Changes in brain‐derived neurotrophic factor and trkB receptor in the adult Rana pipiens retina and optic tectum after optic nerve injury

Abstract

In this study we used immunocytochemistry to investigate the distribution of brain-derived neurotrophic factor (BDNF) and its receptor tyrosine kinase (trkB) in retina and optic tectum of the frog Rana pipiens during regeneration after axotomy. We also measured changes in BDNF mRNA in retina and tectum. Retrograde labeling was used to identify retinal ganglion cells (RGCs) prior to quantification of the BDNF immunoreactivity. In control animals, BDNF was found in the majority of RGCs and displaced amacrine cells and in some cells in the inner nuclear layer (INL). After axotomy, BDNF immunoreactivity was reduced in RGCs but increased in the INL. BDNF mRNA levels in the retina remained high before and after axotomy. Three months after axotomy, after reconnection to the target, the staining intensity of many of the surviving RGCs had partially recovered. In the control tectum, BDNF staining was present in ependymoglial cells and in neurons throughout layers 4, 6, 8, and 9. After axotomy, BDNF staining in tectal neurons became more intense, even though mRNA synthesis was transiently down-regulated. In control retinas, trkB receptor immunostaining was present in most RGCs; no significant changes were observed after axotomy. In control tectum, trkB was detected only in ependymoglial cells. After axotomy, many neuronal cell bodies were transiently labeled. Our data are consistent with the hypothesis that a considerable fraction of the BDNF normally present in RGCs is acquired from their targets in the tectum. However, there are also intraretinal sources of BDNF that could contribute to the survival of RGCs.

Brain-Derived Neurotrophic Factor mRNA Expression in the Brain of the Teleost Fish, <i>Anguilla anguilla,</i> the European Eel

“…Our survey of BDNF mRNA expression in the eel reveals a pattern similar to that reported for the mammalian [Wetmore et al, 1990;Conner et al, 1997], avian [Herzog and von Bartheld, 1998] and amphibian brain [Duprey-Díaz et al, 2002;Wang et al, 2005]. As in these species, eel expression was seen in portions of all brain regions.…”

“…It is important dur- [Theiss and Güntürkün, 2001] and frog [Duprey-Díaz et al, 2002] tectum and in the hypothalamo-hypophyseal system of Xenopus [Wang et al, 2005]. With regard to teleost fish, BDNF expression has been confirmed in the brain of the southern platyfish [Götz et al, 1992], in the developing zebrafish brain and retina [Hashimoto and Heinrich, 1997;Lum et al, 2001], and in the tench retina [Caminos et al, 1999].…”

Expression of BDNF and NT‐3 during the ontogeny and regeneration of the lacertidian (Gallotia galloti) visual system

“…Specifically, BDNF has been described as the major neurotrophin participating in visual system development (Cellerino and Maffei, 1996;Furukawa et al, 1998). Its distribution in the optic pathway has been partially investigated during the ontogeny of mammalian (Vecino et al, 1998;Bennett et al, 1999;Lein et al, 2000;Garcia et al, 2003), avian (Das et al, 1997;von Bartheld and Butowt, 2000;Theiss and Güntürkün, 2001), amphibian (Duprey-Diaz et al, 2002) and fish species (Caminos et al, 1999), but not yet in reptiles. In all of these species, BDNF has consistently been localized to neurons of the inner nuclear layer and ganglion cell layer and fibers of the nerve fiber layer, as well as in the tectum (OT) during ontogeny and persisting into adulthood.…”

Differential regulation of the expression of neurotrophin receptors in rat extraocular motoneurons after lesion

“…Indeed, both the neurotrophin requirement and the expression of different neurotrophin receptors are usually modified in lesioned neurons (Koliatsos et al, 1991;Connor et al, 1996;Canals et al, 1999;Duprey-Díaz et al, 2002). Motoneurons represent one of the most widely used models for the study of trophic dependence.…”