Chronic morphine reduces pain-related disability in a rodent model of chronic, inflammatory pain.

Abstract

Chronic pain is disabling, and the adverse effects of morphine are also disabling. The best way to assess the beneficial effects relative to the potential adverse effects of chronic morphine may be through the use of quantitative measures of functional disability in people and animals experiencing pain. If chronic morphine alleviates chronic pain and its beneficial analgesic effects outweigh whatever adverse effects it may produce, then it should reduce pain-related disability. Rats with adjuvant-induced arthritis were implanted with subcutaneous morphine pellets. Continuous morphine reduced pain-related disability in tasks motivated by food reward or shock avoidance throughout the 35 days of continuous administration--first, in tests that primarily assessed the function of the less severely affected forelimbs, and later, as the inflammation subsided, in tests more dependent on the function of the more severely affected hind limbs.

Cognitive Impairment in Patients with Chronic Neuropathic or Radicular Pain: An Interaction of Pain and Age

“…There was no effect of pain condition or pain-age interaction on the D-prime measure of attention in the CPT, contrary to previous findings of impaired attention in chronic pain (Eccleston, 1994; Grisart and Plaghki, 1999; Dick et al, 2002; Veldhuijzen et al, 2006; Dick and Rashiq, 2007; Oosterman et al, 2011) and pain-related attentional deficits in rodent models of chronic pain (Cain et al, 1997; Lindner et al, 1999; Millecamps et al, 2004; Boyette-Davis et al, 2008; Pais-Vieira et al, 2009; Kodama et al, 2011). A pain-age interaction effect was observed in the model for the number of false alarms (and for number of random responses, though this was just below the level of statistical significance).…”

“…Deficits in recognition memory have been observed previously in chronic pain (fibromyalgia) patients, independent of an interaction with age (Park et al, 2001). Recognition memory deficits have also been shown in rodent models of chronic pain (Cain et al, 1997; Lindner et al, 1999; Millecamps et al, 2004; Kodama et al, 2011). Thus, pain, or the interaction of pain with age, contributed to decreased IQ and deficits on specific subtests of memory.…”

Glucosamine Dose/Concentration-Effect Correlation in the Rat with Adjuvant Arthritis

“…Another indicator of AA progression is the reduced body weight gain rate ( Table 1) that is suggested to be due to the inability of reaching food because of the inflammatory condition. 39 Interestingly, GlcN at a lower dose than those demonstrating significant therapeutic benefits prevents this effect of AA in reducing the weight gain.…”

Impaired recognition memory and cognitive flexibility in the ratL5–L6 spinal nerve ligation model of neuropathic pain

“…However, the mechanisms by which pain affects cognition are still poorly understood. Recent research has demonstrated that cognitive deficits associated with chronic pain can be modelled in rodents [4][5][6][7][8][9][10][11][12][13][14], thus allowing for the neurobiological mechanisms underpinning this association to be investigated.…”