The Effect of Oral Consumption of Perchlorate, Alone and in Combination with Ethanol, on Plasma Thyroid Hormone and Brain Catecholamine Concentrations in the Rat

Abstract

Literature has reported a controversy concerning the effects of the environmental pollutant perchlorate on pertinent physiological systems. However, no research to date has evaluated the effect of concomitant consumption of perchlorate and an additional environmental contaminant on physiological systems. The present preliminary investigation served to assess the effects of oral consumption of perchlorate, alone and in combination with ethanol, on thyroid hormone and brain catecholamine concentrations in female rats of gestational age. Forty, female Myers' high ethanolpreferring rats were randomly assigned to 1 of 7 groups that received: (1) deionized water, both bottles (2) deionized water and 10% ethanol (v/v), two separate bottles (3) 300 mg/l perchlorate solution in deionized water, both bottles (4) 300 mg/l perchlorate in deionized water and in 10% ethanol (v/v), two separate bottles (5) 3000 mg/l perchlorate solution in deionized water, both bottles (6) 3000 mg/l perchlorate in deionized water and in 10% ethanol (v/v), two separate bottles (7) 0.01% propylthiouracil solution in deionized water, both bottles. At cessation of the treatment period, plasma triiodothyronine (T3) and thyroxine (T4) levels were measured by radioimmunoassay and brain area concentrations of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC), and norepinephrine were measured by high performance liquid chromatography. Perchlorate consumption, alone and/or in combination with ethanol consumption, failed to produce significant alterations from control values for triiodothyronine, thyroxine, dopamine, DOPAC, or norepinephrine. The data suggest that the noobserved effect level of perchlorate consumption on thyroid hormone and brain catecholamine concentrations is above the 3000 mg/l concentration in the adult female rat.