Characterization of the mechanisms underlying the inflammatory response to Polistes lanio lanio (paper wasp) venom in mouse dorsal skin

Stings by Polistes wasps can cause life-threatening allergic reactions, pain and inflammation. We examined the changes in microvascular permeability and neutrophil influx caused by the venom of Polistes lanio a paper wasp found in southeastern Brazil. The intradermal injection of wasp venom caused long-lasting paw oedema and dose-dependently increased microvascular permeability in mouse dorsal skin. SR140333, an NK(1) receptor antagonist, markedly inhibited the response, but the NK(2) receptor antagonist SR48968 was ineffective. The oedema was reduced in capsaicin-treated rats, indicating a direct activation of sensory fibres. Dialysis of the venom partially reduced the oedema and the remaining response was further inhibited by SR140333. Mass spectrometric analysis of the venom revealed two peptides (QPPTPPEHRFPGLM and ASEPTALGLPRIFPGLM) with sequence similarities to the C-terminal region of tachykinin-like peptides found in Phoneutria nigniventer spider venom and vertebrates. Wasp venom failed to release histamine from mast cells in vitro and spectrofluorometric assay of the venom revealed a negligible content of histamine in the usual dose of P.l. lanio venom (1 nmol of histamine/7 mu g of venom)that was removed by dialysis. The histamine H(1) receptor antagonist pyrilamine, but not bradykinin B(1) or B(2) receptor antagonists, inhibited venom-induced oedema. In conclusion, P. l. lanio venom induces potent oedema and increases vascular permeability in mice, primarily through activation of tachykinin NK(1) receptors by substance P released from sensory C fibres, which in turn releases histamine from dermal mast cells. This is the first description of a neurovascular mechanism for P. l. lanio venom-mediated inflammation. The extent to which the two tachykinin-like peptides identified here contribute to this neurogenic inflammatory response remains to be elucidated. (c) 2008 Elsevier Ltd. All rights reserved.

Ablation of primary afferent neurons by neonatal capsaicin treatment reduces the susceptibility of the portal hypertensive gastric mucosa to ethanol-induced injury in cirrhotic rats

Primary sensory afferent neurons modulate the hyperdynamic circulation in Cirrhotic rats with portal hypertension.The stomach of cirrhotic rats is prone to damage induced by ethanol, a phenomenon associated with reduced gastric hyperemic response to acid-back diffusion. The aim of this study was to examine the impact of ablation of capsaicin-sensitive neurons and the tachykinin NK(1) receptor antagonist A5330 on the susceptibility of the portal hypertensive gastric mucosa, to ethanol-induced injury and its effects on gastric cyclooxygenase (COX) and nitric oxide synthase (NOS) mRNA expression. Capsaicin was administered to neonatal, male, Wistar rats and the animals were allowed to grow. Cirrhosis was then induced by bile duct ligation in adult rats while controls had sham operation. Ethanol-induced gastric damage was assessed using ex vivo gastric chamber experiments. Gastric blood flow was measured as well as COX/NOS mRNA expression. Topical application of ethanol produced significant gastric damage in cirrhotic rats compared to controls, which was reversed in capsaicin- and A5330-treated animals. Mean arterial and portal pressure was normalized in capsaicin-treated cirrhotic rats. Capsaicin and A5330 administration restored gastric blood flow responses to topical application of ethanol followed by acid in cirrhotic rats. Differential COX and NOS mRNA expression was noted in bile duct ligated rats relative to controls. Capsaicin treatment significantly modified gastric eNOS/iNOS/COX-2 mRNA expression in cirrhotic rats. Capsaicin-sensitive neurons modulate the susceptibility of the portal hypertensive gastric mucosa to injury induced by ethanol via tachykinin NK(1) receptors and signalling of prostaglandin and NO production/release. (c) 2008 Elsevier B.V. All rights reserved.

Role of neurokinin-1 expressing neurons in the locus coeruleus on ventilatory and cardiovascular responses to hypercapnia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Plasticidade induzida por treinamento locomotor na medula espinal intacta em ratos: correlatos morfológicos

The locomotion is one of the most important capabilities developed by the animals, whose improvement is dependent on several neural centers, including the spinal cord. This activity promotes a lot of spinal modifications that enable it to adapt and improve their connections. This study aimed to observe the morphological changes occurring in the spinal cord after locomotor training in intact rats. For that we used male Wistar rats, which were submitted to locomotor training in wheel activity in protocols 1, 3 and 7 days (30min/day), and the results were compared to a control group not subjected to exercise. Coronal sections of 40 μm of the lumbosacral spinal cord were subjected to immunohistochemical techniques anti-Egr1, anti-NMDA and anti-SP, to characterize the spinal plasticity related to these substances. Egr1-immunoreactive cells were increased in all laminas, essentially in those more intensely activated by locomotion, laminas IV-X levels L4-S3. All observed sections expressed NMDA-immunoreactivity. Analysis of SP in the spinal dorsal horn resulted no significant variations of this neuropeptide related to locomotion. The results suggest that locomotor training provides synaptic plasticity similar to LTP in all laminas of the lumbosacral spinal cord, in different intensities. However, the SP appears do not participate of this process in the spinal dorsal horn. This work will contribute for consolidating and characterization of synaptic plasticity in the spinal cord

