Showing papers on "Cuneate nucleus published in 2019"

Involvement of the cuneate nucleus in the acupuncture inhibition of drug-seeking behaviors

Abstract: Our previous studies have shown that acupuncture suppresses addictive behaviors induced by drugs of abuse, including cocaine, morphine and ethanol, by modulating GABA neurons in the ventral tegmental area (VTA) and dopamine (DA) release in the nucleus accumbens (NAc). The mechanisms by which the peripheral signals generated by acupoint stimulation are transmitted to brain reward systems are largely unexplored. The present study aims to investigate the role of spinal dorsal column (DC) somatosensory pathways in the acupuncture inhibition of drug addictive behaviors. Thus, we tested whether acupuncture at Shenmen (HT7) points reduces drug-seeking behaviors in rats self-administering morphine or ethanol and whether such effects are inhibited by the disruption of the cuneate nucleus (CN). The stimulation of HT7 suppressed morphine and ethanol self-administration, which were completely abolished by surgical lesioning of the CN. In in vivo extracellular recordings, single-unit activity of the CN was evoked during acupuncture stimulation. The results suggest that acupuncture suppresses morphine- and ethanol-seeking behaviors through the modulation of the CN, second-order neurons of the DC somatosensory pathway.

Innervated Properties of Acupuncture Points LI 4 and LR 3 in the Rat: Neural Pathway Tracing with Cholera Toxin Subunit B

Abstract: Objective: Increasing evidence from acupuncture research suggests that the nervous system corresponds closely with classical acupuncture points. The aim of this research was to provide neuroanatomical evidence for revealing the innervated properties of different acupuncture points through comparing the sensory and motor pathways associated with Hegu (LI 4) and Taichong (LR 3) in rat extremities. Materials and Methods: Cholera toxin subunit B (CTB) was injected into LI 4 and LR 3 in different rats, and CTB neural labeling was examined using fluorescent immunohistochemistry and observed under fluorescent microscopy in the corresponding areas from the peripheral nervous system to the central nervous system, including the dorsal root ganglia (DRG), spinal cord, and brainstem. Results: When LI 4 was injected with CTB, CTB-labeled sensory neurons ranged from C-5 to T-1 DRG, and their transganglionic axons terminated in the C-5 to C-8 spinal dorsal horn as far as the cuneate nucleus, while labeled motor neurons were located in the C-7 to T-1 spinal ventral horn. In contrast, similar neural labeling was observed for LR 3 CTB injection, with an orderly arrangement in the L-3 to L-5 DRG, L-3 to L-5 spinal dorsal horn, gracile nucleus, and L-4 to L-6 spinal ventral horn. Conclusions: The present results provide further evidence to aid understanding of the differential innervation of acupuncture points LI 4 and LR 3. This innervation establishes its connection with the nervous system in a distinct segmental and regional pattern through the spinal sensory and motor pathways.

Neuroanatomy, Nucleus Gracilis

Abstract: Several ascending and descending tracts are present in the spinal cord. The three most important tracts in the spinal cord are: Dorsal Column Medial Lemniscus Pathway - This is an ascending sensory tract. Spinothalamic Tract - This is an ascending sensory tract. Corticospinal Tract - This is a descending motor pathway which has upper motor neurons (UMN) and lower motor neurons (LMN). The gracile nucleus, along with the cuneate nucleus, is a part of the dorsal column medial lemniscus pathway (DCML). The gracile nucleus situates in the midline dorsal medulla at the junction of the brainstem and the spinal cord. The gracile fasciculus carries sensory input from vertebral level T6 and below and ascends into the gracile nucleus to form the gracile tubercle. The cuneate fasciculus carries information from T6 and above and ascends into the cuneate nucleus to form the cuneate tubercle. These tubercles appear as bumps on the dorsal part of the medulla.