No abstract

The term 'neurogenic inflammation' refers to a series of proinflammatory responses produced by the stimulation of peripheral terminals of a subset of primary sensory neurons and the subsequent release of the neuropeptides, calcitonin gene-related peptide (CGRP) and the tachykinins, substance P (SP) and neurokinin A (NKA) [1]. The neurons that produce inflammation comprise a heterogeneous cell population with A-delta and C fibres, defined as polymodal nociceptors because they sense thermal, chemical and high-threshold mechanical stimuli. These neurons express on their plasma membrane a large panel of excitatory and inhibitory receptors and channels, and some of these signalling proteins have been successfully used as targets for analgesic or anti-inflammatory drugs. Among the channels expressed on peptidergic primary sensory neurons, transient receptor potential vanilloid-1 (TRPV1) [2], activated by the xenobiotic capsaicin, the pungent ingredient of plants of the genus Capsicum, is of paramount importance. Capsaicin produces burning pain by stimulating TRPV1 and by releasing sensory neuropeptides causes neurogenic inflammation. However, high concentrations/doses of capsaicin have the ability, after an initial excitatory phase, to desensitise the sensory nerve terminals, thus reducing the transmission of sensory/pain signals and abolishing neurogenic inflammation [3, 4]. This specific feature of capsaicin has greatly contributed to define the role of this subset of sensory nerves in pathophysiological models of human diseases and has been Pierangelo Geppetti Jay Guido Capone Marcello Trevisani Paola Nicoletti Giovanni Zagli Maria Rosalia Tola Abstract For more than a century neurogenic inflammation has been proposed to have a role in various human diseases. The present review will cover the conceptual steps of the itinerary that has led to the conclusion that neurogenic inflammation is important in migraine. Of particular relevance for the object of this article is the observation that tachykinindependent neurogenic inflammatory responses are evident in rodents, but much less pronounced or absent in other mammal species, including man, whereas neurogenic vasodilatation, most likely mediated by CGRP, occurs in most mammalian species and also in man. Recent evidence that a CGRP receptor antagonist was effective in the treatment of migraine attack supports the hypothesis that neurogenic vasodilatation is a major underlying mechanism of migraine.

The effect of Botulinum Toxin type A (BoNT/A) on pain and neurogenic vasodilatation induced by application to the human skin of thermal stimuli and capsaicin was evaluated in a double blind study. A capsaicin cream (0.5 ml of a 0.075%) was applied to the skin of both forearms of eighteen subjects randomly pretreated with either BoNT/A (Botox Ò ) or 0.9% saline (NS). Capsaicin was applied to a skin area either inside (protocol A) or adjacent to the BoNT/A treated area (protocol B). Pre-treatment with BoNT/A did not affect thermal-specific and thermal-pain thresholds (by quantitative sensory testing). However, capsaicin-induced pain sensation (by a visual analogue scale), flare area (by acetate sheet) and changes in cutaneous blood flow (CBF, by laser Doppler flowmetry) were reduced when capsaicin was administered inside (protocol A) the BoNT/A treated area. In Protocol B, capsaicininduced pain was unchanged, and capsaicin-induced flare/increase in CBF were reduced only in the area treated with BoNT/A, but not in the BoNT/A untreated area. Results indicate that (i) BoNT/A reduces capsaicin-induced pain and neurogenic vasodilatation without affecting the transmission of thermal and thermal-pain modalities; (ii) reduction in capsaicin-induced pain occurs only if capsaicin is administered into the BoNT/A pretreated area; (iii) reduction in neurogenic vasodilatation by BoNT/A does not contribute to its analgesic action. BoNT/A could be tested for the treatment of conditions characterised by neurogenic inflammation and inflammatory pain. Ó

Ethanol stimulating transient receptor potential vanilloid 1 (TRPV1) on primary sensory neurons promotes neurogenic inflammation, including calcitonin generelated peptide (CGRP)-mediated coronary dilation. Alcoholic beverages trigger migraine attacks and activation of trigeminal neurons plays a role in migraine. We have investigated in guinea pigs whether ethanol by TRPV1 stimulation causes neurogenic inflammation in the trigeminovascular system. Ethanolevoked release of neuropeptides from slices of dura mater was abolished by Ca 2+ removal, capsaicin pretreatment and the TRPV1 antagonist, capsazepine. Intragastric ethanol increased plasma extravasation in dura mater, an effect abolished by capsazepine and the NK1 receptor antagonist, SR140333, and caused vasodilation around the middle meningeal artery, an effect abolished by capsazepine and the CGRP receptor antagonist, BIBN4096BS. Vasodilation of meningeal vessels by TRPV1 activation and CGRP release may be relevant to the mechanism by which alcohol ingestion triggers migraine attacks. ᮀ BIBN4096BS, CGRP, dural neurogenic vasodilation, ethanol, TRPV1

Many studies confirmed the efficacy and safety of continuous infusion of intrajejunal levodopa/carbidopa gel (CIILG) for advanced Parkinson's disease (PD). Although this treatment is widely used, definite inclusion/exclusion criteria do not exist. In this prospective open-label study, we evaluated the long-term outcome in 28 consecutive patients and sought to detect any predictive factor to identify the best candidates for CIILG therapy. The assessment was carried out routinely at baseline, after 6 months and every year with UPDRS III-IV, FOG Questionnaire, non-motor symptoms scale, PD questionnaire (PDQ-8), cognitive and psychiatric status evaluation (MMSE, FAB, NPI) and caregiver's quality of life. 17/28 patients reached the 24-month follow-up. A statistically significant beneficial effect was shown on motor complications in short- and long-term follow-up, also on axial symptoms like gait disturbances. A concomitant improvement in PDQ8 score was observed, with a parallel mild amelioration, but not significant, on Caregivers QoL. When classified according to their outcome on QoL, the only predictive positive factor was less severe at Neuropsychiatric Inventory (NPI) score at baseline. Considering the improvement in motor scores (duration of "off" period), the more advanced age was associated with a poorer outcome. Our results confirmed a sustained efficacy and safety in long-term follow-up and suggest that younger age at operation and absence or mild presence of psychiatric/behavioural symptoms could be considered valid predicting factors in selecting the best candidates for this efficacious therapy.