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Trindade-Filho EM, Pai JD, Castro DND, Silva ATMD, Costa AF, Vieira JSS, Santos SDBD, Félix VB, Leão SABF, Zambrano LI, Saldanha-Filho AJM, Carvalho EGA, Cavalcante JBN, Quintella GB, Lino ATS, Costa MV, Lima JA, Tavares MMA, de Melo MR, Mousinho KC, Biase CLCLD, Leite ML, Costa PJMS, Becker EL, Moura IMFB, Silva JCD. Dopamine depletion in wistar rats with epilepsy. BRAZ J BIOL 2022; 84:e248411. [PMID: 35544785 DOI: 10.1590/1519-6984.248411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 02/20/2022] [Indexed: 11/22/2022] Open
Abstract
The dopamine content in cerebral structures has been related to neuronal excitability and several approaches have been used to study this phenomenon during seizure vulnerability period. In the present work, we describe the effects of dopamine depletion after the administration of 6-hidroxidopamine (6-OHDA) into the substantia nigra pars compacta of male rats submitted to the pilocarpine model of epilepsy. Susceptibility to pilocarpine-induced status epilepticus (SE), as well as spontaneous and recurrent seizures (SRSs) frequency during the chronic period of the model were determined. Since the hippocampus is one of main structures in the development of this experimental model of epilepsy, the dopamine levels in this region were also determined after drug administration. In the first experiment, 62% (15/24) of 6-OHDA pre-treated rats and 45% (11/24) of those receiving ascorbic acid as control solution progressed to motor limbic seizures evolving to SE, after the administration of pilocarpine. Severeness of seizures during the model´s the acute period, was significantly higher in epileptic experimental rats (56.52%), than in controls (4.16%). In the second experiment, the frequency of seizures in the model's chronic phase did not significantly change between groups. Our data show that dopamine may play an important role on seizure severity in the pilo's model acute period, which seems to be due to dopamine inhibitory action on motor expression of seizure.
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Affiliation(s)
- E M Trindade-Filho
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil.,Universidade Estadual de Ciências da Saúde de Alagoas - UNCISAL, Maceió, AL, Brasil
| | - J Dal Pai
- Instituto do Cérebro do Rio Grande do Sul - InsCer, Porto Alegre, RS, Brasil
| | - D N de Castro
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil
| | - A T M da Silva
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil
| | - A F Costa
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil
| | - J S S Vieira
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil
| | | | - V B Félix
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil.,Hospital Universitário de Alagoas Professor Alberto Antunes - HUPAA, Maceió, AL, Brasil
| | - S A B F Leão
- Santa Casa de Misericórdia de Maceió, AL, Brasil.,Universidade Federal de Alagoas - UFAL, Campus de Arapiraca, AL, Brasil
| | - L I Zambrano
- Universidad Nacional Autónoma de Honduras - UNAH, Facultad de Ciencias Medicas, Tegucigalpa, Honduras
| | - A J M Saldanha-Filho
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil.,Centro Universitário Tiradentes - UNIT-AL, Maceió, AL, Brasil
| | - E G A Carvalho
- Centro Universitário Tiradentes - UNIT-PE, Jaboatão dos Guararapes, Pernambuco, PE, Brasil
| | - J B N Cavalcante
- Universidade Estadual de Ciências da Saúde de Alagoas - UNCISAL, Maceió, AL, Brasil
| | - G B Quintella
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil
| | - A T S Lino
- Universidade Federal de Alagoas - UFAL, Campus de Rio Largo, Alagoas, Brasil
| | - M V Costa
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil.,Universidade Estadual de Ciências da Saúde de Alagoas - UNCISAL, Maceió, AL, Brasil
| | - J A Lima
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil.,Universidade Estadual de Ciências da Saúde de Alagoas - UNCISAL, Maceió, AL, Brasil
| | - M M A Tavares
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil
| | - M R de Melo
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil
| | - K C Mousinho
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil.,Universidade Estadual de Ciências da Saúde de Alagoas - UNCISAL, Maceió, AL, Brasil
| | - C L C L De Biase
- Hospital Universitário de Alagoas Professor Alberto Antunes - HUPAA, Maceió, AL, Brasil
| | - M L Leite
- Universidade Estadual de Ciências da Saúde de Alagoas - UNCISAL, Maceió, AL, Brasil
| | - P J M S Costa
- Universidade Estadual de Ciências da Saúde de Alagoas - UNCISAL, Maceió, AL, Brasil
| | - E L Becker
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil
| | - I M F B Moura
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil
| | - J C da Silva
- Centro Universitário - CESMAC, Campus I, Maceió, AL, Brasil.,Universidade Estadual de Ciências da Saúde de Alagoas - UNCISAL, Maceió, AL, Brasil
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2
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Serikawa T, Mashimo T, Kuramoro T, Voigt B, Ohno Y, Sasa M. Advances on genetic rat models of epilepsy. Exp Anim 2014; 64:1-7. [PMID: 25312505 PMCID: PMC4329510 DOI: 10.1538/expanim.14-0066] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Considering the suitability of laboratory rats in epilepsy research, we and other groups
have been developing genetic models of epilepsy in this species. After epileptic rats or
seizure-susceptible rats were sporadically found in outbred stocks, the epileptic traits
were usually genetically-fixed by selective breeding. So far, the absence seizure models
GAERS and WAG/Rij, audiogenic seizure models GEPR-3 and GEPR-9, generalized tonic-clonic
seizure models IER, NER and WER, and Canavan-disease related epileptic models TRM and SER
have been established. Dissection of the genetic bases including causative genes in these
epileptic rat models would be a significant step toward understanding epileptogenesis.
