Decrease in serotonin concentration in raphe magnus nucleus and attenuation of morphine analgesia in two mice models of neuropathic pain

Streptozotocin-induced diabetes progressively increases blood-brain barrier permeability in specific brain regions in rats

“…Clinical case reports cite an increased susceptibility to third nerve palsies in diabetics due to an increased prevalence of midbrain lesions and hemorrhaging (24,37). Furthermore, diabetes-induced lesions have been reported to attenuate morphine analgesia due to decreased serotonergic activity in the raphe magnus nucleus (48,55). Of particular interest in this investigation was the finding that other brain areas with greater cerebral flow were affected as diabetes progressed to 56 and 90 days.…”

Role of serotonin 5-HT1A and opioid receptors in the antiallodynic effect of tramadol in the chronic constriction injury model of neuropathic pain in rats

“…The release of 5-HT in the raphe nuclei is decreased in neuropathy (sciatic nerve ligation and diabetic neuropathy; Sounvoravong et al 2004). In contrast, in animals suffering from inflammation, it is increased (Palazzo et al 2004).…”

Effect of Magnesium Administration on Passive Avoidance Memory and Formalin-Induced Nociception in Diabetic Rats

“…Neuropathic pain is a chronic pain manifested by a change in pain nociception, accelerated feeling of pain in response to painful stimuli (hyperalgesia), and abnormal painful sensitivity to those stimuli that were not painful earlier (allodynia) [23]. In an acute thermal test for pain processing, which involved measurement of pain threshold through tail flick latency, it was shown that oral magnesium administration prevents thermal hyperalgesia induced by diabetes in rats [24].…”