Analgesic effect of baclofen (beta-p-chlorofenil GABA) in experimental neuropathic pain

Santos, Terezinha de Jesus Teixeira

doi:10.1590/s0004-282x1996000400028

Cited by 2 publications

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“…This effect involved the GABA system and not the opioid system, and this corroborated findings of other authors 24 . Santos 29 has also reported similar results with baclofen, a gabaergic agent.…”

Section: Discussionmentioning

confidence: 55%

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Possible analgesic effect of vigabatrin in animal experimental chronic neuropathic pain

Alves

Castro-Costa

Carvalho

et al. 1999

Arq. Neuro-Psiquiatr.

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-Since anticonvulsants have been used for treating neuralgias, an interest has arisen to experimentally test vigabatrin for its gabaergic mechanism of action. For this, 41 Wistar rats were used, and in 25 of them a constrictive sciatic neuropathy was induced (Bennet & Xie model). For testing pain symptoms, spontaneous (scratching) and evoked behaviors to noxious (46 o C) and non-noxious (40 o C) thermal stimuli were quantified. Moreover, a comparative pharmacological study of vigabatrin with other analgesic anticonvulsant drugs was also performed. The results showed a possible dose-dependent analgesic effect of vigabatrin (gamma-vinyl-GABA) on experimental neuropathic pain, as shown by the significant (p<0.05) decreasing effect of vigabatrin on scratching and by its significant (p<0.05) increasing effect on the latency of the right hindpaw withdrawal of the animals to noxious thermal stimulus. This was corroborated by similar findings with analgesic anticonvulsants (carbamazepine, phenytoin and valproic acid). This possible and not yet described analgesic effect of vigabatrin seems not to be opioid mediated.KEY WORDS: vigabatrin, experimental, neuropathic pain, scratching behavior, thermal tests, Wistar rats, analgesia. Possível efeito analgésico da vigabatrina na dor neuropática crônica experimental animalRESUMO -O uso de anticonvulsivantes no tratamento de neuralgias despertou um interesse em testar novas drogas anticonvulsivantes, e dentre essas a vigabatrina por possuir mecanismo de ação gabaérgico. Para isso, foram usados 41 ratos Wistar e em 25 deles induziu-se neuropatia ciática constritiva (modelo de Bennett & Xie). Para testar sintomas de dor, foram quantificados comportamentos espontâneos (coçar-se) e evocados, por meio de estímulos térmicos nocivos (46 o C) e não-nocivos (40 o C). Além disso, realizou-se estudo comparativo da vigabatrina com outros anticonvulsivantes analgésicos. Os resultados mostraram um possível efeito analgésico, dose-dependente, de vigabatrina (gama-vinil-GABA) em dor neuropática experimental. Isso foi evidenciado pela diminuição significativa (p<0,05) do comportamento de coçar-se e pelo aumento significativo (p<0,05) da latência de retirada da pata posterior direita a estímulos térmicos nocivos. Isso foi corroborado por achados semelhantes em experimentos com anticonvulsivantes (carbamazepina, fenitoína e ácido valpróico) analgésicos. Esse possível efeito analgésico da vigabatrina (ainda não descrito na literatura) não é mediado pelo sistema opióide. PALAVRAS-CHAVE: vigabatrina, experimental, dor neuropática, comportamento de coçar-se, testes térmicos, ratos Wistar, analgesia.The treatment of chronic neuropathic pain is varied and only partially effective 1 . Davies et al.2 have reported on the use of anticonvulsant and antidepressive drugs in the treatment of chronic neuropathic pain. The anticonvulsant drugs are able of reverting or avoiding seizures. These drugs act by decreasing the neuronal response to seizures-inducing stimuli. Since it is known that in neuropathi...

