Retrosplenial Cortex is Involved in Analgesia Induced by 2- but not 100-Hz Electroacupuncture in the Rat Tail-Flick Test

The role of the anterior pretectal nucleus in pain modulation: A comprehensive review

Descending pain modulation involves multiple encephalic sites and pathways that range from the cerebral cortex to the spinal cord. Behavioral studies conducted in the 1980s revealed that electrical stimulation of the pretectal area causes antinociception dissociation from aversive responses. Anatomical and physiological studies identified the anterior pretectal nucleus and its descending projections to several midbrain, pontine, and medullary structures. The anterior pretectal nucleus is morphologically divided into a dorsal part that contains a dense neuron population (pars compacta) and a ventral part that contains a dense fiber band network (pars reticulata). Connections of the two anterior pretectal nucleus parts are broad and include prominent projections to and from major encephalic systems associated with somatosensory processes. Since the first observation that acute or chronic noxious stimuli activate the anterior pretectal nucleus, it has been established that numerous mediators participate in this response through distinct pathways. Recent studies have confirmed that at least two pain inhibitory pathways are activated from the anterior pretectal nucleus. This review focuses on rodent anatomical, behavioral, molecular, and neurochemical data that have helped to identify mediators of the anterior pretectal nucleus and pathways related to its role in pain modulation.

Violet laser acupuncture - Part 5: An investigation of different stimulation frequencies on heart rate and variability

Violet laser acupuncture was recently described by our research group. Neurochemical studies of acupuncture analgesia revealed that 2- and 100-Hz peripheral stimulation induce differential peptide release from preproenkephalin and preprodynorphin via different neural pathways. The goal of the fifth part of this series was to perform a pilot investigation on the effects of 2- and 100-Hz violet laser acupuncture on heart rate (HR) and its variability (HRV) in 13 healthy volunteers (mean age ± standard deviation: 23.9 ± 1.7 years) using a new non-invasive method. We found a significant difference in mean HR before, during, and after 2- or 100-Hz violet laser acupuncture, and there was a significant difference of the low frequency/ high frequency ratio before, during, and after 2- or 100-Hz violet laser acupuncture. However, we did not observe a significant difference in total HRV before, during, or after treatment. Further studies should be carried out to compare the effects of different violet laser acupuncture frequencies.