N-ethyl-N-nitrosourea (ENU) mutagenesis provides a systematic approach which allowed us to
develop two novel epileptic rat models: heat-induced seizure susceptible (Hiss) rats with
an Scn1a missense mutation and autosomal dominant lateral temporal epilepsy (ADLTE) model
rats with an Lgi1 missense mutation. In addition, we have established episodic ataxia type
1 (EA1) model rats with a Kcna1 missense mutation derived from the ENU-induced rat mutant
stock, and identified a Cacna1a missense mutation in a N-Methyl-N-nitrosourea
(MNU)-induced mutant rat strain GRY, resulting in the discovery of episodic ataxia type 2
(EA2) model rats. Thus, epileptic rat models have been established on the two paths:
‘phenotype to gene’ and ‘gene to phenotype’. In the near future, development of novel
epileptic rat models will be extensively promoted by the use of sophisticated genome
editing technologies.
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Affiliation(s)
- Tadao Serikawa
- Graduate School of Medicine, Kyoto University, Sakyo-ku 606-8501; Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki 569-1094, Japan
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3
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Tanabe M, Tokuda Y, Takasu K, Ono K, Honda M, Ono H. The synthetic TRH analogue taltirelin exerts modality-specific antinociceptive effects via distinct descending monoaminergic systems. Br J Pharmacol 2007; 150:403-14. [PMID: 17220907 PMCID: PMC2189720 DOI: 10.1038/sj.bjp.0707125] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND AND PURPOSE Exogenously administered thyrotropin-releasing hormone (TRH) is known to exert potent but short-acting centrally-mediated antinociceptive effects. We sought to investigate the mechanisms underlying these effects using the synthetic TRH analogue taltirelin, focusing on the descending monoaminergic systems in mice. EXPERIMENTAL APPROACH The mice received systemic or local injections of taltirelin combined with either central noradrenaline (NA) or 5-hydroxytryptamine (5-HT) depletion by 6-hydroxydopamine (6-OHDA) or DL-p-chlorophenylalanine (PCPA), respectively, or blockade of their receptors. The degree of antinociception was determined using the tail flick and tail pressure tests. KEY RESULTS Subcutaneously (s.c.) administered taltirelin exhibited dose-dependent antinociceptive effects in the tail flick and tail pressure tests. These effects appeared to be primarily supraspinally mediated, since intracerebroventricularly (i.c.v.) but not intrathecally (i.t.) injected taltirelin generated similar effects. Depletion of central NA abolished only the analgesic effect of taltirelin (s.c. and i.c.v.) on mechanical nociception. By contrast, depletion of central 5-HT abolished only its analgesic effect on thermal nociception. Intraperitoneal (i.p.) and i.t. injection of the alpha2-adrenoceptor antagonist yohimbine respectively reduced the analgesic effect of taltirelin (s.c. and i.c.v.) on mechanical nociception. By contrast, the 5-HT1A receptor antagonist WAY-100635 (i.p. and i.t.) reduced the effect of taltirelin (s.c. and i.c.v.) on thermal nociception. Neither the 5-HT2 receptor antagonist ketanserin nor the opioid receptor antagonist naloxone altered the antinociceptive effect of taltirelin. CONCLUSIONS AND IMPLICATIONS These findings suggest that taltirelin activates the descending noradrenergic and serotonergic pain inhibitory systems, respectively, to exert its analgesic effects on mechanical and thermal nociception.
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Affiliation(s)
- M Tanabe
- Laboratory of CNS Pharmacology, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan.
