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Search Results: 1 - 10 of 517289 matches for " Prado W.A. "
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Involvement of calcium in pain and antinociception
Prado, W.A.;
Brazilian Journal of Medical and Biological Research , 2001, DOI: 10.1590/S0100-879X2001000400003
Abstract: calcium ions are widely recognized to play a fundamental role in the regulation of several biological processes. transient changes in cytoplasmic calcium ion concentration represent a key step for neurotransmitter release and the modulation of cell membrane excitability. evidence has accumulated for the involvement of calcium ions also in nociception and antinociception, including the analgesic effects produced by opioids. the combination of opioids with drugs able to interfere with calcium ion functions in neurons has been pointed out as a useful alternative for safer clinical pain management. alternatively, drugs that reduce the flux of calcium ions into neurons have been indicated as analgesic alternatives to opioids. this article reviews the manners by which calcium ions penetrate cell membranes and the changes in these mechanisms caused by opioids and calcium antagonists regarding nociceptive and antinociceptive events.
Involvement of calcium in pain and antinociception
Prado W.A.
Brazilian Journal of Medical and Biological Research , 2001,
Abstract: Calcium ions are widely recognized to play a fundamental role in the regulation of several biological processes. Transient changes in cytoplasmic calcium ion concentration represent a key step for neurotransmitter release and the modulation of cell membrane excitability. Evidence has accumulated for the involvement of calcium ions also in nociception and antinociception, including the analgesic effects produced by opioids. The combination of opioids with drugs able to interfere with calcium ion functions in neurons has been pointed out as a useful alternative for safer clinical pain management. Alternatively, drugs that reduce the flux of calcium ions into neurons have been indicated as analgesic alternatives to opioids. This article reviews the manners by which calcium ions penetrate cell membranes and the changes in these mechanisms caused by opioids and calcium antagonists regarding nociceptive and antinociceptive events.
Anti-hyperalgesic effect of electroacupuncture in a model of post-incisional pain in rats
Oliveira, R.;Prado, W.A.;
Brazilian Journal of Medical and Biological Research , 2000, DOI: 10.1590/S0100-879X2000000800012
Abstract: electroacupuncture has been proposed to be a low cost and practical method that allows effective pain management with minimal collateral effects. in this study we have examined the effect of electroacupuncture against the hyperalgesia developed in a model of post-incisional pain in rats. a 1-cm longitudinal incision was made through the skin and fascia of the plantar region of the animal hind paw. mechanical hyperalgesia in the incision was evaluated 135 min after the surgery with von frey filaments. the tension threshold was reduced from 75 g (upper limit of the test) to 1.36 ± 0.36 g (mean ± sem) in control rats. it is shown that a 15-min period of electroacupuncture applied 120 min after surgery to the zusanli (st36) and sanyinjiao (sp6) points, but not to non-acupoints, produces a significant and long-lasting reduction of the mechanical hyperalgesia induced by the surgical incision of the plantar surface of the ipsilateral hind paw. the tension threshold was reduced from 75 to 27.6 ± 4.2 g in animals soon after the end of electroacupuncture. the mechanical threshold in this group was about 64% less than in control. electroacupuncture was ineffective in rats treated 10 min earlier with naloxone (1 mg/kg, ip), thus confirming the involvement of opioid mechanisms in the antinociceptive effects of such procedure. the results indicate that post-incisional pain is a useful model for studying the anti-hyperalgesic properties of electroacupuncture in laboratory animals.
Anti-hyperalgesic effect of electroacupuncture in a model of post-incisional pain in rats
Oliveira R.,Prado W.A.
Brazilian Journal of Medical and Biological Research , 2000,
Abstract: Electroacupuncture has been proposed to be a low cost and practical method that allows effective pain management with minimal collateral effects. In this study we have examined the effect of electroacupuncture against the hyperalgesia developed in a model of post-incisional pain in rats. A 1-cm longitudinal incision was made through the skin and fascia of the plantar region of the animal hind paw. Mechanical hyperalgesia in the incision was evaluated 135 min after the surgery with von Frey filaments. The tension threshold was reduced from 75 g (upper limit of the test) to 1.36 ± 0.36 g (mean ± SEM) in control rats. It is shown that a 15-min period of electroacupuncture applied 120 min after surgery to the Zusanli (ST36) and Sanyinjiao (SP6) points, but not to non-acupoints, produces a significant and long-lasting reduction of the mechanical hyperalgesia induced by the surgical incision of the plantar surface of the ipsilateral hind paw. The tension threshold was reduced from 75 to 27.6 ± 4.2 g in animals soon after the end of electroacupuncture. The mechanical threshold in this group was about 64% less than in control. Electroacupuncture was ineffective in rats treated 10 min earlier with naloxone (1 mg/kg, ip), thus confirming the involvement of opioid mechanisms in the antinociceptive effects of such procedure. The results indicate that post-incisional pain is a useful model for studying the anti-hyperalgesic properties of electroacupuncture in laboratory animals.
