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Sharma K, Sharma KK, Mahindra A, Sehra N, Bagra N, Aaghaz S, Parmar R, Rathod GK, Jain R. Design, synthesis, and applications of ring-functionalized histidines in peptide-based medicinal chemistry and drug discovery. Med Res Rev 2023. [PMID: 36710510 DOI: 10.1002/med.21936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 12/12/2022] [Accepted: 01/06/2023] [Indexed: 01/31/2023]
Abstract
Modified and synthetic α-amino acids are known to show diverse applications. Histidine, which possesses numerous applications when subjected to synthetic modifications, is one such amino acid. The utility of modified histidines varies widely from remarkable biological activities to catalysis, and from nanotechnology to polymer chemistry. This renders histidine residue an important place in scientific research. Histidine is a well-studied scaffold and constitutes the active site of various enzymes catalyzing important reactions in the biological systems. A rational modification in histidine structure with a distinctly developed protocol extensively changes its physical and chemical properties. The utilization of modified histidines in search of potent, target selective and proteostable scaffolds is vital in the development of bioactive peptides with enhanced drug-likeliness. This review is a compilation and analysis of reported side-chain ring modifications at histidine followed by applications of ring-modified histidines in the synthesis of various categories of bioactive peptides and peptidomimetics.
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Affiliation(s)
- Komal Sharma
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Nagar, Punjab, India
| | - Krishna K Sharma
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Nagar, Punjab, India
| | - Amit Mahindra
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Nagar, Punjab, India
| | - Naina Sehra
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Nagar, Punjab, India
| | - Nitin Bagra
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Nagar, Punjab, India
| | - Shams Aaghaz
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Nagar, Punjab, India
| | - Rajesh Parmar
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Nagar, Punjab, India
| | - Gajanan K Rathod
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Nagar, Punjab, India
| | - Rahul Jain
- Department of Medicinal Chemistry, National Institute of Pharmaceutical Education and Research, Nagar, Punjab, India
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Trubacova R, Drastichova Z, Novotny J. Biochemical and physiological insights into TRH receptor-mediated signaling. Front Cell Dev Biol 2022; 10:981452. [PMID: 36147745 PMCID: PMC9485831 DOI: 10.3389/fcell.2022.981452] [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: 06/29/2022] [Accepted: 08/16/2022] [Indexed: 11/13/2022] Open
Abstract
Thyrotropin-releasing hormone (TRH) is an important endocrine agent that regulates the function of cells in the anterior pituitary and the central and peripheral nervous systems. By controlling the synthesis and release of thyroid hormones, TRH affects many physiological functions, including energy homeostasis. This hormone exerts its effects through G protein-coupled TRH receptors, which signal primarily through Gq/11 but may also utilize other G protein classes under certain conditions. Because of the potential therapeutic benefit, considerable attention has been devoted to the synthesis of new TRH analogs that may have some advantageous properties compared with TRH. In this context, it may be interesting to consider the phenomenon of biased agonism and signaling at the TRH receptor. This possibility is supported by some recent findings. Although knowledge about the mechanisms of TRH receptor-mediated signaling has increased steadily over the past decades, there are still many unanswered questions, particularly about the molecular details of post-receptor signaling. In this review, we summarize what has been learned to date about TRH receptor-mediated signaling, including some previously undiscussed information, and point to future directions in TRH research that may offer new insights into the molecular mechanisms of TRH receptor-triggered actions and possible ways to modulate TRH receptor-mediated signaling.
