Isolectin B4 (IB4)-conjugated streptavidin for the selective knockdown of proteins in IB4-positive (+) nociceptors.

In vivo analysis of protein function in nociceptor subpopulations using antisense oligonucleotides and short interfering RNAs is limited by their non-selective cellular uptake. To address the need for selective transfection methods, we covalently linked isolectin B4 (IB4) to streptavidin and analyzed whether it could be used to study protein function in IB4(+)-nociceptors. Rats treated intrathecally with IB4-conjugated streptavidin complexed with biotinylated antisense oligonucleotides for protein kinase C epsilon (PKCε) mRNA were found to have: a) less PKCε in dorsal root ganglia (DRG), b) reduced PKCε expression in IB4(+) but not IB4(-) DRG neurons, and c) fewer transcripts of the PKCε gene in the DRG. This knockdown in PKCε expression in IB4(+) DRG neurons is sufficient to reverse hyperalgesic priming, a rodent model of chronic pain that is dependent on PKCε in IB4(+)-nociceptors. These results establish that IB4-streptavidin can be used to study protein function in a defined subpopulation of nociceptive C-fiber afferents.

Management of defoliation in Trifolium vesiculosum S. for the production of seeds / [Manejo da desfolha em Trifolium vesiculosum Savi para a produção de sementes]

The present study aims to determine the appropriate defoliation management for the production of seeds and forage in arrowleaf clover via trail analysis. The results obtained demonstrated that defoliation practices have a great influence on the composition of seed yield and germination power. In addition, when the goal is the maximum balance between dry matter production and seed yield, this can be achieved in up to two defoliation practices. These results are confirmed by analyzing the positive association between the weight of a thousand seeds and the seed yield. When the third defoliation practice is performed, it negatively correlates with the weight of a thousand seeds, suggesting that, with the increase in defoliation frequency, there is a lower weight of a thousand seeds, and, therefore, lower seed yield. Therefore, management planning in Trifolium vesiculosum Savi that aims at natural reseeding, maximum yield and seed germination must prioritize one to two defoliation practices, aiming to promote favorable conditions for the perennialization of the species. In this context, the trail analysis proved to be a useful tool as a criterion for obtaining the ideal management aiming at the production of seeds and forage in vesicular clover.(AU)

O presente estudo visa determinar o manejo de desfolha adequado para a produção de sementes e de forragem em trevo-vesiculoso via análise de trilha. Os resultados obtidos demonstraram que as práticas de desfolha possuem grande influência na composição do rendimento de sementes e no poder germinativo. Além disso, quando o objetivo for o máximo equilíbrio entre a produção de matéria seca e o rendimento de sementes, esse pode ser alcançado em até duas práticas de desfolha. Esses resultados são confirmados ao se analisar a associação positiva entre o peso de mil sementes e o rendimento de sementes. Quando realizada a terceira prática de desfolha, esta se correlaciona negativamente com o peso de mil sementes, sugerindo que, com o aumento da frequência de desfolha, ocorre menor peso de mil sementes e, por conseguinte, menor rendimento de sementes. Portanto, o planejamento do manejo em T. vesiculosum Savi que objetive a ressemeadura natural, o máximo rendimento e a germinação de sementes deve priorizar até duas práticas de desfolha, visando promover condições favoráveis para a perenização da espécie. Nesse contexto, a análise de trilha demonstrou ser uma ferramenta útil como critério para obtenção do manejo ideal visando à produção de sementes e de forragem em trevo-vesiculoso.(AU)

Extracellular matrix hyaluronan signals via its CD44 receptor in the increased responsiveness to mechanical stimulation.

