Figure 5.

Prostaglandin E₂ (PGE₂) induces no significant alteration in circadian locomotor activity. (A) Representative double-plotted actograms show locomotor activity records of PBS alone (left) or PGE₂-injected (right) mouse at ZT21 (arrowheads). Mice were housed in a light–dark cycle for a week and injected with PBS or PGE₂ intraperitoneally at ZT21. Then, mice were maintained in constant darkness. (B) Activity profile over 2 days from 10 h after intraperitoneal injection of PBS or PGE₂ at ZT21. Bars represent mean (±s.e.m., n=4) summed number of movement detections during 30 min of recording. Grey and black bars represent the subjective day and night, respectively. Shaded background also represents the subjective night. CT0 corresponds to ZT0 in constant dark conditions.