RESUMO
The involvement of purinergic signaling in several brain functions has been recognized, but the modulation on maternal behavior by the purinergic system is not established, even though there are functional interactions between the purinergic and oxytocinergic systems. Therefore, the aim of our study was to investigate whether central administration of P2 receptor antagonists affected the maternal behavior of lactating rats and c-Fos immunoreactivity in the forebrain. On day 7 of lactation, female rats were treated with vehicle (5µL; i.c.v.), suramin (9.4-75.0µg/5µL; i.c.v.) or PPADS (9.4-75.0µg/5µL; i.c.v.) 30min before the experiment began. The maternal behavior was evaluated during the 30min following suramin or PPADS administration. In addition, c-Fos-positive nuclei were counted in the medial preoptic area (MPOA) and in the bed nucleus of the stria terminalis (BNST), and neurons that were double-labeled for c-Fos/OT were counted in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus of lactating rats. The results show that P2 receptor antagonists decreased maternal care and decreased neuronal activation in the MPOA and BNST and activation of oxytocinergic neurons in hypothalamic nuclei. Our results indicate that the purinergic system modulates maternal behavior and neuronal activation induced by suckling during lactation.
Assuntos
Comportamento Animal , Lactação , Antagonistas do Receptor Purinérgico P2/farmacologia , Animais , Feminino , Prosencéfalo/efeitos dos fármacos , Prosencéfalo/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo , Fosfato de Piridoxal/análogos & derivados , Fosfato de Piridoxal/farmacologia , Ratos , Ratos Wistar , Suramina/farmacologiaRESUMO
Preventing damage caused by nerve degeneration is a great challenge. There is a growing body of evidence implicating extracellular nucleotides and their P2 receptors in many pathophysiological mechanisms. In this work we aimed to investigate the effects of the administration of Brilliant Blue G (BBG) and Pyridoxalphosphate-6-azophenyl-2', 4'- disulphonic acid (PPADS), P2X7 and P2 non-selective receptor antagonists, respectively, on sciatic nerve regeneration. Four groups of mice that underwent nerve crush lesion were used: two control groups treated with vehicle (saline), a group treated with BBG and a group treated with PPADS during 28days. Gastrocnemius muscle weight was evaluated. For functional evaluation we used the Sciatic Functional Index (SFI) and the horizontal ladder walking test. Nerves, dorsal root ganglia and spinal cords were processed for light and electron microscopy. Antinoceptive effects of BBG and PPADS were evaluated through von Frey E, and the levels of IL-1ß and TNF-α were analyzed by ELISA. BBG promoted an increase in the number of myelinated fibers and on axon, fiber and myelin areas. BBG and PPADS led to an increase of TNF-α and IL-1ß in the nerve on day 1 and PPADS caused a decrease of IL-1ß on day 7. Mechanical allodynia was reversed on day 7 in the groups treated with BBG and PPADS. We concluded that BBG promoted a better morphological regeneration after ischiatic crush injury, but this was not followed by anticipation of functional improvement. In addition, both PPADS and BBG presented anti-inflammatory as well as antinociceptive effects.
