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Cisplatin and other widely employed platinum-based anticancer agents produce chemotherapy-induced peripheral neuropathy (CIPN) that often results in pain and hyperalgesia that are difficult to manage. We investigated the efficacy of a novel bivalent ligand, MCC22, for the treatment of pain arising from CIPN. MCC22 consists of mu opioid receptor (MOR) agonist and chemokine receptor 5 (CCR5) antagonist pharmacophores connected through a 22-atom spacer and was designed to target a putative MOR-CCR5 heteromer localized in pain processing areas. Mice received once daily intraperitoneal (i.p.) injections of cisplatin (1 mg/kg) for seven days and behavior testing began 7 days later. Cisplatin produced mechanical hyperalgesia that was decreased dose-dependently by MCC22 given by intrathecal (ED = 0.004 pmol) or i.p. (3.07 mg/kg) routes. The decrease in hyperalgesia was associated with decreased inflammatory response by microglia in the spinal cord. Unlike morphine, MCC22 given daily for nine days did not exhibit tolerance to its analgesic effect and its characteristic antihyperalgesic activity was fully retained in morphine-tolerant mice. Furthermore, MCC22 did not alter motor function and did not exhibit rewarding properties. Given the exceptional potency of MCC22 without tolerance or reward, MCC22 has the potential to vastly improve management of chronic pain due to CIPN.
The trigeminal autonomic cephalalgias (TACs) are a group of primary headache syndromes all marked by unilateral headache and ipsilateral cranial autonomic features. The TACs include cluster headache, paroxysmal hemicrania, short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing, and hemicrania continua. Pathophysiology includes the trigeminal pain system, autonomic system, hypothalamus, and more recently an identified role for the vagus nerve. Diagnosis is made after looking at headache frequency, duration, and accompanying symptoms. Each TAC has its own unique treatment, which is discussed in depth.
Sickle cell disease (SCD) is one of the most common severe genetic diseases around the world. A majority of SCD patients experience intense pain, leading to hospitalization, and poor quality of life. Opioids form the bedrock of pain management, but their long-term use is associated with severe side effects including hyperalgesia, tolerance and addiction. Recently, excellent research has shown some new potential mechanisms that underlie SCD-associated pain. This review focused on how transient receptor potential vanilloid 1, endothelin-1/ endothelin type A receptor, and cannabinoid receptors contributed to the pathophysiology of SCD-associated pain. Understanding these mechanisms may open a new avenue in managing SCD-associated pain and improving quality of life for SCD patients.
To identify structural changes in the brain regions of patients with vestibular migraine (VM) so as to better understand its pathophysiology.
Alexithymia refers to reduced emotional awareness and is associated with higher levels of burden and disability in adults with chronic pain. Limited research has examined alexithymia in adolescents with chronic pain. The current study aimed to (a) determine whether alexithymia was higher in adolescents with (vs. without) chronic pain and (b) examine the relationship between alexithymia and pain experiences in youth. Research Method/Design: We assessed alexithymia in 22 adolescents with chronic pain and in 22 adolescents without chronic pain (otherwise healthy), and its relation to pain experiences (i.e., self-reported pain intensity, pain bothersomeness, and pain interference), while controlling for the concomitant effects of psychological distress (i.e., depressive and anxiety symptoms).
Nociceptive trigeminal afferents innervating craniofacial area, e.g. facial skin and cranial meninges, project to a broad region in the medullary and upper cervical dorsal horn designated as the trigeminocervical complex. Lamina I neurons in the trigeminocervical complex integrate and relay peripheral inputs, thus playing a key role in both cranial nociception and primary headache syndromes. Because of the technically challenging nature of recording, the long-range trigeminal afferent inputs to the medullary and cervical lamina I neurons were not intensively studied so far. Therefore, we have developed an ex vivo brainstem-cervical cord preparation with attached trigeminal nerve for the visually-guided whole-cell recordings from the medullary and cervical lamina I neurons. Two-thirds of recorded neurons generated intrinsic rhythmic discharges. The stimulation of the trigeminal nerve produced a complex effect; it interrupted the rhythmic discharge for hundreds of milliseconds but, if the neuron was silenced by a hyperpolarizing current injection, could elicit a discharge. The monosynaptic inputs from the trigeminal Aδ-, high-threshold-Aδ-, low-threshold-C- and C-afferents were recorded in the medullary neurons, as well as in the cervical neurons located in the segments C1-C2 and, to lesser degree, in C3-C4. This pattern of supply was consistent with our labelling experiments showing extensive cervical projections of trigeminal afferents. Excitatory inputs were mediated, although not exclusively, via AMPA/kainate and NMDA receptors, while inhibitory inputs via both GABA and glycine receptors. In conclusion, the trigeminocervical lamina I neurons receive a complex pattern of long-range mono- and polysynaptic inputs from a variety of the trigeminal nociceptive afferents.
To investigate whether treatment by lactic acid bacteria for 100 days is associated with change of disability and pain in chronic low back pain (CLBP) patients with type 1 or mixed Modic changes (MC) during 1-year follow-up.
Treatment of cancer‑induced bone pain (CIBP) is challenging in clinical settings. Oxycodone (OXY) is used to treat CIBP; however, a lack of understanding of the mechanisms underlying CIBP limits the application of OXY. In the present study, all rats were randomly divided into three groups: The sham group, the CIBP group, and the OXY group. Then, a rat model of CIBP was established by inoculation of Walker 256 tumor cells from rat tibia. Phosphoproteomic profiling of the OXY‑treated spinal dorsal cords of rats with CIBP was performed, and 1,679 phosphorylated proteins were identified, of which 160 proteins were significantly different between the CIBP and sham groups, and 113 proteins were significantly different between the CIBP and OXY groups. Gene Ontology analysis revealed that these proteins mainly clustered as synaptic‑associated cellular components; among these, disks large homolog 3 expression was markedly increased in rats with CIBP and was reversed by OXY treatment. Subsequent domain analysis of the differential proteins revealed several significant synaptic‑associated domains. In conclusion, synaptic‑associated cellular components may be critical in OXY‑induced analgesia in rats with CIBP.