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Dubovy SR, Fernandez MP, Echegaray JJ, Block NL, Unoki N, Perez R, Vidaurre I, Lee RK, Nadji M, Schally AV. Expression of hypothalamic neurohormones and their receptors in the human eye. Oncotarget 2017; 8:66796-66814. [PMID: 28977997 PMCID: PMC5620137 DOI: 10.18632/oncotarget.18358] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2017] [Accepted: 05/20/2017] [Indexed: 12/27/2022] Open
Abstract
Extrapituitary roles for hypothalamic neurohormones have recently become apparent and clinically relevant, based on the use of synthetic peptide analogs for the treatment of multiple conditions including cancers, pulmonary edema and myocardial infarction. In the eye, it has been suggested that some of these hormones and their receptors may be present in the ciliary body, iris, trabecular meshwork and retina, but their physiological role has yet to be elucidated. Our study intends to comprehensively demonstrate the expression of some hypothalamic neuroendocrine hormones and their receptors within different retinal and extraretinal structures of the human eye. Immunofluorescence, Western blot analysis, and RT-PCR were used to evaluate the qualitative and quantitative expression of Luteinizing Hormone Releasing Hormone (LHRH), Growth Hormone Releasing Hormone (GHRH), Thyrotropin Releasing Hormone (TRH), Gastrin Releasing Peptide (GRP) and Somatostatin as well as their respective receptors (LHRH-R, GHRH-R, TRH-R, GRP-R, SST-R1) in cadaveric human eye tissue and in paraffinized human eye tissue sections. The hypothalamic hormones LHRH, GHRH, TRH, GRP and Somatostatin and their respective receptors (LHRH-R, GHRH-R, TRH-R, GRPR/BB2 and SST-R1), were expressed in the conjunctiva, cornea, trabecular meshwork, ciliary body, lens, retina, and optic nerve.
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Affiliation(s)
- Sander R Dubovy
- Florida Lions Ocular Pathology Laboratory, Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida, USA.,Department of Pathology, University of Miami, Miller School of Medicine, Miami, Florida, USA
| | - Maria P Fernandez
- Florida Lions Ocular Pathology Laboratory, Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida, USA
| | - Jose J Echegaray
- Florida Lions Ocular Pathology Laboratory, Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida, USA.,Department of Ophthalmology, University of Puerto Rico School of Medicine, San Juan, PR, USA
| | - Norman L Block
- Department of Pathology, University of Miami, Miller School of Medicine, Miami, Florida, USA.,Divisions of Hematology/Oncology, Endocrinology, Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida, USA
| | - Noriyuki Unoki
- Florida Lions Ocular Pathology Laboratory, Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida, USA
| | - Roberto Perez
- Miami Veterans Affairs Medical Center, Miami, Florida, USA.,Divisions of Hematology/Oncology, Endocrinology, Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida, USA
| | | | - Richard K Lee
- Florida Lions Ocular Pathology Laboratory, Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, Florida, USA
| | - Mehrdad Nadji
- Department of Pathology, University of Miami, Miller School of Medicine, Miami, Florida, USA
| | - Andrew V Schally
- Miami Veterans Affairs Medical Center, Miami, Florida, USA.,Department of Pathology, University of Miami, Miller School of Medicine, Miami, Florida, USA.,Divisions of Hematology/Oncology, Endocrinology, Department of Medicine, University of Miami, Miller School of Medicine, Miami, Florida, USA
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Anadón R, Becerra M, Díaz ML, Manso MJ. Presence and development of thyrotropin-releasing hormone-immunoreactive amacrine cells in the retina of a teleost, the brown trout (Salmo trutta fario). Neurosci Lett 2001; 299:225-8. [PMID: 11165776 DOI: 10.1016/s0304-3940(01)01531-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The presence of thyrotropin-releasing hormone-immunoreactive (TRHir) amacrine cells is described for the first time in the retina of a teleost. These amacrine cells were mostly located in the inner nuclear layer, with occasional perikarya in the ganglion cell layer. Their processes formed a conspicuous plexus at the level of the ganglion cell perikarya. The TRHir amacrine cells appeared in posthatching stages, with the total number in retinas of juveniles approximately four times the number of cells in adults. Two types of TRHir cells, large and small, can be distinguished in developing stages, small cells outnumbering large cells. The TRHir cells of adults appears mainly to correspond to large, multistratified amacrine cells of developing stages. The possibility of transient expression of TRH in small amacrine cells during development is discussed.
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Affiliation(s)
- R Anadón
- Department of Fundamental Biology, University of Santiago de Compostela, 15706-, Santiago de Compostela, Spain.
