Daily variations in concentration of vasoactive intestinal peptide immunoreactivity in hypothalamic nuclei of rats rendered diurnal by restricted-schedule feeding.
We previously described that in the suprachiasmatic (SCN), peri-(PeVN) and paraventricular (PaVN) nuclei of normal rats, vasoactive intestinal peptide (VIP)-like immunoreactivity (VIP-LI) accumulates during the night period and decreases during the day. In order to determine whether these variations are linked to the light-dark cycle or are a consequence of sleep-wake rhythm expression, we dissociated these two parameters by restricting feeding to diurnal hours. In these conditions which inverse the paradoxical sleep rhythm, the VIP-LI pattern is perturbed and its minimum advanced by 4 h in the SCN. In the PeVN, the daily pattern is maintained but the minimum is also advanced by 4 h. Finally, the rhythm is abolished in the PaVN. These circadian fluctuations indicate that the hypothalamic VIP-LI rhythm is not linked to the paradoxical sleep rhythm but could be sensitive to photic and non-photic Zeitgeber.
Laboratoire de Médecine Expérimentale, INSERM U 52, CNRS URA 1995, Université Claude Bernard, Lyon, France.
A J
AJ
Morin
L
L
Denoroy
M
M
Jouvet
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D004435:Eating; D008297:Male; D010286:Paraventricular Hypothalamic Nucleus / Q000737:chemistry / Q000502:physiology; D051381:Rats / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000737:chemistry / Q000502:physiology*; D013997:Time Factors; D014660:Vasoactive Intestinal Peptide / Q000032:analysis / Q000502:physiology*
D014660:Vasoactive Intestinal Peptide