Melatonin Action on the Circadian Pacemaker in Siberian Hamsters
Abstract
This research investigates the effect of the hormone melatonin on the circadian clock of mammals, by examining daily activity rest cycles and body temperature rhythms in melatonin-infused Siberian hamsters, under a variety of environmental lighting conditions. In experiments simulating jet-lag conditions, melatonin significantly accelerated re-adjustment of sleep/wake rhythms to phase-shifted light cycles. Within days after an 8-hr phase-advance of the light/dark cycle, all melatonin-treated hamsters, but none of the saline-treated controls, had achieved the proper phase relationship with the new photoschedule. These results are consistent with reports of melatonin treatment reducing jet lag in humans. Under conditions of constant darkness, daily melatonin infusions synchronized the hamster activity/rest rhythm. IN constant light, melatonin also acted as a weak entraining agent and prevented the internal desynchronization which occurs in Siberian hamsters and in many mammals exposed to constant light. These results offer encouragement about Siberian hamsters as an appropriate model system to investigate melatonin action on the circadian clock.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 29, 1991
- Accession Number
- ADA243057
Entities
People
- Janet M. Darrow
Organizations
- Wellesley College