Miniature excitatory postsynaptic currents

In the hippocampus, presynaptic P2X2 receptors mediated increases in the frequencies of miniature excitatory postsynaptic currents in stratum radiatum intemeu-rons, but not in pyramidal neurons (Khakh et al. 2003). Glutamate release from hippocampal mossy fibers, in contrast, was found to be inhibited by P2X7 receptor activation (Armstrong et al. 2002). 

Knock-down of kalirin-7 levels reduces basal spine density and the frequency of miniature excitatory postsynaptic currents (mEPSCs) (Xie et al., 2007). Also, kalirin has been linked to the EphB receptor. Activation of the EphB receptor by ephrin-B has been shown to translocate kalirin-7 to synapses where it locally... 

Y receptors in the rat spinal cord a direct effect on the vesicle release machinery (step 4 in Figure 3) can be assumed, since agonists inhibited the frequency of the miniature inhibitory or excitatory postsynaptic currents (Moran et al. 2004 italics in Table 3). 

Since the orexin receptors are Gq protein-coupled (Alexander et al. 2006), one may assume that this also holds true for the presynaptic orexin receptor(s), but so far no data are available. Nonetheless, the six studies carried out in central nervous preparations permit some conclusions on the post-G protein mechanisms. In all instances, the orexins increased the frequency of spontaneous inhibitory or excitatory postsynaptic potentials or currents. The results differed, however, with respect to the influence of tetrodotoxin. In the medial and lateral hypothalamus (van den Pol et al. 1998 Li et al. 2002), dorsal vagal complex (Davis et al. 2003), and caudal nucleus tractus solitarii (Smith et al. 2002), orexins increased the frequency of the miniature potentials or currents also in the presence of tetrodotoxin, suggesting that they directly influenced the vesicle release machinery (references in italics in Table 5). On the other hand, in the prefrontal cortex (Lambe and Aghajanian 2003) and lat-erodorsal tegmentum (Burlet et al. 2002), the orexins did not retain their facilitatory effect in the presence of tetrodotoxin, suggesting an effect further upstream e.g., on Ca2+ and/or K+ channels. 

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