Defensive-like behaviors and antinociception induced by NMDA injection into the periaqueductal gray of mice depend on nitric oxide synthesis

Glutamate NMDA receptor activation within the periaqueductal gray (PAG) leads to antinociceptive, autonomic and behavioral responses characterized as the fear reaction. Considering that NMDA receptor triggers activation of neuronal nitric oxide synthase (nNOS), enzyme that produces nitric oxide (NO), this study investigated the effects of intra-PAG infusions of NPLA (N omega-propyl-L-arginine), an nNOS inhibitor, on behavioral and antinociceptive responses induced by local injection of NMDA receptor agonist in mice. The behaviors measured were frequency of jumping and rearing as well as duration (in seconds) of running and freezing. Nociception was assessed during the second phase of the formalin test (injection of 50 mu l of formalin 2.5% into the dorsal surface of the right hind paw). Five to seven days after stereotaxic surgery for intracerebral cannula implantation, mice were injected with formalin into the paw, and 10 min later, they received intra-dPAG injection of NPLA (0, 0.2, or 0.4 nmol/0.1 mu l). Ten minutes later, they were injected with NMDA (N-methyl-D-aspartate: 0 or 0.04 nmol/0.1 mu l) into the same midbrain site and were immediately placed in glass holding cage for recording the defensive behavior and the time spent on licking the injected paw with formalin during a period of 10 min. Microinjections of NMDA significantly decreased nociception response and produced jumping, running, and freezing reactions. Intra-dPAG injections of NPLA (0.4 nmol) completely blocked the NMDA effects without affecting either behavioral or nociceptive responses in intra-dPAG saline-injected animals, except for the rearing frequency that was increased by the nNOS inhibitor. These results strongly suggest the involvement of NO within the PAG in the antinociceptive and defensive reactions induced by local glutamate NMDA receptor activation in this midbrain structure. (c) 2006 Elsevier B.V. All rights reserved.

Concurrent nociceptive stimulation impairs the anxiolytic effect of midazolam injected into the periaqueductal gray in mice

This study investigated whether the opportunity to avoid or escape the open arms of an elevated plus-maze (EPM) affects the antinociceptive response observed when mice are subjected to open arm confinement. Furthermore, in order to better characterize the relationship between emotion and antinociception in the EPM, we examined the behavioral effects of midazolam injection into the midbrain periaqueductal gray matter (PAG). As our main aim was to evaluate the relevance of different levels of approach-avoid conflict (i.e. The presence of open and closed arms) to maze-induced antinociception, mice were exposed to one of three types of EPM-a standard EPM (sEPM), an open EPM (oEPM: four open arms) or, as a control condition, an enclosed EPM (eEPM: four enclosed arms). Nociception was assessed using the formalin test. Twenty minutes after formalin injection (50 mu l, 2.5% formalin) into the dorsal right hind paw, mice received an intra-PAG injection of saline or midazolam (10-20 nmol). Five minutes later, they were individually exposed to one of the mazes for 10 min (25-35 min after formalin injection). Videotapes of the test sessions were scored for a variety of behavioral measures including time spent licking the formalin-injected paw. To examine whether the effects of midazolam on anxiety-like behavior may have been influenced by concurrent nociceptive stimulation (i.e. formalin pretreatment), naive mice were submitted to a similar procedure to that described above for the sEPM test but without formalin pretreatment. Results showed that mice exposed to the oEPM spent significantly less time licking the injected paw compared to groups exposed to either the sEPM or eEPM. Although exposure to the sEPM induced anxiety-like behaviors (i.e. open arm avoidance), it did not result in antinociception. Intra-PAG infusions of midazolam failed to block oEPM-induced antinociception or to alter sEPM-induced anxiety in mice that had received formalin injection. However, under normal test conditions (i.e. in the absence of formalin-induced nociceptive stimulation), intra-PAG midazolam produced clear anti-anxiety effects in mice exposed to the sEPM. Findings are discussed in terms of different emotional states induced by the oEPM and sEPM and the influence of concurrent nociceptive stimulation on the anti-anxiety effect of intra-PAG midazolam. (c) 2005 Elsevier B.V. All rights reserved.