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β-Arrestin2 Is Critically Involved in the Differential Regulation of Phosphosignaling Pathways by Thyrotropin-Releasing Hormone and Taltirelin. Cells 2022; 11:cells11091473. [PMID: 35563779 PMCID: PMC9103620 DOI: 10.3390/cells11091473] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/22/2022] [Accepted: 04/25/2022] [Indexed: 12/17/2022] Open
Abstract
In recent years, thyrotropin-releasing hormone (TRH) and its analogs, including taltirelin (TAL), have demonstrated a range of effects on the central nervous system that represent potential therapeutic agents for the treatment of various neurological disorders, including neurodegenerative diseases. However, the molecular mechanisms of their actions remain poorly understood. In this study, we investigated phosphosignaling dynamics in pituitary GH1 cells affected by TRH and TAL and the putative role of β-arrestin2 in mediating these effects. Our results revealed widespread alterations in many phosphosignaling pathways involving signal transduction via small GTPases, MAP kinases, Ser/Thr- and Tyr-protein kinases, Wnt/β-catenin, and members of the Hippo pathway. The differential TRH- or TAL-induced phosphorylation of numerous proteins suggests that these ligands exhibit some degree of biased agonism at the TRH receptor. The different phosphorylation patterns induced by TRH or TAL in β-arrestin2-deficient cells suggest that the β-arrestin2 scaffold is a key factor determining phosphorylation events after TRH receptor activation. Our results suggest that compounds that modulate kinase and phosphatase activity can be considered as additional adjuvants to enhance the potential therapeutic value of TRH or TAL.
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Structural insights into thyrotropin-releasing hormone receptor activation by an endogenous peptide agonist or its orally administered analogue. Cell Res 2022; 32:858-861. [PMID: 35352031 PMCID: PMC9437008 DOI: 10.1038/s41422-022-00646-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Accepted: 03/04/2022] [Indexed: 12/15/2022] Open
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Therapeutic peptides: current applications and future directions. Signal Transduct Target Ther 2022; 7:48. [PMID: 35165272 PMCID: PMC8844085 DOI: 10.1038/s41392-022-00904-4] [Citation(s) in RCA: 437] [Impact Index Per Article: 218.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 02/08/2023] Open
Abstract
Peptide drug development has made great progress in the last decade thanks to new production, modification, and analytic technologies. Peptides have been produced and modified using both chemical and biological methods, together with novel design and delivery strategies, which have helped to overcome the inherent drawbacks of peptides and have allowed the continued advancement of this field. A wide variety of natural and modified peptides have been obtained and studied, covering multiple therapeutic areas. This review summarizes the efforts and achievements in peptide drug discovery, production, and modification, and their current applications. We also discuss the value and challenges associated with future developments in therapeutic peptides.
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Liu WY, Liu H, Aggarwal J, Huang ZL, Horner RL. Differential activating effects of thyrotropin-releasing hormone and its analog taltirelin on motor output to the tongue musculature in vivo. Sleep 2021; 43:5813557. [PMID: 32227104 PMCID: PMC7487885 DOI: 10.1093/sleep/zsaa053] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 02/12/2020] [Indexed: 02/06/2023] Open
Abstract
Thyrotropin-releasing hormone (TRH) is produced by the hypothalamus but most brain TRH is located elsewhere where it acts as a neuromodulator. TRH-positive neurons project to the hypoglossal motoneuron pool where TRH receptor RNA shows a high degree of differential expression compared with the rest of the brain. Strategies to modulate hypoglossal motor activity are of physiological and clinical interest given the potential for pharmacotherapy for obstructive sleep apnea (OSA), a common and serious respiratory disorder. Here, we identified the effects on tongue motor activity of TRH and a specific analog (taltirelin) applied locally to the hypoglossal motoneuron pool and systemically in vivo. Studies were performed under isoflurane anesthesia and across sleep–wake states in rats. In anesthetized rats, microperfusion of TRH (n = 8) or taltirelin (n = 9) into the hypoglossal motoneuron pool caused dose-dependent increases in tonic and phasic tongue motor activity (both p < 0.001). However, the motor responses to TRH were biphasic, being significantly larger “early” in the response versus at the end of the intervention (p ≤ 0.022). In contrast, responses to taltirelin were similar “early” versus “late” (p ≥ 0.107); i.e. once elicited, the motor responses to taltirelin were sustained and maintained. In freely behaving conscious rats (n = 10), microperfusion of 10 μM taltirelin into the hypoglossal motoneuron pool increased tonic and phasic tongue motor activity in non-rapid-eye-movement (REM) sleep (p ≤ 0.038). Intraperitoneal injection of taltirelin (1 mg/kg, n = 16 rats) also increased tonic tongue motor activity across sleep–wake states (p = 0.010). These findings inform the studies in humans to identify the potential beneficial effects of taltirelin for breathing during sleep and OSA.
