Pain
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Migraine attacks are often preceded by premonitory symptoms (PS) that may be triggered pharmacologically. We investigated the incidence of PS after administration of calcitonin gene-related peptide (CGRP) or pituitary adenylate cyclase-activating peptide-38 (PACAP38) in patients with migraine without aura (MO) who reported and did not report migraine-like attacks induced by these pharmacological triggers. In addition, we investigated the association between PS and familial predisposition for migraine. ⋯ Additionally, we found no difference in PS between patients with familial predisposition of migraine (75%) and patients with no family predisposition (56%) (P = 0.101). In conclusion, CGRP did not induce PS, whereas PACAP38 induced PS in 48% of patients. However, CGRP and PACAP38 did not induce more PS in patients who developed an attack compared with those who did not develop an attack.
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Cannabinoids may hold potential for the management of rheumatic pain. Arthritis, often self-reported, is commonly cited as the reason for the use of medicinal herbal cannabis (marijuana). We have examined the prevalence of marijuana use among 1000 consecutive rheumatology patients with a rheumatologist-confirmed diagnosis and compared in an exploratory manner the clinical characteristics of medicinal users and nonusers. ⋯ Therefore, less than 3% of rheumatology patients reported current use of medicinal marijuana. This low rate of use in patients with a rheumatologist-confirmed diagnosis is in stark contrast to the high rates of severe arthritis frequently reported by medicinal marijuana users, especially in Canada. Familiarity with marijuana as a recreational product may explain use for some as disease status was similar for both groups.
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Rewards influence responses to acute painful stimuli, but the relationship of chronic pain to hedonic or motivational aspects of reward is not well understood. We independently evaluated hedonic qualities of sweet or bitter tastants and motivation to seek food reward in rats with experimental neuropathic pain induced by L5/6 spinal nerve ligation. Hedonic response was measured by implantation of intraoral catheters to allow passive delivery of liquid solutions, and "liking/disliking" responses were scored according to a facial reactivity scale. ⋯ However, rats with inflammation showed decrements in lever pressing and break points on days 1 and 2 after complete Freund adjuvant injection that normalized by day 4, consistent with transient ongoing pain. Thus, although acute ongoing inflammatory pain may transiently reduce reward motivation, we did not detect influences of chronic neuropathic pain on hedonic or motivational responses to food rewards. Adaptations that allow normal reward responding to food regardless of chronic pain may be of evolutionary benefit to promote survival.
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Migraine is one of the most common and most disabling disorders. Between attacks, migraine patients are otherwise normal but are sensitized to nonnoxious events known as triggers. The purpose of these studies was to investigate whether a headache-like event causes sensitization, or priming, to subsequent subthreshold events. ⋯ Finally, hind paw IL-6 produced paw allodynia but not priming to paw injection of pH 7.0 at 72 hours demonstrating differences in priming depending on location. These data indicate that afferent input from the meninges produces BDNF-dependent priming of the dural nociceptive system. This primed state mimics the interictal period of migraine where attacks can be triggered by normally nonnoxious events and suggests that BDNF-dependent plasticity may contribute to migraine.