Paired-pulse depression

Jiittner R, Meier J, Grantyn R (2001) Slow IPSC kinetics, low levels of al subunit expression and paired-pulse depression are distinct properties of neonatal inhibitory GABAergic synaptic connections in the mouse superior colliculus. Eur J Neurosci 13 2088-2098... 

Daniel H, Rancillac A, Crepel F (2004) Mechanisms underlying cannabinoid inhibition of presynaptic Ca2+ influx at parallel fibre synapses of the rat cerebellum. J Physiol 557 159-74 Davies CH, Davies SN, Coflingridge GL (1990) Paired-pulse depression of monosynaptic GABA-mediated inhibitory postsynaptic responses in rat hippocampus. J Physiol 424 513-31 De Camilli P, Greengard P (1986a) Synapsin I a synaptic vesicle-associated neuronal phospho-protein. Biochem Pharmacol 35 4349-57... 

Cholinergic Actions in MOB Only limited information is available about cholinergic actions in MOB. Electrical activation of NDB has been reported to depress (Nickell and Shipley, 1988a) or increase (Kunze et al., 1991, 1992) mitral cell activity indirectly via primary effects on GABAergic GCs. NDB stimulation also reduced the field potential in the MOB caused by stimulation of the anterior commissure (Nickell and Shipley, 1993), an effect mediated by presynaptic inhibition of anterior commissure terminals via muscarinic receptors. One interpretation of these results is that cholinergic input to MOB may function to modulate interhemispheric transmission of olfactory information. In this regard, it is noteworthy that anterior commissural fibers are required for access and recall of olfactory memories between the two hemispheres. Infusion of ACh into MOB was reported to reduce paired-pulse depression of lateral olfactory tract (LOT)-evoked field potentials recorded in the GCL. This effect was attributed to... 

Physiological Actions of NE Although, NE clearly plays significant roles in olfactory function, the effects of NE at the cellular and network levels are somewhat discrepant. For example, LC stimulation was reported to have no effect on LOT-evoked field-potentials recorded in the GCL (Perez et al., 1987). A subsequent study reported that LC stimulation initially decreased and then subsequently increased paired-pulse depression of GC field-potential responses to LOT stimulation (Okutani et al., 1998). These effects were attributed to activation of fi receptors. Another field-potential study reported that NE infusion into MOB, acting at al receptors, increased the depolarization of GC dendrites elicited by LOT stimulation. Mitral cell responses to antidromic shocks were not affected, suggesting that NE excites GC (Mouly et al.,... 

The most pronounced effect of paired-pulse depression occurs at an interstimulus interval of 200 ms [64]. The impact of paired-pulse depression is significantly larger for the GABAb receptor mediated inhibitory postsynaptic currents. The IPSCb evoked by the second stimulus was depressed by 62 8%, whereas the IPSCa evoked by the second stimulus was depressed by 37 4% as shown in Fig. 10 [64]. 

Figure 10. Time course of paired-pulse depression of the amplitudes of both inhibitory postsynaptic currents IPSCa and IPSCb- (Reproduced with permission of principal investigator and editor of [64]).

Paton GS, Pertwee RG, Davies SN (1998) Correlation between cannabinoid mediated effects on paired pulse depression and induction of long term potentiation in the rat hippocampal slice. Neuropharmacology 37 1123-1130... 

Al-Hayani, A., Di Marzo, V., and Davies S. (2003) Homo-N-arachidonoyl-dopamine mimics vanilloid receptor agonists in enhancing paired pulse depression of hippocampal population spikes, Int. Cannabinoid Res. Soc. Symposium, p. 83. 

Tuff, LP, Racine, RJ, Adamec, R (1983) The effects of kindling on GABA-mediated inhibition in the dentate gyrus of the rat. 1. Paired-pulse depression. Brain Res, 277 79-90. 

Kainate receptors mediate a depression of evoked excitatory synaptic transmission in areas CA1 (40,88-90) and CA3 (35,37,91,92) of the hippocampus. There is strong evidence that in area CA1 the locus of this effect is presynaptic. Thus, activation of kainate receptors depresses release of L-glutamate from synaptosomes (88) and depresses both NMDA and AMPA receptor-mediated components of the evoked EPSC in parallel (88,90). Furthermore, the effects of kainate receptor activation on excitatory synaptic transmission in CA1 are associated with changes in presynaptic Ca2+ (89), an increase in paired-pulse facilitation (35,88,89), and a reduction in quantal content, as assessed using 1/CV2, but no change in mEPSC amplitude (90). 

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