The induction of LTD in the IC required activation of the N-methyl-d-aspartate (NMDA) receptor, metabotropic glutamate receptor (mGluR)5, and L-type voltage-gated calcium channel. Protein phosphatase 1/2A and endocannabinoid signaling are also critical for the induction of LTD. In contrast, inhibiting protein kinase C, protein kinase A, protein kinase Mζ or calcium/calmodulin-dependent protein kinase II did not affect LFS-evoked LTD in

the IC. Bath application of the group I mGluR agonist (RS)-3,5-dihydroxyphenylglycine produced another form of LTD in the IC, which was NMDA receptor-independent and could not be occluded by LFS-induced LTD. Our studies have characterised the basic mechanisms of LTD in the IC at the network level, and suggest that two different forms of LTD may co-exist in the same population PLX4032 nmr of IC synapses. “
“The

prototypical effects of the cannabis extract delta9-tetrahydrocannabinol (THC) are characterized by a tetrad of actions, consisting of analgesia, catalepsy, sedation, and hypothermia, all of which are mediated by activation of CB1 receptors. Initial studies of the cellular distribution of CB1 receptors have indicated that they are located primarily on axon terminals of GABAergic interneurons, and their most obvious cellular action is a reduction in transmitter release at these inhibitory synapses. However, the behavioral effects of THC are attenuated by removing CB1 receptors from cortical Palbociclib mouse and striatal projection neurons

(Monory et al., 2007). Collectively, these findings indicate that complex physiological mechanisms mediate the effects of cannabinoids and CB1 receptor stimulation. This complexity is also apparent in the spinal dorsal horn, a CNS area critically involved in the processing Farnesyltransferase of pain signals, as highlighted in the study by Zhang et al. (2010) published in this issue of EJN. Part of the analgesic action of cannabinoids is believed to originate from blockade of excitatory neurotransmission between C-fiber nociceptors and central neurons located in the spinal dorsal horn and trigeminal sensory nucleus (Morisset & Urban, 2001; Liang et al., 2004). Yet, when studied at a cellular level, the most prominent action of CB1 receptor activation again is a reduction in GABAergic and glycinergic inhibition mediated by dorsal horn interneurons (Jennings et al., 2001; Pernia-Andrade et al., 2009). In this issue of EJN, Zhang et al. (2010) used a new approach to quantify the effect of CB1 receptor activation on nociceptive transmission. In slices of rat spinal cord with incoming sensory nerve fibers attached, they electrically stimulated incoming C-fiber nociceptors to evoke neurotransmitter release from these axons.