Is blood glucose associated with descending modulation of spinal nociception as measured by the nociceptive flexion reflex?
OBJECTIVE
Prior research has shown a relationship between blood glucose levels and some forms of self-regulation (eg, executive function), with low blood glucose levels associated with impaired self-regulation. Further, engagement in self-regulation tasks depletes blood glucose. Given these relationships, the present study examined whether blood glucose is associated with another form of self-regulation, ie, descending pain modulatory processes.


METHODS
Forty-seven (32 female) pain-free participants were recruited and completed testing. Blood glucose was measured from finger sticks and a digital meter before and after experimental pain tests. Pain tests included the nociceptive flexion reflex (NFR) threshold to assess descending modulation of spinal nociception, but also electric pain threshold to assess perceptual pain detection. The Stroop color word naming test was also assessed before and after pain testing to examine changes in executive function.


RESULTS
Results indicated that mean blood glucose levels decreased after pain testing, but Stroop performance did not significantly change. Importantly, changes in blood glucose were correlated with NFR threshold, such that decreases in blood glucose were associated with lower NFR thresholds (reduced descending inhibition). Changes in blood glucose were unrelated to pain threshold or executive function.


CONCLUSIONS
This study suggests that glucose depletion may impair performance of descending inhibitory processes, without impacting the perceptual detection of pain (pain threshold). Although findings need to be replicated, maintaining adequate glucose levels may be necessary to support inhibition of spinal nociception.
Department of Psychology, The University of Tulsa, Tulsa, OK, USA.
Ellen L
EL
Terry
Department of Psychology, The University of Tulsa, Tulsa, OK, USA.
Yvette M
YM
Güereca
Department of Psychology, The University of Tulsa, Tulsa, OK, USA.
Satin L
SL
Martin
Department of Psychology, The University of Tulsa, Tulsa, OK, USA.
Jamie L
JL
Rhudy
descending modulation; executive function; glucose; nociception; pain