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Neuropathic pain (NP) is caused by a lesion that triggers pain chronification and central sensitization and it can develop in a different manner, dependent of age. Recent studies have demonstrated the efficacy of transcranial direct current stimulation (tDCS) for treating NP. Then, we aimed to investigate the effects of tDCS and BDNF levels in neuropathic pain rats in development, with 30 days old in the beginning of experiments. Eight-five male Wistar rats were subjected to chronic constriction injury. After establishment of NP, bimodal tDCS was applied to the rats for eight consecutive days, for 20 minutes each session. Subsequently, nociceptive behavior was assessed at baseline, 14 days after surgery, 1 day and 7 days after the end of tDCS. The rats were sacrificed 8 days after the last session of tDCS. An increase in the nociceptive threshold was observed in rats in development 1 day after the end of tDCS (short-term effect), but this effect was not maintained 7 days after the end of tDCS (long-term effect). Furthermore, brain derived neurotrophic factor (BDNF) levels were analyzed in the frontal cortex, spinal cord and serum using ELISA assays. The neuropathic pain model showed an effect of BDNF in the spinal cord of rats in development. There were no effects of BNDF levels of pain or tDCS in the frontal cortex or serum. In conclusion, tDCS is an effective technique to relieve nociceptive behavior at a short-term effect in neuropathic pain rats in development, and BDNF levels were not altered at long-term effect., Competing Interests: Conflict of interests: The authors declare no competing interests that are relevant to the content of this article., (© 2023 the Author(s), licensee AIMS Press.)

The present study aimed to determine whether isoflurane interferes with the analgesic effects of acupuncture (Ac) and electroacupuncture (EA), using a neuropathic pain (NP) rat model. In total, 140 male Wistar rats were used; isoflurane-induced nociceptive response was evaluated using the von Frey test, serum calcium-binding protein β (S100β) levels and nerve growth factor (NGF) levels in the left sciatic nerve. The NP model was induced by chronic constriction injury of the sciatic nerve at 14 days after surgery. Treatment was initiated after NP induction with or without isoflurane anesthesia (20 min/day/8 days). The von Frey test was performed at baseline, 14 days postoperatively, and immediately, 24 h, and 48 h after the last treatment. Results of the nociceptive test and three-way analysis of variance were analyzed by generalized estimating equations, the Bonferroni test, followed by Student-Newman-Keuls or Fisher's least significant difference tests for comparing biochemical parameters (significance defined as p ≤ 0.05). At baseline, no difference was noted in the nociceptive response threshold among all groups. Fourteen days after surgery, compared with other groups, NP groups showed a decreased pain threshold, confirming establishment of NP. Ac and EA enhanced the mechanical pain threshold immediately after the last session in the NP groups, without anesthesia. Isoflurane administration caused increased nociceptive threshold in all groups, and this effect persisted for 48 h after the last treatment. There was an interaction between the independent variables: pain, treatments, and anesthesia in serum S100β levels and NGF levels in the left sciatic nerve. Isoflurane enhanced the analgesic effects of Ac and EA and altered serum S100β and left sciatic nerve NGF levels in rats with NP., (Copyright © 2018. Published by Elsevier B.V.)

Objective: The aim was to assess the neuromodulation techniques effects (repetitive transcranial magnetic stimulation [rTMS] and deep intramuscular stimulation therapy [DIMST]) on pain intensity, peripheral, and neurophysiological biomarkers chronic myofascial pain syndrome (MPS) patients., Design: Randomized, double blind, factorial design, and controlled placebo-sham clinical trial., Setting: Clinical trial in the Laboratory of Pain and Neuromodulation at Hospital de Clínicas de Porto Alegre (NCT02381171)., Subjects: We recruited women aged between 19- and 75-year old, with MPS diagnosis., Methods: Patients were randomized into four groups: rTMS + DIMST, rTMS + sham-DIMST, sham-rTMS + DIMST, sham-rTMS + sham-DIMST; and received 10 sessions for 20 minutes each one (rTMS and DIMST). Pain was assessed by visual analogue scale (VAS); neurophysiological parameters were assessed by transcranial magnetic stimulation; biochemical parameters were: BDNF, S100β, lactate dehydrogenase, inflammatory (TNF-α, IL6, and IL10), and oxidative stress parameters., Results: We observed the pain relief assessed by VAS immediately assessed before and after the intervention (P < 0.05, F(1,3)= 3.494 and F(1,3)= 4.656, respectively); in the sham-rTMS + DIMST group and both three active groups in relation to sham-rTMS + sham-DIMST group, respectively. There was an increase in the MEP after rTMS + sham-DIMST (P < 0.05). However, there was no change in all-peripheral parameters analyzed across the treatment (P > 0.05)., Conclusion: Our findings add additional evidence about rTMS and DIMST in relieving pain in MPS patients without synergistic effect. No peripheral biomarkers reflected the analgesic effect of both techniques; including those related to cellular damage. Additionally, one neurophysiological parameter (increased MEP amplitude) needs to be investigated., (Published by Oxford University Press on behalf of the American Academy of Pain Medicine. 2016. This work is written by US Government employees and is in the public domain in the US.)