Központi idegrendszeri kannabinoid receptorok farmakológiai és funkcionális feltérképezése = Pharmacological and functional mapping central nervous system cannabinoid receptors

Kimutattuk, hogy bár a kannabinoidok GABA felszabadulásra gyakorolt hatását a hippokampuszban a CB1 receptorok közvetítik, ezek a hatások részben fennmaradnak a CB1 receptor genetikai törlése esetén is, valószínűleg egy "tartalék" kannabinoid receptor feldúsulása révén. Elsőként írtuk le és jellemeztük a kannabinoidok gátló hatását a szerotonin felszabadulásra a hippokampuszban. A kannabinoidok hatását a CB1-receptorok közvetítik, és az a szerotonerg terminálisoknak elsősorban egy szubpopulációjára terjed ki. Kimutattuk, hogy az endokannabinoidok a hippokampuszban a bazális IL-1beta produkció szabályozásában is szerepet játszanak, mégpedig stimuláló jelleggel és a P2X7 receptorok közvetítésével. Eredményeink elsőként igazolják, hogy a nucleus accumbens drog addikcióban kiemelten fontos szerepet játszó dopaminerg végződéseiből a kannabinoidok nemcsak a dopaminerg neuronok ventralis tegmentum-ban elhelyezkedő sejttestjeinek stimulálásával, hanem a nucleus accumbensen belüli hatással, dizinhibíciós mechanizmussal is képesek dopamint felszabadítani. Leírtuk a noradrenalin és acetilkolin felszabadulás frekvenciafüggő kannabinerg modulációját a prefrontális kéregben. Kimutattuk, hogy GPR3 receptor genetikai törlése az agyi monoamin tartalmak csökkenéséhez és ezzel korreláló magatartásváltozásokkal jár a szorongás és a depresszió állatkísérletes modelljeiben. | We showed that the effect of cannabinoids on GABA release in the hippocampus is mediated by CB1-cannabinoid receptors. However, these effects are partly maintained after genetic deletion of CB1 receptors, and probably due to a residual, 'backup' cannabinoid receptor, which is overexpressed in CB1 knockouts. We reported for the first time the inhibitory effect of cannabinoids on serotonin release from the hippocampus. The action of cannabinoids is mediated by CB1 receptors, but affects only one subpopulation of serotonergic nerve terminals. We showed that endocannabinoids stimulate basal IL-1beta production in the hippocampus, partly with the participation of P2X7 receptors. We provided the first neurochemical evidence that the activation of CB1 cannabinoid receptors leads to the augmentation of [3H]dopamine efflux via a local GABAA receptor-mediated disinhibitory mechanism in the rat nucleus accumbens. In addition, the frequency dependent modulation of noradrenaline and acetylcholine release by cannabinoids is characterized in the prefrontal cortex. We also showed that genetical deletion of GPR3 receptor leads to the depletion of monoamine content in the brain and consistent alterations of behavior in animal models of anxiety and depression

Central P2Y12 receptor blockade alleviates inflammatory and neuropathic pain and cytokine production in rodents.

In this study the role of P2Y12 receptors (P2Y12R) was explored in rodent models of inflammatory and neuropathic pain and in acute thermal nociception. In correlation with their activity to block the recombinant human P2Y12R, the majority of P2Y12R antagonists alleviated mechanical hyperalgesia dose-dependently, following intraplantar CFA injection, and after partial ligation of the sciatic nerve in rats. They also caused an increase in thermal nociceptive threshold in the hot plate test. Among the six P2Y12R antagonists evaluated in the pain studies, the selective P2Y12 receptor antagonist PSB-0739 was most potent upon intrathecal application. P2Y12R mRNA and IL-1beta protein were time-dependently overexpressed in the rat hind paw and lumbar spinal cord following intraplantar CFA injection. This was accompanied by the upregulation of TNF-alpha, IL-6 and IL-10 in the hind paw. PSB-0739 (0.3mg/kg i.t.) attenuated CFA-induced expression of cytokines in the hind paw and of IL-1beta in the spinal cord. Subdiaphragmatic vagotomy and the alpha7 nicotinic acetylcholine receptor antagonist MLA occluded the effect of PSB-0739 (i.t.) on pain behavior and peripheral cytokine induction. Denervation of sympathetic nerves by 6-OHDA pretreatment did not affect the action of PSB-0739. PSB-0739, in an analgesic dose, did not influence motor coordination and platelet aggregation. Genetic deletion of the P2Y12R in mice reproduced the effect of P2Y12R antagonists on mechanical hyperalgesia in inflammatory and neuropathic pain models, on acute thermal nociception and on the induction of spinal IL-1beta. Here we report the robust involvement of the P2Y12R in inflammatory pain. The anti-hyperalgesic effect of P2Y12R antagonism could be mediated by the inhibition of both central and peripheral cytokine production and involves alpha7-receptor mediated efferent pathways

