Report

Neuronal Gene Expression in the Waking State: A Role for the Locus Coeruleus

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Science  15 Nov 1996:
Vol. 274, Issue 5290, pp. 1211-1215
DOI: 10.1126/science.274.5290.1211

Figures

  • Fig. 1.

    (A) Fos expression in sleep and waking in rats with an intact noradrenergic system. Plots (top panel) illustrate the last three recording hours (tick marks) for a rat that was mostly asleep (left panel) and for one that was kept awake by sleep deprivation (right panel); W, waking; N, NREM sleep; R, REM sleep [see (10) for details]. Photomicrographs of Fos staining in piriform cortex from these two rats show that Fos expression is low after sleep (left panel) and high after waking (right panel). Scale bar, 200 μm. (B) Fos expression after 3 hours of sleep deprivation after unilateral neurotoxic lesions of the LC. The plot of the last three recording hours shows that the animal was kept awake. The photomicrograph below the sleep-waking plot shows a brainstem section at the level of the LC stained with tyrosine hydroxylase (TH) immunocytochemistry. TH-positive cells in the left LC were lesioned (lower arrow), whereas the right LC and more ventral catecholaminergic nuclei were spared. Upper arrow indicates the track of the injection through the cerebellum. Scale bar, 1 mm. Photomicrographs of dopamine-β-hydroxylase (DBH) immunocytochemistry in piriform cortex show the decrease in noradrenergic innervation on the side where the LC was lesioned (left panel) with respect to the side where it was intact (right panel). Photomicrographs of Fos staining from adjacent sections on the lesioned side (left panel) and on the intact side (right panel) show that the expression of Fos after 3 hours of sleep deprivation in areas in which noradrenergic innervation is reduced is as low as after periods of sleep.

  • Fig. 2.

    Expression of IEGs after 3 hours of spontaneous waking following unilateral neurotoxic lesions of the LC. (A) TH immunocytochemistry of a rat with a lesion of the left LC that was killed after 3 hours of spontaneous waking in the dark. The panels show left and right parietal cortex, respectively. Scale bar, 200 μm. (B) Expression of Fos. Photomicrographs from adjacent sections show that Fos staining after spontaneous waking is high on the intact side (right) and almost absent on the lesioned side (left). (C) Expression of NGFI-A. NGFI-A staining is also higher on the intact side (right) than on the lesioned side (left). (D) Expression of P-CREB. The number of P-CREB-positive cells is lower on the side where the noradrenergic innervation has disappeared (left).

  • Fig. 3.

    Dissociation between the effects of lesions of the noradrenergic system on gene expression and on EEG activation. (A) Fos, NGFI-A, and P-CREB immunoreactivity in waking decreases after unilateral neurotoxic lesions of the LC. Mean percentage of stained cells on the lesioned side (intact side = 100%) in rats killed after sleep deprivation or after spontaneous waking where there was a widespread unilateral decrease in cortical NE innervation. Values refer to cortical areas where noradrenergic innervation was reduced by >80%. The decrease on the lesioned side was significant for Fos, NGFI-A, and P-CREB (N = 9, P < 0.001, Wilcoxon signed-rank test for matched pairs). (B) Raw EEG patterns are not modified. Raw EEGs were recorded from the intact (EEG R) and lesioned (EEG L) sides of the rat whose brain sections are shown in Fig. 2. The EEG (scale bar, 500 μV) and the electromyogram [scale bars, 150 μV (vertical) and 1 s (horizontal)] correspond to the transition between sleep and waking.

  • Fig. 4.

    (A) Reduction of Fos expression after 3 hours of sleep deprivation following bilateral lesions of LC terminals as a result of DSP-4 injections. TH immunocytochemistry in parietal cortex of a control animal (left panel) and of an animal that had received an injection of DSP-4 leading to a decrease in noradrenergic innervation (right panel). Photomicrographs are of Fos staining from adjacent sections from the control animal (left panel) and the animal injected with DSP-4 (right panel). Both animals were sleep-deprived for 3 hours. Fos concentrations are high in the control and low in the animal injected with DSP-4. Scale bar, 200 μm. (B) EEG power density is not modified. Mean power density of the EEG for different behavioral states recorded before (solid line) and after (dashed line) DSP-4 injections, resulting in a >90% decrease in noradrenergic innervation with respect to matched controls. Power densities expressed as percentage of the mean value during NREM sleep for each animal are plotted on a logarithmic scale. Dots indicate the standard deviation of power density values before the injections (N = 5) for each frequency bin. Despite the marked bilateral reduction in Fos, NGFI-A, and P-CREB staining in cortex and hippocampus in these animals, the mean spectrum after DSP-4 injection was within 1 SD of the values observed before DSP-4 injection, and no significant difference was found for any frequency bin (Wilcoxon signed-rank test for matched pairs).

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