The Effect Manipulating AMPK Activity has on Ouabain-Induced Spreading Depression in Fed and Starved Locusta Migratoria.
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Neurons, though highly metabolically active, have a poor capacity for nutrient storage and are sensitive to energy fluctuations. One mechanism for maintaining energetic homeostasis involves activation of the heterotrimeric AMP-activated protein kinase (AMPK), a cell- autonomous sensor to energetic changes regulated by ATP to AMP ratios. Starvation, which reduces nutrient availability, has been shown to decrease susceptibility to spreading depression (SD) in Locusta migratoria. Although AMPK activation is thought to be involved in this phenomenon, its presence has not yet been confirmed in the locust. In my thesis I established that AMPK is present in locust neural tissue, and that starvation increases its activation. I also investigated the effects of manipulating AMPK activity, via pharmacological agents and RNA interference (RNAi), on ouabain-induced SD in fed and starved locusts. Application of 5x10-5 M A-769662, a potent AMPK activator, did not have an effect on susceptibility to or recovery from ouabain-induced SD, in either fed or starved animals. Increasing the concentration of A-769662 to 10-4 M also yielded no significance. However, injecting AMPK dsRNA reduced the number of preparations that displayed SD-like events. This suggests that RNAi-mediated downregulation of AMPK decreased susceptibility to SD. Overall, I provide evidence of AMPK’s involvement in potassium ion homeostasis, which may further our understanding of SD and its effects within the nervous system.