Brain levels of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) were determined at three-hour intervals in roaches acclimated to a 12-hour lightl12-hour dark cycle (light onset 0600 h) at 25 ± 2° C using high performance liquid chromatography coupled with fluorometnc detection GABA levels were found to be highest at noon and lowest at 1800 h. A difference between the high and low levels at these two times remained during the second day under constant dark conditions, indicating that GABA levels do indeed vary on a circadian basis. Brain GABA levels were highest at a time of day that corresponded with the time of day of greatest clock output measured electrophysiologically. The fact that these two parameters correspond and occur at a time of day when locomotor activity and eye sensitivity to light are low is suggestive that clock output is inhibitory.
Advisor(s) or Committee Chair
Blaine R. Ferrell
Animal Sciences | Biology
McCay, Juli Martin and Gibson, Jeanette Marie, "Circadian Rhythm of Brain GABA Levels in the Cockroach, Leucophaea maderae" (1995). Mahurin Honors College Capstone Experience/Thesis Projects. Paper 131.