The roles of different subtypes of opioid receptors in mediating the nucleus submedius opioid-evoked antiallodynia in a neuropathic pain model of rats

The role of endogenous opioid neuropeptides in neurostimulation-driven analgesia

Due to the prevalence of chronic pain worldwide, there is an urgent need to improve pain management strategies. While opioid drugs have long been used to treat chronic pain, their use is severely limited by adverse effects and abuse liability. Neurostimulation techniques have emerged as a promising option for chronic pain that is refractory to other treatments. While different neurostimulation strategies have been applied to many neural structures implicated in pain processing, there is variability in efficacy between patients, underscoring the need to optimize neurostimulation techniques for use in pain management. This optimization requires a deeper understanding of the mechanisms underlying neurostimulation-induced pain relief. Here, we discuss the most commonly used neurostimulation techniques for treating chronic pain. We present evidence that neurostimulation-induced analgesia is in part driven by the release of endogenous opioids and that this endogenous opioid release is a common endpoint between different methods of neurostimulation. Finally, we introduce technological and clinical innovations that are being explored to optimize neurostimulation techniques for the treatment of pain, including multidisciplinary efforts between neuroscience research and clinical treatment that may refine the efficacy of neurostimulation based on its underlying mechanisms.

The influence of thiamin on the efficacy of pregabalin in rats with spinal nerve ligation (SNL)-induced neuropathic pain

OBJECTIVE

The thiamin is often used in the treatment of neuropathy, and pregabalin is often used to treat neuropathic pain. Our study examined the influence of thiamin on the efficacy of pregabalin in a rat model of spinal nerve ligation (SNL)-induced neuropathic pain.

METHODS

Sprague-Dawley male rats were randomly divided into six groups. The neuropathic pain-relieving properties were measured by plantar test, cold plate test, and hot plate test after administration of pregabalin (i.v) and/or thiamin (i.p) in SNL rats 14 days after operation.

RESULTS

In the therapy period, pregabalin, or thiamin alone all produced antinociceptive effects in rats with neuropathic pain. And combination treatment of thiamin and pregabalin resulted in an enhanced pain relief compared to the administration of pregabalin or thiamin alone.

CONCLUSION

Combination of thiamin and pregabalin produces an additive antinociceptive effect in neuropathic pain rats, this drug combination may offer a beneficial treatment option for neuropathic pain.

Opioids for persistent noncancer pain

This article concentrates on recent evidence about opioid analgesics for persistent noncancer pain. Evidence confirms that opioids are drugs with a definite risk of adverse events. Therefore, before prescribing opioids, careful consideration must be given to be certain that the intended benefit of a particular opioid merits its use despite the potential side effects and to determine if the co-prescription of other pharmacologic agents could reduce the risk of adverse events. Strong opioids should be reserved for patients who fail to respond to other lower-risk options and only after proper consideration is given to the long-term consequences of strong opioid use. Problems associated with opioids dictate that more efficacious and safer drugs need to be found.

Endogenous opiates and behavior: 2006

This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

Sedation in palliative care

PURPOSE OF REVIEW

Palliative sedation, the conscious induction of sleep in patients with a very short life expectancy who suffer intractable physical and existential distress, may offer the patient and his or her relatives a more peaceful dying. This technique is still subject to several ethical and medical controversies justifying a review of the recent literature on this subject.

RECENT FINDINGS

The available evidence consists of few prospective trials and mainly retrospectively collected case reports. Two guidelines are published in the period under review. The most important points stressed in these reviews are the careful information exchange with the patient, if possible, and his or her proxies, a gradually increased sedation allowing respite if possible to evaluate the effect of the sedation and the need for consultation with colleagues, preferentially physicians experienced in palliative care. Stopping artificial nutrition and hydration is a medical decision that should be taken after evaluation of the potential side effects and consultation with the patient and relatives.

SUMMARY

Palliative sedation may be considered for terminally ill patients who suffer intractable symptoms. Ideally it should be included in the patient's trajectory that has been described and discussed earlier when the disease was judged to be incurable. The main goal is to offer comfort.

Opioids for persistent noncancer pain

Opioids are extensively used in the management of all types of pain and their use is underpinned by extensive trial evidence and an abundance of practical experience. We are still amassing insight into how they achieve their pain-relieving effects, however, and this understanding becomes more complex as time progresses and shows that opioids are medications with complex and diverse central and peripheral nervous system effects. Despite the 200 years that have passed since the chemical isolation of morphine, every year brings new understanding of the mode of action, propensity to cause side effects, and appropriate clinical use of opioids. This article concentrates on this "new" evidence as disclosed by recent publications.