We propose that the extracellular matrix (ECM) signals CD44, a hyaluronan receptor, to increase the responsiveness to mechanical stimulation in the rat hind paw. We report that intradermal injection of hyaluronidase induces mechanical hyperalgesia, that is inhibited by co-administration of a CD44 receptor antagonist, A5G27. The intradermal injection of low (LMWH) but not high (HMWH) molecular weight hyaluronan also induces mechanical hyperalgesia, an effect that was attenuated by pretreatment with HMWH or A5G27. Pretreatment with HMWH also attenuated the hyperalgesia induced by hyaluronidase. Similarly, intradermal injection of A6, a CD44 receptor agonist, produced hyperalgesia that was inhibited by HMWH and A5G27. Inhibitors of protein kinase A (PKA) and Src, but not protein kinase C (PKC), significantly attenuated the hyperalgesia induced by both A6 and LMWH. Finally, to determine if CD44 receptor signaling is involved in a preclinical model of inflammatory pain, we evaluated the effect of A5G27 and HMWH on the mechanical hyperalgesia associated with the inflammation induced by carrageenan. Both A5G27 and HMWH attenuated carrageenan-induced mechanical hyperalgesia. Thus, while LMWH acts at its cognate receptor, CD44, to induce mechanical hyperalgesia, HMWH acts at the same receptor as an antagonist. That the local administration of HMWH or A5G27 inhibits carrageenan-induced hyperalgesia supports the suggestion that carrageenan produces changes in the ECM that contributes to inflammatory pain. These studies define a clinically relevant role for signaling by the hyaluronan receptor, CD44, in increased responsiveness to mechanical stimulation.

Neuronal P2X3 receptor activation is essential to the hyperalgesia induced by prostaglandins and sympathomimetic amines released during inflammation.

We have demonstrated that the activation of P2X3 receptor on peripheral afferent neurons is critical to development of inflammatory hyperalgesia in peripheral tissue, although pharmacological administration of prostaglandin E(2) or sympathomimetic amines is enough to sensitize primary afferent neurons by acting directly in neuronal receptors. Therefore, to clarify this ambiguity this study verifies whether P2X3 receptor activation on primary afferent neurons enables the sensitization induced by prostaglandin E(2) or sympathomimetic amine. Initially, this study confirmed that co-administration of A317491 (60 µg/paw), a selective P2X3 receptor antagonist, or pre-treatment with dexamethasone (1 mg/mL/kg) prevents the mechanical hyperalgesia induced by carrageenan (300 µg/paw) in the rat's hind paw. Sub-threshold doses of PGE(2) (4 ng/paw) or dopamine (0.4 µg/paw), that do not induce hyperalgesia by themselves, when injected just following αßmeATP or carrageenan in rats treated with dexamethasone induced hyperalgesia, which is prevented by A317491 or treatment with periganglionar (DRG-L5) injections of ODN-antisense, against P2X3 receptor. Furthermore, because PKCɛ translocation induces an increase of neuronal susceptibility to inflammatory mediators, this study demonstrates that αßmeATP in peripheral tissue increases the expression of PKCɛ in cell membranes of DRG-L5, and in contrast, the administration of PKCɛ translocation inhibitor (1 µg/paw) in peripheral tissue 45 min before αßmeATP, prevented the hyperalgesia induced by sub-threshold dose of PGE(2) (4 ng/paw). In conclusion, this study suggests that neuronal P2X3 receptor activation and the consequent PKCɛ translocation increase the susceptibility of nociceptor to inflammatory mediators allowing the development of inflammatory hyperalgesia.

Antinociceptive properties of acetylenic thiophene and furan derivatives: evidence for the mechanism of action.

The aim of the present study was to evaluate the antinociceptive potential of the acetylenic thiophene and furan derivatives: 3-(furan-2-il) prop-2-yn-1-ol 1, 1-(thiofen-2-il) pent-1yn-3-ol 2 and 4-(thiofen-2-il)-2-metilbut-3-yn-2-ol 3 on three different pain models in mice. The pain models evaluated were the acetic acid-induced writhing, capsaicin-induced pain and the tail immersion test. The possible mechanisms involved in the antinociceptive effect of these compounds were also investigated. Thus, the acetylenic thiophene and furan derivatives presented antinociceptive effect in the pain tests caused by chemical agents. Statistical analysis showed that compounds 1 and 3 increased the latency for tail withdrawal in the tail immersion test (phasic pain). Besides, the role of the opioidergic, muscarinic cholinergic and dopaminergic systems in the acetic acid-induced writhing was examined. The antinociceptive effect of compounds 2 and 3 was prevented by pretreatment with naloxone (1 mg/kg, s.c), but not by atropine (5 mg/kg, s.c) or metoclopramide (1 mg/kg, s.c). Neither naloxone nor metoclopramide prevented the antinociceptive effect caused by compound 1, while the pretreatment with atropine antagonized the antinociceptive action of this compound. The compounds 1-3 used in this study did not reveal any motor impairment to mice in the open field. The results suggest that compounds 2 and 3 induced antinociception in the abdominal writhing test and that their effects are mediated by opiodergic receptors, while the antinociceptive effect of compound 1 may involve muscarinic cholinergic receptors.