Date of Award

Winter 12-2019

Document Type

Honors Thesis

Degree Name

Bachelor of Science



Advisor/Committee Chair

Lawrence Schell, Ph.D.

Committee Member

Ewan McNay, Ph.D.


Insulin is the most common treatment for hyperglycemia, such as that caused by type 1 or type 2 diabetes mellitus. Insulin causes cellular uptake and storage of glucose to maintain homeostasis and also plays important roles in other systems; an important example is regulation of potassium. In the periphery, insulin administration has been shown to increase the cellular uptake of potassium via Na+/K+ ATPase, leading to hypokalemia. Research in our lab and others has shown that insulin is a key regulator of cognitive function and local metabolism within the hippocampus. To date, however, no studies have examined whether insulin acts to regulate potassium levels within the brain, nor whether such regulation might correlate with cognitive effects caused by administration of exogenous insulin. The current study sought to extend our previous work on the impact of exogenous insulin delivery to the hippocampus: specifically, we measured the impact of intrahippocampal insulin administration on local extracellular potassium levels, both at baseline and during a cognitive task. Rats were tested using a spontaneous alternation task in a four-arm maze with concurrent microdialysis and retrodialysis of insulin for the period corresponding to the behavioral task. Insulin was added to the perfusate at 10 μl in an artificial extracellular fluid vehicle. Samples were collected throughout acclimation, baseline, testing, and recovery periods, and will be analyzed for potassium and glucose. Hippocampi and prefrontal cortices were collected and will be analyzed for Na+/K+ ATPase protein concentrations. We hypothesize that insulin administration will lower extracellular potassium levels, and Na+/K+ ATPase will be upregulated in relation to controls. Future research should investigate the specific cognitive impacts of potassium imbalances.