Neonatal treatment with 5-HT antiserum alters 5-HT metabolism and function in adult rats

Adult rats were studied for serotonin and its metabolite in basal ganglia, nociceptive responses to electric current and tremor induced by 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) to assess the effects of a single systemic injection of serotonin antiserum given at 1 day old. Antiserum-treated animals showed no overt behavioural abnormalities, but tremor induced by 5-MeODMT was augmented. Basal nociceptive thresholds for tail withdrawal and vocalization were unaffected, whereas vocalization after-discharge was significantly reduced. Significantly decreased serotonin levels and increased turnover were found in nucleus caudatus putamen, nucleus accumbens and tuberculum olfactorium of adult rats treated as neonates with serotonin antiserum. These results demonstrate long-lasting functional alterations and neurochemical suppression of the central serotoninergic system following neonatal administration of serotonin antiserum.