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Iwasaki T, Yamada M, Satoh T, Konaka S, Ren Y, Hashimoto K, Kohga H, Kato Y, Mori M. Genomic organization and promoter function of the human thyrotropin-releasing hormone receptor gene. J Biol Chem 1996; 271:22183-8. [PMID: 8703031 DOI: 10.1074/jbc.271.36.22183] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We isolated and characterized the gene for the human thyrotropin-releasing hormone receptor. The gene spanned more than 30 kilobases and contained three exons and two introns. Intron 1 exists in the 5'-untranslated region, and intron 2 is more than 25 kilobases in length which interrupts the coding region before the beginning of the putative sixth transmembrane domain. Exon 3 encodes the rest of the coding region and the entire 3'-untranslated region. The 3'-flanking region contains four potential polyadenylation signals, and 3'-rapid amplification of cDNA ends studies showed that only a signal at 2076 base pairs downstream of the stop codon was functional in the anterior pituitary. Primer extension and anchor-polymerase chain reaction studies indicated a transcriptional start site at 344 base pairs upstream of the translational start site. The promoter region does not contain either a TATA box or a CAAT box in the appropriate location. Transient transfection study revealed significant activity of the promoter in GH4C1 cells, and the region between -338 and -933 bp from the transcriptional start site worked as a negative regulator. Knowledge of the genomic organization and the promoter region of thyrotropin-releasing hormone (TRH) receptor gene will allow further studies of possible disorders of the TRH receptor, as well as facilitate elucidation of transcriptional control of the human TRH receptor gene.
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Affiliation(s)
- T Iwasaki
- First Department of Internal Medicine, Gunma University School of Medicine, Maebashi 371 Japan
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Vonhof S, Feuerstein GZ, Cohen LA, Labroo VM. Norvaline2-TRH: binding to TRH receptors in rat brain homogenates. Eur J Pharmacol 1990; 180:1-12. [PMID: 2163861 DOI: 10.1016/0014-2999(90)90586-u] [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: 12/30/2022]
Abstract
Norvaline2-thyrotropin-releasing hormone ([Nva2]TRH) has been described as a thyrotropin-releasing hormone (TRH) analog with no thyrotropin (TSH)-releasing capacity but enhanced analeptic activity compared with TRH, as shown by the reversal of haloperidol-induced catalepsy. We have evaluated the receptor-binding properties of [Nva2]TRH in homogenates of rat anterior pituitary, hypothalamus, brainstem and cortex tissue, using [3H]TRH and [3H][3-Me-His2]TRH as radioligands. Apparent Ki values at high affinity TRH-binding sites, labelled predominantly by [3H][3-Me-His2]TRH, ranged from 17.0 to 36.9 microM in all tested regions. Additionally, [Nva2]TRH was shown to compete with [3H]TRH at low affinity TRH-binding sites with similar affinities. It is concluded that the loss of TSH-releasing activity of [Nva2]TRH appears to be due to a drastic reduction in binding affinity to the high affinity TRH receptor subtype. Its analeptic activity, however, may be mediated by low affinity TRH binding sites which are predominantly labelled by [3H]TRH or by yet unidentified mechanisms.
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Affiliation(s)
- S Vonhof
- Laboratory of Chemistry, NIDDK, National Institutes of Health, Bethesda, MD 20892
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Vonhof S, Paakkari I, Feuerstein G, Cohen LA, Labroo VM. Receptor binding of fluorinated histidine analogs of thyrotropin-releasing hormone in various regions of the rat brain. Eur J Pharmacol 1989; 164:77-83. [PMID: 2753081 DOI: 10.1016/0014-2999(89)90233-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Binding properties of [4(5)-fluoro-imidazole-His2]-TRH (4(5)-F-TRH), [2-trifluoromethyl-imidazole-His2]-TRH (2-CF3-TRH) and [4(5)-trifluoromethyl-imidazole-His2]-TRH (4(5)-CF3-TRH), three novel TRH analogs, have been evaluated in rat pituitary, hypothalamus, brainstem and cortex tissue. 4(5)-F-TRH, previously shown to elicit arterial pressor responses and prolactin release similar to those of TRH, binds to TRH receptors with low, micromolar affinity (Ki = 7.5-13.5 microM). 2-CF3-TRH, an analog of less cardiovascular but increased prolactin-releasing activity, shows Ki values of 3.3-4.9 microM. 4(5)-CF3-TRH, which shows comparable biological activity to 2-CF3-TRH, demonstrates a binding affinity which is virtually nonspecific (Ki = 0.39-1.01 mM). It is therefore concluded that the biological effects of these analogs are mediated either through low affinity TRH binding sites not recognized by [3H][3Me-His2]-TRH or through mechanisms not involving TRH receptors as such.