The inhibitory action of exo- and endocannabinoids on [ 3H]GABA release are mediated by both CB 1 and CB 2 receptors in the mouse hippocampus

Exogenous and endogenous cannabinoids play an important role in modulating the release of neurotransmitters in hippocampal excitatory and inhibitory networks, thus having profound effect on higher cognitive and emotional functions such as learning and memory. In this study we have studied the effect of cannabinoid agonists on the potassium depolarization-evoked [ 3H]GABA release from hippocampal synaptosomes in the wild-type (WT) and cannabinoid 1 receptor (CB 1R)-null mutant mice. All tested cannabinoid agonists (WIN55,212-2, CP55,940, HU-210, 2-arachidonoyl-glycerol, 2-AG; delta-9-tetra-hydrocannabinol, THC) inhibited [ 3H]GABA release in WT mice with the following rank order of agonist potency: HU-210 > CP55,490 > WIN55,212-2 >> 2-AG > THC. By contrast, 2-AG and THC displayed the greatest efficacy eliciting almost complete inhibition of evoked [ 3H]GABA efflux, whereas the maximal inhibition obtained by HU-210, CP55,490, and WIN55,212-2 were less, eliciting not more than 40% inhibition. The inhibitory effect of WIN55,212-2, THC and 2-AG on evoked [ 3H]GABA efflux was antagonized by the CB 1 receptor inverse agonist AM251 (0.5 μM) in the WT mice. In the CB 1R knockout mice the inhibitory effects of all three agonists were attenuated. In these mice, AM251 did not antagonize, but further reduced the [ 3H]GABA release in the presence of the synthetic agonist WIN55,212-2. By contrast, the concentration-dependent inhibitory effects of THC and 2-AG were partially antagonized by AM251 in the absence of CB 1 receptors. Finally, the inhibition of evoked [ 3H]GABA efflux by THC and 2-AG was also partially attenuated by AM630 (1 μM), the CB 2 receptor-selective antagonist, both in WT and CB 1 knockout mice. Our data prove the involvement of CB 1 receptors in the effect of exo- and endocannabinoids on GABA efflux from hippocampal nerve terminals. In addition, in the effect of the exocannabinoid THC and the endocannabinoid 2-AG, non-CB 1, probably CB 2-like receptors are also involved. © 2011 Elsevier Ltd. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Purkinje cell number-correlated cerebrocerebellar circuit anomaly in the valproate model of autism

While cerebellar alterations may play a crucial role in the development of core autism spectrum disorder (ASD) symptoms, their pathophysiology on the function of cerebrocerebellar circuit loops is largely unknown. We combined multimodal MRI (9.4 T) brain assessment of the prenatal rat valproate (VPA) model and correlated immunohistological analysis of the cerebellar Purkinje cell number to address this question. We hypothesized that a suitable functional MRI (fMRI) paradigm might show some altered activity related to disrupted cerebrocerebellar information processing. Two doses of maternal VPA (400 and 600 mg/kg, s.c.) were used. The higher VPA dose induced 3% smaller whole brain volume, the lower dose induced 2% smaller whole brain volume and additionally a focal gray matter density decrease in the cerebellum and brainstem. Increased cortical BOLD responses to whisker stimulation were detected in both VPA groups, but it was more pronounced and extended to cerebellar regions in the 400 mg/kg VPA group. Immunohistological analysis revealed a decreased number of Purkinje cells in both VPA groups. In a detailed analysis, we revealed that the Purkinje cell number interacts with the cerebral BOLD response distinctively in the two VPA groups that highlights atypical function of the cerebrocerebellar circuit loops with potential translational value as an ASD biomarker