Delayed aversive effects of high-dose fentanyl

Tolerance and efficacy of a polyamine-deficient diet for the treatment of perioperative pain

BACKGROUND

Polyamines have been identified as pain agonists and interact with N-methyl-D-aspartate receptors. A prospective, randomized, multicenter, and blinded phase II clinical trial was conducted to evaluate a polyamine-deficient diet for the treatment of perioperative pain in patients during spinal surgery.

METHODS

All analyses followed the intention-to-treat principle. The trial was designed to evaluate the dose-ranging effect of a low polyamine diet with respect to a total (group 1) or partial (group 2) polyamine diet on perioperative pain (7 d before and 5 d after surgery). Pain (numerical scale at rest and motion), quality of life questionnaires (Brief Pain Inventory, EIFEL questionnaire, and Short Form-12 acute questionnaire), and tolerance of and compliance with the nutritional program were measured.

RESULTS

Compliance (preoperatively: 100% in group 1 and 83% in group 2; postoperatively: 83% in group 1 and 71% in group 2) and tolerance were good. After 7 d following the diet before surgery, decreased pain was observed in group 1 whereas no effect was observed in group 2 (P = 0.144). This analgesic effect became significant in group 1 in the subgroup of patients with initial high levels of pain (NS ≥ 4) at rest (P = 0.03) and during motion (P = 0.011). Quality of life was significantly improved in group 1 (P = 0.0465). In the postoperative period, pain was significantly decreased in group 1 compared to group 2 at rest (P = 0.022) and during motion (P = 0.029). The effect was significantly better on patients with higher initial pain both at rest (P = 0.013) and during motion (P = 0.005) in group 1 compared to group 2.

CONCLUSION

Suppression of polyamines from the diet offers a nutrition-based treatment option for perioperative pain reduction independent of and complementary to typical analgesic approaches.

A polyamine-deficient diet opposes hyperalgesia, tolerance and the increased anxiety-like behaviour associated with heroin withdrawal in rats

In humans, hyperalgesia, tolerance and anxiety disorders are common symptoms during heroin withdrawal syndrome. Significant evidence supports a role of NMDA receptors in these phenomena. Because polyamines may positively modulate the functioning of NMDA receptors and mainly originate from dietary intake, one hypothesis is that a polyamine deficient diet (PD diet) may reduce withdrawal symptoms. To address this question, we investigated the ability of a PD diet to prevent or to alleviate some symptoms of withdrawal syndrome as hyperalgesia, and increased anxiety-like behaviour in rats receiving 14 once daily subcutaneous heroin injections. Here, we show that a PD diet has both preventive and curative properties for reducing certain signs of withdrawal such as hyperalgesia, tolerance and increased anxiety-like behaviour observed in rats fed with a standard diet. Moreover, in heroin-withdrawn rats which were returned to basal pain sensitivity level, hyperalgesia following acute analgesia induced by a single heroin dose was observed in heroin-treated rats fed with standard diet, not in rats fed with a PD diet. Similarly, a stress-induced hyperalgesia induced by a non-nociceptive environmental stress session was observed in heroin-treated rats fed with standard diet. In contrast, a stress-induced analgesia was observed in heroin-treated rats fed with a PD diet, as it was observed in non heroin-treated rats. Since a PD diet for several weeks did not induce appreciable side-effects in rats, these preclinical results suggest that a PD diet could be an effective strategy for improving the relief of certain negative emotional states of heroin withdrawal syndrome and to allow reducing other medications generally used, such as opioid maintenance drugs.

Episodic withdrawal promotes psychomotor sensitization to morphine

The relative intermittency or continuity of drug delivery is a major determinant of addictive liability, and also influences the impact of drug exposure on brain function and behavior. Events that occur during the offset of drug action (ie, acute withdrawal) may have an important role in the consequences of intermittent drug exposure. We assessed whether recurrent episodes of acute withdrawal contribute to the development of psychomotor sensitization in rodents during daily morphine exposure. The acoustic startle reflex--a measure of anxiety induced by opiate withdrawal-was used to resolve and quantify discrete withdrawal episodes, and pharmacological interventions were used to manipulate withdrawal severity. Startle potentiation was observed during spontaneous withdrawal from a single morphine exposure, and individual differences in initial withdrawal severity positively predicted the subsequent development of sensitization. Manipulations that reduce or exacerbate withdrawal severity also produced parallel changes in the degree of sensitization. These results demonstrate that the episodic experience of withdrawal during daily drug exposure has a novel role in promoting the development of psychomotor sensitization--a prominent model of drug-induced neurobehavioral plasticity. Episodic withdrawal may have a pervasive role in many effects of intermittent drug exposure and contribute to the development of addiction.

Distinct profiles of anxiety and dysphoria during spontaneous withdrawal from acute morphine exposure

The negative motivational aspects of withdrawal include symptoms of both anxiety and depression, and emerge after termination of chronic drug use as well as after acute drug exposure. States of acute withdrawal are an inherent part of intermittent drug use in humans, but the contribution of acute withdrawal to the development of addiction has received limited systematic investigation, because of a lack of preclinical models for withdrawal states that emerge spontaneously after acute drug exposure. Here, we have characterized a spontaneous increase in the magnitude of the acoustic startle reflex (ie, spontaneous withdrawal-potentiated startle) that emerges after acute morphine administration in rats, and compared the time course of startle potentiation and place conditioning. We find that startle potentiation seems to be related to a decrease in opiate receptor occupancy and reflects an anxiety-like state with a pharmacological profile similar to other signs of opiate withdrawal. Spontaneous startle potentiation emerges before the rewarding effects of morphine have subsided, even though naloxone administration after a single morphine exposure causes both startle potentiation and conditioned place aversion (CPA). These results show that negative emotional signs of withdrawal develop after just one exposure to morphine, and are likely a recurrent aspect of intermittent drug use that may contribute to the earliest adaptations underlying the development of addiction. Furthermore, the dissociation between spontaneous startle potentiation and CPA suggests anxiogenic and dysphoric manifestations of opiate withdrawal may be mediated by distinct neural mechanisms that are progressively engaged as withdrawal unfolds.