Painful Nerve Injury Decreases Resting Cytosolic Calcium Concentrations in Sensory Neurons of Rats

Abstract

Painful SNL nerve injury depresses resting [Ca]c in sensory neurons. This is most marked in axotomized neurons, especially the large and capsaicin-insensitive neurons presumed to transmit non-nociceptive sensory information.

The control of brain mitochondrial energization by cytosolic calcium: The mitochondrial gas pedal

“…However, the high redox pressure also can cause a large ROS formation (Fig. 4) (97). The decreased basal Ca 2þ level in striatal neurons has been found in experiments on HD knock-in mouse model (98).…”

Painful Nerve Injury Shortens the Intracellular Ca2+ Signal in Axotomized Sensory Neurons of Rats

“…This offset after the transient has not previously been quantified and indicates a prolonged memory-like residual after activation of sensory neurons. We have previously shown that resting [Ca 2+ ] c is particularly depressed in L5 neurons after SNL, 12 perhaps because of the lack of postactivation offset. The resting [Ca 2+ ] c is regulated by the balanced operation of endoplasmic reticulum Ca 2+ release, plasma membrane Ca 2+ adenosine triphosphatase extrusion, and Ca 2+ influx through channels sensitive to intracellular Ca 2+ stores (storeoperated Ca 2+ channels), 27 indicating effects on these processes specific to injury and neuronal types.…”

“…12,19 This segregates neurons into a population of large neurons with predominantly low-threshold receptive field properties and small neurons predominantly responsive to nociceptive stimuli. 20 Because sensitivity to capsaicin is a feature that distinguishes thermal nociceptors, 21 a subset of neurons were further characterized by their response to capsaicin.…”

“…Specifically, if R increased by 50% over baseline after bath application of 100 nM capsaicin, the neuron was considered responsive. 12 Data for measurement of transients are expressed as median and 25th and 75th percentile, and main effects were tested by univariate nonparametric Kruskal-Wallis analysis of variance by ranks (Prism 4; GraphPad Software, Inc., San Diego, CA) because the number of neurons in some groups was small. When a significant main effect was confirmed, planned post hoc comparisons were performed using the Dunn multiple comparisons test.…”

“…5,10,11 We have further observed that resting Ca 2+ levels are lower in sensory neurons after injury. 12 The influence of these alterations on depolarization-induced Ca 2+ transients is unknown. We hypothesized that the documented injury-induced loss of inward Ca 2+ flux across the plasmalemma will lead to diminished amplitude and duration Ca 2+ transients in sensory neurons.…”