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Target Enzymes Considered for the Treatment of Alzheimer's Disease and Parkinson's Disease. BIOMED RESEARCH INTERNATIONAL 2020; 2020:2010728. [PMID: 33224974 PMCID: PMC7669341 DOI: 10.1155/2020/2010728] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 09/15/2020] [Accepted: 10/29/2020] [Indexed: 12/14/2022]
Abstract
Various amyloidogenic proteins have been suggested to be involved in the onset and progression of neurodegenerative diseases (ND) such as Alzheimer's disease (AD) and Parkinson's disease (PD). Particularly, the aggregation of misfolded amyloid-β and hyperphosphorylated tau and α-synuclein are linked to the pathogenesis of AD and PD, respectively. In order to care the diseases, multiple small molecules have been developed to regulate the aggregation pathways of these amyloid proteins. In addition to controlling the aggregation of amyloidogenic proteins, maintaining the levels of the proteins in the brain by amyloid degrading enzymes (ADE; neprilysin (NEP), insulin-degrading enzyme (IDE), asparagine endopeptidase (AEP), and ADAM10) is also essential to cure AD and PD. Therefore, numerous biological molecules and chemical agents have been investigated as either inducer or inhibitor against the levels and activities of ADE. Although the side effect of enhancing the activity of ADE could occur, the removal of amyloidogenic proteins could result in a relatively good strategy to treat AD and PD. Furthermore, since the causes of ND are diverse, various multifunctional (multitarget) chemical agents have been designed to control the actions of multiple risk factors of ND, including amyloidogenic proteins, metal ions, and reactive oxygen species. Many of them, however, were invented without considerations of regulating ADE levels and actions. Incorporation of previously created molecules with the chemical agents handling ADE could be a promising way to treat AD and PD. This review introduces the ADE and molecules capable of modulating the activity and expression of ADE.
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Charli JL, Rodríguez-Rodríguez A, Hernández-Ortega K, Cote-Vélez A, Uribe RM, Jaimes-Hoy L, Joseph-Bravo P. The Thyrotropin-Releasing Hormone-Degrading Ectoenzyme, a Therapeutic Target? Front Pharmacol 2020; 11:640. [PMID: 32457627 PMCID: PMC7225337 DOI: 10.3389/fphar.2020.00640] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Accepted: 04/21/2020] [Indexed: 12/17/2022] Open
Abstract
Thyrotropin releasing hormone (TRH: Glp-His-Pro-NH2) is a peptide mainly produced by brain neurons. In mammals, hypophysiotropic TRH neurons of the paraventricular nucleus of the hypothalamus integrate metabolic information and drive the secretion of thyrotropin from the anterior pituitary, and thus the activity of the thyroid axis. Other hypothalamic or extrahypothalamic TRH neurons have less understood functions although pharmacological studies have shown that TRH has multiple central effects, such as promoting arousal, anorexia and anxiolysis, as well as controlling gastric, cardiac and respiratory autonomic functions. Two G-protein-coupled TRH receptors (TRH-R1 and TRH-R2) transduce TRH effects in some mammals although humans lack TRH-R2. TRH effects are of short duration, in part because the peptide is hydrolyzed in blood and extracellular space by a M1 family metallopeptidase, the TRH-degrading ectoenzyme (TRH-DE), also called pyroglutamyl peptidase II. TRH-DE is enriched in various brain regions but is also expressed in peripheral tissues including the anterior pituitary and the liver, which secretes a soluble form into blood. Among the M1 metallopeptidases, TRH-DE is the only member with a very narrow specificity; its best characterized biological substrate is TRH, making it a target for the specific manipulation of TRH activity. Two other substrates of TRH-DE, Glp-Phe-Pro-NH2 and Glp-Tyr-Pro-NH2, are also present in many tissues. Analogs of TRH resistant to hydrolysis by TRH-DE have prolonged central efficiency. Structure-activity studies allowed the identification of residues critical for activity and specificity. Research with specific inhibitors has confirmed that TRH-DE controls TRH actions. TRH-DE expression by β2-tanycytes of the median eminence of the hypothalamus allows the control of TRH flux into the hypothalamus-pituitary portal vessels and may regulate serum thyrotropin secretion. In this review we describe the critical evidences that suggest that modification of TRH-DE activity in tanycytes, and/or in other brain regions, may generate beneficial consequences in some central and metabolic disorders and identify potential drawbacks and missing information needed to test these hypotheses.
