Circadian rhythm in brain gamma aminobutyric acid levels in the cockroach,Leucophaea maderae

✍ Scribed by McCay, J.; Romero, K.; Gibson, J.; Newton, J.; Wilson, L.; Wright, Jennifer; Dahl, D.B.; Ferrell, B.R.

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 787 KB
• Volume: 276
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/(sici)1097-010x(19961101)276:4<262::aid-jez3>3.0.co;2-m

✦ Synopsis

Brain levels of y-aminobutyric acid (GABA) were determined using high performance liquid chroinatography coupled with fluorometeric detection at 3-h intervals throughout a 24-h time period in roaches acclimated to a photoperiodic cycle of 12 h of light and 12 h of darkness at 25 1?: 2°C to establish whether or not the levels of this inhibitory neurotransmitter vaned temporally. Brain levels of GABA did vary temporally, with highest levels occurring at midday. Therefore, an additional experiment was conducted to determine if this rhythm persisted on a circadian basis. Brain levels of GABA were determined at two circadian times (CT) that corresponded to the times during the daily cycle when levels were highest and lowest in animals held under constant darkness. The differences in GABA levels observed at these two times of day in animals held under a lightldark cycle persisted on the second cycle under conditions of constant darkness, indicating that the rhythm of brain GABA levels may persist on a circadian basis.