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

Abstract

-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...

Hypolocomotion, Asymmetrically Directed Behaviors (Licking, Lifting, Flinching, and Shaking) and Dynamic Weight Bearing (Gait) Changes are Not Measures of Neuropathic Pain in Mice

“…Abbreviations: CCI, chronic constriction injury; CST, complete sciatic transection; PSNL, partial sciatic nerve ligation; PST, partial sciatic transection; SNL, spinal nerve ligation. References (from top; only first author noted): D'Almeida, 1999 [16], Paccola, 2008 [61], Guttierez, 2008 [62], Mao, 1993 [63], DeLeo, 1994 [64], Vos, 1994 [65], Deseure, 2004 [66], Kupers, 1992 [67], Kupers, 1998 [18], Kawasaki, 2008 [12], Jin, 2008 [68], Robinson, 2005 [69], Dowdall, 2005 [53], Shimoyama, 2002 [70], Sato, 2001 [71], Decosterd, 1998 [72], Kim, 1997 [52], and Choi, 1994 [73]. …”

Behavioral indices of ongoing pain are largely unchanged in male mice with tissue or nerve injury-induced mechanical hypersensitivity

“…Animals occasionally display measurable signs of pain, such as flinching or guarding in some pain models, but this has proved hard to detect in persistent pain models [9,21,26,29,39,63]. Further, if the animal is indeed experiencing spontaneous pain similar to humans, there should be an impact on its daily life activity and affective state, behaviors we will herein refer to as “quality of life” measures.…”

Intrapancreatic Axonal Hyperbranching of Dorsal Root Ganglia Neurons in Chronic Pancreatitis Model Rats and its Relation to Pancreatic Pain

“…50 Furthermore, grooming behavior was significantly reduced in a rat model for painful diabetic neuropathy induced by streptozotocin treatment. 51 Other reports have also shown reduction of grooming behavior in chronic mild stress including food deprivation, water deprivation, crowding, change of cage mates, isolation, sleep deprivation, and soiling cage bedding and increase in grooming duration with administration of desipramine, an antidepressant. 52 These findings suggest that reduction of grooming behavior in WBN/Kob rats in the present study was induced by mild chronic pain rather than by acute pain.…”