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Section: Discussionmentioning

confidence: 55%

“…Other drugs corroborate the antinociceptive effect of GABA. The baclofen (β-p-chlorophenyl-GABA), for instance, has been used in the treatment of trigeminal neuralgia 25 , atypical facial pain 26 , diabetic neuropathy 27 , central pain 28 and experimental neuropathic pain 29 .…”

Section: Discussionmentioning

confidence: 99%

Possible analgesic effect of vigabatrin in animal experimental chronic neuropathic pain

Alves

Castro-Costa

Carvalho

et al. 1999

Arq. Neuro-Psiquiatr.

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Behavioral changes of Wistar rats with experimentally-induced painful diabetic neuropathy

D'Almeida

Castro-Costa

Frota³

et al. 1999

Arq. Neuro-Psiquiatr.

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-With the purpose of studying data on spontaneous customary changes in diabetic rats, we induced diabetes in 28 Wistar rats with streptozotocin. The animals were observed for 27 weeks in an attempt to characterize spontaneous customary changes that could suggest signs of chronic pain. Morphine, as a central-acting potent analgesic and its specific antagonist naloxone, were used. Our results evidenced in the animals a clinical syndrome similar to human diabetes. Long-term customary analysis revealed a significant (p<0.05) increase of scratching and resting/sleeping behaviors, but diminished motor, eating and grooming customs. Moreover, the thermal tests revealed hyperalgesia in 43% of the animals, what may corroborate the meaning of scratching as a sign of pain. Pharmacological tests with morphine showed a significant (p<0.05) inhibition of scratch, with concomitant increase of motor and eating activities and diminished rest/sleep capacity. Naloxone antagonized the effects induced by morphine. Such results suggest that these animals exhibit evoked behavior of hyperalgesia and that scratch may possibly be a spontaneous manifestation of chronic pain also in Wistar rats with this experimental model of painful diabetic neuropathy.KEY WORDS: chronic pain, painful neuropathy, experimental diabetic neuropathy, spontaneous scratching behavior, morphine, naloxone, long-term profile. Mudança do comportamento de ratos Wistar no modelo experimental de neuropatia diabética dolorosaRESUMO -Com o objetivo de estudar dados sobre mudança de comportamento em ratos com neuropatia diabética dolorosa, induzimos diabetes em 28 ratos Wistar com estreptozotocina. Os animais foram então observados ao longo de 27 semanas com o propósito de caracterizar mudanças espontâneas em seus hábitos que pudessem sugerir sinais de dor crônica. Morfina como um potente analgésico de ação central e seu antagonista específico naloxona foram utilizados. Nossos resultados evidenciaram nos animais uma síndrome clínica semelhante ao diabetes humano (poliúria, catarata, perda de peso, neuropatia sensitivo-motora de predomínio distal). A análise comportamental revelou aumento dos comportamentos de coçar-se e descansar/dormir, e diminuição das atividades motoras e hábitos de comer e limpar-se. Além disso, os testes térmicos revelaram sinais de hiperalgesia em 43% desses animais, o que corrobora o significado de coçar-se como sinal de dor. Os testes farmacológicos com morfina evidenciaram inibição significativa (p<0,05) no hábito de coçar-se, com aumento recíproco das atividades motoras e de alimentar-se, e diminuição do tempo de descansar/dormir. A naloxona antagonizou os efeitos da morfina. Tais resultados sugerem que esses animais exibiram comportamento evocado de hiperalgesia e que o hábito de coçar-se é possivelmente uma manifestação espontânea de dor crônica nesse modelo de neuropatia diabética dolorosa em ratos Wistar. PALAVRAS-CHAVE: dor crônica, neuropatia dolorosa, neuropatia diabética experimental, comportamento espontâneo de coçar-se, morfin...

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Analgesic effect of baclofen (beta-p-chlorofenil GABA) in experimental neuropathic pain

Cited by 2 publications

References 0 publications

Possible analgesic effect of vigabatrin in animal experimental chronic neuropathic pain

Possible analgesic effect of vigabatrin in animal experimental chronic neuropathic pain

Behavioral changes of Wistar rats with experimentally-induced painful diabetic neuropathy

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