Articles: hyperalgesia.
-
Randomized Controlled Trial Clinical Trial
Dose-dependent effects of smoked cannabis on capsaicin-induced pain and hyperalgesia in healthy volunteers.
Although the preclinical literature suggests that cannabinoids produce antinociception and antihyperalgesic effects, efficacy in the human pain state remains unclear. Using a human experimental pain model, the authors hypothesized that inhaled cannabis would reduce the pain and hyperalgesia induced by intradermal capsaicin. ⋯ This study suggests that there is a window of modest analgesia for smoked cannabis, with lower doses decreasing pain and higher doses increasing pain.
-
Dysmenorrhoea patients experience intense visceral pain during menstruation. Recurrent and/or intense visceral pain can induce facilitation of somatic and visceral nociceptive processing which can lead to viscero-somatic (referred) and viscero-visceral hyperalgesia. Our aim was to study if dysmenorrhoea is associated with hypersensitivity in the referred somatic skin area or in the large bowel, i.e., viscero-visceral hyperalgesia. ⋯ There were no differences in compliance between the groups. These findings suggest that, despite the absence of overt gastro-intestinal symptoms or viscero-somatic sensitisation, dysmenorrhoea patients demonstrate intestinal hypersensitivity. This can be regarded as the result of centrally mediated viscero-visceral hyperalgesia due to recurrent intense menstrual pain.
-
Behavioural pharmacology · Nov 2007
Chronic forced swim stress inhibits ultra-low dose morphine-induced hyperalgesia in rats.
Ultra-low doses of morphine (UL-morphine) induce hyperalgesia, which is assumed to be mediated by stimulatory G proteins (G(alphas)) signaling pathway. G(alphas) pathway inhibition and chronic stress both attenuate development of tolerance to analgesic effect of morphine. This study evaluated the effect of chronic stress on UL-morphine-induced hyperalgesia to find out if chronic stress interacts with the G(alphas) signaling pathway. ⋯ Inhibition of UL-morphine hyperalgesia by chronic stress suggests that chronic stress interacts with the G(alphas) signaling pathway, which is responsible for UL-morphine-induced hyperalgesia. The absence of this effect in the ADX-rats or after repetitive dexamethasone administration demonstrates that hypothalamic-pituitary-adrenal (HPA) axis activation is necessary for controlling UL-morphine-induced hyperalgesia. Finally, the interaction of stress with the G(alphas) signaling pathway may provide an explanation for the inhibitory effect of stress on development of tolerance to the analgesic effect of morphine.
-
Endometriosis (ENDO) is a painful disorder defined by extrauteral endometrial growths. It is created in rats by autotransplanting pieces of uterus (which form cysts), or, for shamENDO, fat (no cysts). ENDO induces vaginal hyperalgesia, likely via central sensitization. ⋯ We predicted that the opposing influences of estradiol on ENDO- and OVX-induced hyperalgesia would cancel each other. As predicted, OVX had no effect on ENDO-induced hyperalgesia and estradiol replacement alleviated it. These results suggest that, in intact rats, ENDO-induced vaginal hyperalgesia is exacerbated by estradiol, and that different mechanisms underlie ENDO-induced versus OVX-induced vaginal hyperalgesia.
-
Improving rehabilitation after a severe tissue injury does not only require a reduction in pain, but also requires alleviation of negative affects, particularly anxiety. Although opioids remain unsurpassed analgesics to relieve moderate to severe pain, it has been shown that they also induce latent pain sensitization leading to long-lasting hyperalgesia via N-methyl-D-aspartate-(NMDA)-dependent pronociceptive systems. The present study evaluated the ability of nitrous oxide (N2O), a gas with NMDA antagonist properties, to prevent latent pain sensitization and long-term anxiety-like behavior (ALB) in rats with pain and opioid experiences. ⋯ Moreover, we provide first evidence that a high fentanyl dose induces long-term ALB 2 weeks after its administration. When associated with fentanyl, 50% N2O prevented such long-term ALB. These results suggest that a single exposure to N2O could improve post-injury pain management and facilitate rehabilitation especially when potent analgesics as opioids have to be used.