Pain
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The objective of this study was to explore the relationship between suicidal ideation, suicidal attempts, depression and chronic abdominal pain in data gathered during a systematic epidemiologic survey, the Hispanic Health and Nutrition Examination Survey of the United States National Centre for Health Statistics. The material comprises data collected between 1982 and 1984 in samples of Hispanic groups in the United States. A sub-sample which initially comprised 5498 subjects had provided answers to questions concerning the thoughts about death, wishes to die, thoughts of committing suicide and suicide attempts, as well as information about complaints of chronic abdominal pain and responses to the Centre for Epidemiologic Studies Depression Scale (CES-D). ⋯ This was particularly evident in the Puerto Rican population of the United States where both rates were much increased compared with other Hispanic citizens. The present data are new, but no conclusion can be drawn concerning causality because they are cross-sectional. They indicate the importance of the link between chronic abdominal pain and depression in this population.
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Sensory abnormalities and changes in spontaneous behavior were examined after a photochemically induced ischemic lesion of the rat sciatic nerve. Male adult rats were anesthetized and the sciatic nerve was exposed. After the intravenous injection of a photosensitizing dye, erythrosin B, the exposed nerve was irradiated just proximal to the nerve trifurcation with light from an argon laser. ⋯ The incidence and severity of the behavioral changes are clearly dependent on the exposure time and are probably due to, at least in part, a demyelinaton. These results partly confirm previous data using a similar technique and suggest that this may represent a new animal model for peripheral neuropathy of ischemic origin. The advantages of the present model are its good reproducibility and the fact that the nerve injury can be easily quantified and graded.
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Noxious stimulation of the rat's face evokes intense face grooming with face wash strokes almost exclusively directed to the stimulated area (e.g. Clavelou et al., Neurosci. Lett., 14 (1989) 3263-3270). ⋯ Only formalin-injected rats displayed significantly more face grooming activity directed to the affected infraorbital nerve territory than unstimulated control rats. Non-painful sensory disturbances (especially mineral oil application) induced an initial bout of directed face grooming; this response was transient and short-lasting. These observations suggest that directed face grooming can be used as a sign of unilateral facial pain in freely moving rodents; unilateral non-painful facial sensory disturbances do not lead to intense and persistent directed face grooming.
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This study used streptozotocin (STZ; 50 mg/kg i.p.) diabetic rats and monitored weekly thermal and mechanical nociceptive thresholds for 8 weeks diabetes. Rats developed mechanical hyperalgesia as soon as 2 weeks after STZ injection. Thermal nociceptive threshold was not altered up to 8 weeks after STZ injection. ⋯ An increased release of glutamate and activation of the NMDA receptor, would maintain the hyperalgesic state. Reduced activity of both opioidergic and GABA(B)ergic inhibitory systems, might exacerbate the increased excitation thus contributing to the ongoing pain. It is suggested that NMDA receptor antagonists may constitute an alternative therapy for diabetic neuropathic pain.