Figure 3. VIP is a regulator of circadian motor activity (58). The top panel compares motor activity and spectral analysis from rats treated with saline, a VIP antagonist or antagonist plus VIP. The VIP antagonist (neurotensin6-11 -VIP7-28) disrupted the diurnal pattern of locomotor activity. Co-treatment with VIP restored normal locomotor rhythmicity. The bottom left panel shows an in situ hybridization for VIP mRNA (R. Avidor, R. Levy-Holtman, I. Gozes). The bottom right panel compares the effect of dark rearing on ribosomal and VIP mRNA in the suprachiasmatic nucleus (48).