Entrainment of methamphetamine-induced locomotor activity rhythm to feeding cycles in SCN-lesioned rats.
Suprachiasmatic nuclei (SCN)-lesioned rats, showing a locomotor activity rhythm with a circadian period by chronic methamphetamine treatment, were subjected to the periodic food restriction (RF) of 4 h per every 27 h and 24 h. All rats were phase set by the feeding schedule of both 24-h and 27-h periods. Phase angle differences between the activity onset and food presentation were more positive under the RF with a period of 27 h than that of 24 h. Methamphetamine-induced locomotor rhythm showed a stable entrainment to RF of the 27-h period in all rats. Under the RF of the 24-h period, on the other hand, some rats showed circabidian rhythms, i.e., an activity band appeared at every second food presentation. After the termination of feeding schedule, the locomotor rhythm started to free-run from the phase set by the previous feeding schedule in all rats examined. Methamphetamine-induced locomotor rhythm was shown to be entrained by the RF with a predictable manner of an oscillation theory.
Honma
S
S
Department of Physiology, Hokkaido University School of Medicine, Sapporo, Japan.
Kanematsu
N
N
Honma
K
K
D000818:Animals; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D008694:Methamphetamine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013238:Stereotaxic Techniques; D013493:Suprachiasmatic Nucleus / Q000033:anatomy & histology / Q000502:physiology*
D008694:Methamphetamine