF (10 nmol/h for 2 h, i.c.v.) on ADT and the generalized seizure threshold (GST) was subsequently determined. RESULTS In naive rats, NPFF significantly increased the ADT compared to control (435 ± 72 μA vs 131 ± 23 μA [P < 0.05]). When rats underwent daily stimulations above the ADT, NPFF did not delay or prevent kindling acquisition. Furthermore, a high dose of NPFF did not alter ADT or GST in fully kindled rats. CONCLUSIONS I.c.v. administration of NPFF reduced excitability in the amygdala in naive, but not in fully kindled rats, and had no effect on kindling acquisition.
Collapse
Affiliation(s)
- I. Buffel
- Laboratory for Clinical and Experimental Neurophysiology; Neurobiology and Neuropsychology; Department of Neurology; Ghent University; Ghent University Hospital; Ghent Belgium
| | - A. Meurs
- Laboratory for Clinical and Experimental Neurophysiology; Neurobiology and Neuropsychology; Department of Neurology; Ghent University; Ghent University Hospital; Ghent Belgium
| | - J. Portelli
- Laboratory for Clinical and Experimental Neurophysiology; Neurobiology and Neuropsychology; Department of Neurology; Ghent University; Ghent University Hospital; Ghent Belgium
- Center for Neurosciences; Department of Pharmaceutical Chemistry; Drug Analysis & Drug information; University of Brussels; Brussels Belgium
| | - R. Raedt
- Laboratory for Clinical and Experimental Neurophysiology; Neurobiology and Neuropsychology; Department of Neurology; Ghent University; Ghent University Hospital; Ghent Belgium
| | - V. De Herdt
- Laboratory for Clinical and Experimental Neurophysiology; Neurobiology and Neuropsychology; Department of Neurology; Ghent University; Ghent University Hospital; Ghent Belgium
| | - L. Poppe
- Laboratory for Clinical and Experimental Neurophysiology; Neurobiology and Neuropsychology; Department of Neurology; Ghent University; Ghent University Hospital; Ghent Belgium
| | - V. De Meulenaere
- Laboratory for Clinical and Experimental Neurophysiology; Neurobiology and Neuropsychology; Department of Neurology; Ghent University; Ghent University Hospital; Ghent Belgium
| | - W. Wadman
- Swammerdam Institute of Life Sciences; Department of Neurobiology; University of Amsterdam; Amsterdam The Netherlands
| | - F. Bihel
- Therapeuthic Innovation Laboratory; Faculty of Pharmacy; UMR 7200; CNRS; University of Strasbourg; Illkirch Graffenstaden France
| | - M. Schmitt
- Therapeuthic Innovation Laboratory; Faculty of Pharmacy; UMR 7200; CNRS; University of Strasbourg; Illkirch Graffenstaden France
| | - K. Vonck
- Laboratory for Clinical and Experimental Neurophysiology; Neurobiology and Neuropsychology; Department of Neurology; Ghent University; Ghent University Hospital; Ghent Belgium
| | - J.-J. Bourguignon
- Therapeuthic Innovation Laboratory; Faculty of Pharmacy; UMR 7200; CNRS; University of Strasbourg; Illkirch Graffenstaden France
| | - F. Simonin
- Research Institute of ESBS; CNRS; UMR7242; University of Strasbourg; Illkirch France
| | - I. Smolders
- Center for Neurosciences; Department of Pharmaceutical Chemistry; Drug Analysis & Drug information; University of Brussels; Brussels Belgium
| | - P. Boon
- Laboratory for Clinical and Experimental Neurophysiology; Neurobiology and Neuropsychology; Department of Neurology; Ghent University; Ghent University Hospital; Ghent Belgium
| |
Collapse
|
6
|
Buffel I, Meurs A, Portelli J, Raedt R, De Herdt V, Sioncke L, Wadman W, Bihel F, Schmitt M, Vonck K, Bourguignon JJ, Simonin F, Smolders I, Boon P. Neuropeptide FF and prolactin-releasing peptide decrease cortical excitability through activation of NPFF receptors. Epilepsia 2015; 56:489-98. [PMID: 25684325 DOI: 10.1111/epi.12928] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2014] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Drugs with a novel mechanism of action are needed to reduce the number of people with epilepsy that are refractory to treatment. Increasing attention is paid to neuropeptide systems and several anticonvulsant neuropeptides have already been described, such as galanin, ghrelin, and neuropeptide Y (NPY). Many others, however, have not been investigated for their ability to affect epileptic seizures. In this study, the potential anticonvulsant activities of three members of the RF-amide neuropeptide family, neuropeptide FF (NPFF), prolactin-releasing peptide (PrRP), and kisspeptin (Kp) and other receptor ligands (NPFF1/2 R, GPR10, and GRP54, respectively) were tested in the motor cortex stimulation model. METHODS A train of pulses with increasing intensity (0-10 mA over 150 s, 50 Hz, pulse width 2 msec) was delivered to the motor cortex of rats. The threshold intensity for eliciting a motor response (i.e., motor threshold) was determined through behavioral observation and used as a measure for cortical excitability. The threshold was determined before, during, and after the intracerebroventricular (i.c.v.) administration of various NPFF1/2 R, GPR10, and GPR54 receptor ligands. RESULTS NPFF and PrRP significantly increased the motor threshold by a maximum of 143 ± 27 and 83 ± 13 μA, respectively, for the doses of 1 nmol/h (p < 0.05). The increase of motor threshold by NPFF and PrRP was prevented by pretreatment and co-treatment with the NPFF1/2 R antagonist RF9. Pretreatment with a selective NPFF1 R antagonist also prevented the threshold increase induced by NPFF. Kp did not increase motor threshold. SIGNIFICANCE Intracerebroventricular infusion of NPFF or PrRP decreases cortical excitability in rats through activation of NPFFRs. Furthermore, the NPFF1 R is required for the NPFF-induced decrease in cortical excitability.
