Influence of long-term zimelidine treatment on LSD-induced behavioural effects

The effect of lysergic acid diethylamide (LSD) on copulatory and exploratory behaviour in hormone-treated, ovariectomized rats was investigated 4 weeks after chronic treatment with either saline or zimelidine (ZIM). A decrease in sensitivity to the lordosis-inhibiting effect of LSD was observed in the group treated with ZIM. The two groups also differed in their reaction to LSD in the exploratory test. The ZIM-treated animals seemed to be less sensitive to LSD. We therefore suggest that long-term treatment with ZIM reduces the sensitivity of the postsynaptic serotonin receptor.