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Affiliation(s)
- Jean-Louis Charli
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Mexico
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Zheng C, Chen G, Tan Y, Zeng W, Peng Q, Wang J, Cheng C, Yang X, Nie S, Xu Y, Zhang Z, Papa SM, Ye K, Cao X. TRH Analog, Taltirelin Protects Dopaminergic Neurons From Neurotoxicity of MPTP and Rotenone. Front Cell Neurosci 2018; 12:485. [PMID: 30618632 PMCID: PMC6306470 DOI: 10.3389/fncel.2018.00485] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 11/28/2018] [Indexed: 01/06/2023] Open
Abstract
Dopaminergic neurons loss is one of the main pathological characters of Parkinson’s disease (PD), while no suitable neuroprotective agents have been in clinical use. Thyrotropin-releasing hormone (TRH) and its analogs protect neurons from ischemia and various cytotoxins, but whether the effect also applies in PD models remain unclear. Here, we showed that Taltirelin, a long-acting TRH analog, exhibited the neuroprotective effect in both cellular and animal models of PD. The in vitro study demonstrated that Taltirelin (5 μM) reduced the generation of reactive oxygen species (ROS) induced by MPP+ or rotenone, alleviated apoptosis and rescued the viability of SH-SY5Y cells and rat primary midbrain neurons. Interestingly, SH-SY5Y cells treated with Taltirelin also displayed lower level of p-tau (S396) and asparagine endopeptidase (AEP) cleavage products, tau N368 and α-synuclein N103 fragments, accompanied by a lower intracellular monoamine oxidase-B (MAO-B) activity. In the subacute MPTP-induced and chronic rotenone-induced PD mice models, we found Taltirelin (1 mg/kg) significantly improved the locomotor function and preserved dopaminergic neurons in the substantia nigra (SN). In accordance with the in vitro study, Taltirelin down-regulated the levels of p-tau (S396), p-α-synuclein (S129) tau N368 and α-synuclein N103 fragments in SN and striatum. Together, this study demonstrates that Taltirelin may exert neuroprotective effect via inhibiting MAO-B and reducing the oxidative stress and apoptosis, preventing AEP activation and its subsequent pathological cleavage of tau and α-synuclein, thus provides evidence for Taltirelin in protective treatment of PD.
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Affiliation(s)
- Cong Zheng
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Guiqin Chen
- Department of Neurology, Renmin Hospital, Wuhan University, Wuhan, China
| | - Yang Tan
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Weiqi Zeng
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qiwei Peng
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ji Wang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chi Cheng
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoman Yang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shuke Nie
- Department of Neurology, Renmin Hospital, Wuhan University, Wuhan, China
| | - Yan Xu
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhentao Zhang
- Department of Neurology, Renmin Hospital, Wuhan University, Wuhan, China
| | - Stella M Papa
- Yerkes National Primate Research Center, Emory University School of Medicine, Atlanta, GA, United States.,Department of Neurology, Emory University School of Medicine, Atlanta, GA, United States
| | - Keqiang Ye
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, United States
| | - Xuebing Cao
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Zheng C, Chen G, Tan Y, Zeng W, Peng Q, Wang J, Cheng C, Yang X, Nie S, Xu Y, Zhang Z, Papa SM, Ye K, Cao X. TRH Analog, Taltirelin Improves Motor Function of Hemi-PD Rats Without Inducing Dyskinesia via Sustained Dopamine Stimulating Effect. Front Cell Neurosci 2018; 12:417. [PMID: 30555300 PMCID: PMC6282053 DOI: 10.3389/fncel.2018.00417] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 10/25/2018] [Indexed: 01/08/2023] Open
Abstract
Thyrotropin-releasing hormone (TRH) and its analogs are able to stimulate the release of the endogenic dopamine (DA) in the central nervous system. However, this effect has not been tested in the Parkinson’s disease (PD), which is characterized by the DA deficiency due to the dopaminergic neurons loss in the substantia nigra. Here, we investigated the therapeutic effect of Taltirelin, a long-acting TRH analog on 6-hydroxydopamine-lesioned hemi-Parkinsonian rat model. 1–10 mg/kg Taltirelin i.p. administration significantly improved the locomotor function and halted the electrophysiological abnormities of PD animals without inducing dyskinesia even with high-dose for 7 days treatment. Microdialysis showed that Taltirelin gently and persistently promoted DA release in the cortex and striatum, while L-DOPA induced a sharp rise of DA especially in the cortex. The DA-releasing effect of Taltirelin was alleviated by reserpine, vanoxerine (GBR12909) or AMPT, indicating a mechanism involving vesicular monoamine transporter-2 (VMAT-2), dopamine transporter (DAT) and tyrosine hydroxylase (TH). The in vivo and in vitro experiments further supported that Taltirelin affected the regulation of TH expression in striatal neurons, which was mediated by p-ERK1/2. Together, this study demonstrated that Taltirelin improved motor function of hemi-PD rats without inducing dyskinesia, thus supporting a further exploration of Taltirelin for PD treatment.
