NEONATAL SCOPOLAMINE OR ANTIDEPRESSANT TREATMENT - EFFECT ON DEVELOPMENT OF HAMSTER CIRCADIAN-RHYTHMS

Chronic treatment of young rodents with drugs altering monoamine metab olism has been reported to produce lasting effects on behavior that re semble human affective disorders. To test the generality of this findi ng, scopolamine, imipramine, or clomipramine was injected daily betwee n the ages of 8 and 21 days in golden hamsters, Wheel-running rhythms were monitored continuously from the age of 4 to 20 weeks of age to te st the hypothesis that neonatal treatments would lower the amplitude o f biological activity rhythms in adults. Of these three neonatal treat ments only scopolamine altered running rhythms, significantly increasi ng the amplitude of running rhythms in adult hamsters under both entra ined and free-running conditions. Hamsters treated neonatally with sco polamine were also more sensitive to the hypothermic effects of the mu scarinic agonist, oxotremorine, as adults. These data indicate that ne onatal exposure to cholinergic receptor blockade may produce long-last ing changes in biological rhythm characteristics related to upregulati on of muscarinic receptors. (C) 1998 Elsevier Science Inc.