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Affiliation(s)
- Wen-Ying Liu
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Pharmacology, Institute of Brain Science, School of Basic Medical Science, Fudan University, Shanghai, China.,Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Hattie Liu
- Department of Medicine, University of Toronto, Toronto, ON, Canada
| | - Jasmin Aggarwal
- Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Zhi-Li Huang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Department of Pharmacology, Institute of Brain Science, School of Basic Medical Science, Fudan University, Shanghai, China
| | - Richard L Horner
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.,Department of Medicine, University of Toronto, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
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Tsuchiya A, Terayama K, Sakakibara R, Panicker J, Tateno F, Aiba Y, Haruta H, Akiba T, Ogawa A, Shimizu A, Takahashi O, Yamamoto T, Uchiyama T, Suzuki H, Yano M. Urodynamic and gait analyses in multiple system atrophy. J Neurol Sci 2020; 411:116676. [PMID: 32001376 DOI: 10.1016/j.jns.2020.116676] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 12/07/2019] [Accepted: 01/07/2020] [Indexed: 01/06/2023]
Abstract
BACKGROUND Limited attention has been paid to the relationship between bladder dysfunction and motor disorder in multiple system atrophy (MSA). OBJECTIVE We aimed to correlate pressure-flow urodynamic parameters with video-gait analysis parameters in MSA. METHODS We recruited 34 patients with MSA: 20 men, 14 women; age 64.0 + - 7.9 years; disease duration 2 years (1-4 years). Nineteen cases had the cerebellar form, and 15 had the parkinsonian form; the patients were taking levodopa 300 mg/day (100-400 mg). All patients underwent pressure-flow urodynamics (parameters: detrusor overactivity [noted in 72%] and Watts factor) and video-gait analysis (parameters: time and the number of strides taken to walk 5 m (simple task) and time for timed up and go (complex task). Statistical analysis was done using Student's t-test to analyze the relation between detrusor overactivity and gait, and Spearman's rank correlation coefficient test to analyze the relation between the remaining parameters and gait. RESULTS We found no relation between filling-phase urodynamics (detrusor overactivity) and video-gait analysis parameters. Also, we found no relation between voiding-phase urodynamics (Watts factor, reflecting detrusor power) and all three video-gait analysis parameters in our MSA patients. CONCLUSION The fact that neither detrusor overactivity nor the Watts factor was related with motor disorders in the present study suggests that bladder dysfunction occurs independently from motor disorder in MSA.
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Affiliation(s)
- Akari Tsuchiya
- Rehabilitation Unit, Sakura Medical Center, Toho University, Sakura, Japan
| | - Keiichiro Terayama
- Rehabilitation Unit, Sakura Medical Center, Toho University, Sakura, Japan
| | - Ryuji Sakakibara
- Neurology, Internal Medicine, Sakura Medical Center, Toho University, Sakura, Japan.
