UTILIZAÇÃO DA OCITOCINA EM GADO GIROLANDO: AVALIAÇÃO DA VIA VAGINAL COMO ALTERNATIVA À VIA ENDOVENOSA

O objetivo deste trabalho foi testar a viabilidade da utilização da via vaginal em fêmeas bovinas visando à aplicação de ocitocina a partir de formulações específicas. A ocitocina foi utilizada associada a facilitadores de absorção e na forma injetável (para comparação). Foram produzidas sete formulações, todas com concentração de 5 UI/mL de ocitocina. O delineamento experimental foi em quadrado latino 8x8 (oito dias, oito tratamentos e oito novilhas ciclando). As administrações de ocitocina foram pela via vaginal e a ocitocina injetável pela via endovenosa, contendo 10 UI cada. Amostras de sangue (n=7) foram coletadas de cada animal, no tempo 0, anterior à administração dos tratamentos, e de três em três minutos até 18 minutos. A ocitocina foi extraída do plasma utilizando coluna cromatográfica C-18 e dosada utilizando o kit comercial Oxytocin EIA. Os resultados obtidos foram avaliados por análise estatística não paramétrica utilizando o teste Kruskal Wallis para comparação das médias. A concentração de ocitocina diferiu entre o tempo 0 e o tempo 12 minutos (p<0,05) para a formulação ocitocina em glicerina. Concluiu-se que houve absorção através da via vaginal para essa formulação. Mais estudos serão necessários para seu emprego no manejo com as fêmeas bovinas de forma efetiva.  Palavras-chave: vacas, produção de leite, ordenha, ejeção do leit

Crucial involvement of actin filaments in celecoxib and morphine analgesia in a model of inflammatory pain.

Background: Celecoxib exerted analgesic effects (hypoalgesia) reversed by opioid receptor antagonists in a model of inflammatory pain. To analyze this celecoxib-induced hypoalgesia further, we assessed the effects of several disruptors of cytoskeletal components in our model of inflammation. Methods: Hyperalgesia to mechanical stimuli was induced in rat hind paws by intraplantar injection of carrageenan and measured using the Randall-Selitto method over the next 8 hours. The effects of systemic pretreatment with celecoxib and a range of cytoskeletal disruptors (colchicine, nocodazole, cytochalasin B, latrunculin B, acrylamide, each given by intraplantar injection) on carrageenan-induced hyperalgesia were similarly investigated. Morphine and other selective cyclo-oxygenase 1 (SC-560), cyclo-oxygenase 2 (SC-236), and nonselective cyclo-oxygenase (indomethacin) inhibitors were also tested under similar conditions. Results: None of the cytoskeletal disruptors affected the peak intensity of carrageenan-induced hyperalgesia, and its duration was increased only by nocodazole and colchicine. Pretreatment with celecoxib 30 minutes before carrageenan reversed the hyperalgesia and raised the nociceptive threshold (hypoalgesia). All analgesic effects of celecoxib were blocked by nocodazole, colchicine, cytochalasin B, and latrunculin B. Pretreatment with morphine also induced hypoalgesia in carrageenan-inflamed paws, an effect reversed by colchicine and cytochalasin B. However, the analgesic effects of indomethacin were not reversed by disruption of actin filaments with cytochalasin B or latrunculin B. Conclusion: These data strengthen the correlation between cytoskeletal structures and the processes of pain and analgesia

A spider derived peptide, PnPP-19, induces central antinociception mediated by opioid and cannabinoid systems

Abstract Background Some peptides purified from the venom of the spider Phoneutria nigriventer have been identified as potential sources of drugs for pain treatment. In this study, we characterized the antinociceptive effect of the peptide PnPP-19 on the central nervous system and investigated the possible involvement of opioid and cannabinoid systems in its action mechanism. Methods Nociceptive threshold to thermal stimulation was measured according to the tail-flick test in Swiss mice. All drugs were administered by the intracerebroventricular route. Results PnPP-19 induced central antinociception in mice in the doses of 0.5 and 1 μg. The non-selective opioid receptor antagonist naloxone (2.5 and 5 μg), μ-opioid receptor antagonist clocinnamox (2 and 4 μg), δ-opioid receptor antagonist naltrindole (6 and 12 μg) and CB1 receptor antagonist AM251 (2 and 4 μg) partially inhibited the antinociceptive effect of PnPP-19 (1 μg). Additionally, the anandamide amidase inhibitor MAFP (0.2 μg), the anandamide uptake inhibitor VDM11 (4 μg) and the aminopeptidase inhibitor bestatin (20 μg) significantly enhanced the antinociception induced by a low dose of PnPP-19 (0.5 μg). In contrast, the κ-opioid receptor antagonist nor-binaltorphimine (10 μg and 20 μg) and the CB2 receptor antagonist AM630 (2 and 4 μg) do not appear to be involved in this effect. Conclusions PnPP-19-induced central antinociception involves the activation of CB1 cannabinoid, μ- and δ-opioid receptors. Mobilization of endogenous opioids and cannabinoids might be required for the activation of those receptors, since inhibitors of endogenous substances potentiate the effect of PnPP-19. Our results contribute to elucidating the action of the peptide PnPP-19 in the antinociceptive pathway

Small cyclic sodium channel inhibitors

Voltage-gated sodium (NaV) channels play crucial roles in a range of (patho)physiological processes. Much interest has arisen within the pharmaceutical industry to pursue these channels as analgesic targets following overwhelming evidence that NaV\ua0channel subtypes NaV1.7–NaV1.9 are involved in nociception. More recently, NaV1.1, NaV1.3 and NaV1.6 have also been identified to be involved in pain pathways. Venom-derived disulfide-rich peptide toxins, isolated from spiders and cone snails, have been used extensively as probes to investigate these channels and have attracted much interest as drug leads. However, few peptide-based leads have made it as drugs due to unfavourable physiochemical attributes including poor\ua0in vivo\ua0pharmacokinetics and limited oral bioavailability. The present work aims to bridge the gap in the development pipeline between drug leads and drug candidates by downsizing these larger venom-derived NaV\ua0inhibitors into smaller, more “drug-like” molecules. Here, we use molecular engineering of small cyclic peptides to aid in the determination of what drives subtype selectivity and molecular interactions of these downsized inhibitors across NaV\ua0subtypes. We designed a series of small, stable and novel NaV\ua0probes displaying NaV\ua0subtype selectivity and potency\ua0in vitro\ua0coupled with potent\ua0in vivo\ua0analgesic activity, involving yet to be elucidated analgesic pathways in addition to NaV\ua0subtype modulation