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The objective of this study was to develop a viable and reliable technique of delivering viral vectors to rat trigeminal ganglia. Adult Sprague-Dawley rats (200-300 g) were used, and lentiviral vectors containing enhanced green fluorescence protein and calcitonin gene-related peptide short hairpin RNA (sh RNA) were generated. Following general anesthesia, viral vectors were delivered to rat trigeminal ganglia using the technique described in this study. Both X-ray and micro-computed tomography (micro- CT) were employed to verify the position of the needles when injecting the vectors. In vivo fluorescence imaging and immunostaining against enhanced green fluorescence protein were performed to determine the success of viral transduction.The levels of calcitonin gene-related peptide in trigeminal ganglia were determined using real-time PCR, and pain levels following injections were evaluated using the Rat Grimace Scale. Our results show that injection needles can be advanced precisely at the trigeminal fossa and that viral vectors can successfully transduce trigeminal ganglia. Moreover, the levels of calcitonin gene-related peptide at trigeminal ganglia were down-regulated on day 7 after viral transduction. Pain levels returned to baseline by day 7 following injection. Therefore, we suggest that our trigeminal ganglion-targeting technique could be used for delivering genes or drugs to rat trigeminal ganglia. [ABSTRACT FROM AUTHOR]

• Periodontal injection of BoNT/A can alleviate orofacial nociception. • BoNT/A can promote the expression of N/OFQ in trigeminal ganglion. • UFP-101 can completely block BoNT/A's antinociceptive effect. • BoNT/A alleviates orofacial nociception induced by orthodontic tooth movement through N/OFQ signaling. To investigate the effect and mechanism of botulinum neurotoxin type A (BoNT/A) in the modulation of orofacial nociception induced by orthodontic tooth movement in rats. An orofacial nociception model was established in male Sprague-Dawley rats by ligating closed-coil springs between incisors and ipsilateral molars. There were two group sets of animals. For the first group set, 120 rats were randomly divided into four groups: no-force group (n = 30), force + saline group (n = 30), force + low dose BoNT/A group (1U/6 μL, n = 30), and force + high dose BoNT/A group (1U/6 μL, n = 30). BoNT/A and saline were injected into periodontal ligament to explore the nociceptive effect of BoNT/A. Ipsilateral trigeminal ganglia (TG) were harvested for detecting the expression levels of nociceptin/orphanin-FQ (N/OFQ). For the second group set, 36 rats were randomly divided into three force groups: BoNT/A + saline group (n = 12), BoNT/A + UFP-101 group (n = 12), and saline + UFP-101 group (n = 12). A potent N/OFQ receptor (NOP) antagonist (UFP-101) was used to examine the role of N/OFQ in BoNT/A-induced antinociception. Tooth-movement nociception level of all groups was evaluated by bite force and rat grimace scale (RGS) at baseline, day 1, day 3, day 5, day 7, day 14. The behavioral assessments showed the orofacial nociception level in the force + low dose BoNT/A group and force + high dose BoNT/A group were lower than that in the force + saline group. No significant difference was observed in orofacial nociception among no-force group, force + low dose and force + high dose group. The expression levels of N/OFQ in TG were elevated from day 1 and maintained a high level, presenting in descending order among the force + high dose, force + low dose, force + saline and no-force group, respectively. The nociception level of the BoNT/A + UFP-101 group was higher than that of the BoNT/A + saline group. No significant difference was observed between the BoNT/A + UFP-101 group and the saline + UFP-101 group. BoNT/A can exert an antinociceptive effect on orofacial nociception induced by tooth movement by stimulating the expression of N/OFQ in TG. [ABSTRACT FROM AUTHOR]