Effects on synaptic transmission

We have already noted that potentized Agaricus muscarius influences catalepsy in mice. It is known that neurotransmitters such as dopamine and serotonin 

Agaricus 12 was administered orally on 6 mice at the rate of 3.1 ml/kg. The same amount of blank ethanol (90%) was administered on another group of 6 mice to serve as controls. All the mice (30 - 35 g) were sacrificed by decapitation 6 hr after the administration of the drug or the control. The brain was quickly removed, kept over ice and the hypothalamus scooped out by means of a sharp needle, placed in a microcentrifuge tube, weighed, and then frozen at -70°C. Hypothalamic mass ranged from 7 to 12 mg for the controls and 8.5 to 18 mg for the treated group. The levels of dopamine (DA), serotonin (5 - HT) and their metabolites 

Animal group Dopamine ng/gm DOPAC ng/gm 5-HT ng/gm 5HIAA ng/gm DOPAC/DA 5HIAA/HT 

---

Effects on synaptic transmission by inhibition of amine re-uptake and by receptor antagonism... 

Cooper, G.P., J.W. Suszkie, and R.S. Manalis. 1984. Heavy metals Effects on synaptic transmission. NeuroToxicol. 5 247-266. 

The main mechanism of action of caffeine is the antagonism of adenosine receptors 69-71). Adenosine decreases the firing rate of neurones and exerts an inhibitory effect on synaptic transmission and on the release of most... 

Ameri A. Effects of the Aconitum alkaloid songorine on synaptic transmission and paired-pulse facilitation of CA1 pyramidal cells in rat hippocampal slices. Br J Pharmacol 1998 125 461—468. 

Szerb, J. C. and Butterworth, R. F. Effect of ammonium ions on synaptic transmission in the mammalian central nervous system. Prog. Neurobiol. 39 135-153,1992. 

Figure 4. Effect of LSD-25 on synaptic transmission in the cerebral cortex of the cat. The response, recorded from the visual projection area, was produced by electrical shock to optic radiation. This response shows several typical deflections, the discussion of whose origin is beyond the scope of this paper. A control, B after injecting 1.5 mg of LSD-25 into the carotid artery. Note particularly the increase of late components after the drug (from Evarts et al., 1955).

Terbush DR, Holz RW (1990) Activation of protein kinase C is not required for exocytosis from bovine adrenal chromaffin cells. The effects of protein kinase C(19-31), Ca/CaM kinase 11(291— 317), and staurosporine. J Biol Chem 265 21179-84 Tesmer VM, Kawano T, Shankaranarayanan A et al (2005) Snapshot of activated G proteins at the membrane the Galphaq-GRK2-Gbetagamma complex. Science 310 1686-90 Thakur P, Stevens DR, Sheng ZH et al (2004) Effects of PKA-mediated phosphorylation of Snapin on synaptic transmission in cultured hippocampal neurons. J Neurosci 24 6476-81 Thompson SM, Capogna M, Scanziani M (1993) Presynaptic inhibition in the hippocampus. Trends Neurosci 16 222-7... 

Thakur P, Stevens DR, Sheng Z-H, Rettig J. 2004. Effects of PKA-mediated phosphorylation of snapin on synaptic transmission in cultured hippocampal neurons. J Neurosci... 

In contrast to the potentiating effects of dopamine D1 receptor stimulation, D2 receptor activation attenuates responses evoked by both NMDA and nonNMDA receptor agonists (Cepeda et al., 1992, 1993). Conversely, glutamatergic transmission is increased in D2 and D4 receptor knockout mice, compared to the wild-type mice, consistent with an inhibitory effect of D2 like receptors on synaptic transmission (Cepeda et al., 2001). 

Schlichter R, Keller AF, De Roo M, Breton LD, Inquimbert P, Poisbeau P (2006) Fast nongenomic effects of steroids on synaptic transmission and role of endogenous neurosteroids in spinal pain pathways. J Mol Neurosci 28 33-51... 

The only published study on presynaptlc effects of the more potent ChE inhibitors is that of Abraham and Edery (49), who examined the effect of soman on synaptic transmission in rat diaphragm. In vitro, soman increased the frequency of MEPPs (an effect blocked by Mg ), caused muscle depolarization that reversed spontaneously, and Increased quantal content. It was suggested that the observed changes in transmitter release resulted from an effect on the action potential invading the nerve terminal, although no direct evidence was offered. 

Collins GG. 1982. Some effects of excitatory amino acid receptor antagonists on synaptic transmission in the rat olfactory cortex slice. Brain Res 244 311-318. 

Fig. 6. Effects of cannabinoids on synaptic transmission in nuclei belonging to the extrapyramidal motor control system. DA, dopamine FSN, fast spiking neuron MSN, medium spiny neuron SNC, substantia nigra pars compacta SNR, substantia nigra pars reticulata. CBi receptor-mediated inhibition of neurotransmission was demonstrated at many synapses of this motor control system. In addition to the proved sites of inhibition, inhibition is very probable at additional sites (based on the localisation of the CBi receptor). For the sake of simplicity, the pathway including the entopeduncular nucleus (globus pallidus medialis/internus) is not shown...

Fig. 8. Effects of cannabinoids on synaptic transmission. Activation ofthe CBq receptor at the presynaptic axon terminal inhibits transmitter release from the synaptic vesicle. Three mechanisms can be involved in presynaptic inhibition X refers to unknown second messengers) inhibition of voltage-dependent calcium channels, activation of potassium channels and direct interference with the vesicle release machinery.TheCBi receptor can be activated by exogenous agonists, but also by the endocannahinoids anandamide (A 4) and 2-arachidonoylglycerol (2-AG i, which are released from the postsynaptic neuron by passive and/or facilitated diffusion. The synthesis of endocannahinoids is triggered by a depolarisation-induced ( / , membrane potential) calcium influx or by activation ofGq/n protein-coupled receptors...

Engler B, Szabo B (2004) Characterization of the effects of cannabinoids on synaptic transmission between caudate-putamen and globus pallidus. Naunyn-Schmiedeberg s Arch Pharmacol 369 R80... 

Szabo B, Than M, Wallmichrath I, Thorn D (2004) Analysis of the effects of cannabinoids on synaptic transmission between basket and Purkinje cells in the cerebellar cortex of the rat. J Pharmacol Exp Ther 310 915-925... 

---