Various folk remedies employ certain odorous compounds with analgesic effects. In fact, linalool, a monoterpene alcohol found in lavender extracts, has been found to attenuate pain responses via subcutaneous, intraperitoneal, intrathecal, and oral administration. However, the analgesic effects of odorous compounds mediated by olfaction have not been thoroughly examined. We performed behavioural pain tests under odourant vapour exposure in mice. Among six odourant molecules examined, linalool significantly increased the pain threshold and attenuated pain behaviours. Olfactory bulb or epithelium lesion removed these effects, indicating that olfactory sensory input triggered the effects. Furthermore, immunohistochemical analysis revealed that linalool activated hypothalamic orexin neurons, one of the key mediators for pain processing. Formalin tests in orexin neuron-ablated and orexin peptide-deficient mice showed orexinergic transmission was essential for linalool odour-induced analgesia. Together, these findings reveal central analgesic circuits triggered by olfactory input in the mammalian brain and support a potential therapeutic approach for treating pain with linalool odour stimulation.
Transient receptor potential ankyrin 1 (TRPA1), a member of the TRP superfamily, exists in sensory neurons such as trigeminal neurons innervating the nasal cavity and vagal neurons innervating the trachea and the lung. Although TRPA1 has been proposed as an irritant receptor that, when stimulated, triggers bradypnea, precise locations of the receptors responsible have not been elucidated. Here, we examined the relative importance of TRPA1 located in the upper airway (nasal) and the lower airway (trachea/lungs) in urethane‐anesthetized mice. To stimulate the upper and lower airways separately, two cannulas were inserted through a hole made in the trachea just caudal to the thyroid cartilage, one into the nasal cavity and the second into the lower trachea. A vapor of one of the TRPA1‐agonists, allyl isothiocyanate (AITC), was introduced by placing a piece of cotton paper soaked with AITC solution into the airline. AITC decreased the respiratory frequency when applied to the upper airway (ca −30%) but not to the lower airway (ca −5%). No response was observed in TRPA1 knockout mice. Contribution of the olfactory nerve seemed minimal because olfactory bulbectomized wild‐type mice showed a similar response to that of the intact mice. AITC‐induced bradypnea seemed to be mediated, at least in part, by the trigeminal nerve because trigeminal ganglion neurons were activated by AITC as revealed by an increase in the phosphorylated form of extracellular signal‐regulated kinase in the neurons. These data clearly show that trigeminal TRPA1 in the nasal cavity play an essential role in irritant‐induced bradypnea.
Background Cancer pain management in children is challenging owing to their unique patient characteristics. We present the case of a 10-year-old girl whose cancer pain was successfully managed using an intrathecal neurolytic block. Case presentation The patient experienced severe cancer pain due to recurrent right ilium osteosarcoma. The tumor progressed rapidly despite chemoradiotherapy and gradually invaded the right lumbar plexus, which resulted in severe neuropathic pain in the right lower extremity. Systemic analgesics failed to attenuate the pain. We performed an intrathecal neurolytic block using 10% phenol-glycerol. The neurolytic block completely relieved her right lower extremity pain. After the block, the patient’s quality of life improved, and she spent her time with family. Conclusions The intrathecal neurolytic block successfully relieved the patient’s cancer pain. Successful intrathecal neurolytic blocks require meticulous pain assessment of individual patients, to avoid possible serious complications such as paresis/paralysis and bladder/bowel dysfunction.
Six specimens (48.1-75.1 mm standard length) of Opistognathus solorensis Bleeker, 1853, previously recorded from Palau, Papua New Guinea, Timor Leste, Indonesia, Brunei, the Philippines and Taiwan, were collected from the Osumi Islands, southern Japan. The specimens, which are described and compared with previous reports, represent the first records of the species from Japanese waters, a Tanega-shima island specimen being the northernmost known record of the species. The new standard Japanese name "Hoshikage-ago-amadai" is proposed for the species.
A single specimen (31.6 mm standard length) of Plectranthias fourmanoiri Randall, 1980, previously known from Christmas Island (western Indian Ocean) and from the Mariana Islands south to Indonesia and east to the Pitcairn Islands (Pacific Ocean), was collected from Yoron-jima island, Ryukyu Islands, Japan. A full description is given and comparisons made. The specimen represents the first record of P. fourmanoiri from Japan and northernmost record of the species.
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