Section 9
Chapter 8,202

Attenuating effect of serotonin receptor antagonists on impairment of mealtime-associated activity rhythm in old rats

Shibata, S.; Ono, M.; Minamoto, Y.; Watanabe, S.

Pharmacology Biochemistry and Behavior 51(2-3): 541-544


ISSN/ISBN: 0091-3057
PMID: 7667383
DOI: 10.1016/0091-3057(95)90577-8
Accession: 008201604

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In the present study, we examined attenuating effect of serotonin (5-HT) receptor antagonists on the impairment of the time perception presented by daily scheduled feeding in old rats. When feeding was restricted to a single meal at a fixed time of day (1300-1700 h) for six consecutive days, young rats exhibited intense locomotor activity from 1-3 h before feeding time. Intense locomotor activity was observed between 1200 and 1700 h in young animals even on the fasting day (day 7) (mealtime-associated activity). However, this mealtime-associated activity was impaired in 24-mo-old rats. Daily injections of 5-HT-2 receptor antagonists, mianserin or ritanserin, or a 5-HT-3 receptor antagonist, Y25130, at 1700 h for 6 consecutive days significantly and dose-dependently attenuated the impairment of mealtime-associated activity on the fasting day in old rats without affecting the food intake. Our results suggest that the blockade of 5-HT-2 and/or 5-HT-3 receptors attenuates impairment of the manifestation of mealtime-associated anticipatory activity related to temporal learning in old rats.

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