| | - Jalesh Panicker
- Uro-Neurology, the National Hospital for Neurology and Neurosurgery and UCL Institute of Neurology, Queen Square, London, United Kingdom
| | - Fuyuki Tateno
- Neurology, Internal Medicine, Sakura Medical Center, Toho University, Sakura, Japan
| | - Yosuke Aiba
- Neurology, Internal Medicine, Sakura Medical Center, Toho University, Sakura, Japan
| | - Hiroyuki Haruta
- Rehabilitation Unit, Sakura Medical Center, Toho University, Sakura, Japan
| | - Takashi Akiba
- Rehabilitation Unit, Sakura Medical Center, Toho University, Sakura, Japan
| | - Akihiro Ogawa
- Rehabilitation Unit, Sakura Medical Center, Toho University, Sakura, Japan
| | - Ayami Shimizu
- Clinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, Japan
| | - Osamu Takahashi
- Clinical Physiology Unit, Sakura Medical Center, Toho University, Sakura, Japan
| | - Tatsuya Yamamoto
- Neurology, Chiba Prefectural University of Health Sciences, Chiba, Japan
| | - Tomoyuki Uchiyama
- Neurology, International University of Health and Welfare, Narita, Japan
| | | | - Masashi Yano
- Urology, Sakura Medical Center, Toho University, Sakura, Japan
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Kobayashi N, Sato N, Fujimura Y, Kihara T, Sugita K, Takahashi K, Koike K, Sugawara T, Tada Y, Nakai H, Yoshikawa T. Discovery of the Orally Effective Thyrotropin-Releasing Hormone Mimetic: 1-{ N-[(4 S,5 S)-(5-Methyl-2-oxooxazolidine-4-yl)carbonyl]-3-(thiazol-4-yl)-l-alanyl}-(2 R)-2-methylpyrrolidine Trihydrate (Rovatirelin Hydrate). ACS OMEGA 2018; 3:13647-13666. [PMID: 30411045 PMCID: PMC6217654 DOI: 10.1021/acsomega.8b01481] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 09/25/2018] [Indexed: 06/01/2023]
Abstract
We have explored orally effective thyrotropin-releasing hormone (TRH) mimetics, showing oral bioavailability and brain penetration by structure-activity relationship (SAR) study on the basis of in vivo antagonistic activity on reserpine-induced hypothermia in mice. By primary screening of the synthesized TRH mimetics, we found a novel TRH mimetic: l-pyroglutamyl-[3-(thiazol-4-yl)-l-alanyl]-l-prolinamide with a high central nervous system effect compared with TRH as a lead compound. Further SAR optimization studies of this lead compound led to discovery of a novel orally effective TRH mimetic: 1-{N-[(4S,5S)-(5-methyl-2-oxooxazolidine-4-yl)carbonyl]-3-(thiazol-4-yl)-l-alanyl}-(2R)-2-methylpyrrolidine trihydrate (rovatirelin hydrate), which was selected as a candidate for clinical trials.
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Affiliation(s)
- Naotake Kobayashi
- Medicinal
Chemistry Research Laboratory, Research Laboratory for Development, and Drug Discovery
& Disease Research Laboratory, Shionogi
& Co., Ltd., 3-1-1,
Futaba-cho, Toyonaka-shi, Osaka 561-0825, Japan
| | - Norihito Sato
- Medicinal
Chemistry Research Laboratory, Research Laboratory for Development, and Drug Discovery
& Disease Research Laboratory, Shionogi
& Co., Ltd., 3-1-1,
Futaba-cho, Toyonaka-shi, Osaka 561-0825, Japan
| | - Yuko Fujimura
- Medicinal
Chemistry Research Laboratory, Research Laboratory for Development, and Drug Discovery
& Disease Research Laboratory, Shionogi
& Co., Ltd., 3-1-1,
Futaba-cho, Toyonaka-shi, Osaka 561-0825, Japan
| | - Tsuyoshi Kihara
- Business
Search & Evaluation, Shionogi &
Co., Ltd., 3-1-8, Doshomachi, Chuo-ku, Osaka-shi, Osaka 541-0045, Japan
| | - Katsuji Sugita
- Medicinal
Chemistry Research Laboratory, Research Laboratory for Development, and Drug Discovery
& Disease Research Laboratory, Shionogi
& Co., Ltd., 3-1-1,
Futaba-cho, Toyonaka-shi, Osaka 561-0825, Japan
| | - Kouji Takahashi
- DMPK
