1
|
Hankins GR, Harris RT. The Opioid Growth Factor in Growth Regulation and Immune Responses in Cancer. ADVANCES IN NEUROBIOLOGY 2024; 35:45-85. [PMID: 38874718 DOI: 10.1007/978-3-031-45493-6_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2024]
Abstract
It has become apparent that endogenous opioids act not only as neurotransmitters and neuromodulators, but have multiple functions in the body. Activation of the opioid system by opiate drugs is associated with a risk of cancer development through direct stimulation of tumor cell proliferation and through immunosuppression. In contrast, the endogenous peptide opioid [Met5]-enkephalin, now commonly referred to as Opioid Growth Factor (OGF), negatively regulates cell proliferation in a wide number of cells during development, homeostasis, and neoplasia. This action is mediated through the opioid growth factor receptor, originally designated the zeta (ζ) opioid receptor. Further, contrary to the traditional notion of opiates as immunosuppressive, endogenous OGF has been shown to possess a number of positive immunomodulatory properties and may provide a beneficial effect in cancer by augmenting the activity of cells involved in both innate and acquired immunity. Taken together, the evidence supports consideration of opioid peptides such as OGF as new strategies for cancer therapy.
Collapse
Affiliation(s)
- Gerald R Hankins
- Department of Biology, West Virginia State University, Institute, WV, USA.
| | - Robert T Harris
- Department of Biology, West Virginia State University, Institute, WV, USA
| |
Collapse
|
2
|
Purushothaman I, Zagon IS, Sassani JW, McLaughlin PJ. Ocular surface complications in diabetes: The interrelationship between insulin and enkephalin. Biochem Pharmacol 2021; 192:114712. [PMID: 34324868 PMCID: PMC8478878 DOI: 10.1016/j.bcp.2021.114712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 07/22/2021] [Accepted: 07/23/2021] [Indexed: 12/17/2022]
Abstract
Diabetes is a multi-faceted disorder with increasing prevalence and rising healthcare costs. The burden of diabetes is increased because of associated complications affecting nearly all organs including the eye. The underlying pathophysiology for the onset of these ocular surface disorders is not well known. Enkephalins are endogenous opioids that originate in the brain and have numerous actions in the human body. Opioid growth factor (OGF), chemically termed [Met5]-enkephalin, binds to a novel, nuclear-associated receptor and mediates cellular homeostasis. Serum OGF levels are elevated in diabetic individuals and rodent models of diabetes. Sustained blockade of the OGF receptor (OGFr) with opioid receptor antagonists, such as naltrexone (NTX), reverses many complications of diabetes in the animal model, including delayed cutaneous wound healing, dry eye, altered corneal surface sensitivity, and keratopathy. The increased enkephalin levels observed in diabetes suggest a relationship between endogenous opioid peptides and the pathophysiology of diabetes. It is common for diabetic patients to undergo insulin therapy to restore normal blood glucose levels. However, this restoration does not alter OGF serum levels nor ameliorate ocular surface complications in the animal model of diabetes. Moreover, sex differences in the prevalence of diabetes, response to insulin therapy, and abnormalities in the OGF-OGFr axis have been reported. This review highlights current knowledge on the dysregulation of the OGF-OGFr pathway and possible relationships of insulin and enkephalins to the development of ocular surface defects in diabetes. It proposes that this dysregulation is a fundamental mechanism for the pathobiology of diabetic complications.
Collapse
Affiliation(s)
- Indira Purushothaman
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Ian S Zagon
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Joseph W Sassani
- Department of Ophthalmology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Patricia J McLaughlin
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA 17033, USA.
| |
Collapse
|
3
|
Husain S, Potter DE. The opioidergic system: potential roles and therapeutic indications in the eye. J Ocul Pharmacol Ther 2008; 24:117-40. [PMID: 18355128 DOI: 10.1089/jop.2007.0112] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Shahid Husain
- Department of Ophthalmology, Storm Eye Institute, Hewitt Laboratory of the Ola B Williams Glaucoma Center, Medical University of South Carolina, Charleston, SC 29425, USA.
