Granule cells receptor

Bachis A, Mocchetti I (2004) The chemokine receptor CXCR4 and not the N-methyl-D-aspartate receptor mediates gpl20 neurotoxicity in cerebellar granule cells. J Neurosci Res 75(1) 75-82... 

There have been a number of observations which show increased excitation and/or reduced inhibition in slices prepared from human epileptic brain tissue. Thus burst discharges can be evoked with stimuli that would not do so in normal animal tissue and these can be blocked by NMD A receptor antagonists. The inhibitory postsynaptic currents (IPSCs) in hippocampal dentate granule cells in slices prepared from temporal lobe epileptic tissue are in fact reduced by stimulation that activates NMDA currents (Isokawa 1996), which are more prolonged than usual and show changes in slope conductance. 

Isokawa, M (1996) Decrement of GABAa receptor mediated inhibitory postysynaptic currents in dentate granule cells in epileptic hippocampus. J. Neurophysiol. 75 1901-1908. 

Fig. 5.12 (a) Synaptic types along dendritic spines of M/T and GC units uni-, and bi-directional junctions, (b) Transmitter systems at a reciprocal synapse, Mitral-Granule cell junction. [Glu, glutamate (R, receptor) GABA, y-aminobutyric acid (R, receptor) E, intracellular effector and aAR, alpha-adrenergic receptor.]. (From Hayashi et al., 1993.)... 

A second type of NMDA-receptor-independent LTP exists in the mossy-fiber pathway at the dentate granule cell-to-CA3 pyramidal cell synapse [19]. This form of LTP, termed mossy fiber-CA3 LTP, is believed to involve PKA activation in the presynaptic cell which leads to increased neurotransmitter release. However, the exact induction mechanism is not yet clear. 

Brickley, S. G., Cull-Candy, S. G., and Farrant, M. (1996) Development of a tonic form of synaptic inhibition in rat cerebellar granule cells resulting from persistent activation of GABAA receptors. J. Physiol. 497(Pt 3), 753-759. 

Nusser, Z., Sieghart, W., and Somogyi, R (1998) Segregation of different GABAA receptors to synaptic and extrasynaptic membranes of cerebellar granule cells. J. Neurosci. 18, 1693-1703. 

Knockout mice have also revealed further subunit requirements for the assembly of particular GABAa receptor subtypes. Thus, the absence of the a6 subunit in cerebellar granule cells results in a complete loss of 5 subunit protein, although mRNA expression levels were unaffected (59,62). These results indicate that the 8 subunit cannot be incorporated in a receptor lacking a() in cerebellar granule cells. Likewise, in 50/0 mice, the levels of a4 subunit protein are reduced in all forebrain regions in which the 8 subunit is normally abundant, pointing to a preferential co-assembly of these subunits in several neuronal populations (63). 

Tretter, V., Hauer, B., Nusser, Z et al. (2001) Targeted disruption of the GABAa receptor 8 subunit gene leads to an up-regulation of y2 subunit-containing receptors in cerebellar granule cells. J. Biol. Chem. 276, 10532-10538. 

Wojcik, W. J. and Neff, N. H. (1984) Gamma-aminobutyric acid B receptors are negatively coupled to adenylate cyclase in brain and in the cerebellum these receptors may be associated with granule cells. Mol. Pharmacol. 25, 24-28. 

Both anandamide and 2-AG are inactivated by enzymatic hydrolysis (Goparaju et al. 1998). Fatty acid amide hydrolase (FAAH) is an enzyme that catalyses their hydrolysis. High concentrations of FAAH were found in the cerebellum, hippocampus and neocortex of rat brain, which are also rich in cannabinoid receptors. Further, there is a complementary pattern of distribution of FAAH and the CBl receptor. For example, in the cerebellum, FAAH is found in the cell bodies of Purkinje cells and the CBl receptor is found in the axons of granule cells and basket cells, which are presynaptic to Purkinje cells. 2-AG may also be inactivated by direct esterification into membrane phospholipids. Cannabinoid Receptors... 

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