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.

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-1β 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-α, IL-6 and IL-10 in the hind paw. PSB-0739 (0.3 mg/kg i.t.) attenuated CFA-induced expression of cytokines in the hind paw and of IL-1β in the spinal cord. Subdiaphragmatic vagotomy and the α7 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-1β.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 α7-receptor mediated efferent pathways.

3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") causes long-term disturbance of the serotonergic system. We examined the temporal, spatial, and cellular distribution of three molecular chaperones, Hsp27, Hsp72, and Hsp90, 3 and 7 days after treatment with 7.5, 15, and 30 mg/kg single intraperitoneal (i.p.) doses of MDMA in Dark Agouti rat brains. Furthermore, we compared the immunostaining patterns of molecular chaperones with serotonergic axonalvulnerability evaluated by tryptophan-hydroxylase (TryOH) immunoreactivity and with astroglial-activation detected by GFAP-immunostaining. There was a marked reduction in TryOH-immunoreactive axon density after MDMA treatment in all examined areas at both time points. Three days after treatment, a significant dose-dependent increase in Hsp27-immunoreactive protoplasmic astrocytes was found in the cingulate, frontal, occipital, and pyriform cortex, and in the hippocampus CA1. However, there was no increase in astroglial Hsp27-immunoreactivity in the caudate putamen, lateral septal nucleus, or anterior hypothalamus. A significant increase in the GFAP immunostaining density of protoplasmic astrocytes was found only in the hippocampus CA1. In addition, numerous strong Hsp72-immunopositive neurons were found in some brain areas only 3 days after treatment with 30 mg/kg MDMA. Increased Hsp27-immunoreactivity exclusively in the examined cortical areas reveals that Hsp27 is a sensitive marker of astroglial response to the effects of MDMA in these regions of Dark Agouti rat brain and suggests differential responses in astroglial Hsp27-expression between distinct brain areas. The co-occurrence of Hsp27 and GFAP response exclusively in the hippocampus CA1 may suggest the particular vulnerability of this region. The presence of strong Hsp72-immunopositive neurons in certain brain areas may reflect additional effects of MDMA on nonserotonergic neurons.