Role of nitric oxide in the periaqueductal gray in defensive behavior in mice: influence of prior local N-methyl-D-aspartate receptor activation and aversive condition

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

Estudo etnofarmacológico e fitoquímico das espécies medicinais Cleome spinosa Jacq, Pavonia varians Moric e Croton cajucara Benth

In this present work an ethnographic research was performed with 84 native medicinal specimens from the Litoral Norte Riograndense, from which two plants Cleome spinosa Jacq e Pavonia varians Moric were submitted to ethnobotanic, phytochemistry and pharmacologic investigations. Additionally, a phytopharmacological research of the medicinal specimen Croton cajucara Benth ( native plant of the Amazon region of Brazil) was improved. The obtained phytochemical results of the C. spinosa and P. varians showed the presence of flavonoids constituents, among other components. The two flavonoids (2S)-5-hydroxy-7,4 -dimethoxy-flavanone and 5,4 -dihydroxy-3,7,3 -trimethoxy-flavone were isolated from C. spinosa. The antioxidant activity of the hydroalcoholic extracts of C. spinosa and P. varians solubilized in the microemulsion systems SME-1 and SME-4, was evaluated in the DPPHmethod. The used SME systems [obtained with Tween 80: Span 20 (3:1) and isopropyl myristate (IPM)] improved the dissolution of those tested polar extracts, with higher efficacy to the SME-1 system (in which ethanol was included as cosurfactant). The CE50 values evidenced for P. varians were 114 [g/mL (SME-1) and 246 [g/mL (SME-4); for C. spinosa it was 224 [g/mL (SME-1) and 248 [g/mL (SME-4), being the system SME-1 more effective for both tested extracts. The hydroalcoholic extracts of P. varians (HAE-PV) was also submitted to pharmacological screening for antinociceptive activity in animal models. The oral administration of this extract (100, 300 and 1000 mg/kg) inhibited the acetic acid-induced writhing in mice. The higher inhibition (74%) was evidenced to the 1000 mg/kg administered dose. Its effect on the central nervous system (CNS) was investigated by tail flick and formalin-method and reveled that it has negligible antinociceptive action on the CNS. After taking consideration of HAE-PV interaction, Pavonia varians Moric could be used as a potent analgesic agent in case of peripheral algesia, without affecting the CNS. The phytochemical study of the stem bark of Croton cajucara Benth lead to the isolation of 19-nor-clerodanetype diterpenes, as well as to the separation of its fixed oil FO-CC. This non polar oil material reveled to be rich in sesquiterpenes and 19-nor-clerodanes components. The biologic effect of OF-CC was evaluated in the development in vitro of the fungis phytopatogens such as Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsii. Significant inhibitory effect of the tested fungis (at 0,2 mg.mL-1 dosage) were comproved. A Mass Spectrometry study of clerodane-type diterpenes was developed in order to identify characteristic fragments on mass spectrometra of both clerodane and 19-nor-clerodane presenting an α,β-insaturated carbonyl moiety at ring A of the decalin-system. For that study, mass spectroscopy data were analysed for 19-nor-clerodanes [trans-dehydrocrotonin (DCTN), trans-crotonin (CTN), cis-cajucarin B (c-CJC-B), and cajucarinolide (CJCR)] and for clerodanes [isosacacarin (ISCR) and transcajucarin A (t-CJC-A)] obtained from the stem bark of C. cajucara, and also clerodane-type from other species. The trans-junction of the enone-system clerodanes was clear correlated with the presence of the characteristic ions at m/z 95, 121 e 205. Meanwhile, the characteristics ions at m/z 122 e 124 were correlated to cis-junction. The trans-junction of the enone-system 19-nor-clerodanes showed characteristics ions at m/z 161, 134 e 121. This study could be successful employed for identification of clerodane constituents from other specimens without any additional spectroscopic analyses, as well as a previously phytochemical analyzes in clerodane project search

Efeitos antinociceptivos e sedativos da buprenorfina, da acepromazina ou da associação buprenorfina e acepromazina em gatos

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

Evaluation of the analgesic and antiedematogenic activities of Quassia amara bark extract

We evaluated the possible antiedematogenic, antinociceptive and/or sedative effects of four different extracts obtained from the bark of Quassia amara namely, 70% ethanol (70EtOH), 100% ethanol (100EtOH), dichloromethane (DCM) and hexane extracts (HEX). The oral administration (100, 250 and 500 mg/kg) of these extracts did not show significant effects in any experiment. However, when administered intraperitoneally, the HEX extract decreased the paw edema induced by carrageenan, showed antinociceptive effects on the hot-plate test and on acetic acid-induced writhing, and showed sedative effects on pentobarbital-induced sleep. Naloxone did not reverse the antinociceptive effect of this extract. In conclusion, although the mechanisms are uncertain, the results demonstrated that these effects are apparently related to sedative and muscle relaxant or psychomimetic activities of the HEX extract of the plant. (C) 2002 Elsevier B.V. Ireland Ltd. All rights reserved.