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4
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Abstract
The activity of the thalamus is state dependent. During slow-wave sleep, rhythmic burst firing is prominent, whereas during waking or rapid eye movement sleep, tonic, single-spike activity dominates. These state-dependent changes result from the actions of modulatory neurotransmitters. In the present study, we investigated the functional and cellular effects of the neuropeptide thyrotropin-releasing hormone (TRH) on the spontaneously active ferret geniculate slice. This peptide and its receptors are prominently expressed in the thalamic network, yet the role of thalamic TRH remains obscure. Bath application of TRH resulted in a transient cessation of both spindle waves and the epileptiform slow oscillation induced by application of bicuculline. With intracellular recordings, TRH application to the GABAergic neurons of the perigeniculate (PGN) or thalamocortical cells in the lateral geniculate nucleus resulted in depolarization and increased membrane resistance. In perigeniculate neurons, this effect reversed near the reversal potential for K+, suggesting that it is mediated by a decrease in K+ conductance. In thalamocortical cells, the TRH-induced depolarization was of sufficient amplitude to block the generation of rebound Ca2+ spikes, whereas the even larger direct depolarization of PGN neurons transformed these cells from the burst to tonic, single-spike mode of action potential generation. Furthermore, application of TRH prominently enhanced the afterdepolarization that follows rebound Ca2+ spikes, suggesting that this transmitter may also enhance Ca2+-activated nonspecific currents. These data suggest a novel role for TRH in the brain as an intrinsic regulator of thalamocortical network activity and provide a potential mechanism for the wake-promoting and anti-epileptic effects of this peptide.
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Affiliation(s)
- Christian Broberger
- Kavli Institute for Neuroscience and Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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5
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Meng R, Xia W, Sandberg M, Stephens R, Weber SG. Online preconcentration of thyrotropin-releasing hormone (TRH) by SDS-modified reversed phase column for microbore and capillary high-performance liquid chromatography (HPLC). J Chromatogr A 2005; 1071:179-84. [PMID: 15865191 DOI: 10.1016/j.chroma.2004.12.032] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Thyrotropin-releasing hormone (TRH, pGlu-His-Pro-amide) is an important tripeptide existing in biological systems at low concentrations. It is a fairly hydrophilic peptide, cationic in acidic solutions. Preconcentration online before reversed phase chromatography separation can enhance concentration detection limits of hydrophobic, but not hydrophilic species. The hydrophilic TRH can be preconcentrated using a reversed phase precolumn charged with sodium dodecyl sulfate (SDS). The separation also uses SDS. The preconcentration is effective for a microbore system, achieving detection limit of 250 pM for a sample size of 500 microl with electrochemical detection of the biuret complex formed post column. Preconcentration using an online precolumn is also effective in packed capillary high-performance liquid chromatography (HPLC) with a detection limit of 3 nM in 24 microl.
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Affiliation(s)
- Rong Meng
- Department of Chemistry, University of Pittsburgh, 603 Chevron Science Center, 219 Parkman Drive, Pittsburgh, PA 15260, USA
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6
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Abstract
Intractable seizures remain a significant therapeutic challenge despite current advances in the treatment of epilepsy. Thyrotropin-releasing hormone, the first neuroendocrine releasing factor to be isolated and fully characterized, was also the first releasing factor investigated as a possible neurotransmitter/neuromodulator outside the hypothalamus. Basic and clinical research has revealed a distinct neuroanatomic distribution and a neurochemical role for thyrotropin-releasing hormone in seizure modulation. Thyrotropin-releasing hormone and selected analogs were reported to have antiepileptic effects in several animal seizure paradigms, including kindling and electroconvulsive shock. Clinically, thyrotropin-releasing hormone treatment has been reported to be efficacious in such intractable epilepsies as infantile spasms, Lennox-Gastaut syndrome, myoclonic seizures, and other generalized and refractory partial seizures. Herein, we review evidence that suggests that thyrotropin-releasing hormone and selected thyrotropin-releasing hormone analogs may represent a new class of novel antiepileptic drugs, namely, antiepileptic neuropeptides and provide insights into potential new treatments for the intractable epilepsies.
