Changes of spontaneous motor activity of rats after acute exposure to tributyltin chloride

The effects of a single acute exposure to tributyltin chloride (TBTCl) on spontaneous motor activity (SMA) in home cage were studied in male Wistar rats. The rats were given TBTCl intraperitoneally at a dosage of 0, 1.6 or 3.3 mg/kg, and the SMA was measured for five days after administration of TBTCl. Body weight gain in the 3.3 mg/kg group was significantly lowered, but that in the 1.6 mg/kg group was comparable to that in the control group. The SMA during light phase was not affected by TBTCl treatment. However, the SMA during dark phase was decreased in both of the TBTCl-treated groups. These decreases in SMA gradually returned to the control levels. The 24-hr total daily and 12-hr nocturnal activity in the TBTCl-treated groups were decreased in a dose-dependent manner. These data indicate that TBTCl possesses behavioral toxicity and suggest that the decreased nocturnal SMA is a sensitive index for detecting toxicity of chemicals in rats.