Collapse
Affiliation(s)
- Ine Buffel
- Laboratory for Clinical and Experimental Neurophysiology, Neurobiology and Neuropsychology, Department of Neurology, Ghent University Hospital, Ghent University, Ghent, Belgium
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Abstract
Neuropeptides play an important role in modulating seizures and epilepsy. Unlike neurotransmitters which operate on a millisecond time-scale, neuropeptides have longer half lives; this leads to modulation of neuronal and network activity over prolonged periods, so contributing to setting the seizure threshold. Most neuropeptides are stored in large dense vesicles and co-localize with inhibitory interneurons. They are released upon high frequency stimulation making them attractive targets for modulation of seizures, during which high frequency discharges occur. Numerous neuropeptides have been implicated in epilepsy; one, ACTH, is already used in clinical practice to suppress seizures. Here, we concentrate on neuropeptides that have a direct effect on seizures, and for which therapeutic interventions are being developed. We have thus reviewed the abundant reports that support a role for neuropeptide Y (NPY), galanin, ghrelin, somatostatin and dynorphin in suppressing seizures and epileptogenesis, and for tachykinins having pro-epileptic effects. Most in vitro and in vivo studies are performed in hippocampal tissue in which receptor expression is usually high, making translation to other brain areas less clear. We highlight recent therapeutic strategies to treat epilepsy with neuropeptides, which are based on viral vector technology, and outline how such interventions need to be refined in order to address human disease.
Collapse
Affiliation(s)
- Stjepana Kovac
- UCL Institute of Neurology, University College London, Queen Square, London, UK.
| | | |
Collapse
|
8
|
Kantorovich S, Astary GW, King MA, Mareci TH, Sarntinoranont M, Carney PR. Influence of neuropathology on convection-enhanced delivery in the rat hippocampus. PLoS One 2013; 8:e80606. [PMID: 24260433 PMCID: PMC3832660 DOI: 10.1371/journal.pone.0080606] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 10/03/2013] [Indexed: 01/08/2023] Open
Abstract
Local drug delivery techniques, such as convention-enhanced delivery (CED), are promising novel strategies for delivering therapeutic agents otherwise limited by systemic toxicity and blood-brain-barrier restrictions. CED uses positive pressure to deliver infusate homogeneously into interstitial space, but its distribution is dependent upon appropriate tissue targeting and underlying neuroarchitecture. To investigate effects of local tissue pathology and associated edema on infusate distribution, CED was applied to the hippocampi of rats that underwent electrically-induced, self-sustaining status epilepticus (SE), a prolonged seizure. Infusion occurred 24 hours post-SE, using a macromolecular tracer, the magnetic resonance (MR) contrast agent gadolinium chelated with diethylene triamine penta-acetic acid and covalently attached to albumin (Gd-albumin). High-resolution T1- and T2-relaxation-weighted MR images were acquired at 11.1 Tesla in vivo prior to infusion to generate baseline contrast enhancement images and visualize morphological changes, respectively. T1-weighted imaging was repeated post-infusion to visualize final contrast-agent distribution profiles. Histological analysis was performed following imaging to characterize injury. Infusions of Gd-albumin into injured hippocampi resulted in larger distribution volumes that correlated with increased injury severity, as measured by hyperintense regions seen in T2-weighted images and corresponding histological assessments of neuronal degeneration, myelin degradation, astrocytosis, and microglial activation. Edematous regions included the CA3 hippocampal subfield, ventral subiculum, piriform and entorhinal cortex, amygdalar nuclei, middle and laterodorsal/lateroposterior thalamic nuclei. This study demonstrates MR-visualized injury processes are reflective of cellular alterations that influence local distribution volume, and provides a quantitative basis for the planning of local therapeutic delivery strategies in pathological brain regions.
