Expression of TrkB subtypes in the adult monkey cerebellar cortex
Introduction
BDNF and its specific receptor, TrkB, are highly expressed in the mammalian central nervous system (CNS) (Masana et al., 1993, Nawa et al., 1995, Yan et al., 1997a, Yan et al., 1997b, Ohira et al., 1999). The TrkB locus encodes at least three different subtypes: full-length TrkB (TK+) and two truncated TrkB (TK−; T1 and T2) (Klein et al., 1990a, Klein et al., 1990b). TK+ has been shown to be involved in signal transduction, and while T1 and T2 lack the tyrosine kinase domain, they exhibit various physiological functions (Beck et al., 1993, Allendoerfer et al., 1994, Biffo et al., 1995, Eide et al., 1996, Baxter et al., 1997, Fryer et al., 1997, Haapasalo et al., 1999). Both BDNF and TrkB have been shown to participate in processes of neuronal plasticity in the CNS (Bibel and Barde, 2000, Thoenen, 1995). BDNF is localized to the pre- and postsynaptic terminals (Fawsett et al., 1997, Lin et al., 1998, Aloyz et al., 1999), secreted in an activity-dependent fashion (Haubensak et al., 1998), and induces the autophosphorylation of TrkB (Aloyz et al., 1999). This BDNF-induced activation of TrkB is essential to the neuronal plasticity (Figurov et al., 1996, Akaneya et al., 1997, Kang et al., 1997, Korte et al., 1998).
Expression levels of BDNF and TrkB isoforms have been shown to be high in the cerebellum (Yan et al., 1997a, Yan et al., 1997b, Ohira et al., 1999). In the developing cerebellum, BDNF promotes survival and neurite extension of internal granule cell layers in rats (Segal et al., 1992, Gao et al., 1995). Further, BDNF knockout mice exhibit abnormal cerebellar development (Schwartz et al., 1997). Although Purkinje cells lack TrkB during embryonic development (Lindholm et al., 1997), TK+ is expressed in more mature Purkinje cells (Yan et al., 1997a, Ohira and Hayashi, 1999). In addition, BDNF mRNA levels have been reported to increase with the development of Purkinje cells (Neveu and Arenas, 1996). These results suggest that both BDNF and TrkB are of importance in the survival and maintenance of neurons in the mature cerebellum.
The cerebellum has been thought to contribute to motor skills, but recent data have led to a revision of this hypothesis regarding non-motor functions of the cerebellum (Leiner et al., 1993). Anatomically, the cerebellar efferent fibers project to thalamic neurons that innervate the dorsolateral prefrontal cortex (Middleton and Strick, 1994), which is involved in ‘spatial working memory’. Moreover, physiological and functional neuroimaging studies suggest that the cerebellum participates in the organization of higher-order functions such as concept formation and learning of paired-associates (Kim et al., 1994, Gao et al., 1996, Schmahmann and Sherman, 1998).
Taking the above into account, we consider it important to investigate the distribution of BDNF and TrkB subtypes in the non-human primate cerebellum. In this study, we immunohistochemically investigated the distribution of BDNF, TK+, and T1, and examined the interaction between TrkB subtypes in the adult monkey cerebellum by means of covalent cross-linking.
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Experimental animals and tissue preparation
Two adult rhesus monkeys (8 and 9-years-old, Macaca mulatto) were the subjects for the cross-linking and Western blot analysis. For the immunohistochemical analysis, two adult rhesus monkeys (7 and 8-years-old) were used. All animals were pretreated with ketamine hydrochloride (10 mg/kg, intramuscularly) and deeply anesthetized with pentobarbital sodium (25 mg/kg, intraperitoneally).