Services, Shionogi Techno Advance Research
Co., Ltd., 3-1-1, Futaba-cho, Toyonaka-shi, Osaka 561-0825, Japan
| | - Katsumi Koike
- Medicinal
Chemistry Research Laboratory, Research Laboratory for Development, and Drug Discovery
& Disease Research Laboratory, Shionogi
& Co., Ltd., 3-1-1,
Futaba-cho, Toyonaka-shi, Osaka 561-0825, Japan
| | - Tamio Sugawara
- Medicinal
Chemistry Research Laboratory, Research Laboratory for Development, and Drug Discovery
& Disease Research Laboratory, Shionogi
& Co., Ltd., 3-1-1,
Futaba-cho, Toyonaka-shi, Osaka 561-0825, Japan
| | - Yukio Tada
- Medicinal
Chemistry Research Laboratory, Research Laboratory for Development, and Drug Discovery
& Disease Research Laboratory, Shionogi
& Co., Ltd., 3-1-1,
Futaba-cho, Toyonaka-shi, Osaka 561-0825, Japan
| | - Hiroshi Nakai
- Medicinal
Chemistry Research Laboratory, Research Laboratory for Development, and Drug Discovery
& Disease Research Laboratory, Shionogi
& Co., Ltd., 3-1-1,
Futaba-cho, Toyonaka-shi, Osaka 561-0825, Japan
| | - Takayoshi Yoshikawa
- Pharmacovigilance
Japan, Allergan Japan K.K., 4-20-3-35, Ebisu, Shibuya-ku, Tokyo 150-6035, Japan
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Schrage R, De Min A, Hochheiser K, Kostenis E, Mohr K. Superagonism at G protein-coupled receptors and beyond. Br J Pharmacol 2015; 173:3018-27. [PMID: 26276510 DOI: 10.1111/bph.13278] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 07/01/2015] [Accepted: 08/08/2015] [Indexed: 12/18/2022] Open
Abstract
Ligands targeting GPCRs can be categorized according to their intrinsic efficacy to trigger a specific, receptor-mediated response. A ligand endowed with the same level of efficacy as the endogenous agonist can be classified as a full agonist, whereas a compound that displays greater efficacy, that is, higher receptor signalling output than the endogenous agonist, can be called a superagonist. Subsequent to GPCR activation, an intracellular signalling cascade is set in motion, which may generate substantial amplification of the signal. This may obscure superagonism in pharmacological assays and, therefore, the definition of superagonism necessitates a combination of operational approaches, reduction of spare receptors or estimation of receptor activation close to the receptor level to quantify relative agonist efficacies in a particular system. The first part of this review will compare GPCR superagonism with superagonism in the field of immunology, where this term is well established. In the second part, known GPCR superagonists will be reviewed. Then, the experimental and analytical challenges in the deconvolution of GPCR superagonism will be addressed. Finally, the potential benefit of superagonism is discussed. The molecular mechanisms behind GPCR superagonism are not completely understood. However, crystallography shows that agonist binding alone is not sufficient for a fully active receptor state and that binding of the G protein is at least equally important. Accordingly, the emerging number of reported superagonists implies that ligand-induced receptor conformations more active than the ones stabilized by the endogenous agonist are indeed feasible. Superagonists may have therapeutic potential when receptor function is impaired or to induce negative feedback mechanisms. Linked Articles This article is part of a themed section on Molecular Pharmacology of G Protein-Coupled Receptors. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v173.20/issuetoc.
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Affiliation(s)
- R Schrage
- Pharmacology & Toxicology Section, Institute of Pharmacy, University of Bonn, 53121, Bonn, Germany.