| | | |
Collapse
|
4
|
Linden R, Martins RAP, Silveira MS. Control of programmed cell death by neurotransmitters and neuropeptides in the developing mammalian retina. Prog Retin Eye Res 2004; 24:457-91. [PMID: 15845345 DOI: 10.1016/j.preteyeres.2004.10.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
It has long been known that a barrage of signals from neighboring and connecting cells, as well as components of the extracellular matrix, control cell survival. Given the extensive repertoire of retinal neurotransmitters, neuromodulators and neurotrophic factors, and the exhuberant interconnectivity of retinal interneurons, it is likely that various classes of released neuroactive substances may be involved in the control of sensitivity to retinal cell death. The aim of this article is to review evidence that neurotransmitters and neuropeptides control the sensitivity to programmed cell death in the developing retina. Whereas the best understood mechanism of execution of cell death is that of caspase-mediated apoptosis, current evidence shows that not only there are many parallel pathways to apoptotic cell death, but non-apoptotic programs of execution of cell death are also available, and may be triggered either in isolation or combined with apoptosis. The experimental data show that many upstream signaling pathways can modulate cell death, including those dependent on the second messengers cAMP-PKA, calcium and nitric oxide. Evidence for anterograde neurotrophic control is provided by a variety of models of the central nervous system, and the data reviewed here indicate that an early function of certain neurotransmitters, such as glutamate and dopamine, as well as neuropeptides such as pituitary adenylyl cyclase-activating polypeptide and vasoactive intestinal peptide is the trophic support of cell populations in the developing retina. This may have implications both regarding the mechanisms of retinal organogenesis, as well as pathological conditions leading to retinal dystrophies and to dysfunctional cellular behavior.
Collapse
Affiliation(s)
- Rafael Linden
- Centro de Ciencias da Saude, Instituto de Biofísica da UFRJ, Cidade Universitária, bloco G, Rio de Janeiro 21949-900, Brazil.
| | | | | |
Collapse
|
5
|
Sassani JW, Zagon IS, McLaughlin PJ. Opioid growth factor modulation of corneal epithelium: uppers and downers. Curr Eye Res 2003; 26:249-62. [PMID: 12854052 DOI: 10.1076/ceyr.26.4.249.15427] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE This paper presents a concise review of the role of the intrinsic opioid growth regulation system (IOGRS) in homeostasis and wound repair of the corneal epithelium. METHODS The article is a summary of published research on the topic. RESULTS The native opioid peptide, [Met(5)]-enkephalin, also termed opioid growth factor (OGF), has been demonstrated to be present in a wide variety of classes of the phylum. Chordata, and acts as an autocrine/paracrine produced, tonically active, receptor specific, negative growth modulating factor in homeostatic (uninjured) corneal epithelium in humans and non-primates. Similarly, OGF acts to down-regulate epithelial cell division and migration of corneal epithelium in the closing of corneal epithelial abrasions. Such repair can be up-regulated (hastened) in non-diabetic animals by treatment with exogenous administration of the potent opioid antagonist, naltrexone (NTX). The system also is functional in diabetic animals and can be manipulated to restore epithelial wound healing rates to normal. CONCLUSIONS The IOGRS plays a vital role in supporting corneal epithelial homeostasis, and in modulating closure of epithelial wounds. The system should provide opportunities for novel therapies especially for corneal epithelial wound healing disorders.
Collapse
Affiliation(s)
- Joseph W Sassani
- Department of Ophthalmology, Penn State's Milton S. Hershey Medical Center, 500 University Drive, Hershey, PA 17033, USA.
