Acetylcholine Concentrations in Rat Brain: Diurnal Oscillation

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Science  16 Oct 1970:
Vol. 170, Issue 3955, pp. 341-342
DOI: 10.1126/science.170.3955.341


A diurnal oscillation of acetylcholine concentrations in rat brain has been demonstrated by gas chromatography. Peak concentrations occur at 2 hours of light, and a trough is seen at 6 hours of darkness. This pattern is observed only in grouped rats, and emerges after at least 18 days of prior conditioning in an environment with controlled light, humidity, and temperature.