Protocol for recording the discharge of locus coeruleus neurons in free-moving mice during different sleep-wake stages.

Cortical electroencephalography (EEG) is generally used to detect the different sleep-wake states of animals. EEG combined with in vivo multichannel recording provides a powerful tool for decoding the neural network of sleep-wake regulation. Here, we detail a protocol using cortical EEG combined with in vivo multichannel recording to examine the activity of locus coeruleus (LC) neurons in free-moving mice at different sleep-wake stages. The procedures for electrode fabrication, the surgery to implant electrodes, and post-recording data analysis are also included. For complete details on the use and execution of this protocol, please refer to Liang et al. (2021).

Approach Behavior Induced by 10.6-µm Laser Stimulation at Acupoint ST36 in a Rat Model of Incisional Pain.

Objective: Laser stimulation (LS) at both the injury site and specific acupoints may induce analgesic effects. The purpose of this study is to investigate the effects of LS at injury site or acupoint on analgesic-associated approach behavior and determine whether opioid receptors in the anterior cingulate cortex (ACC) were involved. Methods: The left hindpaw incision was established in rats. LS (10.6 µm) was performed at the ipsilateral (left) acupoint ST36 (Zusanli) or locally to the incision site. Characteristic guarding pain behavior was measured to assess incision-induced pain. A two-chamber conditioned place preference (CPP) paradigm was used to measure approach behavior induced by pain relief. To inhibit opioid receptors, naloxone was microinjected into the ACC before LS. Results: A delayed analgesic effect (24 h after treatment) was induced in both the LS groups (ST36 and incision site) as compared with the sham control or model groups (p < 0.05). An immediate (30 min after the end of the LS) decrease in guarding pain (p < 0.001) and CPP for the LS chamber (p < 0.001) were observed only in the ST36 LS group. The administration of naloxone in ACC inhibited the LS-induced analgesic effect and CPP (p < 0.05). Conclusions: Our results highlight the novel approach behavior of pain relief induced by 10.6-µm LS at ST36 in a rat model of incisional pain, and implicate ACC opioid receptor signaling in these actions.

Laser photobiomodulation for cartilage defect in animal models of knee osteoarthritis: a systematic review and meta-analysis.

To review and assess the efficacy of laser photobiomodulation for cartilage defect in animal models of knee osteoarthritis (KOA). Medline, Web of Science, and EMBASE were searched. Studies were considered if the global quality score of cartilage were parallelly reported between laser and untreated control groups. The methodological quality of each study was assessed using a modified 10-item checklist. The effect size was estimated by standardized mean difference (SMD) and pooled based on the random-effects model. Stratified analysis and regression analysis were conducted to partition potential heterogeneity. An adjusted significant level of 0.01 was acceptable. Five hundred eight initial search recordings were identified, of which 14 studies (including 274 animals) were included for quantitative analysis. The global quality scores mostly weighted by the structural integrity and chondrocyte distribution were measured by different four scales including Histologic Histochemical Grading System (HHGS), Osteoarthritis Research Society International (OARSI), Pineda, and Huang. There were considerable variances on laser parameters and irradiation time among those included studies. Overall, a moderate level of methodological qualities was determined. The synthesis results indicated that the SMD effect size was significantly larger in HHGS (z = 2.61, P = 0.01) and Huang (z = 4.90, P < 0.01) groups. Stratified by irradiance, SMD of low (< 1 W/cm2) but not high (≥ 1 W/cm2) level estimated significant difference (z = 5.62, P < 0.01). Meta-regression identified a significant association for SMDs and irradiation time (P < 0.01). Yet, Egger's test detected small study effect (P < 0.01). No individual study with significant variance was found in homogeneity tests. The results demonstrated the positive effect of laser photobiomodulation for cartilage defect in animal models of KOA under proper irradiance and adequate irradiation time.