| | | | | |
Collapse
|
6
|
Zagon IS, Wylie JD, Hurst WJ, McLaughlin PJ. Transplacental transfer of the opioid growth factor, [Met(5)]-enkephalin, in rats. Brain Res Bull 2001; 55:341-6. [PMID: 11489341 DOI: 10.1016/s0361-9230(01)00518-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Placental transfer of the pentapeptide [Met5]-enkephalin, known to function as a growth regulating factor and neuromodulatory agent, was studied in pregnant Sprague-Dawley rats. Using separation by reversed phase high-performance liquid chromatography, and analysis by derivative spectroscopy, [Met5]-enkephalin was detected in 20-day-old fetal tissue including brain, heart, lung, and kidney. Fetal tissues from pregnant rats given an injection of 40 mg/kg [Met5]-enkephalin on gestation day 20 had markedly elevated levels of peptide within 1 h, indicating the transplacental transfer of this opioid. [Met5]-enkephalin levels were increased from control samples at 1, 2, 4, and 14 h post-injection of peptide, but not at 24 h. Evaluation of breakdown products of [Met5]-enkephalin, along with the related peptide [Leu5]-enkephalin, revealed that elution times differed substantially from [Met5]-enkephalin. These data indicate that [Met5]-enkephalin is present in fetal organs, crosses the placenta, does not appear to be restrictive in organ specificity, and is sustained in fetal tissues at detectable levels for at least 14 h. Given that [Met5]-enkephalin tonically inhibits DNA synthesis in the fetus, these results raise the question of whether an elevated level of this peptide (either maternally or from the fetus) may be detrimental to cellular ontogeny in the fetus, and perhaps have long-term implications for postnatal development.
Collapse
Affiliation(s)
- I S Zagon
- Department of Neuroscience and Anatomy, The Milton S. Hershey Medical Center, The Pennsylvania State University, Hershey, PA 17033, USA.
| | | | | | | |
Collapse
|
7
|
Abstract
In addition to neurotransmission, the native opioid peptide, [Met5]enkephalin, is a tonically active inhibitory growth molecule that is termed opioid growth factor (OGF). OGF interacts with the zeta (zeta) opioid receptor to influence cell proliferation and tissue organization. We now identify OGF and the zeta receptor in embryonic derivatives including ectoderm, mesoderm, and endoderm of the rat on gestation day 20. Messenger RNA for preproenkephalin (PPE), the precursor of OGF, was detected in the developing cells, suggesting an autocrine production of this peptide. Acute exposure of the pregnant female to OGF resulted in a decrease in DNA synthesis in cells of organs representing all three germ layers, and did so in a receptor-mediated fashion. The influence of OGF was direct, as evidenced in organ culture studies. Blockade of endogenous opioid interaction using naltrexone (NTX) produced an increase in DNA synthesis, indicating the constitutive and functional nature of opioid activity on growth during prenatal life. Human fetal cells contained OGF and the zeta receptor. These data support the hypothesis that endogenous opioid modulation of organ development is a fundamental principle of mammalian embryogenesis, and that OGF has a profound influence on ontogeny. Irregularities in the role of opioids as growth regulators in relationship to the more than 500,000 newborns suffering from birth defects each year in the US needs to be examined.
Collapse
Affiliation(s)
- I S Zagon
- Department of Neuroscience and Anatomy, Milton S. Hershey Medical Center, Pennsylvania State University College of Medicine, Hershey 17033, USA.
| | | | | |
Collapse
|
8
|
Zagon IS, Hurst WJ, McLaughlin PJ. Naltrexone is not detected in preweaning rats following transplacental exposure: implications for growth modulation. Life Sci 1998; 62:221-8. [PMID: 9488100 DOI: 10.1016/s0024-3205(97)01090-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Extracts of brain and heart from rats at birth and postnatal days 2 and 10 were evaluated for naltrexone following maternal injection of 50 mg/kg opioid antagonist throughout gestation. Samples were prepared by ultrafiltration, lyophilized, reconstituted in mobile phase, and separated by reversed-phase high performance liquid chromatography with ultraviolet detection. Qualitative analysis revealed the presence of naltrexone in tissues from neonates, but not in rats of 2 and 10 days, that were transplacentally exposed to drug. These results confirm earlier reports showing that naltrexone, maternally administered, passes through the placenta and enters the fetus. Moreover, the data suggest that the somatic and neurobiological acceleration observed in offspring exposed to naltrexone during gestation is not due to opioid receptor blockade during the postnatal period.