| | - A De Min
- Pharmacology & Toxicology Section, Institute of Pharmacy, University of Bonn, 53121, Bonn, Germany
| | - K Hochheiser
- Peter Doherty Institute, Department of Microbiology and Immunology, University of Melbourne, Melbourne, VIC, 3100, Australia
| | - E Kostenis
- Molecular-, Cellular-, and Pharmacobiology Section, Institute of Pharmaceutical Biology, University of Bonn, 53115, Bonn, Germany
| | - K Mohr
- Pharmacology & Toxicology Section, Institute of Pharmacy, University of Bonn, 53121, Bonn, Germany
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Ijiro T, Nakamura K, Ogata M, Inada H, Kiguchi S, Maruyama K, Nabekura J, Kobayashi M, Ishibashi H. Effect of rovatirelin, a novel thyrotropin-releasing hormone analog, on the central noradrenergic system. Eur J Pharmacol 2015; 761:413-22. [DOI: 10.1016/j.ejphar.2015.05.047] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 05/15/2015] [Accepted: 05/20/2015] [Indexed: 01/05/2023]
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Wozniak DR, Quinnell TG. Unmet needs of patients with narcolepsy: perspectives on emerging treatment options. Nat Sci Sleep 2015; 7:51-61. [PMID: 26045680 PMCID: PMC4447169 DOI: 10.2147/nss.s56077] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The treatment options currently available for narcolepsy are often unsatisfactory due to suboptimal efficacy, troublesome side effects, development of drug tolerance, and inconvenience. Our understanding of the neurobiology of narcolepsy has greatly improved over the last decade. This knowledge has not yet translated into additional therapeutic options for patients, but progress is being made. Some compounds, such as histaminergic H3 receptor antagonists, may prove useful in symptom control of narcolepsy. The prospect of finding a cure still seems distant, but hypocretin replacement therapy offers some promise. In this narrative review, we describe these developments and others which may yield more effective narcolepsy treatments in the future.
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Affiliation(s)
- Dariusz R Wozniak
- Respiratory Support and Sleep Centre, Papworth Hospital, Cambridge, UK
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12
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Thirunarayanan N, Nir EA, Raaka BM, Gershengorn MC. Thyrotropin-releasing hormone receptor type 1 (TRH-R1), not TRH-R2, primarily mediates taltirelin actions in the CNS of mice. Neuropsychopharmacology 2013; 38:950-6. [PMID: 23303050 PMCID: PMC3629383 DOI: 10.1038/npp.2012.256] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Thyrotropin-releasing hormone receptor type 2 (TRH-R2), not TRH-R1, has been proposed to mediate the CNS effects of TRH and its more effective analog taltirelin (TAL). Consistent with this idea, TAL exhibited higher binding affinity and signaling potency at mouse TRH-R2 than TRH-R1 in a model cell system. We used TRH-R1 knockout (R1ko), R2ko and R1/R2ko mice to determine which receptor mediates the CNS effects of TAL. There was no TRH-R1 mRNA in R1ko and R1/R2ko mice and no TRH-R2 mRNA in R2ko and R1/R2ko mice. Specific [(3)H]MeTRH binding to whole brain membranes was 5% of wild type (WT) for R1ko mice, 100% for R2ko mice and 0% for R1/R2ko mice, indicating TRH-R1 is the predominant receptor expressed in the brain. In arousal assays, TAL shortened sleep time with pentobarbital sedation in WT and R2ko mice by 44 and 49% and with ketamine/xylazine sedation by 66 and 55%, but had no effect in R1ko and R1/R2ko mice. In a tail flick assay of nociception, TAL increased response latency by 65 and 70% in WT and R2ko mice, but had no effect in R1ko and R1/R2ko mice. In a tail suspension test of depression-like behavior, TAL increased mobility time by 49 and 37% in WT and R2ko mice, but had no effect in R1ko and R1/R2ko mice. Thus, in contrast to the generally accepted view that the CNS effects of TAL are mediated by TRH-R2, these effects are mediated primarily if not exclusively by TRH-R1 in mice.
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Affiliation(s)
- Nanthakumar Thirunarayanan
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Eshel A Nir
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Bruce M Raaka
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Marvin C Gershengorn
- Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD, USA,Laboratory of Endocrinology and Receptor Biology, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), 50 South Drive, Room 4134, Bethesda, MD 20892, USA, Tel: +1 301 451 6305, Fax: +1 301 480 4214, E-mail:
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