Comparison of pre- versus post-incision administration of intraplantar indomethacin and MK886 in a rat model of postoperative pain
Gaspar, A.F.;Prado, W.A.;
Brazilian Journal of Medical and Biological Research , 2007, DOI: 10.1590/S0100-879X2006005000136
Abstract: the amplification of pain long after the initial stimulus may be avoided if the treatment of pain is introduced before its initiation. however, conflicting evidence exists about the efficacy of such preemptive analgesia for the management of postoperative pain. this study compares the efficacy of intraplantar administration of indomethacin (a non-selective inhibitor of cyclooxygenase) and mk886 (an inhibitor of 5-lipoxygenase-activating protein), separately or in combination to produce preemptive analgesia in a model of surgical incisional pain in male wistar rats. all incised rats (5 to 6 rats per group) had allodynia at 2, 6, and 24 h after surgery as evaluated using von frey filaments. mk886, but not indomethacin (50 to 200 μg/paw), reduced the allodynia when injected either 1 h before or 1 h after surgery. the effect of preoperative mk886 (160 μg/paw) against incisional allodynia had a magnitude apparently similar to that produced by postoperative mk886. pre-, but not postoperative mk886 (80 μg/paw) reduced the allodynia but the effect was seen only at 6 h after surgery. in contrast, mk886 (40 μg/paw) intensified the allodynia observed 2 h after the incision either injected before or after surgery. mk886 or indomethacin alone did not provide preemptive analgesia in the model of incisional pain. in contrast, the combination of mk886 with indomethacin reduced the allodynia more effectively when used before than after surgery, thus fulfilling the criteria for preemptive analgesia. in conclusion, preoperative inhibition of the local generation of both prostaglandins and leukotrienes by surgical incision may be an alternative to provide preemptive analgesia.
Antinociceptive effect of intrathecal neostigmine evaluated in rats by two different pain models
Prado, W.A.;Gon?alves, A.S.;
Brazilian Journal of Medical and Biological Research , 1997, DOI: 10.1590/S0100-879X1997001000014
Abstract: the analgesic efficacy of cholinergic agonists and anticholinesterase agents has been widely recognized. the analgesic effect obtained by activating cholinergic mechanisms, however, seems to depend on the experimental pain model utilized for its evaluation. the antinociceptive effect of intraspinal neostigmine was examined in rats submitted concurrently to the tail flick and formalin tests. neostigmine (8.25 and 16.5 nmol) produced a dose-dependent antinociceptive effect in the tail flick test (a model of phasic pain) and reduced the first phase (phasic pain) of the animal response to formalin also in a dose-dependent manner. the second phase (tonic pain) of the response to formalin, however, was slightly reduced after a longer period of time only by the higher dose of the anticholinesterase. the effect of neostigmine was not significantly different when the drug was injected into rats submitted exclusively to the tail flick test. the second phase of the animal response to formalin was slightly reduced by neostigmine (8.25 nmol) and strongly inhibited by the higher dose of the anticholinesterase when injection was made after the first phase. we conclude that phasic and tonic pain can both be controlled by high doses of neostigmine. in addition, we show that inhibition by a lower dose of neostigmine of the formalin-induced phasic pain did not prevent the subsequent occurrence of tonic pain produced by the irritant
Antinociception induced by stimulating amygdaloid nuclei in rats: changes produced by systemically administered antagonists
Oliveira, M.A.;Prado, W.A.;
Brazilian Journal of Medical and Biological Research , 1998, DOI: 10.1590/S0100-879X1998000500013
Abstract: the antinociceptive effects of stimulating the medial (me) and central (ce) nuclei of the amygdala in rats were evaluated by the changes in the latency for the tail withdrawal reflex to noxious heating of the skin. a 30-s period of sine-wave stimulation of the me or ce produced a significant and short increase in the duration of tail flick latency. a 15-s period of stimulation was ineffective. repeated stimulation of these nuclei at 48-h intervals produced progressively smaller effects. the antinociception evoked from the me was significantly reduced by the previous systemic administration of naloxone, methysergide, atropine, phenoxybenzamine, and propranolol, but not by mecamylamine, all given at the dose of 1.0 mg/kg. previous systemic administration of naloxone, atropine, and propranolol, but not methysergide, phenoxybenzamine, or mecamylamine, was effective against the effects of stimulating the ce. we conclude that the antinociceptive effects of stimulating the me involve at least opioid, serotonergic, adrenergic, and muscarinic cholinergic descending mechanisms. the effects of stimulating the ce involve at least opioid, ?-adrenergic, and muscarinic cholinergic descending mechanisms.