Collapse
Affiliation(s)
- I S Zagon
- Department of Neuroscience and Anatomy, The Pennsylvania State University College of Medicine, Hershey 17033, USA
| | | | | |
Collapse
|
9
|
Abstract
Extracts of fetal (20 days gestation) brain, heart, and liver were evaluated for naltrexone in rats 1 hour following maternal injection of 50 mg/kg opioid antagonist; adult plasma from the pregnant rats was analyzed. Samples were prepared by ultrafiltration, lyophilized, reconstituted in mobile phase, and separated by reversed phase high-performance liquid chromatography with ultraviolet detection. This qualitative analysis revealed the presence of naltrexone in all fetal tissues, as well as in adult plasma. These results indicate naltrexone, maternally administered, passes through the placenta and enters the fetus. The data would suggest that reports concerning somatic and neurobiological acceleration in offspring exposed to naltrexone during gestation may be the result of a direct opioid antagonist action in the fetus.
Collapse
Affiliation(s)
- I S Zagon
- Department of Neuroscience and Anatomy, The Pennsylvania State University College of Medicine, Hershey 17033, USA
| | | | | |
Collapse
|
10
|
Zagon IS, Hurst WJ, McLaughlin PJ. Identification of [Met5]-enkephalin in developing, adult, and renewing tissues by reversed-phase high performance liquid chromatography and radioimmunoassay. Life Sci 1997; 61:363-70. [PMID: 9244362 DOI: 10.1016/s0024-3205(97)00393-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Extracts of adult corneal epithelium, and developing and adult cerebellum, aorta, and heart, from rats were evaluated for [Met5]-enkephalin. Samples were prepared by ultrafiltration and solid phase extraction with a C-18 Sep-pak, separated by reversed phase high-performance liquid chromatography, and analyzed by radioimmunoassay (RIA). This qualitative analysis revealed the presence of [Met5]-enkephalin in all tissues but the adult cerebellum. These results confirm and extend earlier reports that have used RIA or immunohistochemistry with regard to the presence of this opioid peptide in developing and renewing tissues, and indicate that [Met5]-enkephalin is indeed being recognized by immunological assays.
Collapse
Affiliation(s)
- I S Zagon
- Department of Neuroscience and Anatomy, The Pennsylvania State University College of Medicine, Hershey 17033, USA
| | | | | |
Collapse
|
11
|
Isayama T, McLaughlin PJ, Zagon IS. Ontogeny of preproenkephalin mRNA expression in the rat retina. Vis Neurosci 1996; 13:695-704. [PMID: 8870226 DOI: 10.1017/s0952523800008580] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Endogenous opioid systems (i.e. opioid peptides and opioid receptors) modulate developmental events in the neonatal mammalian retina. In the present study, the mRNA encoding preproenkephalin A (PPE), the prohormone for the opioid growth factor (OGF), [Met5]-enkephalin, was studied in the developing and the adult retinas of rats. Northern analysis indicated the presence of a 1.4-kb message in the developing and adult retinas corresponding to rat PPE mRNA. Quantitation showed that PPE message was present on postnatal day 1 at 5% of the adult level, and increased during development until the adult quantity was reached by postnatal day 27. In situ hybridization experiments first detected the presence of PPE mRNA in retinal tissues during late gestation. In late prenatal and neonatal retinas, PPE message was associated with areas of the developing retina containing proliferating neuroblasts and postmitotic cells. Later in development, message appeared to be located primarily within the inner retina, with abundant PPE mRNA associated with putative horizontal cells of the inner nuclear layer (INL). The adult retina showed a similar pattern of PPE gene expression in the cells of the INL. These findings document that the gene expression in the retina for PPE begins in the fetus, continues during retinal development, and coincides with the presence of a PPE mRNA derivative ([Met5]-enkephalin) that regulates DNA synthesis during retinal ontogeny. Our results are also the first to show the presence of PPE message in the adult mammalian retina, suggesting transcription of an opioid gene in the mature visual system.
Collapse
Affiliation(s)
- T Isayama
- Department of Neuroscience and Anatomy, Milton S. Hershey Medical Center, Pennsylvania State University, College of Medicine, Hershey 17033, USA
| | | | | |
Collapse
|
12
|
Abstract
This article is the eighteenth installment of our annual review of research concerning the opiate system. It includes articles published during 1995 reporting the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects. The specific topics covered this year include stress: tolerance and dependence; eating; drinking; gastrointestinal, renal, and hepatic function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunological responses; and other behaviors.
Collapse
Affiliation(s)
- G A Olson
- Department of Psychology, University of New Orleans, LA 70148, USA
| | | | | |
Collapse
|