Figure 4.

The effect of shortened daily photoperiod on open-field test (OFT) parameters. Horizontal and vertical motor activity of animals was registered for 15 min in a sound-attenuated area with 12 lux red lighting surrounded by black walls, 40-cm high. The whole area was divided into 16 imaginary squares with 4 middle squares marked as the central area. Representative images of animal ambulation are presented (A–D). Parameters obtained in this test included: (E) total ambulation distance, (F) centre ambulation distance, (G) time spent in the centre of the field, (H) peripheral ambulation distance, (I) velocity in the centre, (J) velocity in the periphery, (K) number of rearings, (L) index of thigmotaxy, defined as a ratio between the distance of rat ambulatory movements in the peripheral zones and the total distance of ambulatory movements. Anxiety is inversely related to the time spent in the central area and directly related to the thigmotaxis index. The significance of the difference was estimated by an analysis of variance (ANOVA) with Dunnett’s post hoc test (* p < 0.05 vs. C_12/12, # p < 0.05 vs. DM_12/12). For additional information, see Figure 2.