Efeito analgésico de longa duração da dipirona sobre a hiperalgesia persistente induzida pela constrição do nervo ciático em ratos: participação do óxido nítrico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Applications of the hexanic fraction of Agave sisalana Perrine ex Engelm (Asparagaceae): control of inflammation and pain screening

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

Anti-inflammatory and analgesic potential of hydrolyzed extract of Agave sisalana Perrine ex Engelm., Asparagaceae

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

Injeção epidural preventiva de xilazina ou amitraz, em eqüinos: efeito antinociceptivo

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

Ausência de efeito antinociceptivo decorrente da administração intravenosa de crotalfina em comparação com morfina, U50-488H ou fenilbutazona em equinos submetidos à estimulação térmica da pele íntegra

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

Effects of buprenorphine on nociception and spontaneous locomotor activity in horses

Objective-To investigate spontaneous locomotor activity (SLA) and antinociceptive effects of buprenorphine in horses.Animals-6 healthy adult horses.Procedures-Horses received each of 3 treatments (10 mL of saline [0.9% NaCl] solution, 5 mu g of buprenorphine/kg, or 10 mu g of buprenorphine/kg). Treatments were administered IV Order of treatments was randomized, and there was a 10-day interval between subsequent treatments. Spontaneous locomotor activity was investigated in a behavioral box by use of infrared photoelectric sensors connected to a computer, which detected movement of each horse. Antinociceptive effect was investigated by hoof-withdrawal reflex latency (HWRL) and skin-twitching reflex latency (STBL) after painful stimulation with a heat lamp.Results-Moderate excitement was observed in all horses from 5 to 10 minutes after the administration of both dosages of buprenorphine. The SLA increased significantly for 6 and 14 hours after IV administration of 5 and 10 mu g of buprenorphine/kg, respectively. Values for HWRL increased significantly only at 30 minutes after injection of 5 mu g of buprenorphine/kg, whereas STRL and HWRL each increased significantly from 1 to 6 hours (except at 2 and 4 hours) and 11 hours, respectively, after injection of 10 mu g of buprenorphine/kg.Conclusions and Clinical Relevance-IV injection of buprenorphine caused a dose-dependent increase in SLA, but only the dose of 10 mu g/kg induced analgesia on the basis of results for the experimental method used.

Open elevated plus maze-induced antinociception in rats: A non-opioid type of pain inhibition?

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The analgesic effect of crotoxin on neuropathic pain is mediated by central muscarinic receptors and 5-lipoxygenase-derived mediators

Crotoxin (CTX). a neurotoxin isolated from the venom of the South American rattlesnake Crotalus durissus terrificus. induces analgesia. In this study, we evaluated the antinociceptive effect of CTX in a model of neuropathic pain induced by rat sciatic nerve transection. Hyperalgesia was detected 2 h after nerve transection and persisted for 64 days. Immersion of proximal and distal nerve stumps in CTX solution (0.01 mM for 10 s), immediately after nerve transection, blocked hyperalgesia. The antinociceptive effect of CTX was long-lasting, since it was detected 2 h after treatment and persisted for 64 days. CTX also delayed, but did not block, neurectomy-induced neuroma formation. The effect of CTX was blocked by zileuton (100 mg/kg, p.o.) and atropine (10 mg/kg. i.p.), and reduced by yohimbine (2 mg/kg, i.p.) and methysergide (5 mg/kg, i.p.). on the other hand. indomethacin (4 mg/kg, i.v.). naloxone (1 mg/kg, i.p.). and N-methyl atropine (30 mg/kg, i.p.) did not interfere with the effect of CTX. These results indicate that CTX induces a long-lasting antinociceptive effect in neuropathic pain, which is mediated by activation of central muscarinic receptors and partially, by activation of alpha-adrenoceptors and 5-HT receptors. Eicosanoids derived from the lipoxygenase pathway modulate the action of crotoxin. (C) 2008 Elsevier B.V. All rights reserved.

K-ATP(+) Channels-Independent Analgesic Action of Crotalus durissus cumanensis venom

The effect was investigated of the K+ channel blocker, glibenclamide, on the ability of Crotalus durissus cumanensis venom (CDCM) to promote peripheral antinociception. This was measured by formalin-induced nociception in male Swiss mice. CDCM (200 and 300 mu g/kg) produced an antinociceptive effect during phase 2 in the formalin test. The effect of CDCM (200 mu g/kg) was unaffected by the ATP-sensitive K+ channel blocker glibenclamide (2 mg/kg). These results suggest that CDCM is effective against acute pain. However, the ATP-sensitive K+ channels pathway is not contributable to the antinoeiceptive mechanism of CDCM.