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Affiliation(s)
- Michael J Kubek
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, Indianapolis, IN 46202-5120, USA
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7
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Jaworska-Feil L, Turchan J, Przewłocka B, Budziszewska B, Leśkiewicz M, Lasoń W. Effects of pentylenetetrazole-induced kindling on thyrotropin-releasing hormone biosynthesis and receptors in rat brain. Neuroscience 1999; 90:695-704. [PMID: 10215171 DOI: 10.1016/s0306-4522(98)00446-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
It has been postulated that changes in thyrotropin-releasing hormone biosynthesis may be involved in the mechanism of kindling--an animal model of epileptogenesis. To test this hypothesis, a time-course study was carried out to investigate the effects of pentylenetetrazole kindling (40 mg/kg i.p., daily for eight days) on the expression of gene coding for preprothyrotropin-releasing hormone, the thyrotropin-releasing hormone tissue level and thyrotropin-releasing hormone receptor parameters in rat brain. As shown by an in situ hybridization study, a single, convulsant dose of pentylenetetrazole (70 mg/kg i.p.) increased the preprothyrotropin-releasing hormone messenger RNA level in the dentate gyrus of the hippocampal formation and piriform cortex after 3 h and, to a greater extent, after 24 h. Those changes were accompanied with increases in the thyrotropin-releasing hormone level in the striatum, hippocampus, amygdala and piriform cortex. Seven days after single pentylenetetrazole administration, the thyrotropin-releasing hormone level was still significantly elevated in the piriform cortex and striatum. Acute pentylenetetrazole decreased the density (Bmax) of thyrotropin-releasing hormone receptors in the striatum after 3 and 24 h, and increased that density in the piriform cortex and amygdala after 24 h and seven days, respectively. The thyrotropin-releasing hormone receptor affinity (Kd) was decreased in the striatum and increased in the amygdala after only 3 h. Kindled rats showed a moderate increase in the preprothyrotropin-releasing hormone messenger RNA content in the dentate gyrus of the hippocampal formation and piriform cortex after 3 and 24 h; however, a significant decrease in those parameters was found after 14 days. After 3 and 24 h, pentylenetetrazole kindling also elevated the thyrotropin-releasing hormone content in the hippocampus, piriform cortex, and striatum (in the latter structure after 24 h only), whereas in the septum the thyrotropin-releasing hormone level was decreased. After seven days, the thyrotropin-releasing hormone level was still elevated in the hippocampus and piriform cortex of kindled rats, but after 14 days it was significantly lowered in the hippocampus. The kindled rats also showed a significant decrease in the density (Bmax) of thyrotropin-releasing hormone receptors in the striatum (after 24 h, seven and 14 days), and an increase in the piriform cortex (after seven days). The thyrotropin-releasing hormone receptor affinity (Kd) value was increased in the hippocampus after seven and 14 days, and in the piriform cortex after seven days. These results indicate that pentylenetetrazole kindling induces long-lasting alterations in the thyrotropin-releasing hormone biosynthesis and thyrotropin-releasing hormone receptor affinity in discrete regions of rat brain. These region-specific changes, in particular down-regulation of the thyrotropin-releasing hormone biosynthesis in the hippocampus, may be involved in chronic neuronal hyperexcitability associated with kindling.
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Affiliation(s)
- L Jaworska-Feil
- Department of Endocrinology, Institute of Pharmacology, Polish Academy of Sciences, Kraków
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8
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Pizzi M, Boroni F, Benarese M, Moraitis C, Memo M, Spano P. Neuroprotective effect of thyrotropin-releasing hormone against excitatory amino acid-induced cell death in hippocampal slices. Eur J Pharmacol 1999; 370:133-7. [PMID: 10323261 DOI: 10.1016/s0014-2999(99)00139-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Thyrotropin-releasing hormone (TRH) and some of its stable analogues have recently been shown to improve functional recovery after neurologic dysfunctions, such as brain trauma and epilepsy, in both animals and humans. The exact mechanism by which TRH produces its neuroprotective effects is still uncertain. The present study provides the first evidence that TRH exerts a neuroprotective effect against N-methyl-D-aspartate (NMDA)-mediated excitotoxicity in rat hippocampal slices. TRH concentration dependently reduced NMDA toxicity by a mechanism that was highly sensitive to the protein kinase C blocker, bisindolilmaleimide. Delayed application of TRH, during NMDA exposure, still produced neuroprotection.
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Affiliation(s)
- M Pizzi
- Department of Biomedical Sciences and Biotechnologies, School of Medicine, University of Brescia, Italy.
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9
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Kubek MJ, Liang D, Byrd KE, Domb AJ. Prolonged seizure suppression by a single implantable polymeric-TRH microdisk preparation. Brain Res 1998; 809:189-97. [PMID: 9853110 DOI: 10.1016/s0006-8993(98)00860-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Thyrotropin-releasing hormone (TRH; Protirelin) is an endogenous neuropeptide known to have anticonvulsant effects in several seizure models and in intractable epileptic patients. Like most neuropeptides, its duration of action may be limited by a lack of sustained site-specific bioavailability. To attempt to provide long-term delivery, we attached TRH to a biodegradable polyanhydride copolymer as a sustained-release carrier. Utilizing the rat kindling model of temporal lobe epilepsy, a single TRH microdisk implanted stereotaxically into the seizure focus (amygdala) significantly suppressed kindling expression when assessed by the number of stimulations required to reach each behavioral stage and to become fully kindled (8.63 +/- 0.92 vs. 16.17 +/- 1.37; Mean +/- S.E.M.). Two indices of seizure severity, afterdischarge duration (Mean +/- S.E.M., sec.) (stimulated amygdala [87.40 +/- 5.47 vs. 51.80 +/- 15.65] and unstimulated amygdala [89.60 +/- 5.55 vs. 48.67 +/- 15.8] and clonus duration (71.2 +/- 5.94 vs. 29.40 +/- 8.87; Mean +/- S.E.M., sec.), were also significantly reduced by a single polymeric-TRH implant. Fifty days after initiation of the study a significant reduction in clonus duration (53.90 +/- 3.27 vs. 40.09 +/- 4.14) still remained in the TRH-implanted groups. This report is the first to provide evidence in support of in situ microdisk pharmacotherapy for potential neuropeptide delivery in intractable epilepsy and possibly other neurological disorders.
