Glutamate climbing fibers

The climbing fibers are now believed to use glutamate as transmitter, like the major proportion of mossy fibers. They are strongly enriched in glutamate (Ottersen et al., 1992) and their terminals are apposed to Purkinje cell thorns that exhibit a high density of AMPA receptors (Landsend et al., 1997). 

Landsend AS, Amiry-Moghaddam M, Matsubara A, Bergersen L, Usami S, Wentbold RJ, Ottersen OP (1997) Differential localization of glutamate receptors in the rat cerebellum coexpression with AMPA receptors in parallel fiber-spine synapses and absence from climbing fiber-spine synapses. J Neurosci /7 834 842. 

Vollenweider FX, Cuenod M, Do KQ (1990) Effect of climbing fiber deprivation on release of endogenous aspartate, glutamate, and homocysteate in slices of rat cerebellar hemispheres and vermis. J Neurochem 54 1533-1540. 

Zhao HM, Wenthold RJ, Wang YX, Petralia RS (1997) 8-Glutamate receptors are differentially distributed at parallel and climbing fiber synapses on Purkinje cells. J Neurochem 68 1041-1052. 

Fig. 6. Summary histogram of development of glutamate receptors at parallel [postnatal day 10 (PI0) to adult] and climbing (P2 to adult) fiber synapses on Purkinje cells of the cerebellum. Note especially the peak in immunogold labeling of the delta receptors at PI0-PI4 in climbing fiber synapses (cO, the peaks of the AMPA receptors (GluR2, GluR2/3 antibodies) at P2-P5, and the inverse patterns of peaks for parallel fiber synapses (pf) and climbing fiber synapses in adults for AMPA versus delta receptors. Modified from Zhao et al. (1998).

Petralia RS, Zhao H-M, Wang Y-X, Wenthold RJ (1998) Variations in the tangential distribution of postsynaptic glutamate receptors in Purkinje cell parallel and climbing fiber synapses during development. Neuropharmacology 37 32l- 3M. 

Otis TS, Kavanaugh MP, Jahr CE (1997) Postsynaptic glutamate transport at the climbing fiber Purkinje cell synapse. Science 277 1515-1518. 

Aspartate is closely related metabolically and chemically to glutamate. In many respects it is difficult to differentiate between aspartate and glutamate as neurotransmitter candidates (Fonnum, 1984). There are, however, some fibers and terminals in which aspartate is regarded as a stronger transmitter candidate than glutamate. These include the cerebellar climbing fibers (Wiklund et al., 1982), hippocampal commissural fibers (Nadler et al., 1978), olfactory tract (Collins and Probett, 1981), cochlear nucleus afferents (Wenthold, 1979), and spinal cord intemeurons (Davidoff et al., 1967)... 

Ichikawa R, Miyazaki T, Kano M et al (2002) Distal extension of climbing fiber territory and multiple innervation caused by aberrant wiring to adjacent spiny branchlets in cerebellar Purkinje cells lacking glutamate receptor delta 2. J Neurosci 22 8487-8503... 

Ablation of glutamate receptor GluRd2 in adult Purkinje cells causes multiple innervation of climbing fibers by inducing aberrant invasion to parallel fiber innervation territory. J Neurosci 30 15196-15209... 

---