Collapse
Affiliation(s)
- Svetlana Kantorovich
- Department of Neuroscience, University of Florida, Gainesville, Florida, United States of America
- Wilder Center of Excellence for Epilepsy Research, University of Florida, Gainesville, Florida, United States of America
- Department of Pediatrics, Division of Pediatric Neurology, University of Florida, Gainesville, Florida, United States of America
| | - Garrett W. Astary
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, United States of America
| | - Michael A. King
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, Florida, United States of America
- Malcom Randall Veterans Affairs Medical Center, Gainesville, University of Florida, Gainesville, Florida, United States of America
| | - Thomas H. Mareci
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, United States of America
| | - Malisa Sarntinoranont
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida, United States of America
| | - Paul R. Carney
- Department of Neuroscience, University of Florida, Gainesville, Florida, United States of America
- Wilder Center of Excellence for Epilepsy Research, University of Florida, Gainesville, Florida, United States of America
- Department of Pediatrics, Division of Pediatric Neurology, University of Florida, Gainesville, Florida, United States of America
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, United States of America
| |
Collapse
|
9
|
Kozhemyakin M, Rajasekaran K, Todorovic MS, Kowalski SL, Balint C, Kapur J. Somatostatin type-2 receptor activation inhibits glutamate release and prevents status epilepticus. Neurobiol Dis 2013; 54:94-104. [PMID: 23473742 DOI: 10.1016/j.nbd.2013.02.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/06/2013] [Accepted: 02/25/2013] [Indexed: 02/07/2023] Open
Abstract
Newer therapies are needed for the treatment of status epilepticus (SE) refractory to benzodiazepines. Enhanced glutamatergic neurotransmission leads to SE, and AMPA receptors are modified during SE. Reducing glutamate release during SE is a potential approach to terminate SE. The neuropeptide somatostatin (SST) is proposed to diminish presynaptic glutamate release by activating SST type-2 receptors (SST2R). SST exerts an anticonvulsant action in some experimental models of seizures. Here, we investigated the mechanism of action of SST on excitatory synaptic transmission at the Schaffer collateral-CA1 synapses and the ability of SST to treat SE in rats using patch-clamp electrophysiology and video-EEG monitoring of seizures. SST reduced action potential-dependent EPSCs (sEPSCs) at Schaffer collateral-CA1 synapses at concentrations up to 1μM; higher concentrations had no effect or increased the sEPSC frequency. SST also prevented paired-pulse facilitation of evoked EPSCs and did not alter action-potential-independent miniature EPSCs (mEPSCs). The effect of SST on EPSCs was inhibited by the SST2R antagonist cyanamid-154806 and was mimicked by the SST2R agonists, octreotide and lanreotide. Both SST and octreotide reduced the firing rate of CA1 pyramidal neurons. Intraventricular administration of SST, within a range of doses, either prevented or attenuated pilocarpine-induced SE or delayed the median time to the first grade 5 seizure by 11min. Similarly, octreotide or lanreotide prevented or attenuated SE in more than 65% of animals. Compared to the pilocarpine model, octreotide was highly potent in preventing or attenuating continuous hippocampal stimulation-induced SE in all animals within 60min of SE onset. Our results demonstrate that SST, through the activation of SST2Rs, diminishes presynaptic glutamate release and attenuates SE.
Collapse
Affiliation(s)
- Maxim Kozhemyakin
- Department of Neurology and Neuroscience, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA
| | | | | | | | | | | |
Collapse
|
10
|
Martel G, Dutar P, Epelbaum J, Viollet C. Somatostatinergic systems: an update on brain functions in normal and pathological aging. Front Endocrinol (Lausanne) 2012; 3:154. [PMID: 23230430 PMCID: PMC3515867 DOI: 10.3389/fendo.2012.00154] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 11/20/2012] [Indexed: 11/29/2022] Open
Abstract
Somatostatin is highly expressed in mammalian brain and is involved in many brain functions such as motor activity, sleep, sensory, and cognitive processes. Five somatostatin receptors have been described: sst(1), sst(2) (A and B), sst(3), sst(4), and sst(5), all belonging to the G-protein-coupled receptor family. During the recent years, numerous studies contributed to clarify the role of somatostatin systems, especially long-range somatostatinergic interneurons, in several functions they have been previously involved in. New advances have also been made on the alterations of somatostatinergic systems in several brain diseases and on the potential therapeutic target they represent in these pathologies.
Collapse
Affiliation(s)
| | | | | | - Cécile Viollet
- *Correspondence: Cécile Viollet, Inserm UMR894 - Center for Psychiatry and Neuroscience, Université Paris Descartes, Sorbonne Paris Cité, 2 ter rue d’Alésia, 75014 Paris, France. e-mail:
| |
Collapse
|