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Affiliation(s)
- M J Kubek
- Department of Anatomy, Indiana University School of Medicine, Indianapolis 46202-5120, USA.
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10
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Fukao K, Momiyama T, Ishihara K, Ujihara H, Fujita Y, Taniyama K, Serikawa T, Sasa M. Inhibition by gamma-aminobutyric acid system activation of epileptic seizures in spontaneously epileptic rats. JAPANESE JOURNAL OF PHARMACOLOGY 1998; 76:387-96. [PMID: 9623717 DOI: 10.1254/jjp.76.387] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The effects of muscimol, a gamma-aminobutyric acid (GABA)A-receptor agonist, and aminooxy-acetic acid (AOAA), an inhibitor of GABA-converting enzyme, on tonic and absence-like seizures in spontaneously epileptic rats (SER: zi/zi, tm/tm) were investigated to elucidate whether GABAergic function operates normally in these animals. Muscimol at doses of 1 and 3 mg/kg (i.p.) induced high-voltage slow waves in the cortical and hippocampal EEG of SER, although the behavioral observation suggested inhibition of absence-like seizures. Similar high-voltage slow waves were also observed in the cortical and hippocampal EEG of normal rats with muscimol (1 and 3 mg/kg). Tonic convulsions in SER were dose-dependently inhibited by muscimol. AOAA (3 and 10 mg/kg, i.v.) inhibited both tonic and absence-like seizures in SER, although there were no obvious changes in EEG pattern. The inhibitory effects of AOAA on tonic convulsions appeared more slowly and lasted longer than those on absence-like seizures. Cerebral, hippocampal and cerebellar GABA levels were significantly higher in SER than the normal Kyo:Wistar and zitter rat (zi/zi), which were both the parent strains. These findings suggest that GABA receptors and GABAergic neurons are functional in SER and that the GABA system is involved in the inhibition of both seizures.
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Affiliation(s)
- K Fukao
- Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan
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11
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Knoblach SM, Kubek MJ. Increases in thyrotropin-releasing hormone messenger RNA expression induced by a model of human temporal lobe epilepsy: effect of partial and complete kindling. Neuroscience 1997; 76:85-95. [PMID: 8971761 DOI: 10.1016/s0306-4522(96)00361-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Thyrotropin-releasing hormone and its receptor are differentially distributed throughout the limbic forebrain. In addition to its neuroendocrine function, several non-endocrine central nervous system effects of thyrotropin-releasing hormone and its analogs have been reported, including anticonvulsant effects in animals and humans. Kindling, as a model of temporal lobe epilepsy, produces elevations of endogenous thyrotropin-releasing hormone specifically in seizure-prone limbic regions. The present study used semi-quantitative in situ hybridization to characterize changes in thyrotropin-releasing hormone messenger RNA that occurred during the kindling process (partial kindling), as well as after fully kindled seizures. No significant change in thyrotropin-releasing hormone messenger RNA was detected 1 h postictally, whereas significant elevations were detected in the granule cell layer of the hippocampal dentate gyrus, diffuse nuclei of the amygdala and in layers II and III of piriform and entorhinal cortices from 3 to 48 h after a single generalized seizure in fully kindled rats. Peak messenger RNA expression occurred from 6 to 12 h postictally, with a decline at 24 h, followed by a precipitous return to undetectable levels by 48 h, except in the dentate gyrus. In marked contrast, partial kindling produced no detectable change in thyrotropin-releasing hormone messenger RNA by 6 h after the first occurrence of stage 1-5 seizures. Electrode placement, a single afterdischarge, or a 20-microA stimulation of the amygdala was not associated with accumulation of thyrotropin-releasing hormone messenger RNA. Thus, only full kindled generalized seizures increased thyrotropin-releasing hormone messenger RNA expression in identical limbic regions which also showed postictal elevations in thyrotropin-releasing hormone. However, this enhancement followed a more immediate and shorter lasting time-course than previously demonstrated increases in the tripeptide. These results support the hypothesis that thyrotropin-releasing hormone is an important neuromodulator in epileptic foci.
