Daily Plasma Glucose Rhythm Controlled by GABA and Glutamate
Author Information
Author(s): Andries Kalsbeek, Ewout Foppen, Ingrid Schalij, Caroline van Heijningen, Jan van der Vliet, Eric Fliers, Ruud M. Buijs
Primary Institution: Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
Hypothesis
Does the daily rhythm in plasma glucose concentrations depend on the activity of the autonomic nervous system controlled by the biological clock?
Conclusion
The study found that the pre-autonomic neurons in the paraventricular nucleus are regulated by a balance of GABAergic and glutamatergic inputs, which vary throughout the day.
Supporting Evidence
- Activation of PVN neurons induced hyperglycemia in non-feeding animals.
- The GABA-antagonist increased plasma glucose only during the light period.
- SCN-ablated animals did not show a hyperglycemic effect from the GABA-antagonist.
- Feeding-induced plasma glucose responses were suppressed by inhibiting PVN activity during the dark period.
Takeaway
This study shows that our body's clock helps control blood sugar levels by using different signals at different times of the day.
Methodology
The study used local administration of GABA and glutamate receptor (ant)agonists in the paraventricular nucleus of rats at different times of the light/dark cycle to assess their effects on plasma glucose and insulin concentrations.
Potential Biases
The study may have biases related to the specific timing of drug administration and the effects of surgery on animal behavior.
Limitations
Approximately 20% of the data had to be discarded due to issues with probe placements and animal recovery.
Participant Demographics
Male Wistar rats, aged between 180-350 grams.
Statistical Information
P-Value
p=0.002 for BIC at ZT5, p=0.008 for NMDA at ZT5, p=0.009 for NMDA at ZT15
Statistical Significance
p<0.05
Digital Object Identifier (DOI)
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