Diurnal patterns in homecage behavior of rats after acute exposure to triethyltin

Abstract

Diurnal patterns of eating, drinking, locomotor activity, and rearing in male Fischer-344 rats were examined for 11 days after a single oral dose of triethyltin bromide (TET) at 0, 1.5, 3, or 5 mg/kg. The 5 mg/kg group exhibited a time-related drop in food consumption and body weight until 3 of 10 rats were sacrificed moribund 11 days after dosing. Doses of 1.5 and 3 mg/kg TET did not reduce body weight or consumption of food and water. In contrast, food consumption was significantly increased 7 and 11 days after 3 mg/kg TET, and diurnal patterns of eating and drinking were disrupted 7 days after 3 and 5 mg/kg TET. A phase shift in licking patterns was induced by the high dose. Unlike trimethyltin (TMT), TET did not affect efficiency of eating. Diurnal patterns of both horizontal and vertical activity were disrupted at all dose levels on Day 2 after dosing; by 16 days after dosing, recovery was evident in all rats including those surviving 5 mg/kg TET. These results show that (1) a near-lethal dose of TET produced a reversible syndrome of hypoactivity, aphagia, and weight loss similar to that seen after acute TMT; (2) in the absence of the above signs, diurnal patterns of behavior revealed effects of TET at doses as low as 1.5 mg/kg; (3) the magnitude of the effect depended on the time of day at which the response was measured; and (4) TET did not produce the same effects on ingestive behaviors (polydipsia and reduced feeding efficiency) that were previously observed after acute TMT.