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Affiliation(s)
- S M Knoblach
- Program in Medical Neurobiology, Indiana University School of Medicine, USA
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12
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Kanda T, Kurokawa M, Tamura S, Nakamura J, Ishii A, Kuwana Y, Serikawa T, Yamada J, Ishihara K, Sasa M. Topiramate reduces abnormally high extracellular levels of glutamate and aspartate in the hippocampus of spontaneously epileptic rats (SER). Life Sci 1996; 59:1607-16. [PMID: 8913326 DOI: 10.1016/0024-3205(96)00492-4] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The spontaneously epileptic rat (SER), a double mutant, manifests both tonic and absence-like seizures. The effect of topiramate, a novel antiepileptic drug, on the extracellular levels of excitatory amino acids (EAA) in the hippocampus of SER was investigated using in vivo microdialysis. The basal levels of glutamate and aspartate in dialysates of hippocampus in SER were 2- to 3-fold higher than those in normal Wistar rats. Both the dose-response relationship and the time course of the suppression of tonic seizures by topiramate were similar to the attenuation of glutamate level in SER. Topiramate (40 mg/kg i.p.) significantly (P < 0.05) reduced both glutamate and aspartate levels in SER while showing no effect on normal Wistar rats. These findings suggest that topiramate reduces abnormally high extracellular levels of glutamate and aspartate in the hippocampus of SER. This effect may, at least in part, be related to the anticonvulsant activity of topiramate.
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Affiliation(s)
- T Kanda
- Pharmaceutical Research Laboratories, Kyowa Hakko Kogyo Co. Ltd., Shizuoka, Japan
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13
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Momiyama T, Ishihara K, Kimura K, Todo N, Fujita Y, Serikawa T, Sasa M. Long-term antiepileptic effects of chronic intake of CNK-602A, a thyrotropin-releasing hormone analogue, on spontaneously epileptic rats. Epilepsia 1996; 37:328-31. [PMID: 8603636 DOI: 10.1111/j.1528-1157.1996.tb00567.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Spontaneously epileptic rats (SER), which represent a double mutation (zi/zi, tm/tm), spontaneously exhibit both tonic and absence-like seizures. We examine the long-term effects of a thyrotropin-releasing hormone (TRH) analogue, CNK-602A, acute administration of which was effective inhibiting both types of seizures in SER, to determine if this agent could be used to treat epilepsy for long periods. Food pellets containing 0.001% CNK-602A were given ad libitum to SER from age 7 weeks. CNK-602A significantly inhibited tonic convulsions and prolonged survival. There were no alterations in body weight or plasma levels of triiodotHyronine (T3) and thyroxine (T4). These findings indicate that chronic intake of CNK-602A in a dose that does not affect plasma levels of T3 and T4 inhibits tonic convulsions in SER and suggest that this drug may be an effective treatment for convulsive seizures in patients with epilepsy.
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Affiliation(s)
- T Momiyama
- Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan
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14
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Abstract
The clinical benefits of dopamine agonists in the management of epilepsy can be traced back over a century, whilst the introduction of neuroleptics into psychiatry practice 40 years ago witnessed the emergence of fits as a side effect of dopamine receptor blockade. Epidemiologists noticed a reciprocal relationship between the supposed dopaminergic overactivity syndrome of schizophrenia and epilepsy, which came to be regarded as a dopamine underactivity condition. Early pharmacological studies of epilepsy employed nonselective drugs, that often did not permit dopamine's antiepileptic action to be clearly dissociated from that of other monoamines. Likewise, the biochemical search for genetic abnormalities in brain dopamine function, as predeterminants of spontaneous epilepsy, proved largely inconclusive. The discovery of multiple dopamine receptor families (D1 and D2), mediating opposing influences on neuronal excitability, heralded a new era of dopamine-epilepsy research. The traditional anticonvulsant action of dopamine was attributed to D2 receptor stimulation in the forebrain, while the advent of selective D1 agonists with proconvulsant properties revealed for the first time that dopamine could also lower the seizure threshold from the midbrain. Whilst there is no immediate prospect of developing D2 agonists or D1 antagonists as clinically useful antiepileptics, there is a growing awareness that seizures might be precipitated as a consequence of treating other neurological disorders with D2 antagonists (schizophrenia) or D1 agonists (parkinsonism).
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Affiliation(s)
- M S Starr
- Department of Pharmacology, School of Pharmacy, London, United Kingdom
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Nakamura J, Tamura S, Kanda T, Ishii A, Ishihara K, Serikawa T, Yamada J, Sasa M. Inhibition by topiramate of seizures in spontaneously epileptic rats and DBA/2 mice. Eur J Pharmacol 1994; 254:83-9. [PMID: 8206119 DOI: 10.1016/0014-2999(94)90373-5] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The effects of topiramate, a novel antiepileptic drug, on tonic and absence-like seizures in spontaneously epileptic rats (SER; zi/zi, tm/tm) and on sound-induced seizures in DBA/2 mice were investigated. Topiramate (20 and 40 mg/kg i.p.) inhibited both tonic and absence-like seizures in a dose-dependent manner, whereas phenytoin (20 mg/kg i.p.) and zonisamide (40 mg/kg i.p.) inhibited only the tonic seizures. The inhibitory effects of topiramate on absence-like seizures were antagonized by pretreatment with haloperidol (0.5 mg/kg i.p.), but those on the tonic seizures remained unaffected. Topiramate inhibited sound-induced seizures in DBA/2 mice (ED50 = 8.6 mg/kg p.o.). These findings suggest that topiramate may be effective for treatment of both convulsive and absence seizures of human epilepsy. The inhibitory effect of topiramate on absence-like seizures in SER may be mediated through the central dopaminergic system.