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Affiliation(s)
- Cong Zheng
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Guiqin Chen
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yang Tan
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Weiqi Zeng
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qiwei Peng
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ji Wang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Chi Cheng
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoman Yang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shuke Nie
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Yan Xu
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhentao Zhang
- Department of Neurology, Renmin Hospital of Wuhan University, Wuhan, China
| | - Stella M Papa
- Yerkes National Primate Research Center, Emory University School of Medicine, Atlanta, GA, United States.,Department of Neurology, Emory University School of Medicine, Atlanta, GA, United States
| | - Keqiang Ye
- Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, United States
| | - Xuebing Cao
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Asai H, Watanabe Y, Yamauchi-Kohno R, Doi O. Reversal of hemorrhagic shock in rats using the metabolically stable thyrotropin-releasing hormone analog taltirelin hydrate. J Recept Signal Transduct Res 2011; 31:416-22. [DOI: 10.3109/10799893.2011.625427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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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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Kinoshita K, Yamamura M, Sugihara J, Suzuki M, Matsuoka Y. Taltirelin Hydrate (TA-0910): An Orally Active Thyrotropin-Releasing Hormone Mimetic Agent with Multiple Actions. CNS DRUG REVIEWS 2006. [DOI: 10.1111/j.1527-3458.1998.tb00039.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Horimoto S, Mayumi T, Tagawa K, Yamakita H, Yoshikawa M. Determination of taltirelin, a new stable thyrotropin-releasing hormone analogue, in human plasma by high-performance liquid chromatography turbo-ionspray ionization tandem mass spectrometry. J Pharm Biomed Anal 2002; 30:1361-9. [PMID: 12408927 DOI: 10.1016/s0731-7085(02)00396-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A rapid, selective and sensitive assay of taltirelin, a novel thyrotropin-releasing hormone analogue, in human plasma has been developed. This method is based on a rapid sample preparation and high-performance liquid chromatography (HPLC) turbo-ionspray ionization tandem mass spectrometry (MS-MS). Analytes were purified from human plasma by SPE cartridge and separated by gradient HPLC. Turbo-ionspray ionization and MS-MS analyses were carried out by PE-Sciex API 3000 tandem mass spectrometer. Taltirelin was separated from its metabolite (acid form) on a semi-micro ODS column in methanol - 0.1% (v/v) formic acid. The selected reaction monitoring by precursor-->product ion combination of m/z 406-->264, was used for determination of taltirelin. The linearity was confirmed in the concentration range of 17-4137 pg/ml in human plasma, and the precision of this assay, expressed as a relative deviation, was less than 9.8% over the entire concentration range with adequate assay accuracy. The results obtained by the HPLC-MS-MS method correlated well with those of the radioimmunoassay method reported previously. Therefore, the HPLC-MS-MS method is useful for the determination of taltirelin with sufficient selectivity and sensitivity on pharmacokinetic studies in human.
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Affiliation(s)
- Shingo Horimoto
- Discovery Research Laboratory, Tanabe Seiyaku Co. Ltd, 16-89, Kashima 3-chome, Yodogawa-ku, 532-8505, Osaka, Japan.
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Abstract
This brief review will discuss the recent literature on several of the central actions of TRH and its analogs. The most prominent of these actions include: (1) the arousal or analeptic effect in drug narcotized animals or in concussion models; (2) the reversal of cognitive deficits produced by various drugs or procedures, and (3) the improvement of several neurological deficits produced in animal models of spinal and/or cerebellar injury. The mediation of these TRH effects by neurotransmitters is discussed. While little has been published on the human neuropsychopharmacology of TRH, and especially of its analogs, the future holds considerable therapeutic promise for these interesting drugs.
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Affiliation(s)
- A Horita
- Department of Pharmacology, University of Washington School of Medicine, Seattle 98195, USA
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Morikawa S, Sakai T, Murata K, Banno K, Sato T, Takai T, Suzuki T. Radioimmunoassay for TA-0910, a new stable thyrotropin releasing hormone analogue and its metabolite, TA-0910 acid-type, in human plasma and urine. J Pharm Biomed Anal 1998; 16:1267-74. [PMID: 9777599 DOI: 10.1016/s0731-7085(97)00145-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Radioimmunoassay (RIA) was investigated for the determination of TA-0910 and its main metabolite, TA-0910 acid-type, in human plasma and urine. TA-0910 is a new metabolically stable analogue of thyrotropin releasing hormone (TRH). Antiserum was raised in the rabbit against the 1-fluoro-2,4-dinitrophenyl derivative of TA-0910 or TA-0910 acid-type conjugated to keyhole limpet hemocyanin (KLH). The radioligand was prepared by iodination with 125I of the histidine imidazole ring of TA-0910 or TA-0910 acid-type. Cross-reactivities of anti-TA-0910 or TA-0910 acid-type antiserum for TA-0910, its metabolite and related compounds were low. The calibration range was 0.02-5 ng ml-1 using 100 microliters human plasma or urine. Inter-day variations of TA-0910 and TA-0910 acid-type assay in plasma were 3.5-15.5 and 1.8-9.4%, respectively. The variations of the assay in urine were the same as those in plasma. The recovery of TA-0910 and TA-0910 acid-type spiked in plasma or urine samples was approximately 100%. Furthermore, this method was applied to the determination of TA-0910 and TA-0910 acid-type in human plasma and urine samples, for the evaluation of the pharmacokinetics of TA-0910 in humans. From the results it was demonstrated that he developed RIA was useful for the determination of TA-0910 and TA-0910 acid-type in human plasma and urine, and was applicable to pharmacokinetic studies in humans.