Antinociception induced by stimulating amygdaloid nuclei in rats: changes produced by systemically administered antagonists
Oliveira M.A.,Prado W.A.
Brazilian Journal of Medical and Biological Research , 1998,
Abstract: The antinociceptive effects of stimulating the medial (ME) and central (CE) nuclei of the amygdala in rats were evaluated by the changes in the latency for the tail withdrawal reflex to noxious heating of the skin. A 30-s period of sine-wave stimulation of the ME or CE produced a significant and short increase in the duration of tail flick latency. A 15-s period of stimulation was ineffective. Repeated stimulation of these nuclei at 48-h intervals produced progressively smaller effects. The antinociception evoked from the ME was significantly reduced by the previous systemic administration of naloxone, methysergide, atropine, phenoxybenzamine, and propranolol, but not by mecamylamine, all given at the dose of 1.0 mg/kg. Previous systemic administration of naloxone, atropine, and propranolol, but not methysergide, phenoxybenzamine, or mecamylamine, was effective against the effects of stimulating the CE. We conclude that the antinociceptive effects of stimulating the ME involve at least opioid, serotonergic, adrenergic, and muscarinic cholinergic descending mechanisms. The effects of stimulating the CE involve at least opioid, -adrenergic, and muscarinic cholinergic descending mechanisms.
Antinociceptive effect of intrathecal neostigmine evaluated in rats by two different pain models
Prado W.A.,Gon?alves A.S.
Brazilian Journal of Medical and Biological Research , 1997,
Abstract: The analgesic efficacy of cholinergic agonists and anticholinesterase agents has been widely recognized. The analgesic effect obtained by activating cholinergic mechanisms, however, seems to depend on the experimental pain model utilized for its evaluation. The antinociceptive effect of intraspinal neostigmine was examined in rats submitted concurrently to the tail flick and formalin tests. Neostigmine (8.25 and 16.5 nmol) produced a dose-dependent antinociceptive effect in the tail flick test (a model of phasic pain) and reduced the first phase (phasic pain) of the animal response to formalin also in a dose-dependent manner. The second phase (tonic pain) of the response to formalin, however, was slightly reduced after a longer period of time only by the higher dose of the anticholinesterase. The effect of neostigmine was not significantly different when the drug was injected into rats submitted exclusively to the tail flick test. The second phase of the animal response to formalin was slightly reduced by neostigmine (8.25 nmol) and strongly inhibited by the higher dose of the anticholinesterase when injection was made after the first phase. We conclude that phasic and tonic pain can both be controlled by high doses of neostigmine. In addition, we show that inhibition by a lower dose of neostigmine of the formalin-induced phasic pain did not prevent the subsequent occurrence of tonic pain produced by the irritant
Antinociceptive potency of aminoglycoside antibiotics and magnesium chloride: a comparative study on models of phasic and incisional pain in rats
Prado, W.A.;Machado Filho, E.B.;
Brazilian Journal of Medical and Biological Research , 2002, DOI: 10.1590/S0100-879X2002000300017
Abstract: a close relationship exists between calcium concentration in the central nervous system and nociceptive processing. aminoglycoside antibiotics and magnesium interact with n- and p/q-type voltage-operated calcium channels. in the present study we compare the antinociceptive potency of intrathecal administration of aminoglycoside antibiotics and magnesium chloride in the tail-flick test and on incisional pain in rats, taken as models of phasic and persistent post-surgical pain, respectively. the order of potency in the tail-flick test was gentamicin (ed50 = 3.34 μg; confidence limits 2.65 and 4.2) > streptomycin (5.68 μg; 3.76 and 8.57) = neomycin (9.22 μg; 6.98 and 12.17) > magnesium (19.49 μg; 11.46 and 33.13). the order of potency to reduce incisional pain was gentamicin (ed50 = 2.06 μg; confidence limits 1.46 and 2.9) > streptomycin (47.86 μg; 26.3 and 87.1) = neomycin (83.17 μg; 51.6 and 133.9). the dose-response curves for each test did not deviate significantly from parallelism. we conclude that neomycin and streptomycin are more potent against phasic pain than against persistent pain, whereas gentamicin is equipotent against both types of pain. magnesium was less potent than the antibiotics and effective in the tail-flick test only.
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