Ontogeny of the opioid growth factor, [Met<sup>5</sup>]-enkephalin, and its binding activity in the rat retina

Isayama, Tomoki; Wj, Hurst; Pj, McLaughlin; Zagon, IS

doi:10.1017/s0952523800009494

Cited by 14 publications

(4 citation statements)

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“…Retinal neuroblasts which are migrating, synthesizing DNA, and dividing within the confines of the NB appear to produce OGF, since radiolabel corresponding to PPE mRNA in the present study, as well as OGF immunoreactivity was found throughout the NB during early postnatal life (Isayama et al, 1995). Therefore, the presence of PPE mRNA in the NB, composed of both dividing and differentiating cells, suggests that neuroblast cells produce OGF in an autocrine manner.…”

Section: Discussionsupporting

confidence: 55%

“…Previous immunocytochemistry, HPLC, and functional experiments have established that the endogenous opioid peptide, [Met 5 ]-enkephalin, is an OGF related to the regulation of DNA synthesis in the developing mammalian retina (Isayama et al, , 1995. In addition, binding activity for the OGF has also been detected in the developing rat retina using in vitro receptor autoradiography with radiolabeled [Met 5 ]-enkephalin (Isayama et al, , 1995. Thus, the presence of gene expression for the OGF precursor during late prenatal and early postnatal life coincides with the time period when OGF is known to function during retinal development, and when the presence of OGF and its binding activity are present.…”

Section: Discussionmentioning

confidence: 99%

“…Recent studies by Molnar et al (1995) showed the presence of PPE mRNA in the embryonic chicken retina, suggesting that opioid gene expression may play a role in the regulation of avian retinal development as well. These large cells appear to be the first to express the OGF and PPE mRNA in the retina (Isayama et al, , 1995, suggesting that macroneurons may need OGF for differentiation and maturation, as well as for contributing to the proliferation and differentiation of other neural cell types. Therefore, the postmitotic neurons in the NB and ganglion cells in the GCL could serve as paracrine sources of OGF for neuroblasts in the neonatal retina of mammals.…”

Section: Discussionmentioning

confidence: 99%

“…Although opioid receptors have been reported in the adult rat retina (Howells et al, 1980;Wamsley et al, 1981), neither [Met 5 ]-nor [Leu 5 ]-enkephalin-like peptides have been detected in the retina of the mature rat (Howells et al, 1980;Altschuler et al, 1982;Hoffman, 1983;Isayama et al, , 1995. Although opioid receptors have been reported in the adult rat retina (Howells et al, 1980;Wamsley et al, 1981), neither [Met 5 ]-nor [Leu 5 ]-enkephalin-like peptides have been detected in the retina of the mature rat (Howells et al, 1980;Altschuler et al, 1982;Hoffman, 1983;Isayama et al, , 1995.…”

Section: Discussionmentioning

confidence: 99%

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Ontogeny of preproenkephalin mRNA expression in the rat retina

1996

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A b s t r a c t 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), [Met 5 ]-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 ([Met 5 ]-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. K e y w o r d s : Preproenkephalin A, Retina, Ontogeny, Northern analysis, In situ hybridization, Rat I n t r o d u c t i o n The development of the vertebrate retina has been well docu mented (Braekevelt & Hollenberg, 1970; Griin, 1982; Prada et al., 1991). The various neurons and glia comprising the ret ina arise from a homogeneous matrix of replicating neuroblasts (Sidman, 1961; Meller, 1984). Termination of the proliferation of precursor cells and the initiation of differentiation into adult phenotypes is carefully orchestrated during development, with each cell type leaving the cell cycle in a specific temporal se quence (Sidman, 1961;Meller, 1984; Polleyetal., 1989; Spence & Robson, 1989). The various steps associated with retinal devel opment, such as cell replication, migration, differentiation, are governed by specific growth factors (for review, see Tripathi et al., 1991). Although growth factors associated with the visual system have been studied extensively (Bugra et al., 1993; de la Rosa et al., 1994; Koide et al., 1995; Rickman & Brecha, 1995), the precise identities of the substances which influence retinal development, and the exact phases which they regulate, remain undetermined.

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Section: Discussionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 99%