O complexo nuclear vestibular do sagui (callithrix jacchus): caracterização citoarquitetônica e neuroquímica

To the vertebrates, maintain body balance against the gravitational field and be able to orient themselves in the environment are fundamental aspects for survival, in which the participation of vestibular system is essential. As part of this system, the vestibular nuclear complex is the first central station that, by integrating many information (visual, proprioceptive), and the vestibular, assumes the lead role in maintaining balance. In this study, the vestibular nuclear complex was evaluated in relation to its cytoarchitecture and neurochemical content of cells and axon terminals, through the techniques of Nissl staining and immunohistochemistry for neuronal specific nuclear protein (NeuN), glutamate (Glu), substance P (SP), choline acetyltransferase (ChAT) (enzyme that synthesizes acetylcholine-Ach) and glutamic acid decarboxylase (GAD) (enzyme that synthesizes gamma-amino butyric acid-GABA). The common marmoset (Callithrix jacchus) was used as experimental animal, which is a small primate native from the Atlantic Forest in the Brazilian Northeast. As results, the Nissl technique, complemented by immunohistochemistry for NeuN allowed to delineate the vestibular nucleus superior, lateral, medial and inferior (or descending) in the brain of the common marmoset. Neurons and terminals immunoreactive to Glu and ChAT and only immunoreactive terminals to SP and GAD were seen in all nuclei, although in varying density. This study confirms the presence in the vestibular nuclei of the common marmoset, of Glu and SP in terminals, probably from the first order neurons of vestibular ganglion, and of GABA in terminals, presumably from Purkinge cells of the cerebellum. Second-order neurons of the vestibular nuclei seem to use Glu and Ach as neurotransmitters, judging by their expressive presence in the cell bodies of these nuclei in common marmosets, as reported in other species

Caracterização citoarquitetônica, neuroquímica e de aferência óptica do complexo parabraquial do sagui (Callithrix jacchus)

The parabrachial complex (PB) is an area of the brainstem responsible for the processing and transmission of essential physiologic information for the survival of the organisms. This region is subdivided in approximately nine subregions, considering morphology, cytoarchitectural and functional characteristic. Its neurons have an extensive network of connections with other regions of the nervous system. The objective in this work was to map the retinal projection to the PB and make a citoarchitectonic and neurochemical characterization of this region in the common marmoset (Callithrix jacchus), a primate of the New World. The retinal projections were mapped by anterograde transport of the choleric toxin subunit b (CTb). The citoarchitecture was described through the Nissl method, and the neurochemical characterization was made through immunohistochemical technique to the some neurotransmitters and neuroactives substances present in this neural center. In marmoset PB, in the coronal sections labeled by Nissl method, we found a similar pattern to that evidenced in other animal species. The immunoreactivity against CTb was verified in the PBMv in fibers/terminal, characterizing such as retinal innervations in this area. The immunohistochemical technique reveled that the PB contain cells, fibers and/or terminals immunoreactives to the neuronal nuclear protein, Choline acetyl transferase, nitric oxide synthase, serotonin, enkephalin, substance P, Calcium-binding proteins (calbindin, calretinin e parvalbumin), and glial fibrillary acidic protein. The histochemical technique reveled cells and fibers NADPH-diaphorase reactive. Each one of those substances presented a characteristic pattern of demarcation in PB, and some serve as specific markers of subregions

Retinal projections and neurochemical characterization of the pregeniculate nucleus of the common marmoset (Callithrix jacchus)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

PAR(2) and Temporomandibular Joint Inflammation in the Rat

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ablation of NK1 receptor bearing neurons in the nucleus of the solitary tract blunts cardiovascular reflexes in awake rats

The nucleus of the solitary tract (NTS) receives primary afferents involved in cardiovascular regulation. We investigated the role of NK1-receptor bearing neurons in the NTS on cardiovascular reflexes in awake rats fitted with chronic venous and arterial cannulae. These neurons were lesioned selectively with saporin conjugated with substance P (SP-SAP, 2 mu M, bilateral injections of 20 nL in the subpostremal NTS, or 200 nL in both the subpostremal and the commissural NTS). Before, and 7 and 14 days after injection of SP-SAP, we measured changes in blood pressure and heart rate induced by i.v. injection of phenylephrine and nitroprusside (baroreceptor reflex), cyanide (arterial chemoreceptor reflex), and phenylbiguanide (Bezold-Jarisch reflex). The smaller injections with SP-SAP completely abolished NK1 receptor staining in the subpostremal NTS. The larger injections abolished NK1 receptor immunoreactivity in an area that extended from the commissural NTS to the rostral end of the subpostremal NTS. The lesions seemed to affect only a limited number of neurons, since neutral red stained sections did not show any obvious reduction in cell number. The smaller lesions reduced the gain of baroreflex bradycardia and the hypotension induced by phenylbiguanide. The larger lesions completely abolished the response to phenylbiguanide, blocked the baroreflex bradycardia induced by phenylephrine, severely blunted the baroreflex tachycardia, and blocked the bradycardia and reduced the hypertension induced by cyanide. Thus, these responses depend critically on NK1-receptor bearing neurons in the NTS. (c) 2006 Elsevier B.V. All rights reserved.

