Physiology & Behavior, Vol. 19, pp. 397--400. Pergamon Press and Brain Research Publ., 1977. Printed in the U.S.A.
Light-Dark Patterns in Running-Wheel Activity in Rats During Chronic Administration of Theophylline TOSHIIE SAKATA, MASATAKA FUKUSHIMA, JUNICHI KODAMA AND HIDEAKI FUCHIMOTO
The First Department o f Internal Medicine, Faculty o f Medicine, Kyushu University, Fukuoka, 812 Japan (Received 20 January 1977) SAKATA, T., M. FUKUSHIMA, J. KODAMA AND H. FUCHIMOTO. Light-dark patterns in running-wheel activity in rats during chronic administration of theophylline. PHYSIOL. BEHAV. 19(3) 397-400, 1977. - Running-wheel activity for 24 hr and activity patterns were studied during chronic theophylline administration. Theophylline altered the normal relations between activity level and illumination. Dark-time activity was decreased to approximately 50% and 24 hr activity was unaffected. These observations were consistent with previous results showing that theophyiline suppressed dark-time feeding but had no effect on 24 hr food intake. A possible mechanism to account for these results may be dependent on levels and turnover of brain norepinephrine. Theophylline
Running-wheel activity
Light-dark activity patterns
MOST behavioral rhythms in rodents become entrained to periodic illumination changes. Illumination usuaLLy suppresses dark-time activity and ingestive behavior. Rats are nocturnal animals with more than approximately 90% of activity and 80% of ingestive behavior occurring during the dark of a 12:12 light-dark cycle. Alteration of the external or internal physiological environment, such as bilateral lesion~ of the lateral hypothalamus [10], bilateral removal of the olfactory bulb [9] or the administration of d-amphetamine [7], disrupts the normal relations of illumination with activity and ingestion. Previous studies have demonstrated that chronic administration of theophylline induces circadian desynchronization of feeding leaving the total amount of food intake for 2 4 h r unaffected [14], although the tendency to kill a mouse through diurnal and nocturnal muricide tests [12,13] and ambulatory activity during the daytime [11,12] are not affected. However, there are no studies of the long-term effects of theophylline on circadian locomotor activity in rats. The present study describes long-term changes in running-wheel activity levels and patterns in rats after chronic administration of theophylline.
group-housed under ad lib food and water conditions. The experimental room was illuminated daily from 0900 to 2 1 0 0 h r (a 12:12 light-dark cycle) and maintained at a temperature of approximately 22 °C. Before access to the running-wheel all rats were handled for 5 rain daily for 2 successive days in an attempt to equate their arousal levels.
Apparatus and Procedure An activity wheel 32 cm in diameter adjoining a living cage of 25 x 12 x 1 2 c m was used in each of the experiments. Food and water were available ad lib in the living cage during the course of the experiments but could not be carried into the wheel. Animals were allowed free access to the wheel during the entire experimental period. A masking noise was provided by a 45 cm fan located 2 m from the wheels and prevented the rat in the apparatus from hearing the noise generated by the wheels in motion. Locomotor activity, expressed as n u m b e r of wheel revolutions for 12ohr periods, was recorded at 0900 and 2100 hr each day. Each activity apparatus was placed in the room containing the cages. To diminish interruption of activity cleaning cage pans and replenishment of food and water were made during the period of light of the light-dark cycle when the animals were inactive. As all rats adapted to locomotion in the wheel as an activity outlet within several days, the first 5 days of the experiment were allowed for adaptation and the second 5 days were used to assess baseline data measurement, i.e.,
METHOD
Animals Eighteen male adult rats of the Wistar King A strain, weighing 240 to 290 g at the start 'of the experiment, were
This work was supported in part by grants from the Japanese Ministry of Education and Yamanouchi Foundation for Research on Metabolic Disorders. 397
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Light-Dark Patterns in Running-Wheel Activity in Rats During Chronic Administration of Theophylline TOSHIIE SAKATA, MASATAKA FUKUSHIMA, JUNICHI KODAMA AND HIDEAKI FUCHIMOTO
The First Department o f Internal Medicine, Faculty o f Medicine, Kyushu University, Fukuoka, 812 Japan (Received 20 January 1977) SAKATA, T., M. FUKUSHIMA, J. KODAMA AND H. FUCHIMOTO. Light-dark patterns in running-wheel activity in rats during chronic administration of theophylline. PHYSIOL. BEHAV. 19(3) 397-400, 1977. - Running-wheel activity for 24 hr and activity patterns were studied during chronic theophylline administration. Theophylline altered the normal relations between activity level and illumination. Dark-time activity was decreased to approximately 50% and 24 hr activity was unaffected. These observations were consistent with previous results showing that theophyiline suppressed dark-time feeding but had no effect on 24 hr food intake. A possible mechanism to account for these results may be dependent on levels and turnover of brain norepinephrine. Theophylline
Running-wheel activity
Light-dark activity patterns
MOST behavioral rhythms in rodents become entrained to periodic illumination changes. Illumination usuaLLy suppresses dark-time activity and ingestive behavior. Rats are nocturnal animals with more than approximately 90% of activity and 80% of ingestive behavior occurring during the dark of a 12:12 light-dark cycle. Alteration of the external or internal physiological environment, such as bilateral lesion~ of the lateral hypothalamus [10], bilateral removal of the olfactory bulb [9] or the administration of d-amphetamine [7], disrupts the normal relations of illumination with activity and ingestion. Previous studies have demonstrated that chronic administration of theophylline induces circadian desynchronization of feeding leaving the total amount of food intake for 2 4 h r unaffected [14], although the tendency to kill a mouse through diurnal and nocturnal muricide tests [12,13] and ambulatory activity during the daytime [11,12] are not affected. However, there are no studies of the long-term effects of theophylline on circadian locomotor activity in rats. The present study describes long-term changes in running-wheel activity levels and patterns in rats after chronic administration of theophylline.
group-housed under ad lib food and water conditions. The experimental room was illuminated daily from 0900 to 2 1 0 0 h r (a 12:12 light-dark cycle) and maintained at a temperature of approximately 22 °C. Before access to the running-wheel all rats were handled for 5 rain daily for 2 successive days in an attempt to equate their arousal levels.
Apparatus and Procedure An activity wheel 32 cm in diameter adjoining a living cage of 25 x 12 x 1 2 c m was used in each of the experiments. Food and water were available ad lib in the living cage during the course of the experiments but could not be carried into the wheel. Animals were allowed free access to the wheel during the entire experimental period. A masking noise was provided by a 45 cm fan located 2 m from the wheels and prevented the rat in the apparatus from hearing the noise generated by the wheels in motion. Locomotor activity, expressed as n u m b e r of wheel revolutions for 12ohr periods, was recorded at 0900 and 2100 hr each day. Each activity apparatus was placed in the room containing the cages. To diminish interruption of activity cleaning cage pans and replenishment of food and water were made during the period of light of the light-dark cycle when the animals were inactive. As all rats adapted to locomotion in the wheel as an activity outlet within several days, the first 5 days of the experiment were allowed for adaptation and the second 5 days were used to assess baseline data measurement, i.e.,
METHOD
Animals Eighteen male adult rats of the Wistar King A strain, weighing 240 to 290 g at the start 'of the experiment, were
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