Rapid injection of lumbar dorsal root ganglia under direct vision: Relevant anatomy, protocol, and behaviors

Abstract

IntroductionDorsal root ganglia (DRG) are anatomically well-defined structures that contain all primary sensory neurons and are distension nodules of the dorsal root in the spinal cord near the medial surface of each foramen. Therefore, DRG is considered to be a desirable target for injection to manage chronic pain. But it presents a limitation in probing deep into it without in vivo injection technology.MethodsHere, we described a technique for administering intraganglionic injections of lumbar DRG under direct vision. We use partial osteotomy rather than laminectomy, which removes more bone, to preserve spinal structures while gaining adequate DRG access. To monitor the intraoperative progress of the DRG injection, a non-toxic dye was utilized. The effectiveness of the injection on the diffusion of AAV (adeno-associated virus) within the ganglion was assessed by histopathology at postoperative day 21.ResultsBehavioral tests showed that neither motor nor sensory abilities were affected by saline or AAV injections. Meanwhile, the decreased pain threshold of SNI (spared nerve injury) was considerably restored by pharmacological inhibition of DRG neurons.DiscussionOur research achieved a new minimally invasive and intuitive intra-ganglionic injection in mice. In addition, the present protocol may serve as a valuable resource for planning preclinical studies of DRG injection.

Nerve Growth Factor/Tyrosine Kinase A Receptor Pathway Enhances Analgesia in an Experimental Mouse Model of Bone Cancer Pain by Increasing Membrane Levels of δ-Opioid Receptors

“…As reported, 21 stereotaxic injections of the DRG were performed using a stereotactic frame (RWD, China) under anesthesia induced by intraperitoneal injection of pentobarbital (20 mg/kg). The body temperature of the animals was kept at 36°C throughout the procedure using a heating pad.…”

Near‐Infrared Chemiluminescence Imaging of Chemotherapy‐Induced Peripheral Neuropathy

“…[6] However, no fluorescent probes have been reported for in vivo detection of CIPN. This should be ascribed to (a) the difficulty of fluorescent probes in achieving the imaging penetration depth into the spinal canal where the dorsal root ganglia (DRG) neurons are located, [7] and (b) the requirement of ultrahigh imaging sensitivity as the allowable injection volume of probes through direct DRG injection (such as intrathecal, intraganglionic, and perineuronal injection) is limited to only 10 μL. [8] As compared with fluorescence imaging, chemiluminescence imaging eliminates the need for real-time light excitation, and detects luminescence from a chemical reaction via the chemically initiated electron exchange luminescence (CIEEL) mechanism.…”

“…[ 6 ] However, no fluorescent probes have been reported for in vivo detection of CIPN. This should be ascribed to (a) the difficulty of fluorescent probes in achieving the imaging penetration depth into the spinal canal where the dorsal root ganglia (DRG) neurons are located, [ 7 ] and (b) the requirement of ultrahigh imaging sensitivity as the allowable injection volume of probes through direct DRG injection (such as intrathecal, intraganglionic, and perineuronal injection) is limited to only 10 µL. [ 8 ]…”