Biomolecular information, brain activity and cognitive functions

Molecular neurobiology has provided an explanation of mechanisms supporting mental functions as learning, memory, emotion and consciousness. However, an explanatory gap remains between two levels of description: molecular mechanisms determining cellular and tissue functions, and cognitive functions. In this paper we review molecular and cellular mechanisms that determine brain activity, and then hypothetize about their relation with cognition and consciousness. The brain is conceived of as a dynamic system that exchanges information with the whole body and the environment. Three explanatory hypotheses are presented, stating that: a) brain tissue function is coordinated by macromolecules controlling ion movements, b) structured (amplitude, frequency and phase-modulated) local field potentials generated by organized ionic movement embody cognitive information patterns, and c) conscious episodes are constructed by a large-scale mechanism that uses oscillatory synchrony to integrate local field patterns. © by São Paulo State University.

Avaliação do efeito antinociceptivo, anti-inflamatório e gastroprotetor do extrato hidroalcoolico das entrecascas de Machaerium hirtum (Vell) Stellfeld

Pós-graduação em Ciências Biológicas (Farmacologia) - IBB

Citral: A monoterpene with prophylactic and therapeutic anti-nociceptive effects in experimental models of acute and chronic pain

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento de um método limpo para análise de 5-hidroximetil-2furfuraldeído em mel

Pós-graduação em Química - IQ

The effect of intrathecal gabapentin on neuropathic pain is independent of the integrity of the dorsolateral funiculus in rats

Aim: This study evaluates the contribution of inhibitory pain pathways that descend to the spinal cord through the dorsolateral funiculus (DLF) on the effect of intrathecal gabapentin against spinal nerve ligation (SNL)-induced behavioral hypersensitivity to mechanical stimulation in rats. Main method: Rats were submitted to a sham or complete ligation of the right LS and L6 spinal nerves and a sham or complete DLF lesion. Next, the changes induced by intrathecal administration of gabapentin on the paw withdrawal threshold of rats to mechanical stimulation were evaluated electronically. Key findings: Intrathecal gabapentin (200 mu g/5 mu l) that was injected 2 or 7 days after surgery fully inhibited the SNL-induced behavioral hypersensitivity to mechanical stimulation in sham DLF-Iesioned rats; gabapentin was effective against the SNL-induced behavioral hypersensitivity to mechanical stimulation also in DLF-Iesioned rats. Significance: The effect of intrathecally administered gabapentin against SNL-induced behavioral hypersensitivity to mechanical stimulation in rats does not depend on the activation of nerve fibers that descend to the spinal cord via the DLF. (C) 2012 Elsevier Inc. All rights reserved.

KCNQ Channels Determine Serotonergic Modulation of Ventral Surface Chemoreceptors and Respiratory Drive

Chemosensitive neurons in the retrotrapezoid nucleus (RTN) regulate breathing in response to CO2/H+ changes. Their activity is also sensitive to neuromodulatory inputs from multiple respiratory centers, and thus they serve as a key nexus of respiratory control. However, molecular mechanisms that control their activity and susceptibility to neuromodulation are unknown. Here, we show in vitro and in vivo that KCNQ channels are critical determinants of RTN neural activity. In particular, we find that pharmacological block of KCNQ channels (XE991, 10 mu M) increased basal activity and CO2 responsiveness of RTN neurons in rat brain slices, whereas KCNQ channel activation (retigabine, 2-40 mu M) silenced these neurons. Interestingly, we also find that KCNQ and apamin-sensitive SK channels act synergistically to regulate firing rate of RTN chemoreceptors; simultaneous blockade of both channels led to a increase in CO2 responsiveness. Furthermore, we also show that KCNQ channels but not SK channels are downstream effectors of serotonin modulation of RTN activity in vitro. In contrast, inhibition of KCNQ channel did not prevent modulation of RTN activity by Substance P or thyrotropin-releasing hormone, previously identified neuromodulators of RTN chemoreception. Importantly, we also show that KCNQ channels are critical for RTN activity in vivo. Inhibition of KCNQ channels lowered the CO2 threshold for phrenic nerve discharge in anesthetized rats and decreased the ventilatory response to serotonin in awake and anesthetized animals. Given that serotonergic dysfunction may contribute to respiratory failure, our findings suggest KCNQ channels as a new therapeutic avenue for respiratory complications associated with multiple neurological disorders.