Serotonin and Dopamine Show Different Response Profiles to Acute Stress in the Nucleus Accumbens and Medial Prefrontal Cortex of Rats with Neuropathic Pain

State-of-the-Art Personalized Therapy Approaches for Chronic Non-Specific Low Back Pain: Understanding the Mechanisms and Drivers

Chronic non-specific low back pain (CNSLBP) is a debilitating condition that affects millions of people worldwide, significantly impacting quality of life and imposing a substantial socioeconomic burden. Traditional treatment approaches often rely on a one-size-fits-all strategy, failing to account for individual variations in pathophysiological mechanisms, drivers, and the principles of personalized medicine. Furthermore, an overemphasis on biomechanical findings from imaging may lead to ineffective interventions and unnecessary surgical procedures, obscuring other important factors that contribute to pain perception. While highlighting the limitations of universal treatment approaches, in this review we present a practical clinical approach aimed at elucidating the main pathophysiological mechanisms and various factors underlying the development and maintenance of CNSLBP in order to create a personalized treatment program. In conclusion, this review underscores the need for personalized therapeutic strategies that take into account the unique characteristics of each patient, recognizing the complex interaction of biological, psychological, social, and other factors that contribute to the development of individual pain. By combining a comprehensive understanding of the complexities of this condition, we aim to improve clinical outcomes and provide information on the development of effective personalized treatment algorithms, particularly in the field of neurological practice.

Modulatory effects of acupuncture on raphe nucleus-related brain circuits in patients with chronic neck pain: A randomized neuroimaging trial

OBJECTIVE

Acupuncture has shown promise in treating neck pain. Clinical trials have shown mixed results, possibly due to heterogeneous methodologies and the lack of knowledge regarding underlying brain circuit mechanism of action. In this study, we investigated the specific contribution of the serotonergic system in treating neck pain, and the specific brain circuits involved.

METHODS

A total of 99 patients with chronic neck pain (CNP) were randomized to receive true acupuncture (TA) or sham acupuncture (SA) 3 times weekly for 4 weeks. Patients with CNP in each group were assessed for primary outcomes by measuring the Visual Analog Scale (VAS) and the duration of each attack; secondary outcomes were measured using the Neck Disability Index (NDI), Northwick Park Neck Pain Questionnaire (NPQ), McGill Pain Questionnaire (MPQ), Self-rating Anxiety Scale (SAS), Self-rating Depression Scale (SDS) and the 12-item Short Form Quality Life Scale (SF-12); levels of functional circuits connectivity were assessed using resting-state functional magnetic resonance imaging in the dorsal (DR) and median (MR) raphe nucleus, before and after undergoing acupuncture.

RESULTS

Patients receiving TA showed more extensive symptom improvement compared with SA. Regarding the primary outcomes, changes observed in the TA group were as follows: VAS = 16.9 mm (p < 0.001) and the duration of each attack = 4.30 h (p < 0.001); changes in the SA group: VAS = 5.41 mm (p = 0.138) and the duration of each attack = 2.06 h (p = 0.058). Regarding the secondary outcomes, changes in the TA group: NDI = 7.99 (p < 0.001), NPQ = 10.82 (p < 0.001), MPQ = 4.23 (p < 0.001), SAS = 5.82 (p < 0.001), SDS = 3.67 (p = 0.003), and SF-12 = 3.04 (p < 0.001); changes in the SA group: NDI = 2.97 (p = 0.138), NPQ = 5.24 (p = 0.035) and MPQ = 2.90 (p = 0.039), SAS = 1.48 (p = 0.433), SDS = 2.39 (p = 0.244), and SF-12 = 2.19 (p = 0.038). The modulatory effect of TA exhibited increased functional connectivity (FC) between the DR and thalamus, between the MR and parahippocampal gyrus, amygdala, and insula, with decreased FC between the DR and lingual gyrus and middle frontal gyrus, between the MR and middle frontal gyrus. Furthermore, changes in the DR-related circuit were specifically associated with the intensity and duration of pain, and the MR-related circuit was correlated with the quality of life with CNP.

CONCLUSION

These results demonstrated the effectiveness of TA in treating neck pain and suggested that it regulates CNP by reconfiguring the function of the raphe nucleus-related serotonergic system.

5,7-Dimethoxycoumarin ameliorates vincristine induced neuropathic pain: potential role of 5HT3 receptors and monoamines

Vincristine is the drug of choice for Hodgkin's lymphoma, acute lymphoblastic leukemia, and non-Hodgkin lymphoma. Despite its significant anticancer effects, it causes dose-dependent neuropathy, leading to compulsive dose reduction. The available drugs used for vincristine-induced neuropathic pain (VINP) have a range of safety, efficacy, and tolerability issues prompting a search for new therapies. 5,7-Dimethoxycoumarin (5,7-DMC) also known as citropten, is a natural coumarin found in the essential oils of citrus plants such as lime, lemons, and bergamots, and it possesses both antidepressant and anti-inflammatory effects. This study was designed to investigate the possible analgesic and antiallodynic effects of 5,7-DMC in a murine model of VINP. Vincristine was administered to groups of BALB/c male mice (0.1 mg/kg intraperitoneally) once daily for 14 days to induce VINP. Thermal hyperalgesia and mechanical allodynia were quantified using the tail immersion test and von Frey filament application method. The levels of monoamine neurotransmitters and vitamin C in frontal cortical, striatal and hippocampal tissues, as well as the TNF-α level in plasma, were quantified using high performance liquid chromatography and ELISA respectively. On day 15 of the protocol, acute treatment with 5,7-DMC clearly reversed VINP thermal hyperalgesia, mechanical static allodynia, mechanical dynamic allodynia, and cold allodynia. The activity of 5,7-DMC against hyperalgesia and allodynia was inhibited by pretreatment with ondansetron but not naloxone, implicating a 5-HT3 receptor involvement. VINP vitamin C levels were restored by 5,7-DMC in the frontal cortex, and changes in serotonin, dopamine, adenosine, inosine and hypoxanthine levels caused by vincristine were reversed either fully or partially. Additionally, the vincristine-induced rise in hippocampal serotonin, dopamine, inosine and striatal serotonin was appreciably reversed by 5,7-DMC. 5,7-DMC also reversed the vincristine-induced increase in the plasma level of TNF-α. In negating the changes in the levels of some neurotransmitters in the brain caused by vincristine, 5,7-DMC showed stronger effects than gabapentin. It was concluded that, there is a potential role of 5-HT3 receptors and monoamines in the amelioration of VINP induced by 5,7-DMC, and the use of this compound warrants further investigation.