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Affiliation(s)
- J Nakamura
- Pharmaceutical Research Laboratories, Kyowa Hakko Kogyo Co., Ltd., Shizuoka, Japan
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Ebihara S, Akaike N. Potassium currents operated by thyrotrophin-releasing hormone in dissociated CA1 pyramidal neurones of rat hippocampus. J Physiol 1993; 472:689-710. [PMID: 8145166 PMCID: PMC1160507 DOI: 10.1113/jphysiol.1993.sp019967] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
1. Membrane currents activated by thyrotrophin-releasing hormone (TRH) were investigated in the dissociated rat hippocampal CA1 pyramidal neurone using the nystatin perforated patch recording configuration. 2. Under current-clamp condition, TRH caused a transient hyperpolarization accompanied by a decrease of firing activity and a successive long-lasting depolarization. The latter induced a blockade of firing. 3. When neurones were held at a holding potential (VH) of -40 mV under voltage clamp, TRH elicited a transient outward current with an increase in the membrane conductance, which was followed by a sustained inward current with a decrease in membrane conductance. The inactive TRH metabolite, TRH free acid, did not induce any currents. 4. The reversal potential of TRH-induced outward current (ETRH) was close to the K+ equilibrium potential (EK). The change in ETRH for a 10-fold change in extracellular K+ concentration was 56.4 mV, indicating that the membrane behaves like a K+ electrode in the presence of TRH. On the other hand, the TRH-induced inward current was due to suppression of a slow inward current relaxation during hyperpolarizing voltage commands to -50 mV from a VH of -40 mV, indicating the suppression of the voltage- and time-dependent component of the K+ current (M-current). 5. The TRH-induced outward current (ITRH) increased in a concentration-dependent manner over the concentration range 10(-8)-10(-6) M. The half-maximum concentration was 7.4 x 10(-8) M and the Hill coefficient was 1.5. 6. The TRH-induced outward current (ITRH) was antagonized by K+ channel blockers such as tetraethylammonium (TEA), 4-aminopyridine (4-AP) and Ba2+ in a concentration-dependent manner. ITRH was insensitive to both apamin and iberiotoxin. 7. The first application of TRH to neurones perfused with Ca(2+)-free external solution containing 2 mM EGTA could induce ITRH but the TRH response diminished dramatically with successive applications. Intracellular perfusion with a Ca2+ chelator, 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), also diminished the TRH response. 8. The depletion of Ca2+ from the intracellular Ca2+ store by thapsigargin blocked the TRH response without affecting the caffeine response. Pretreatment with Li+ significantly enhanced ITRH, suggesting that ITRH is involved in the elevation of intracellular free Ca2+ released from the inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ store site but not from the caffeine-sensitive one. 9. Staurosporine, a protein kinase C (PKC) inhibitor, suppressed ITRH in a concentration-dependent manner (the half-maximum inhibitory concentration (IC50), was 2.45 x 10(-8) M).(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- S Ebihara
- Department of Neurophysiology, Tohoku University School of Medicine, Sendai, Japan
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Hara M, Sasa M, Kawabata A, Serikawa T, Yamada T, Yamada J, Takaori S. Decreased dopamine and increased norepinephrine levels in the spontaneously epileptic rat, a double mutant rat. Epilepsia 1993; 34:433-40. [PMID: 8504778 DOI: 10.1111/j.1528-1157.1993.tb02583.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Dopamine (DA) and norepinephrine (NE) brain levels and turnover rate were examined in the spontaneously epileptic rat (SER: zi/zi, tm/tm), a double mutant rat obtained by mating tremor heterozygotes (tm/+) with zitter homozygotes associated with epileptic seizures composed of spontaneously occurring tonic convulsion and absence-like seizure. DA and NE levels were also determined in age-matched male zitter, tremor and Kyo: Wistar rats. DA levels in caudate nucleus were significantly lower in adult age (10-12 weeks) SER, which showed epileptic seizures, and zitter rats than in adult Kyo: Wistar and tremor rats. DA levels in other areas such as thalamus-hypothalamus, midbrain, and pons medulla were not different among SER, zitter, tremor, and Kyo: Wistar rats at age 10-12 weeks. Except in cerebral cortex and hippocampus, there were no differences in brain DA levels between young seizure-free SER (age 5 weeks) and young Kyo: Wistar rats. Furthermore, the turnover rate of DA was significantly lower in caudate nucleus of adult SER than of Kyo: Wistar rat, whereas in pons-medulla there was no difference between the two strains. In contrast, NE levels in the thalamus-hypothalamus, midbrain, cerebellum and pons-medulla were higher in SER and zitter rats at age 10-12 weeks than in age-matched tremor and Kyo: Wistar rats. Higher NE levels were also observed in midbrain, cerebellum, and pons-medulla of young SER as compared with young Kyo: Wistar rats. Turnover rates of NE were significantly lower in pons-medulla and cerebellum of the adult SER than in those of Kyo: Wistar rat.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Hara
- Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan
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Saji H, Iida Y, Takahashi M, Sasa M, Serikawa T, Yamada J, Yokoyama A. Local cerebral glucose utilization in the interictal state of the spontaneously epileptic rat (SER). Brain Res 1993; 601:76-9. [PMID: 8431788 DOI: 10.1016/0006-8993(93)91696-p] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Local cerebral glucose utilization (LCGU) in spontaneously epileptic rats (SER) and in their parent strains, zitter (ZI) and Kyoto-Wistar (KW) rats was studied by autoradiography with [14C]2-deoxyglucose. Compared to the LCGU in age-matched KW rats, LCGU in 8-week-old SERs, which had not yet exhibited epileptic seizures, was low in all brain regions examined, and there were no significant differences among the regions. Moreover, there were no differences in LCGU among all regions examined in both SERs and in ZI rats. By contrast, the interictal LCGU in 13-week-old SERs, which did exhibit epileptic seizures, was generally lower than in the other two strains, particularly in the hippocampus and amygdala. These findings suggest that the epileptogenic focus in SERs may lie in the hippocampus and amygdala.
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Affiliation(s)
- H Saji
- Department of Radiopharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Kyoto University, Japan
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Kubek MJ, Knoblach SM, Sharif NA, Burt DR, Buterbaugh GG, Fuson KS. Thyrotropin-releasing hormone gene expression and receptors are differentially modified in limbic foci by seizures. Ann Neurol 1993; 33:70-6. [PMID: 8388190 DOI: 10.1002/ana.410330112] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Previous studies using two seizure paradigms, electroconvulsive shock and kindling, suggested potential sites of endogenous thyrotropin-releasing hormone (TRH) action in specific epileptogenic areas. We studied TRH gene expression and TRH receptors in rat limbic areas using the kindling model of epilepsy. Immunoassayable TRH increased 4- to 20-fold over control levels in specific subregions of the hippocampus 24 hours after a single stage 5 seizure. Concurrently, TRH receptor binding was significantly reduced in hippocampal (23-39%) and amygdaloid (21-22%) membranes. Dramatic temporal and spatial changes in prepro-TRH messenger RNA were visualized by in situ hybridization histochemistry in the hippocampal dentate gyrus, the piriform cortex, and the amygdala. Peak hybridization occurred 6 and 12 hours postictally in these loci and returned toward basal levels by 24 hours. These results are consistent with the hypothesis that TRH may have an important role in the pathophysiology epilepsy by modulating excitatory processes.
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Affiliation(s)
- M J Kubek
- Department of Anatomy, Indiana University School of Medicine, Indianapolis 46202-5120
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Renming X, Ishihara K, Sasa M, Ujihara H, Momiyama T, Fujita Y, Todo N, Serikawa T, Yamada J, Takaori S. Antiepileptic effects of CNK-602A, a novel thyrotropin-releasing hormone analog, on absence-like and tonic seizures of spontaneously epileptic rats. Eur J Pharmacol 1992; 223:185-92. [PMID: 1478266 DOI: 10.1016/0014-2999(92)94838-m] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The effects of CNK-602A (N-[(6-methyl-5-oxo-3-thiomorpholinyl) carbonyl]-L-histidyl-L-prolinamide), a novel thyrotropin-releasing hormone related analog, were investigated on absence-like seizure and tonic convulsion in the spontaneously epileptic rat (SER), which is a genetically defined double-mutant. When CNK-602A of 0.2-1 mg/kg was given intravenously to the animal, there were no changes in the background EEG except for an increase in low-voltage fast waves concomitant with behavioral alertness. However, CNK-602A suppressed absence-like seizure and tonic convulsion in a dose-dependent manner for over 1 h. These antiepileptic effects of CNK-602A on both seizures were antagonized by pretreatment with haloperidol (1 mg/kg, i.p.). It was found, using a brain in vivo microdialysis method, that CNK-602A at a dose of 1 mg/kg, which inhibits the seizures, increased the release of dopamine in the caudate nucleus. These results suggest that CNK-602A inhibits the seizures of SER in a similar manner to thyrotropin-releasing hormone (TRH), probably by increasing the release of dopamine in the central nervous system. In addition, the antiepileptic effects of CNK-602A were more potent and lasted longer than those of TRH.
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Affiliation(s)
- X Renming
- Department of Pharmacology, Faculty of Medicine, Kyoto University, Japan
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