5-hydroxytryptamine (5-HT) concentrations in the hippocampus, the hypothalamus and the medulla oblongata related to cisplatin-induced pica of rats.

We previously reported that the concentration of 5-hydroxytryptamine (5-HT) in the brainstem of cisplatin-administered ferrets is significantly increased as compared with that of control animals. In an attempt to clarify the mechanisms of emesis induced by cytotoxic drugs, we measured kaolin ingestion (pica) and the tissue concentrations of 5-HT, norepinephrine (NE) and dopamine in various brain regions of rats after cisplatin administration. 5-HT concentrations in the hippocampus, the medulla oblongata and the hypothalamus significantly increased 72 hours after a single dose administration of cisplatin (5 mg/kg, i.p.) compared with those of control rats. NE concentration in the hippocampus significantly increased simultaneously with kaolin ingestion in cisplatin-treated rats. These results suggest that higher brain regions such as the hippocampus and the hypothalamus are involved in cisplatin-induced emesis.