For the immunohistochemical study, heparin sodium (2 ml, 1000 U/ml) was injected directly into the left
Immunoreactivity in single-stained sections
To detect and localize BDNF, TK+, and T1 proteins in the adult monkey cerebellum, we carried out single-staining immunohistochemical studies (Fig. 1). BDNF-immunoreactivity (IR) was strongly detected in cell bodies and dendrites of almost all Purkinje cells (Fig. 1D–F). Granule cells were immunoreactive. There were also abundant BDNF immunoreactive cells in the molecular layer. In addition, the entire molecular layer was weakly stained.
TK+-IR was observed in almost all Purkinje cells (Fig. 1
Distribution of BDNF in the primate cerebellum
In this study, we detected BDNF-IR in granule and Purkinje cells, whose dendrites were also immunopositive (Fig. 1). In rodent, BDNF mRNA is expressed in granule and Purkinje cells (Neveu and Arenas, 1996). In addition, the presence of BDNF protein in dendrites and cell bodies of Purkinje cells has been reported in rodents (Dugich et al., 1995). In cell-culture experiment, granule cells have been shown to synthesize BDNF protein as measured by a sensitive enzyme immunoassay (Lindholm et al.,
Acknowledgements
This work was supported partly by Grants (no. 12680772, no. 12210080) and a Grant-in-Aid for COE Research (10CE2005) from the Ministry of Education, Culture, Sports, Sciences and Technology of Japan.
References (46)
- et al.
Truncated trkB receptors on nonneuronal cells inhibit BDNF-induced neurite outgrowth in vitro
Exp. Neurol.
(1997) - et al.
Changes in BDNF-immunoreactive structures in the hippocampal formation of the aged macaque monkey
Brain Res.
(2001) - et al.
Neurotrophins and time: different roles for TrkB signaling in hippocampal long-term potentiation
Neuron
(1997) - et al.
The trkB tyrosine kinase gene codes for a second neurogenic receptor that lacks the catalytic kinase domain
Cell
(1990) - et al.
A role for BDNF in the late-phase of hippocampal long-term potentiation
Neuropharmacology
(1998) - et al.
Cognitive and language functions of the human cerebellum
Trends Neurosci.
(1993) - et al.
BDNF acutely increases tyrosine kinase phosphorylation of the NMDA receptor subunit 2B in cortical and hippocampal postsynaptic densities
Mol. Brain Res.
(1998) - et al.
Protein measurement with the Folin phenol reagent
J. Biol. Chem.
(1951) - et al.
Change of expression of full-length and truncated TrkBs in the developing monkey central nervous system
Dev. Brain Res.
(1999) - et al.
Abnormal cerebellar development and foliation in BDNF−/− mice reveals a role for neurotrophins in CNS patterning
Neuron
(1997)
Changes in neurotrophin responsiveness during the development of cerebellar granule neurons
Neuron
Functional trkB neurotrophin receptors are intrinsic components of the adult brain postsynaptic density
Mol. Brain Res.
Expression of brain-derived neurotrophic factor protein in the adult rat central nervous system
Neuroscience
Brain-derived neurotrophic factor enhances long-term potentiation in rat visual cortex
J. Neurosci.
Regulation of neurotrophin receptors during the maturation of the mammalian visual system
J. Neurosci.
Activity-dependent activation of TrkB neurotrophin receptors in the adult CNS
Learning Memory
Truncated and catalytic isoforms of trkB are co-expressed in neurons of rat and mouse CNS
Eur. J. Neurosci.
Signal transduction mediated by the truncated trkB receptor isoforms, trkB·T1 and trkB·T2
J. Neurosci.
Induction of noncatalytic TrkB neurotrophin receptors during axonal sprouting in the adult hippocampus
J. Neurosci.
Neurotrophins: key regulators of cell fate and cell shape in the vertebrate nervous system
Genes Dev.
Selective binding and internalisation by truncated receptors restrict the availability of BDNF during development
Development
Immunohistochemical visualization of brain-derived neurotrophic factor in the rat brain
Eur. J. Neurosci.
Naturally occurring truncated trkB receptors have dominant inhibitory effects on brain-derived neurotrophic factor signaling
J. Neurosci.
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