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Affiliation(s)
- S Morikawa
- Analytical Research Laboratory, Tanabe Seiyaku Company Limited, Osaka, Japan
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Kinoshita K, Watanabe Y, Yamamura M, Matsuoka Y. TRH receptor agonists ameliorate 3-acetylpyridine-induced ataxia through NMDA receptors in rats. Eur J Pharmacol 1998; 343:129-33. [PMID: 9570459 DOI: 10.1016/s0014-2999(97)01539-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The effects of thyrotropin-releasing hormone (TRH) receptor agonists were examined on 3-acetylpyridine-induced cerebellar ataxia in rats. 3-acetylpyridine markedly decreased the maximal height of vertical jump, accompanied by motor incoordination. Both TA-0910 ((-)-N-[(S)-hexahydro-1-methyl-2,6-dioxo-4-pyrimidinylcarbonyl]-L- histidyl-L-prolinamide tetrahydrate; 0.3-3 mg/kg), a novel TRH analog, and TRH (10 and 30 mg/kg) significantly increased the suppressed maximal height of vertical jump after single intraperitoneal administration. The effects of these drugs reached a maximum at 1 h and disappeared 24 h after administration. Both the TA-0910 (1 mg/kg)- and TRH (10 mg/kg)-induced increases in the maximal height of vertical jump were completely counteracted by pretreatment with i.p. injected MK-801 (10,11-dihydro-5-methyl-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate; 0.1 mg/kg), an NMDA receptor antagonist. Neither bicuculline, muscimol, baclofen, cyproheptadine nor prazosin affected the effect of the TRH receptor agonists. In conclusion, TA-0910 is more potent than TRH in ameliorating cerebellar functional disorders. The anti-ataxic effects of these TRH receptor agonists may be mediated by NMDA receptors in 3-acetylpyridine-treated rats.
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Affiliation(s)
- K Kinoshita
- Pharmaceutical Development Res. Lab., Tanabe Seiyaku Co., Ltd., Saitama, Japan.
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Kinoshita K, Kawashima K, Kawashima Y, Fukuchi I, Yamamura M, Matsuoka Y. Effect of TA-0910, a novel thyrotropin-releasing hormone analog, on in vivo acetylcholine release and turnover in rat brain. JAPANESE JOURNAL OF PHARMACOLOGY 1996; 71:139-45. [PMID: 8835640 DOI: 10.1254/jjp.71.139] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To examine the action of a novel thyrotropin-releasing hormone (TRH) analog, TA-0910 ((-)-N-[(S)-hexahydro-1-methyl-2,6-dioxo-4-pyrimidinylcarbonyl]-L- histidyl-L-prolinamide tetrahydrate), on the cerebral cholinergic systems, the release of acetylcholine (ACh) and choline in freely-moving rats and ACh accumulation in gamma-butyrolactone (GBL, a nerve impulse flow blocker)- and physostigmine-treated rats were examined. TA-0910 (0.1-1 mg/kg, i.p.) caused a marked dose-dependent increase in extracellular ACh levels and a decrease in choline levels in the hippocampus of freely moving rats. These effects were significantly stronger and longer-lasting than similar effects of TRH. TA-0910 (1, 3 mg/kg, i.p.) depressed the ACh accumulation in the cerebral cortex and hippocampus of GBL (1000 mg/kg, i.p.)-treated rats. Moreover, this analog (1, 3 mg/kg, i.p.) increased the accumulation rate of ACh in these regions in physostigmine (1 mg/kg, i.p.)-treated rats. TRH (30 mg/kg, i.p.) affected the ACh accumulation only in the hippocampus of the GBL-treated rats. These results suggest that TA-0910 not only enhances the release of ACh, but also accelerates the ACh turnover, i.e., ACh release and synthesis, at the cholinergic neuronal terminals in normal rats.
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Affiliation(s)
- K Kinoshita
- Pharmaceutical Development Research Laboratory, Tanabe Seiyaku Co., Ltd., Saitama, Japan
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