Assuntos
Lesões por Esmagamento/tratamento farmacológico , Regeneração Nervosa/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Traumatismos dos Nervos Periféricos/tratamento farmacológico , Antagonistas do Receptor Purinérgico P2X/farmacologia , Analgésicos/farmacologia , Animais , Lesões por Esmagamento/metabolismo , Lesões por Esmagamento/patologia , Modelos Animais de Doenças , Feminino , Gânglios Espinais/efeitos dos fármacos , Gânglios Espinais/metabolismo , Gânglios Espinais/patologia , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Hiperalgesia/patologia , Interleucina-1alfa/metabolismo , Camundongos Endogâmicos C57BL , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Regeneração Nervosa/fisiologia , Traumatismos dos Nervos Periféricos/metabolismo , Traumatismos dos Nervos Periféricos/patologia , Nervos Periféricos/efeitos dos fármacos , Nervos Periféricos/metabolismo , Nervos Periféricos/patologia , Fosfato de Piridoxal/análogos & derivados , Fosfato de Piridoxal/farmacologia , Distribuição Aleatória , Receptores Purinérgicos P2X7/metabolismo , Corantes de Rosanilina/farmacologia , Medula Espinal/efeitos dos fármacos , Medula Espinal/metabolismo , Medula Espinal/patologia , Fator de Necrose Tumoral alfa/metabolismoRESUMO
To investigate if channels with different stoichiometry are formed from P2X2 receptor isoforms during their heterologous co-expression. The two-electrode voltage-clamp technique was used to measured ATP induced currents in Xenopus laevis oocytes. We used a mutant (P2X2-2bm) because its ATP sensitivity is lower than P2X2-2b receptors, which highlights the differences with its splice variant P2X2-1a.Currents through homomeric channels had significantly different Hill coefficients. P2XR are trimeric proteins with three agonist binding sites; therefore, only two homomeric and two heteromeric stoichiometries are possible when both P2X2 isoforms are coexpressed, the heteromeric channels might be formed by: i) 2(P2X2-1a)+1(P2X2-2bm); or ii) 1(P2X2-1a)+2(P2X2-2bm). Because P2X2 channels open when two binding sites are occupied, these stoichiometries are expected to have different ATP sensitivities. Thus, co-expressing both P2X2 isoforms, two oocyte populations were distinguished based on their sensitivity to ATP and Hill coefficients. For the first population (P2X2-1a like), the ATP EC50 and the Hill coefficient were not different than those of homomeric P2X2-1a channels similarly, for the second population (P2X2-2bm like), these variables were also not different than for those of homomeric P2X2-2bm channels. Various findings indicate that homomeric channel expression is not responsible for such differences. Our observations indicate that two heteromeric channels can be assembled from two P2X2 receptor isoforms. Our data support a current model, according to which, ATP activation of two subunits can open P2X2 channel. However, PPADS appears to bind to all three subunits in order to inhibit ATP effects on P2X2 receptors.
Assuntos
Canais Iônicos/metabolismo , Isoformas de Proteínas/metabolismo , Receptores Purinérgicos P2X2/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Células Cultivadas , Cinética , Oócitos/metabolismo , Técnicas de Patch-Clamp , Isoformas de Proteínas/química , Isoformas de Proteínas/efeitos dos fármacos , Fosfato de Piridoxal/análogos & derivados , Fosfato de Piridoxal/farmacologia , Receptores Purinérgicos P2X2/química , Receptores Purinérgicos P2X2/efeitos dos fármacos , Xenopus laevisRESUMO
Activation of purinergic receptors by ATP (P2R) modulates glutamate release and the activation of post-synaptic P2R is speculated to induce nitric oxide (NO) synthesis. Increased glutamatergic and nitrergic signaling have been involved in the neurobiology of stress-related psychiatric disorders such as anxiety and depression. Therefore, the aim of this study was to test the effects of two P2R antagonists (PPADS and iso-PPADS) in animals submitted to models predictive of antidepressant-, anxiolytic- and anticompulsive-like effects. Swiss mice receiving PPADS at 12.5mg/kg showed reduced immobility time in the forced swimming test (FST) similarly to the prototype antidepressant imipramine (30mg/kg). This dose was also able to decrease the number of buried marbles in the marble-burying test (MBT), an anticompulsive-like effect. However, no effect was observed in animals submitted to the elevated plus maze (EPM) and to the open field test. The systemic administration of iso-PPADS, a preferential P2XR antagonist, also reduced the immobility time in FST, which was associated to a decrease in NOx levels in the prefrontal cortex. In addition, P2X7 receptor was found co-immunoprecipitated with neuronal nitric oxide synthase (NOS1) in the prefrontal cortex. These results suggest that P2X7, possibly coupled to NOS1, could modulate behavioral responses associated to stress-related disorders and it could be a new target for the development of more effective treatments for affective disorders.