Possible brainstem involvement in the modification of thermoregulatory processes by chlordecone in rats

The involvement of the central nervous system in the hypothermia induced by chlordecone was studied by evaluating the effects of infusions of chlordecone injected into the lateral and third ventricles and the cisterna magna on colonic temperature (Tcol). Compared to rats given vehicle, infusions of 40, 320 or 800 micrograms of chlordecone into the lateral ventricle or 320 or 800 micrograms of chlordecone into the third ventricle, through chronic indwelling cannulae, did not change significantly Tcol. However, intracisternal infusions of 80, 160, 320 or 800 micrograms of chlordecone produced significant hypothermia (maximally 2.2 degrees C) which persisted for as long as 6 hr. Intracisternal infusions of chlordecone also produced a rapid increase in the temperature of the tail skin (Tsk) which persisted throughout the period of hypothermia. This suggests that the hypothermia produced by central administration of chlordecone is related to peripheral vasodilation. Since chlordecone has been reported to induce release of NE in the brainstem, and NE is known to modulate tonic vasomotor control in the medulla, the effects of NE infused intracisternally were studied. Intracisternal infusions of NE (16 micrograms) significantly decreased Tcol and increased Tsk, supporting the hypothesis that hypothermia induced by chlordecone is associated with vasodilatory effects, mediated by an adrenergic mechanism in the brainstem.