Acute and long-term effects of a single dose of MDMA on aggression in Dark Agouti rats

MDMA causes selective depletion of serotonergic terminals in experimental animals and the consequent decrease in synaptic 5-HT may, inter alia, increase impulsivity. To study the effects of MDMA upon brain function, the behaviour of male Dark Agouti rats exposed to MDMA (15 mg/kg i.p.), two 5-HT1B agonists (CGS-12066A and CP-94,253, both 5 mg/kg i.p.) or saline were investigated in the resident-intruder test. Studies were performed in drug-naive rats and also in rats exposed to MDMA (15 mg/kg i.p.) 21 d earlier. In parallel experiments the functional neuroanatomy of MDMA effects were assessed using 2-deoxyglucose imaging of local cerebral metabolic rate of glucose utilization (LCMRGlu) and neurotoxicity was assessed by measuring [H-3]paroxetine binding. There was no significant difference in aggressive behaviour (biting, boxing, wrestling and their latencies) between drug-naive rats and rats previously exposed to MDMA 21 d earlier, despite reduced social behaviour, decreased LCMRGlu in several brain areas involved in aggression, and reductions in paroxetine binding by 30-60'% in the forebrain. CGS12066A, CP-94,253 and acute MDMA produced marked decreases in aggressive behaviours, especially in biting, boxing and kicking found in drug-naive rats. In animals previously exposed to the drug, acute antiaggressive effects of MDMA were, in general, preserved as were MDMA-induced increases in LCMRGlu. Our studies provide evidence that in the resident-intruder test, where social isolation is a requirement, aggressive behaviour and acute anti-aggressive effects of MDMA and 5-HT,I, receptor agonists remain intact 3 wk after a single dose of the drug despite significant damage to the serotonergic system

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

Az ecstasy hatása a kognitív funkciókra

Az ecstasy főleg entaktogén és eufóriát okozó hatásai miatt közkedvelt kábítószer a fiatalok körében. Akutan az ecstasy a visszavételi mechanizmusok megfordításával megemeli az agyi monoaminok koncentrációját és ezen keresztül fokozza az ébrenlétet, emeli a testhőmérsékletet, valamint csökkenti az agyi vérátáramlást és a táplálékfelvételt. Hosszú távon ugyanakkor az agyi szerotonin koncentrációk és szerotonerg markerek mennyiségének csökkenése figyelhető meg a felhasználókban. Ezzel párhuzamosan funkcionális károsodások is megjelenhetnek, mint például az alvás- és hangulatzavarok, valamint a szorongás és az agresszivitás fokozódása. Mindemellett az ecstasy egyik legjellemzőbb hosszú távú mellékhatása a kognitív deficit. Különösen a szert rendszeresen fogyasztó felhasználók esetén csökkent retro- és prospektív memória, valamint károsodott végrehajtó funkciók figyelhetők meg. Számos tanulmány a szerotonerg károsodás mellett felvetette az endokannabinoid rendszer, az alvásszabályzás és a hypothalamus-hypophysis-mellékvesekéreg tengely szerepét e folyamatban. Ugyanakkor ismert, hogy a fenti rendszerek egymás működését is képesek befolyásolni. Jelen tanulmányunkban a szerotonerg károsodás, az endokannabinoid rendszer és a fenti szabályozó mechanizmusok hatásait külön-külön, valamint egymásra gyakorolt lehetséges interakcióikat is tárgyaljuk, amelyek magyarázhatják az ecstasy által okozott hosszan tartó kognitív funkciócsökkenést

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 absence of P2X7 receptors (P2rx7) on non-haematopoietic cells leads to selective alteration in mood-related behaviour with dysregulated gene expression and stress reactivity in mice

The purpose of this study was to explore how genetic deletion and pharmacological antagonism of the P2X7 receptor (P2rx7) alter mood-related behaviour, gene expression and stress reactivity in the brain. The forced swim test (FST), tail suspension test (TST) and amphetamine-induced hyperlocomotion (AH) tests were used in wild-type (P2rx7+/+) and P2rx7-deficient (P2rx7-/-) mice. Biogenic amine levels were analysed in the amygdala and striatum, adrenocorticotropic hormone (ACTH) and corticosterone levels were measured in the plasma and pituitary after restraint stress. Chimeric mice were generated by bone marrow transplantation. A whole genome microarray analysis with real-time polymerase chain reaction validation was performed on the amygdala. In the absence of P2rx7s decreased behavioural despair in the FST, reduced immobility in the TST and attenuated amphetamine-induced hyperactivity were detected. Basal norepinephrine levels were elevated in the amygdala, whereas stress-induced ACTH and corticosterone responses were alleviated in P2rx7-/- mice. Sub-acute treatment with the selective P2rx7 antagonist, Brilliant Blue G, reproduced the effect of genetic deletion in the TST and AH test in P2rx7+/+ but not P2rx7-/- mice. No change in behavioural phenotype was observed in chimeras lacking the P2rx7 in their haematopoietic compartment. Whole genome microarray analysis indicated a widespread up- and down-regulation of genes crucial for synaptic function and neuroplasticity by genetic deletion. Here, we present evidence that the absence of P2rx7s on non-haematopoietic cells leads to a mood-stabilizing phenotype in several behavioural models and suggest a therapeutic potential of P2rx7 antagonists for the treatment of mood disorders

The role of glutamate release mediated by extrasynaptic P2X7 receptors in animal models of neuropathic pain

Purinergic signaling represents a major non-synaptic signaling mechanism in the normal and pathological nervous system. The expression of the purinergic ligand gated ion channel P2X7 receptor (P2rx7) have been described on nerve terminals as well as in non-neuronal cells, such as astrocytes and microglia. The activation of P2rx7s results in Ca(2+) influx and increased transmitter release in the brain. P2rx7s previously suggested having a pivotal role in different pain modalities, including neuropathic pain. Here we investigated whether the activation of P2rx7 leads to increased glutamate release from the spinal cord in an experimental model of neuropathic pain (partial nerve ligation of the sciatic nerve, PNL). One week after surgery, we studied the effects of PNL on tactile allodynia using aesthesiometry, in parallel with the in vitro release of [(3)H]glutamate from lumbar spinal cord slices. The observed allodynia in wild-type (P2rx7 +/+) mice one week after PNL surgery was lower that was observed in P2rx7 deficient (P2rx7 - /-) animals. Perfusion of spinal cord slices with ATP (10mM) elicited [(3)H]glutamate release in both sham operated and neuropathic P2rx7 +/+ animals. The ATP-induced [(3)H]glutamate release was absent in P2rx7 -/- mice. Electrically evoked release of [(3)H]glutamate from spinal cord slices was not significantly altered in PNL animals and in P2rx7 -/- mice. The results suggest that activation of P2rx7 by ATP releases glutamate in the spinal cord, which might contribute to mechanical allodynia following PNL. On the other hand, this release does not contribute to glutamate efflux evoked by conventional neuronal activity, which is consistent with the idea that P2X7 receptors are either extrasynaptic or expressed on non-neuronal cells

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