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Affiliation(s)
- S Vonhof
- Laboratory of Chemistry, National Institutes of Health, Bethesda, MD 20892
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Simard M, Pekary AE, Smith VP, Hershman JM. Thyroid hormone modulation of TRH precursor levels in rat hypothalamus, pituitary, thyroid and blood. Peptides 1989; 10:145-55. [PMID: 2501768 DOI: 10.1016/0196-9781(89)90091-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In the present study we have examined the in vivo effects of thyroid hormones and TRH on tissue and blood levels of TRH and TRH-Gly (pGlu-His-Pro-Gly), a TRH precursor. Using specific radioimmunoassays (RIAs), we measured TRH immunoreactivity (TRH-IR) and TRH-Gly-IR concentrations in blood, hypothalamus, anterior and posterior pituitary, and thyroid in euthyroid, hypothyroid and thyroxine (T4)-treated 250 g male Sprague-Dawley rats. TRH-Gly-IR and TRH-IR were detected in all of these tissues. Highly significant positive correlations between whole blood TRH-Gly-IR levels and the corresponding serum TSH values (p less than 0.01), whole blood TRH-IR versus serum TSH (p less than 0.01) and whole blood TRH-Gly-IR versus whole blood TRH-IR (p less than 0.01) are consistent with cosecretion of TRH and TRH precursor peptides into the circulation. Euthyroid rats injected with TRH IP (1 microgram/100 g b.wt.) and hypothyroid rats had 4-fold higher whole blood TRH-Gly-IR levels compared to euthyroid controls (p less than 0.0005). Injection of TRH into euthyroid rats significantly increased the TRH-Gly-IR concentration in the hypothalamus, anterior and posterior pituitary and thyroid. The increase in blood TRH-Gly-IR following intravenous TRH may be due, in part, to partial saturation of TRH-degrading enzymes in blood and cell membranes. The ratio of TRH-Gly to TRH was significantly increased in the anterior pituitary by hypothyroidism and TRH injection, suggesting that thyroid hormones and TRH regulate the alpha-amidation of TRH-Gly to form TRH in this tissue. TRH-Gly levels of pooled pituitary and thyroid extracts quantitated by a combination of TRH-Gly RIA and high performance liquid chromatography (HPLC) revealed several-fold increases following incubation at 60 degrees C. Heating at this temperature may block the alpha-amidation activity in extra-hypothalamic tissues but not the "trypsin-like" enzymes which cleave prepro-TRH into TRH-Gly-immunoreactive peptides.
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Affiliation(s)
- M Simard
- Endocrinology Research Laboratory, Veterans Administration Wadsworth Medical Center, Los Angeles, CA 90073
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Taylor RL, Burt DR. Species differences in the brain regional distribution of receptor binding for thyrotropin-releasing hormone. J Neurochem 1982; 38:1649-56. [PMID: 6281386 DOI: 10.1111/j.1471-4159.1982.tb06646.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A survey of the regional distribution of binding of 1 nM [3H](3-Me-His2)thyrotropin-releasing hormone ([3H]MeTRH) to TRH receptors in the brains of eight mammalian species revealed major species differences in both the absolute and relative values of TRH receptor binding in different brain regions. Several brain regions exhibited binding equal to or exceeding that in the anterior pituitary gland of the same species, including the amygdala in the guinea pig and rat, the hypothalamus in the guinea pig, the nucleus accumbens in the rabbit, and all these and other regions in the cat and dog, for which pituitary binding was exceptionally low. Species could be divided into two groups according to which brain region appeared highest in binding: rabbits, sheep, and cattle had highest binding in the nucleus accumbens/septal area, whereas guinea pigs, rats, dogs, cats, and pigs had highest binding in the amygdala/temporal cortex area. The nucleus accumbens consistently exceeded the caudate-putamen in receptor binding. For most brain regions, rabbits, rodents, and sheep tended to be higher than carnivores, cattle, or pigs. Further regions that exhibited appreciable binding in most species included the olfactory bulb and tubercle, hippocampus, and various cortical and brain stem areas. In fact, essentially all brain regions appeared to have detectable levels of TRH receptors in at least some species, but no rat peripheral tissues have yet shown detectable receptor binding. The species differences appeared to reflect largely if not entirely differences in receptor density, although this was not tested in every species.
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